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Showing 1 - 194 of 194 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 20)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 37)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 31)
Agregat     Open Access   (Followers: 1)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 33)
Architectural Engineering     Open Access   (Followers: 5)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 2)
Archives of Civil Engineering     Open Access   (Followers: 12)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 4)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 6)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 9)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 14)
Building & Management     Open Access   (Followers: 1)
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 14)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 11)
Case Studies in Structural Engineering     Open Access   (Followers: 9)
Cement and Concrete Composites     Hybrid Journal   (Followers: 19)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 3)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 6)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 8)
Civil And Environmental Engineering Reports     Open Access   (Followers: 7)
Civil and Environmental Research     Open Access   (Followers: 17)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 21)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 11)
Civil Engineering Dimension     Open Access   (Followers: 10)
Civil Engineering Infrastructures Journal     Open Access   (Followers: 1)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 272)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
Computers & Structures     Hybrid Journal   (Followers: 38)
Concrete Research Letters     Open Access   (Followers: 7)
Construction Economics and Building     Open Access   (Followers: 4)
Construction Engineering     Open Access   (Followers: 11)
Construction Management and Economics     Hybrid Journal   (Followers: 21)
Construction Science     Open Access   (Followers: 5)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 3)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 17)
Enfoque UTE     Open Access   (Followers: 4)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 7)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 10)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 9)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 17)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 3)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 3)
Géotechnique Letters     Hybrid Journal   (Followers: 7)
GISAP : Technical Sciences, Construction and Architecture     Open Access  
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indonesian Journal of Urban and Environmental Technology     Open Access  
Indoor and Built Environment     Hybrid Journal   (Followers: 2)
Infrastructure Asset Management     Hybrid Journal   (Followers: 2)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 29)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 3)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 17)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 15)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 10)
International Journal of Geo-Engineering     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Masonry Research and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Pavement Research and Technology     Open Access   (Followers: 6)
International Journal of Protective Structures     Hybrid Journal   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 8)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Built Environment     Open Access   (Followers: 5)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 8)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 7)
International Journal Sustainable Construction & Design     Open Access   (Followers: 1)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 14)
Journal of Building Engineering     Hybrid Journal   (Followers: 1)
Journal of Building Materials and Structures     Open Access   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 14)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 9)
Journal of Civil Engineering Research     Open Access   (Followers: 7)
Journal of Civil Engineering, Science and Technology     Open Access   (Followers: 1)
Journal of Civil Society     Hybrid Journal   (Followers: 4)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites     Open Access   (Followers: 80)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 23)
Journal of Construction Engineering     Open Access   (Followers: 8)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 18)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 6)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 4)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 6)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 2)
Journal of Green Building     Full-text available via subscription   (Followers: 10)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 14)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 19)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials and Engineering Structures     Open Access   (Followers: 5)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 7)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 9)
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 3)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 6)
Journal of Rehabilitation in Civil Engineering     Open Access   (Followers: 3)
Journal of Solid Waste Technology and Management     Full-text available via subscription   (Followers: 1)
Journal of Structural Engineering     Full-text available via subscription   (Followers: 36)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 3)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the Civil Engineering Forum     Open Access  
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 2)
Journal of Water and Environmental Nanotechnology     Open Access  
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil dan Perencanaan     Open Access   (Followers: 1)
Konstruksia     Open Access  
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 2)
Latin American Journal of Solids and Structures     Open Access   (Followers: 4)
Materiales de Construcción     Open Access   (Followers: 1)
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 4)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 15)
npj Materials Degradation     Open Access  
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 9)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 3)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 13)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 9)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 2)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 3)
Promet : Traffic &Transportation     Open Access  
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 6)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 11)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 5)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 5)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 4)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 8)
Structural Engineering International     Full-text available via subscription   (Followers: 11)
Structural Mechanics of Engineering Constructions and Buildings     Open Access   (Followers: 1)
Structural Safety     Hybrid Journal   (Followers: 6)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 24)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 12)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 10)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access   (Followers: 1)
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 6)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 5)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 2)
Thin-Walled Structures     Hybrid Journal   (Followers: 4)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Underground Space     Open Access  
Water Science & Technology     Partially Free   (Followers: 25)
Water Science and Technology : Water Supply     Partially Free   (Followers: 22)


Journal Cover Cement and Concrete Composites
  [SJR: 3.017]   [H-I: 83]   [19 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0958-9465
   Published by Elsevier Homepage  [3175 journals]
  • A self-reinforced cementitious composite for building-scale 3D printing
    • Authors: Daniel G. Soltan; Victor C. Li
      Pages: 1 - 13
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Daniel G. Soltan, Victor C. Li
      A design scheme for self-reinforced cementitious composites to be used for building-scale 3D printing processes is introduced. The design is based on that of engineered cementitious composites, which include dispersed short polymer fibers to generate robust tensile strain-hardening. The mechanical property profile of these printable ECC materials is meant to eliminate the need for steel reinforcement in printed structures, providing more freedom and efficiency for building-scale 3D printing processes. The fresh state rheological properties have been systematically manipulated to allow printability. Effects on fresh state workability of several compositional ingredients and processing parameters are investigated herein. To maintain consistent printing performance with a batch mixing approach, thixotropy in the fresh state is exploited to temporarily decouple hardening behavior from the processing timeline. Minimal workability loss under continued shear agitation is achieved. Mechanical properties of the printable materials are characterized and the printability of the materials is demonstrated.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.017
      Issue No: Vol. 90 (2018)
  • Reducing setting time of blended cement paste containing high-SO3 fly ash
           (HSFA) using chemical/physical accelerators and by fly ash pre-washing
    • Authors: Franco Zunino; Dale P. Bentz; Javier Castro
      Pages: 14 - 26
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Franco Zunino, Dale P. Bentz, Javier Castro
      Reducing the carbon footprint of the cement industry has become one of the main concerns of researchers in the field. This study explores different strategies to reduce the setting retardation effect of high-SO3 fly ash (HSFA) on cement paste. The SO3 phase was found to correspond to hannebachite (CaSO3·0.5H2O). Chemical (calcium chloride), physical (fine limestone powder), and pre-washing strategies were investigated as means to reduce or eliminate the retardation. Each of these strategies showed some potential to decrease the retardation effect. A combination of fine limestone powder and HSFA pre-washing showed almost the same accelerating power as the calcium chloride, offering a good alternative when chloride incorporation is restricted. The retardation effect can be associated with a combined extension of the induction period and a depression of the initial silicate reactions of the clinker phases. A methodology to assess the hannebachite content based on a thermogravimetric analysis (TGA) technique is proposed, allowing a good alternative control approach for field conditions or for where X-ray (XRD or XRF) equipment is not readily available.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.018
      Issue No: Vol. 90 (2018)
  • Effects of deicers on the performance of concrete pavements containing
           air-cooled blast furnace slag and supplementary cementitious materials
    • Authors: Kho Pin Verian; Ali Behnood
      Pages: 27 - 41
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Kho Pin Verian, Ali Behnood
      This study investigates the effects of continuous deicer exposure on the performance of pavement concretes. For this purpose, the differences in the compressive strength, the changes in the dynamic modulus of elasticity (DME) and the depth of chloride ingress were evaluated during and after the exposure period. Eight different concrete mixtures containing two types of coarse aggregates (i.e. air-cooled blast furnace slag (ACBFS) and natural dolomite) and four types of binder systems (i.e. plain Type I ordinary portland cement (OPC) and three combinations of OPC with fly ash (FA) and/or slag cement (SC)) were examined. These mixtures were exposed to three types of deicers (i.e. MgCl2, CaCl2, and NaCl) combined with two different exposure conditions (i.e. freezing-thawing (FT) and wetting-drying (WD)). In cold climates, these exposure conditions are the primary durability challenges that promote the physical deterioration of concrete pavements. The results indicated that among the studied deicers, CaCl2 had the most destructive effect on the tested concretes while NaCl was found to promote the deepest level of chloride ingress yet was shown to have the least damaging impact on concretes. The microstructure evaluation revealed that the mechanism of concrete deterioration due to the deicer exposure involved chemical reactions between the deicers and concrete hydration products. The use of FA or SC as partial replacements for OPC can offset the detrimental effects of both deicers and FT/WD cycles.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.009
      Issue No: Vol. 90 (2018)
  • Superior photocatalytic NOx removal of cementitious materials prepared
           with white cement over ordinary Portland cement and the underlying
    • Authors: Ming-Zhi Guo; Chi Sun Poon
      Pages: 42 - 49
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Ming-Zhi Guo, Chi Sun Poon
      This study presents experimental results in an attempt to explain why photocatalytic cementitious materials prepared with white cement (WC) had superior photocatalytic NOx removal performance than those prepared with ordinary Portland cement (OPC). The UV–Vis diffuse reflectance spectra (DRS) of dry WC and OPC demonstrated that OPC had a stronger light absorption ability. And electrochemical impedance spectroscopy (EIS) analysis revealed that OPC incurred higher charge transfer resistance on the inter-surface of OPC and TiO2. Moreover, the OPC/P25 dry mixtures displayed a relatively lower photoluminescence (PL) intensity at 420 nm. The addition of iron oxide (Fe2O3) in WC caused a decrease in NOx removal, a boost in light absorption, an increase in the resistance of charge transfer, and a reduction in PL intensity. Collectively, the relatively poor performance of OPC/P25 mixtures in photocatalytic NOx removal is due to a combination of stronger light absorption and lower charge separation caused by OPC.
      Graphical abstract image

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.020
      Issue No: Vol. 90 (2018)
  • In-situ micro-CT characterization of mechanical properties and failure
           mechanism of cementitious syntactic foams
    • Authors: Halim Kerim Bas; Weihua Jin; Nikhil Gupta; Rakesh Kumar Behera
      Pages: 50 - 60
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Halim Kerim Bas, Weihua Jin, Nikhil Gupta, Rakesh Kumar Behera
      The advancements in structural materials are guided by the desire of lowering the density and increasing the strength. Composite materials show promise in tuning the density and strength to meet specific design requirements. Lightweight cementitious materials, such as foamed concretes, are generally known to show poor mechanical properties (e.g., compressive strength and elastic modulus). The lack of control over the size, shape, and distribution of air voids severely limits the improvement of mechanical properties in lightweight cementitious materials. This work is focused on manufacturing and examining the mechanical properties of cementitious syntactic foams with hollow glass microspheres. Use of hollow particles to incorporate porosity allows for the control over the size, shape, and volume fraction of voids present in the composite. Hollow glass microspheres with several different densities (0.15–0.60 g/cm3) are used in different volume fractions (20%–50%) to manufacture the cementitious syntactic foams. The results show that cementitious syntactic foams (CSF) have compressive strengths (32–88 MPa) and elastic moduli (10–20 GPa) for a given range of low density (1.15–1.80 g/cm3), which are better than other cellular cementitious materials in the same density range. In-situ micro-CT scan results reveal that the micro-fracture mechanisms in CSFs under compressive loading depend on the microsphere density and aging of the material.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.007
      Issue No: Vol. 90 (2018)
  • Stochastic multiscale modeling and simulation framework for concrete
    • Authors: David Tal; Jacob Fish
      Pages: 61 - 81
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): David Tal, Jacob Fish
      In this paper we present a computational framework for generating a realistic representative volume element of concrete, which reflects its inherent structural randomness. Computed tomography (CT) images are employed to provide the necessary information for the geometric statistical characterization of aggregate and defect (voids, pores, and micro-cracks) distributions. A Monte-Carlo simulation is used to generate 1000 realizations of statistically equivalent representative volume element (SERVE) and finite element predictions of SERVEs elastic and inelastic response are compared with experiments.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.016
      Issue No: Vol. 90 (2018)
  • Mathematical modeling for quantitative estimation of geometric effects of
           nearby rebar in electrical resistivity measurement
    • Authors: Young-Chul Lim; Takafumi Noguchi; Chang-Geun Cho
      Pages: 82 - 88
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Young-Chul Lim, Takafumi Noguchi, Chang-Geun Cho
      Concrete resistivity in reinforced concrete structures is used as an indicator of durability related to the corrosion risk. This study aims to develop a quantitative analysis method of geometric effects of nearby reinforcement in the electrical resistivity measurement. The A-REM proposed in this study is a mathematical model to enable analysis of not only concrete (or mortar) and reinforcement resistivity, but also of geometric effects such as rebar diameter, cover depth, electrode interval, and the spatial relationship between the rebar and electrodes. The effect of nearby reinforcement on the electrical resistivity measurement was presented to be obtained from the apparent resistivity rate (AR rate) calculated by the A-REM. The A-REM for the estimation of the nearby reinforcement effects was verified by comparing the apparent resistivity values obtained from mortar specimens having different reinforcement diameters and cover depths. The result shows that the calculated values of the A-REM are correlated with the experimental values of apparent resistivity.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.013
      Issue No: Vol. 90 (2018)
  • Monitoring invisible corrosion in concrete using a combination of wave
           propagation techniques
    • Authors: Ashutosh Sharma; Shruti Sharma; Sandeep Sharma; Abhijit Mukherjee
      Pages: 89 - 99
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Ashutosh Sharma, Shruti Sharma, Sandeep Sharma, Abhijit Mukherjee
      The paper reports two non-destructive techniques based on wave propagation for monitoring onset of corrosion in concrete before it is visible. Reinforced concrete beam specimens were subjected to anodic corrosion at a constant voltage. The specimens were instrumented with surface mounted Acoustic Emission (AE) sensors to record acoustic events inside the specimens due to corrosion. They were also monitored using the Ultrasonic Guided Waves (UGW) technique by passing an ultrasonic pulse through the bar. The results are correlated with well-established electrochemical techniques. From simultaneous monitoring of corrosion using the three technologies pros and cons of each technology have been determined. It can be concluded that a judicious combination of electrochemical and wave technologies can reveal the state of corrosion from its early stages.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.014
      Issue No: Vol. 90 (2018)
  • Ternary binder made of CFBC fly ash, conventional fly ash, and calcium
           hydroxide: Phase and strength evolution
    • Authors: Petr Hlaváček; Rostislav Šulc; Vít Šmilauer; Christiane Rößler; Roman Snop
      Pages: 100 - 107
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Petr Hlaváček, Rostislav Šulc, Vít Šmilauer, Christiane Rößler, Roman Snop
      Coal combustion products present a source of aluminosilicate materials for further utilization. The ternary binder studied here is such an example, consisting of circulating fluidized bed combustion (CFBC) fly ash, conventional fly ash and Ca(OH)2 activator. The paste yields a compressive strength of 32 MPa after 28 days of standard sealed curing. Volumetric evolution of crystalline and amorphous phases during hydration is quantified using XRD analysis, differential thermal gravimetry, porosimetry and electron microscopy. A micromechanical model is applied to interpret the evolution of compressive strength due to the growing proportions of C-S-H and ettringite in the system. This opens the way for further optimization and utilization of this ternary binder.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2017.09.020
      Issue No: Vol. 90 (2018)
  • A comprehensive study on thermal conductivities of wavy carbon
           nanotube-reinforced cementitious nanocomposites
    • Authors: M.K. Hassanzadeh-Aghdam; R. Ansari; M.J. Mahmoodi; A. Darvizeh; A. Hajati-Modaraei
      Pages: 108 - 118
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): M.K. Hassanzadeh-Aghdam, R. Ansari, M.J. Mahmoodi, A. Darvizeh, A. Hajati-Modaraei
      The thermal conductivities of cementitious nanocomposites reinforced by wavy carbon nanotubes (CNTs) are determined by the effective medium (EM) micromechanics-based method. The nanocomposite is composed of sinusoidally wavy CNTs as reinforcement and cement paste as matrix. The interfacial region between the CNTs and cementitious material is considered in the analysis. The effects of volume fraction and waviness parameters of CNTs, interfacial thermal resistance, type of CNTs placement within the matrix including aligned or randomly oriented CNTs, cement paste properties on the thermal conductivity coefficients of the nanocomposite are studied. The estimated values of the model are in very good agreement with available experimental data. Two parameters of CNT waviness and interfacial region contributions should be included in the modeling to predict realistic results for both aligned and randomly oriented CNT-reinforced nanocomposites. The results reveal that thermal conductivities K 22 (transverse in-plane thermal conductivity) and K 33 (longitudinal in-plane thermal conductivity) of the nanocomposites are remarkably dependent on the CNT waviness. Also, it is found that the CNT waviness moderately affects the thermal conductivity of a cementitious nanocomposite containing randomly oriented CNTs. However, the non-straight shape of CNTs does not influence the value of thermal conductivity K 11 (transverse out of plane thermal conductivity). The achieved results can be useful to guide the design of cementitious nanocomposites with optimal thermal conductivity properties.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2017.09.021
      Issue No: Vol. 90 (2018)
  • Probabilistic numerical model of cracking in ultra-high performance fibre
           reinforced concrete (UHPFRC) beams subjected to shear loading
    • Authors: Pierre Rossi; Dominic Daviau-Desnoyers; Jean-Louis Tailhan
      Pages: 119 - 125
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Pierre Rossi, Dominic Daviau-Desnoyers, Jean-Louis Tailhan
      The objective of this paper is to verify the validity of the probabilistic explicit cracking model developed for SFRC to simulate the behaviour of a reinforced UHPFRC beam subjected to a bending load leading to shear failure. The relevancy of the model is evaluated through the simulation of the mechanical behaviour of the beam. The parameters characterizing the tensile behaviour of the studied UHPFRC are determined from the 3-point bending tests performed on beams sawed from the reinforced UHPFRC beam. The results suggest that the probabilistic explicit cracking model is relevant to analyze the mechanical behaviour of a reinforced UHPFRC beam and provide precise information about the cracking process of this type of material. The good agreement between the experimental result and the numerical simulations suggests that the studied UHPFRC behaves like usual FRC as the tensile strength and the mechanical effect of the fibres may be modelled by a perfectly brittle behaviour and a nonlinear softening behaviour.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.019
      Issue No: Vol. 90 (2018)
  • Measuring adhesion between steel and early-hydrated Portland cement using
           particle probe scanning force microscopy
    • Authors: Yujie Li; Jie Yang; Ting Tan
      Pages: 126 - 135
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Yujie Li, Jie Yang, Ting Tan
      Particle probe scanning force microscopy was used to measure adhesion between steel and early-hydrated cement in the study. Particle probes, created by attaching steel microspheres to microcantilevers, were successfully used to collect adhesive forces between steel and early-hydrated Portland cement in air and in saturated lime water. Mixed Gaussian models were applied to predict phase distributions in the cement paste, i.e., low density calcium silicate hydrate, high density calcium silicate hydrate, calcium hydroxide, other hydrated products and the unreacted components. Consistent correlations were achieved for volume fractions between areas with different adhesion measurements and predictions from the hydration model. Results showed that low density calcium silicate hydrate, high density calcium silicate hydrate and other hydrated products exhibit intermediate adhesion to steel microspheres. Calcium hydroxide exhibits the smallest adhesion, while the unreacted components exhibits the largest adhesion among all groups.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.025
      Issue No: Vol. 90 (2018)
  • Effects of light crude oil contamination on the physical and mechanical
           properties of geopolymer cement mortar
    • Authors: Rajab Abousnina; Allan Manalo; Weena Lokuge; Zuhua Zhang
      Pages: 136 - 149
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Rajab Abousnina, Allan Manalo, Weena Lokuge, Zuhua Zhang
      Fly ash and oil contaminated sand are considered as the two waste materials that may affect environment. This paper investigated the suitability of producing geopolymer cement mortar using oil contaminated sand. A comparison between physical and mechanical properties of mortar produced using geopolymer and Ordinary Portland Cement (OPC), in terms of porosity, hydration and compressive strength, was conducted. The results showed that heat curing can increase the compressive strength of geopolymer mortar up to 54% compared to ambient curing situation. The geopolymer mortar with 1% of light crude oil contamination yielded a 20% higher compressive strength than OPC mortar containing sand with a saturated surface dry condition. Furthermore, the formation of efflorescence decreased as the level of oil contamination decreased. Moreover, the heat curing method increased the kinetic energy and degree of reaction for geopolymer cement mortar, which cause an increment of the density of the pore system and improving the mechanical properties of the resulting composites. From the results of this study, it was demonstrated that geopolymer mortar has the potential of utilizing oil contaminated sand, and reducing its environmental impacts.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.001
      Issue No: Vol. 90 (2018)
  • High performance cementitious composite from alkali-activated ladle slag
           reinforced with polypropylene fibers
    • Authors: Hoang Nguyen; Valter Carvelli; Elijah Adesanya; Paivo Kinnunen; Mirja Illikainen
      Pages: 150 - 160
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Hoang Nguyen, Valter Carvelli, Elijah Adesanya, Paivo Kinnunen, Mirja Illikainen
      Alkali-activated ladle slag (AALS) is a promising cementitious material with environmental benefits. However, the brittleness of material has been limiting the use in construction. Therefore, in this experimental investigation, different polypropylene (PP) fibers were employed as a short randomly reinforcement in cementitious matrix in order to improve mechanical performance of the AALS composites. The study reveals that the AALS composite could gain very high ductility with an appropriate fibrous reinforcement. Fracture energy and fracture toughness of PP fiber reinforced AALS mortars increased by approximately 150 and 7.6 times, respectively, compared to the unreinforced material. Additionally, the flexural strength of the composite increased by roughly 300%. Pseudo strain hardening (PSH) behavior was observed along with multiple cracks under uniaxial tensile test. Scanning electron microscope (SEM) images confirmed the local fiber bridging effect, which resulted in the high mechanical performance of the PP-reinforced AALS.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.024
      Issue No: Vol. 90 (2018)
  • Properties of fly ash blended magnesium potassium phosphate mortars:
           Effect of the ratio between fly ash and magnesia
    • Authors: Biwan Xu; Barbara Lothenbach; Hongyan Ma
      Pages: 169 - 177
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Biwan Xu, Barbara Lothenbach, Hongyan Ma
      The ratio between fly ash (FA) and magnesia is an important factor for the optimum design of FA blended magnesium potassium phosphate cements (MKPCs). In this study, a high CaO content FA (CaO = 12.5 wt%) was used to partially replace magnesia at 0 wt%, 30 wt%, 50 wt%, 70 wt%, and 90 wt%, respectively. The experimental results showed that a FA replacement of 50 wt% led to the highest compressive strengths. A FA replacement of 70 wt% is considered as upper limit, as the presence of more FA caused significantly lower strength. In the plain and the FA blended MKPCs, K-struvite (MgKPO4⋅6H2O) was the main hydrate. At very high FA contents, additional calcium potassium hydrogen phosphate (CaK3H(PO4)2) was observed as well as the destabilization of K-struvite to cattiite (Mg3(PO4)2⋅22H2O), which could be one of the main factors responsible for the lower strength of high FA blended MKPC mortars stored under water.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.002
      Issue No: Vol. 90 (2018)
  • Impact of microstructure on the performance of composite cements: Why
           higher total porosity can result in higher strength
    • Authors: Maciej Zajac; Jan Skocek; Samuel Adu-Amankwah; Leon Black; Mohsen Ben Haha
      Pages: 178 - 192
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Maciej Zajac, Jan Skocek, Samuel Adu-Amankwah, Leon Black, Mohsen Ben Haha
      This paper describes the underlying principles behind the evolution in performance of ternary composite cements comprising Portland cement clinker, slag and limestone. By using the predicted phase assemblage as an input for the micromechanical model, the mechanisms underlying the evolution of mortar strength and Young's modulus were analyzed and quantified. This allowed the roles of hydrate assemblages and porosity distribution on the evolution of performance to be explained and quantified. Slag hydration results in the formation of a microstructure more efficient for development of compressive strength and elastic stiffness. Limestone further improves microstructure and enhances reactivity of the systems studied.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.023
      Issue No: Vol. 90 (2018)
  • How do fiber shape and matrix composition affect fiber pullout behavior
           and flexural properties of UHPC'
    • Authors: Zemei Wu; Kamal Henri Khayat; Caijun Shi
      Pages: 193 - 201
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Zemei Wu, Kamal Henri Khayat, Caijun Shi
      The use of steel fiber is essential to secure high strength and ductility in producing ultra-high performance concrete (UHPC). In this study, the interfacial bond properties between embedded steel fibers with different shapes (straight, hooked, and corrugated fibers) and UHPC matrices proportioned with either 15% or 20% silica fume, by mass of binder, under different curing times were investigated. Flexural properties of UHPC reinforced with 2% different shaped fibers were also evaluated. Test results showed that corrugated and hooked fibers significantly improved the bond properties by three to seven times when compared to those with straight fibers. The flexural strength of UHPC with corrugated and hooked fibers were enhanced by 8%–28% and 17%–50%, respectively. Microstructural results from MIP, BSEM, and TG confirmed the change in bond properties. The bond strength of straight fibers exponentially increased with the decrease of calcium hydroxide content. Based on the composite theory, the flexural strengths of UHPC made with different shaped fibers can be efficiently predicted using the fiber-matrix bond strength, the flexural strength of the UHPC matrix (non-fibrous matrix), and the parameters of fibers. The ratios of predicted to measured flexural strengths ranged between 0.8 and 1.1, in which straight fibers showed a larger discreteness due to higher sensitivity of flexural strength associated with the orientation of fibers.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.021
      Issue No: Vol. 90 (2018)
  • Effect of inorganic surface treatment on surface hardness and carbonation
           of cement-based materials
    • Authors: Xiaoying Pan; Caijun Shi; Jiake Zhang; Lufeng Jia; Linlin Chong
      Pages: 218 - 224
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Xiaoying Pan, Caijun Shi, Jiake Zhang, Lufeng Jia, Linlin Chong
      Surface treatment is a simple way to improve quality of surface of cement-based materials and thus increase the resistance of cement-based materials to environmental aggressions. Magnesium fluorosilicate, waterglass, sodium fluorosilicate, and combination of waterglass and sodium fluorosilicate were used as surface treatment agents. Their effects on compressive strength, surface hardness and resistance to carbonation were studied. The experimental results indicated that magnesium fluorosilicate and waterglass decreased the carbonation depth and increased surface hardness of concrete, while their effects were limited on compressive strength. A greater reduction in carbonation was found when sodium fluorosilicate pretreatment was used, because it could not only accelerate the hardness of waterglass but also react with cement. A liner relationship between Autoclam air permeability index and carbonation depth was found in all the treated concrete. Meanwhile, effects of treatments on morphology and microstructure were investigated by scanning electron microscope (SEM). Pore-blocking effects of inorganic surface treatment agents and new reaction products were observed.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.026
      Issue No: Vol. 90 (2018)
  • Strain sensing ability of metallic particulate reinforced cementitious
    • Authors: Pu Yang; Swaptik Chowdhury; Narayanan Neithalath
      Pages: 225 - 234
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): Pu Yang, Swaptik Chowdhury, Narayanan Neithalath
      This paper evaluates the capability of waste iron powder-reinforced cementitious matrices as self-sensing materials in lieu of more expensive carbon fiber and nanoparticle reinforced matrices. Electrical impedance spectroscopy coupled with equivalent circuit modeling is used to determine the bulk resistance of the composite beams containing up to 40% by volume of iron particulates under flexural loading. The fractional change in resistance and the gage factor, as functions of the applied stress, increases with increasing iron particulate content, demonstrating the ability of these composites in self-sensing. A microstructure-guided electro-mechanical finite element model is used to simulate the strain sensing response of these composites. The 2D microstructure is subjected to different applied tensile stresses, and the deformed geometry subjected to an electrical potential to simulate the change in resistance. Debonding at the inclusion-paste interface under load, which is found to significantly influence the fractional change in resistance, is accounted for by using a bilinear softening model. The model is found to correlate well with the experimental data, and has the potential to facilitate microstructural design of materials to achieve desired degrees of self-sensing.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.004
      Issue No: Vol. 90 (2018)
  • Investigation on early hydration features of magnesium potassium phosphate
           cementitious material with the electrodeless resistivity method
    • Authors: Shuxian Hong; Jianchao Zhang; Hui Liang; Jindong Xiao; Chuangyi Huang; Guangde Wang; Heng Hu; Yuqing Liu; Ying Xu; Feng Xing; Biqin Dong
      Pages: 235 - 240
      Abstract: Publication date: Available online 11 April 2018
      Source:Cement and Concrete Composites
      Author(s): Shuxian Hong, Jianchao Zhang, Hui Liang, Jindong Xiao, Chuangyi Huang, Guangde Wang, Heng Hu, Yuqing Liu, Ying Xu, Feng Xing, Biqin Dong
      An electrodeless resistivity method is applied to trace the early hydration behavior of magnesium potassium phosphate cement (MKPC). The relationship between setting times (including initial and final setting time) and the characteristic points of the electrodeless resistance is studied, aiming to establish a rapid testing method which could predict the setting time of MKPC. Moreover, a linear relationship between the standard compressive strength at 28 days and the resistivity at 24 h of MKPC is also established, and demonstrates that the resistivity and the standard compressive strength have a compact corresponding relationship. Therefore, the standard compressive strength of magnesium potassium phosphate cement could be predicted by electrodeless resistivity parameters.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.005
      Issue No: Vol. 90 (2018)
  • Micromechanical properties of alkali-activated slag cement binders
    • Authors: R.J. Thomas; Berhan Seium Gebregziabiher; Adom Giffin; Sulapha Peethamparan
      Pages: 241 - 256
      Abstract: Publication date: Available online 12 April 2018
      Source:Cement and Concrete Composites
      Author(s): R.J. Thomas, Berhan Seium Gebregziabiher, Adom Giffin, Sulapha Peethamparan
      An experimental investigation into the micromechanical properties of alkali-activated slag cement (AASC) binders was carried out using targeted and grid nanoindentation. The results of grid indentation techniques were deconvolved using Gaussian mixture modeling with Bayesian model selection to determine the appropriate number of component phases for the model. The information given by the resulting mixture models and from targeted indentation experiments was disseminated in the context of existing information about the composition and development of the microstructure in AASC binders. The microstructure of sodium silicate-activated slag cement contains only two components (ground mass gel and unreacted slag cement) upon microscopic examination, but indentation data suggest that it is much more complex and varied. The microstructure of sodium hydroxide-activated slag cement contains ground mass gel, unreacted slag cement, and an inner product ring surround the unreacted slag. The inner product is denser, harder, and stiffer than the surrounding product phases. The micromechanical properties in sodium hydroxide-activated slag cement are not affected by activator molarity; the macroscale strength is similarly unaffected. Conversely, the micromechanical properties of sodium silicate-activated slag show a slight improvement with increased silica modulus, while the macroscale strength shows a significant improvement. The macroscale improvement is likely due to the increased size of unreacted slag cement grains, which are shown to be very hard and stiff.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.003
      Issue No: Vol. 90 (2018)
  • Area of lineal-path function for describing the pore microstructures of
           cement paste and their relations to the mechanical properties simulated
           from μ-CT microstructures
    • Authors: Tong-Seok Han; Xiaoxuan Zhang; Ji-Su Kim; Sang-Yeop Chung; Jae-Hong Lim; Christian Linder
      Pages: 1 - 17
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Tong-Seok Han, Xiaoxuan Zhang, Ji-Su Kim, Sang-Yeop Chung, Jae-Hong Lim, Christian Linder
      The pore distribution of a cement paste strongly affects its mechanical behavior such as its stiffness and strength. Porosity is an influential parameter that can be used to identify the complex pore microstructures of cement paste, but it has limitations as a scalar parameter. In this study, the lineal-path function, a low-order probability function, is investigated as a supplement or an alternative parameter for describing the microstructural characteristics of cement paste microstructures. In particular, the area of the lineal-path function is used as a measure of the pore microstructural characteristics, which can be linked with its properties. A relatively new method for simulating crack propagation, the crack phase field model, is used to evaluate the stiffness and tensile strength of cement paste microstructures and the evaluated properties are linked to the proposed characterization parameters. The evaluation is performed on virtual specimens obtained from micro-level computerized tomography (μ-CT) images of real cement paste specimens. The validity of the microstructure-property relations obtained from the proposed characterization parameters and the crack phase field model are confirmed through the statistical analysis of dozens of specimens. It is concluded that the correlation between the area of the lineal-path function and the mechanical properties is very strong. The parameter could potentially be used as a supplementary or an alternative parameter to describe the pore microstructures of cement paste.

      PubDate: 2018-02-26T02:40:07Z
      DOI: 10.1016/j.cemconcomp.2018.02.008
      Issue No: Vol. 89 (2018)
  • Bar-concrete bond in mixes containing calcium carbide residue, fly ash and
           recycled concrete aggregate
    • Authors: Charin Namarak; Weerachart Tangchirapat; Chai Jaturapitakkul
      Pages: 31 - 40
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Charin Namarak, Weerachart Tangchirapat, Chai Jaturapitakkul
      A mixture of calcium carbide residue and fly ash (CRFA) is an innovative new binder for concrete instead of using ordinary Portland cement (OPC). Therefore, this study aims at investigating the bond interaction between common steel reinforcing bars and the aforementioned concrete. To this end, both CRFA and OPC concretes using crushed limestone and recycled concrete aggregate (RCA) as a coarse aggregate were prepared to investigate the bond strength of smooth and deformed bars by pull-out tests. The bond stress−slip relationships were also identified to determine the effects of CRFA binder and RCA on the bond strength behavior. The results indicate that the values the of bond-slip behavior and bond strengths of steel bar in CRFA concretes are similar to those embedded in OPC concrete. Moreover, the bond strength was significantly affected by RCA and the types of steel bar. Although the concretes had the same compressive strengths, the deformed bar embedded in CRFA concrete with RCA had a lower bond strength than the one with crushed limestone. However, the reduction in bond strength of the CRFA concrete with RCA was still less than that of OPC concrete with RCA. For the CRFA concretes, the bond strengths of the deformed bars were approximately 1.7–3.6 times higher than that of smooth bars.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.017
      Issue No: Vol. 89 (2018)
  • Fiber-reinforced reactive magnesia-based tensile strain-hardening
    • Authors: Shaoqin Ruan; Jishen Qiu; En-Hua Yang; Cise Unluer
      Pages: 52 - 61
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Shaoqin Ruan, Jishen Qiu, En-Hua Yang, Cise Unluer
      This study focuses on the development of a new strain-hardening composite (SHC) involving carbonated reactive MgO cement (RMC) and fly ash (FA) as the main binder. Rheological properties of the developed composites were investigated by varying FA and water contents to achieve desirable fiber dispersion. A suitable mix design, in which polyvinyl alcohol (PVA) fibers were introduced to provide tensile ductility, was determined. The effect of key parameters such as w/b ratio and curing age on the mechanical properties of carbonated RMC-SHC was evaluated. Adequate binder content and w/b ratio was necessary for desirable fiber dispersion. Lower water contents and longer curing ages contributed to the strength development of RMC-SHC by improving the fiber-matrix interface bond and enhancing the formation of a dense carbonate network.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.002
      Issue No: Vol. 89 (2018)
  • Fire resistance of ultra-high performance strain hardening cementitious
           composite: Residual mechanical properties and spalling resistance
    • Authors: Jin-Cheng Liu; Kang Hai Tan
      Pages: 62 - 75
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Jin-Cheng Liu, Kang Hai Tan
      Ultra high performance strain hardening cementitious composites (UHP-SHCC) is a special type of cement-based composite material with outstanding mechanical and protective performance at room temperature. But its fire performance is unknown and there is a lack of research in this aspect. This study presents an experimental program to study fire resistance of UHP-SHCC under two aspects, viz. high-temperature explosive spalling resistance and residual mechanical performance after a fire. Both compressive strength and tensile strength of UHP-SHCC were found to deteriorate with increasing exposure temperature. Tensile strain-hardening feature of UHP-SHCC would be lost at 200 °C and above. It was found that PE fibers are found not effective in mitigating explosive spalling, although they start to melt at 144 °C. FE-SEM (Field Emission Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray) techniques were used to study the state of fiber, fiber/matrix interaction, and microcracks development. Microscopic study found that melted PE fibers were still present in the cementitious matrix, and the melting did not introduce more microcracks. Furthermore, it was difficult for melted PE fibers to diffuse through the matrix, thus providing the reason that PE fibers did not mitigate explosive spalling in UHP-SHCC.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.014
      Issue No: Vol. 89 (2018)
  • Mixture design of concrete using simplex centroid design method
    • Authors: Dengwu Jiao; Caijun Shi; Qiang Yuan; Xiaopeng An; Yu Liu
      Pages: 76 - 88
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Dengwu Jiao, Caijun Shi, Qiang Yuan, Xiaopeng An, Yu Liu
      The primary goal of concrete mixture design is to strike a balance among workability, compressive strength, durability, economic efficiency and sustainability. In this paper, for a given strength grade, the optimum paste consisting of cement, fly ash and slag, and the optimum ratio among paste, fine aggregate and coarse aggregate were optimized using the simplex centroid design method based on rheological properties. Results showed that the optimum content of total cementitious materials in concrete could be obtained according to the relationships between the workability, yield stress, plastic viscosity and the paste volume fraction. The optimum replacement of supplementary cementitious materials could be determined according to the rheological properties and compressive strength of concrete with ternary cementitious components. It is an effective way to optimize the mixture design of concrete based on the rheological properties using the simplex centroid design method.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.001
      Issue No: Vol. 89 (2018)
  • Stability of the hydrate phase assemblage in Portland composite cements
           containing dolomite and metakaolin after leaching, carbonation, and
           chloride exposure
    • Authors: Alisa Machner; Maciej Zajac; Mohsen Ben Haha; Knut O. Kjellsen; Mette R. Geiker; Klaartje De Weerdt
      Pages: 89 - 106
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Alisa Machner, Maciej Zajac, Mohsen Ben Haha, Knut O. Kjellsen, Mette R. Geiker, Klaartje De Weerdt
      To reduce CO2 emissions during the production of cement and to cope with increasing demands for concrete, and thereby cement, the cement industry needs to identify new supplementary cementitious materials. These new composite cements should provide, among others, a similar or improved durability of the concrete structures. This study investigated the hydrate phase assemblage in Portland cement pastes containing dolomite or a combination of dolomite and metakaolin after leaching, carbonation, and chloride exposure. The phase assemblage and phase compositions of the exposed samples and the unexposed reference samples were investigated using TGA, XRD, and SEM-EDS. The reaction of dolomite in the cement paste resulted in the formation of hydrotalcite. It was found that, unlike most other hydration phases, hydrotalcite can withstand high degrees of leaching and carbonation. When the samples were exposed to a chloride solution, the formation of a chloride-containing hydrotalcite was observed.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.013
      Issue No: Vol. 89 (2018)
  • Concretes made of efficient multi-composite cements with slag and
    • Authors: Tilo Proske; Moien Rezvani; Sebastian Palm; Christoph Müller; Carl-Alexander Graubner
      Pages: 107 - 119
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Tilo Proske, Moien Rezvani, Sebastian Palm, Christoph Müller, Carl-Alexander Graubner
      The present paper deals with the performance of concretes made of multi-composite cements with granulated blast furnace slag (GBFS) and limestone (LL) contents beyond the limits of current EN 197-1. The combined application of ground limestone (up to 50%) and GBFS in multi-composite cements can enable a significant reduction in the Portland cement clinker content of cements for the same concrete strength and durability. The lower the w/c-ratio the higher is the potential for the efficient use of Portland cement clinker together with limestone and slag. A comprehensive experimental study was conducted to analyze the mechanical properties and durability of concrete made of multi-composite cements at both laboratory and plant scale. The efficient use of Portland cement clinker together with GBFS and limestone is analyzed for different cement compositions and w/c-ratios. An approach for the optimization of the slag efficiency is proposed. It was concluded that the efficiency of GBFS increases significantly with decreasing w/c-ratio and slag content. Due to the limited availability of slag, the slag content was limited to 30 wt.-% for multi-composite plant cements. The performance of concretes made of such cements containing 50%, 35% and 20% clinker and 20%, 35% and 50% limestone respectively were experimentally analyzed. The results revealed that concrete made of cement with 50 wt.-% clinker, 30 wt.-% GGBFS and 20 wt.-% limestone and a w/c-ratio of 0.50 could exhibit comparable hardened properties compared to reference concrete made of slag cement CEM III/A 42.5 N (with 50 wt.-% slag) with the same w/c-ratio. Concrete made of cements with clinker content of 35 wt.-% and a reduced w/c-ratio of 0.40 could result in a performance similar to the reference concrete made of CEM III/A 42.5 N. Further reduction of clinker content to 20 wt.-% was possible only at a low w/c-ratio of 0.35. Life cycle assessment (LCA) analysis revealed that the application of such multi-composite cements can lead to a concrete with a remarkable lower global warming potential up to about 35% compared to the concrete made of German average cement with a similar performance.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.012
      Issue No: Vol. 89 (2018)
  • Freeze-thaw crack determination in cementitious materials using 3D X-ray
           computed tomography and acoustic emission
    • Authors: Yasmina Shields; Edward Garboczi; Jason Weiss; Yaghoob Farnam
      Pages: 120 - 129
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Yasmina Shields, Edward Garboczi, Jason Weiss, Yaghoob Farnam
      As concrete freezes and thaws cracks may develop. These cracks can provide a path for water and ionic species to penetrate the concrete. This may reduce the service-life of the concrete element. In this study, X-ray computed tomography (CT) was used as a non-destructive technique to characterize the microstructure of mortar samples that were exposed to different levels of freeze-thaw damage by varying degree of saturation in the samples (75, 90, 95, and 100% degrees of saturation). Acoustic emission (AE) experiments were performed during freezing and thawing to investigate sample cracking behavior. The volume of cracks present within the mortar samples after freezing and thawing were determined using X-ray CT and compared to passive acoustic emission data. The location/source of cracks was also determined using X-ray CT. The crack sources (i.e., void, aggregate, interfacial transition zone, or paste) were determined using X-ray CT and were related to AE activities during cracking. Crack volumes were found to increase with increased levels of saturation, and visual observations of cracking were found to correlate with AE signatures of various crack sources.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.004
      Issue No: Vol. 89 (2018)
  • Shrinkage characteristics of heat-treated ultra-high performance concrete
           and its mitigation using superabsorbent polymer based internal curing
    • Authors: Sung-Hoon Kang; Sung-Gul Hong; Juhyuk Moon
      Pages: 130 - 138
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Sung-Hoon Kang, Sung-Gul Hong, Juhyuk Moon
      The shrinkage and cracking risk of heat-treated ultra-high performance concrete (UHPC) can be mitigated by using the superabsorbent polymer (SAP)-based internal curing method. The heat treatment (HT) accelerates the hydration reaction and resulting self-desiccation of UHPC; consequently, the UHPC experiences severe shrinkage during the HT. This study experimentally demonstrates that the shrinkage is effectively resolved by adopting the SAP-based internal curing method during the HT period as well as early-ages. This method also reduces the strain rate resulting from dimensional change, without showing an increase in drying shrinkage. The accurately conducted experiments herein can help to better understand the shrinkage characteristics of heat-treated UHPC and broaden the application of various internal curing agents.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.003
      Issue No: Vol. 89 (2018)
  • Characterisation of pore structure development of alkali-activated slag
           cement during early hydration using electrical responses
    • Authors: Xiaohong Zhu; Zhilu Zhang; Kai Yang; Bryan Magee; Yaocheng Wang; Linwen Yu; Sreejith Nanukuttan; Qing Li; Song Mu; Changhui Yang; Muhammed Basheer
      Pages: 139 - 149
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Xiaohong Zhu, Zhilu Zhang, Kai Yang, Bryan Magee, Yaocheng Wang, Linwen Yu, Sreejith Nanukuttan, Qing Li, Song Mu, Changhui Yang, Muhammed Basheer
      This paper describes the results of a study investigating early age changes in pore structure of alkali-activated slag cement (AASC)-based paste. Capillary porosity, pore solution electrical conductivity and electrical resistivity of hardened paste samples were examined and the tortuosity determined using Archie's law. X-ray computed micro-tomography (X-ray μCT) and Scanning electron microscope (SEM) analysis were also carried out to explain conclusions based on electrical resistivity measurements. AASC pastes with 0.35 and 0.50 water-binder ratios (w/b) were tested at 3, 7, 14 and 28 days and benchmarked against Portland cement (PC) controls. Results indicated that for a given w/b, the electrical resistivity and capillary porosity of the AASC paste were lower than that of the PC control, whilst an opposite trend was observed for the pore solution conductivity, which is due to AASC paste's significantly higher ionic concentration. Further, capillary pores in AASC paste were found to be less tortuous than that in the PC control according to estimations using Archie's law and from the results of X-ray μCT and SEM analysis. In order to achieve comparable levels of tortuosity, therefore, AASC-based materials are likely to require longer periods of curing. The work confirms that the electrical resistivity measurement offers an effective way to investigate pore structure changes in AASC-based materials, despite threshold values differing significantly from PC controls due to intrinsic differences in pore solution composition and microstructure.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.016
      Issue No: Vol. 89 (2018)
  • Design of strain hardening cement-based composites with alkali treated
           natural curauá fiber
    • Authors: Bartosz Zukowski; Flávio de Andrade Silva; Romildo Dias Toledo Filho
      Pages: 150 - 159
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Bartosz Zukowski, Flávio de Andrade Silva, Romildo Dias Toledo Filho
      The work in hand presents the design process of Strain Hardening Cement-based Composite reinforced with natural curauá fiber. The matrix fracture energy and matrix-fiber bond were studied and implemented into the theoretical model for critical fiber volume prediction, which was verified by mechanical tests for tensile, bending and compression strength. The influence of matrix-fiber bond on critical fiber volume is presented. The fiber properties are improved by two-stage treatment. Firstly, hot water (80 °C) washing in water changed every 3 h. Secondly, immersion in 1% solution of calcium hydroxide Ca(OH)2 with water for 60 min for calcium deposition on fiber surface to increase bond properties. The critical fiber volume predicted by the model was 4% for 20 mm treated curauá fiber and was verified on the composites, which presented strain-hardening behavior under tensile test and deflection-hardening under bending.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.006
      Issue No: Vol. 89 (2018)
  • Strength and self-desiccation of slag-cemented paste backfill at early
           ages: Link to initial sulphate concentration
    • Authors: Wenchen Li; Mamadou Fall
      Pages: 160 - 168
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Wenchen Li, Mamadou Fall
      This paper presents the results of an experimental study on the early age strength and changes in the self-desiccation process of cemented paste backfill (CPB) that contains blast furnace Slag (Slag-CPB) and sulphate. Slag-CPB samples with different initial sulphate concentrations (0, 5000, 15,000 and 25,000 ppm) are prepared and cured in well-sealed molds at early ages (1, 3, 7 and 28 days) in room temperature (∼23 °C). Mechanical and hydraulic conductivity tests are performed on the samples, in which the suction and electrical conductivity of the Slag-CPB specimens are monitored. Furthermore, microstructural analyses are conducted on the Slag-CPB and slag-cement paste samples. The results show that sulphate can have a positive or negative effect on the early age strength and self-desiccation of Slag-CPB, i.e., cause an increase or decrease in strength and acceleration or reduction in the amount and rate of self-desiccation, depending on the initial sulphate content and curing time. This study also shows that an understanding of the positive or negative effect of sulphate on the early strength and self-desiccation of Slag-CPB is critical for designing cost-effective CPB structures with high early strength, speeding up mining cycles or assessing the deterioration of CPB caused by high sulphate attack to ensure safety in mining.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2017.09.019
      Issue No: Vol. 89 (2018)
  • Effect of carbonation of modeled recycled coarse aggregate on the
           mechanical properties of modeled recycled aggregate concrete
    • Authors: Long Li; Jianzhuang Xiao; Dongxing Xuan; Chi Sun Poon
      Pages: 169 - 180
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Long Li, Jianzhuang Xiao, Dongxing Xuan, Chi Sun Poon
      The modeled recycled aggregate concrete (MRAC) which is an idealized model for the real recycled aggregate concrete (RAC) was used in this study. The MRCAs prepared with two types of old mortars were modified by an accelerated carbonation process. The effects of carbonation of MRCA on the micro-hardness of MRCA and the mechanical properties of MRAC were investigated. The results indicated that the micro-hardness of the old interfacial transition zone (ITZ) and the old mortar in the carbonated MRCAs was higher than that in the uncarbonated MRCAs, and the enhancement of the old ITZ was more significant than that of the old mortar. The compressive strength and modulus of MRACs increased when the carbonated MRCAs were utilized, and the improvement was more significant for MRAC prepared with a higher w/c. In addition, a numerical study was carried out and it showed that the improvement in strength by carbonation treatment was less obvious when the difference between the new and old mortar was larger.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.018
      Issue No: Vol. 89 (2018)
  • Quantitative characterization of accelerated aging in cement composites
           using flexural inverse analysis
    • Authors: Vikram Dey; Barzin Mobasher
      Pages: 181 - 191
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Vikram Dey, Barzin Mobasher
      A constitutive model consisting of a tri-linear tensile stress-strain with residual strength was applied in characterization and prediction of long term flexural behavior of several cement-based composite materials. Flexural test results were back-calculated to obtain material parameters and establish their relationship with aging. The material behavior is described by tensile stress-strain parameters consisting of elastic modulus, first cracking strain, post cracking stiffness, ultimate strain, and a residual strength parameter. The relationships between the material parameters and age were established by studying the time dependent flexural performance of various composites with glass and natural fibers as reported by Litherland et al. (1981), Marikunte et al. (1997), Bartos et al. (1996), and natural fibers reported by Toledo-Filho et al. (2000). An analytical model for prediction of rate and extent of damage as a function of time and temperature is proposed for degradation of flexural behavior of strain softening and hardening fiber reinforced concrete subjected to aging. This model is applicable to long-term durability of different classes of materials subject to accelerated aging under different environmental conditions.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.02.019
      Issue No: Vol. 89 (2018)
  • Design and behavior of traditional lime-based plasters and renders. Review
           and critical appraisal of strengths and weaknesses
    • Authors: Rita Nogueira; Ana Paula Ferreira Pinto; Augusto Gomes
      Pages: 192 - 204
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Rita Nogueira, Ana Paula Ferreira Pinto, Augusto Gomes
      Traditional lime-based plasters and renders are complex multilayer systems composed of various mortars; they exhibit behavior affected by their own properties, mutual interaction, interaction with the substrate and by external conditions (e.g. environment). A full understanding of the many mechanisms which impact on system performance is essential to improve the success of interventions on ancient renders. This paper reviews the main aspects that influence the mix design and behavior of traditional lime-based multilayer plasters/renders. Special attention is paid to the differences between fine mortars (rendering mortars frequently used in the outer layers) and coarse mortars (rendering mortars used in the inner layers). The diverse pore structure of these mortar types is analyzed and related, first, to the mix design and, second, to the mechanical and hygric behavior. Finally, the interaction of each mortar layer within the multilayer system is analyzed. The functional and technical requirements of plasters/renders as regards their wall-covering role are also presented and considered in the discussion. The analysis enables a critical appraisal of the strengths and weaknesses of traditional lime-based plasters/renders and provides lines of reasoning to enable professionals working in the field to build specific solutions to real problems.
      Graphical abstract image

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.005
      Issue No: Vol. 89 (2018)
  • Deterioration of bonding capacity of plasma-treated polymer fiber
    • Authors: J. Trejbal; V. Nežerka; M. Somr; J. Fládr; Š. Potocký; A. Artemenko; P. Tesárek
      Pages: 205 - 215
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): J. Trejbal, V. Nežerka, M. Somr, J. Fládr, Š. Potocký, A. Artemenko, P. Tesárek
      Bonding between reinforcing fibers and a brittle cementitious matrix is the key ingredient for a ductile concrete production. Oxygen plasma treatment proved to be a promising technique for increasing the fiber surface adhesion to liquids, but a question about the stability of activated bonding when exposed to atmospheric conditions arises. We present a comprehensive study on deterioration of such treatment in time for different fibers commonly used as dispersed reinforcement. A microscopy investigation allowed to observe changes in the fiber surface morphology, while the changes in chemical bonds were detected by XPS analysis. To quantify the impact of plasma treatment and its deterioration, water contact angle measurements and pull-out tests were carried out. The results indicate that the exposure to atmospheric conditions has a negligible impact on fiber bonding, because surface roughening plays a major role. Therefore, fibers need not be incorporated into a concrete mix immediately after their treatment.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.010
      Issue No: Vol. 89 (2018)
  • Electrical resistivity measurements in steel fibre reinforced cementitious
    • Authors: Carlos G. Berrocal; Karla Hornbostel; Mette R. Geiker; Ingemar Löfgren; Karin Lundgren; Dimitrios G. Bekas
      Pages: 216 - 229
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Carlos G. Berrocal, Karla Hornbostel, Mette R. Geiker, Ingemar Löfgren, Karin Lundgren, Dimitrios G. Bekas
      This paper reports results from experiments aimed at better understanding the influence of fibre dosage and fibre geometry on the AC frequency needed to determine the DC resistivity of cementitious materials containing steel fibres. Impedance spectroscopy and DC galvanodynamic measurements were performed on mortar prisms with varying fibre reinforcement to determine the matrix resistivity (related to ionic current within the pore solution) and composite resistivity (accounting for both ionic current and electronic current through the fibres). The results showed that adding steel fibres did not significantly affect the DC nor the AC matrix resistivity of the mortar prisms. However, the steel fibres yielded a drastic reduction of the frequency associated to the AC matrix resistivity from ∼1 kHz in plain mortar to ∼1 Hz in steel fibre reinforced mortar. These findings revealed the need to adequately adjust the frequency in AC resistivity measurements of steel fibre reinforced cementitious materials.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.015
      Issue No: Vol. 89 (2018)
  • Enhancement of recycled aggregate properties by accelerated CO2 curing
           coupled with limewater soaking process
    • Authors: Bao Jian Zhan; Dong Xing Xuan; Chi Sun Poon
      Pages: 230 - 237
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Bao Jian Zhan, Dong Xing Xuan, Chi Sun Poon
      Strengthening the attached old cement mortar of recycled concrete aggregate (RCA) is a common approach to enhance the RCA properties. Accelerated CO2 curing has been regarded as an alternative way to enhance the properties of RA. However, the improvement of the properties of RCA was limited by the shortage of reactive components in the old cement mortar available for the carbonation reactions. In this study, a CO2 curing process associated with a limewater saturation method was performed cyclically on cement mortar samples, aiming to enhance the properties of cement mortars via artificially introducing additional calcium into the pores of the cement mortars. The results indicated that the adopted treatment method promoted the level of carbonation which was demonstrated by higher CO2 uptake by the limewater saturated cement mortar when compared to that without limewater treatment. After 3-cycles of limewater-CO2 treatment, the density of the cement mortar slightly increased by 5.7%, while the water absorption decreased by over a half. For mechanical properties, the compressive and flexural strength were increased by 22.8% and 42.4%, respectively. Compared to the untreated cement mortar samples, the total porosity of cement mortar was reduced by approximately 33% and the densified microstructure therefore resulted in a higher microhardness.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.011
      Issue No: Vol. 89 (2018)
  • Ordinary Portland Cement composition for the optimization of the synergies
           of supplementary cementitious materials of ternary binders in hydration
    • Authors: Á. Fernández; J.L. García Calvo; M.C. Alonso
      Pages: 238 - 250
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Á. Fernández, J.L. García Calvo, M.C. Alonso
      The synergistic effects of using several supplementary cementitious materials (SCMs), such as Blast Furnace Slags plus Limestone Filler or Fly Ashes, depend on the OPC composition. When using an OPC which is poor in C3A and alkalis in ternary formulations, a similar initial strength gain to that of a plain OPC is detected and at longer hydration ages, the formation of monocarboaluminate, hemicarbonate and hydrotalcite instead of monosulphate can be seen. If an OPC with a higher C3A content and alkalis is used with SCMs, the higher availability of Al causes the early formation of monocarboaluminate and a lower initial strength gain. At longer hydration times, in ternary blends with both OPCs, the mechanical strengths are higher and the C-S-H gels formed are richer in Al and poorer in C/S ratio with a subsequent lowering of the alkali content in the pore solution when compared to that in plain OPC.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2017.12.016
      Issue No: Vol. 89 (2018)
  • Durability of recycled aggregate concrete – A review
    • Authors: Hui Guo; Caijun Shi; Xuemao Guan; Jianping Zhu; Yahong Ding; Tung-Chai Ling; Haibo Zhang; Yuli Wang
      Pages: 251 - 259
      Abstract: Publication date: May 2018
      Source:Cement and Concrete Composites, Volume 89
      Author(s): Hui Guo, Caijun Shi, Xuemao Guan, Jianping Zhu, Yahong Ding, Tung-Chai Ling, Haibo Zhang, Yuli Wang
      Recycling of waste concrete has become an important issue worldwide due to the continued increase of construction wastes. Also, the growing global construction activities urge to find sustainable resources to replace natural materials for the production of concrete. In the past few decades, many researches have been carried out on the use of recycled aggregate (RA) derived from construction and demolition wastes to produce concrete products. This paper reviews the previous findings on the effects of use of RA on durability of concrete. In general, the amount of adhered mortar and the quality of the original concrete have a significant effect on the properties of resulting concrete. The increase of RA content and w/c ratio results in poorer durability of concrete. In comparison, the negative effect of recycled fine aggregate is more obvious than that of recycled coarse aggregate. The use of pozzolanic materials either for surface coating of RA or intermixed within the concrete are effective and feasible to improve the overall durability of concrete. Recent researches on CO2 treatment indicate that it can enhance the properties of RA and durability of concrete significantly.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.008
      Issue No: Vol. 89 (2018)
  • Enhancing fiber/matrix bonding in polypropylene fiber reinforced
           cementitious composites by microbially induced calcite precipitation
    • Authors: Yifei Hao; Liang Cheng; Hong Hao; Mohamed A. Shahin
      Pages: 1 - 7
      Abstract: Publication date: April 2018
      Source:Cement and Concrete Composites, Volume 88
      Author(s): Yifei Hao, Liang Cheng, Hong Hao, Mohamed A. Shahin
      In fiber reinforced cementitious composites (FRCC), bonding between the fibers and matrix governs many important properties, including strengths, fracture energy, ductility, and energy absorption capacities. This study explores the application of a microbiological process of microbially induced calcite precipitation (MICP) to pre-treating surface of polypropylene (PP) fibers for enhancing the interfacial boning strength. This technique utilizes MICP process to produce calcium carbonate that binds onto the fiber surface, leading to increased interfacial bond area and strength. Laboratory tests indicate that MICP modification could increase the post-cracking resistance and energy absorption capacity of the FRCC beam specimens by 58% and 69.3%, respectively. Microstructure analysis reveals that PP fibers after MICP treatment were coated with a layer of CaCO3 with thickness around 20–50 μm depending on the degree of deposition. Results acknowledged a significant role of MICP pre-treatment in enhancing the fiber-matrix bonding properties of FRCC and the corresponding mechanical performance.

      PubDate: 2018-02-05T07:22:51Z
      DOI: 10.1016/j.cemconcomp.2018.01.001
      Issue No: Vol. 88 (2018)
  • Metal powders as foaming agents in fly ash based geopolymer synthesis and
           their impact on the structure depending on the Na /Al ratio
    • Authors: Krcmar
      Abstract: Publication date: July 2018
      Source:Cement and Concrete Composites, Volume 90
      Author(s): E. Kränzlein, H. Pöllmann, W. Krcmar
      Using metal powders, like Al-powder and Zn-powder, as foaming agents in geopolymer synthesis to produce lightweight, cement like building materials, is described in the following article. The influence of the porosity on the structure of the hardened paste is analyzed. Moreover, the influences of the ratio's variations of Na/Al in between 0.4 and 0.8 are investigated. Therefore, analytical methods, including X-ray diffraction, IR spectroscopy for structure analysis, SEM and optical microscopy for morphological analysis and mercury intrusion porosimetry for porosity analysis are used to characterize the synthesized geopolymers. We show the influences of different foaming methods on the geopolymer reaction. Moreover, the differences in element distribution of foamed and not foamed samples are investigated.

      PubDate: 2018-04-16T01:53:18Z
  • An analytical solution for hydraulic conductivity of concrete considering
           properties of the Interfacial Transition Zone (ITZ)
    • Authors: Hassan Baji; Chun-Qing Li
      Abstract: Publication date: Available online 14 April 2018
      Source:Cement and Concrete Composites
      Author(s): Hassan Baji, Chun-Qing Li
      As a composite material, hydraulic conductivity of concrete depends on conductivity of its components that are the mortar, aggregates and the Interfacial Transition Zone (ITZ). Since hydraulic conduction is analogous to heat and electrical conduction, analytical models from these analogous areas relating effective conductivity of composite to conductivity of its components can be used to find the effective hydraulic conductivity of concrete as a function of properties of its components, i.e., aggregate, mortar and the ITZ. However, effect of the conduction in the ITZ has not been considered in these models. This paper presents an analytical solution for the hydraulic conductivity of concrete as a three-phase composite material. The solution is an extension to the model originally proposed for conduction of composite media with randomly suspended spheres. Results of the proposed model compare well against the experimental results and those obtained from rigorous numerical analysis using the Finite Element (FE) method. The principal significance of this study lies in the development of a versatile analytical model that can be employed as a quick tool for assessment of hydraulic conductivity of concrete without the need for sophisticated FE models at the meso-scale level. It offers more insight into effect of different components of concrete on its overall conductivity.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.008
  • Effect of curing time on granulated blast-furnace slag cement mortars
    • Authors: Miguel Ángel Sanjuán; Esteban Estévez; Cristina Argiz; Daniel del Barrio
      Abstract: Publication date: Available online 12 April 2018
      Source:Cement and Concrete Composites
      Author(s): Miguel Ángel Sanjuán, Esteban Estévez, Cristina Argiz, Daniel del Barrio
      Currently, ground granulated blast-furnace slag cements use in cement-based materials is being increasing because perform well in marine and other aggressive environments. However, mortars and concretes made of this type of cement exhibit high carbonation rates, particularly in badly cured cement-based materials and when high blast-furnace slag contents are used. Concrete reinforcement remains passive but can be corroded if the pore solution pH drops as a result of the carbonation process promoting the reinforced concrete structure failure during its service life. Results show the very sensitive response to wet-curing time of slag mortars with regard to the natural carbonation resistance. Then, a minimum period of 3–7 days of wet curing is required in order to guarantee the usual projected service life in reinforced concrete structures. In this work, estimation models of carbonation depth and carbon dioxide diffusion coefficient in ground granulated blast-furnace slag mortars as a function of the curing period and the amount of ground granulated blast-furnace slag are proposed. This information will be useful to material and civil engineers in designing cement-based materials and planning the required curing time depending on their ground granulated blast-furnace slag content.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.04.006
  • Assessment of in-situ alkali-silica reaction (ASR) development of glass
           aggregate concrete prepared with dry-mix and conventional wet-mix methods
           by X-ray computed micro-tomography
    • Authors: Shuqing Yang; Hongzhi Cui; Chi Sun Poon
      Abstract: Publication date: Available online 3 April 2018
      Source:Cement and Concrete Composites
      Author(s): Shuqing Yang, Hongzhi Cui, Chi Sun Poon
      A recent study showed that concrete products prepared with the dry-mix method have better alkali-silica reaction (ASR) resistance than that prepared by the wet-mix method. But the mechanism of ASR in dry-mix glass concrete remains unclear. Meanwhile, the techniques such as Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP) cannot reflect the in-situ evolution of the microstructure with the progress of the ASR. In this study, two common casting methods, the wet-mix and dry-mix methods, were adopted to prepare the glass concrete. The non-destructive X-ray computed micro-tomography (X-ray μCT) technique was applied to observe the pore geometries of both the wet-mix and dry-mix glass concrete, to determine their porosities using 3D volumes and to investigate the generation of cracks during ASR development. This study firstly observed the irregular pore geometry of the glass concretes by quantitatively comparing the pore geometries using the sphericity developed by Wadell for both dry-mix and wet-mix glass concrete. The test results of the porosity measured by 3D volume showed that the porosity of the dry-mix glass concrete decreased after the ASR test. However, no obvious change was observed in the porosity of the wet-mix glass concrete. This change may be attributed to the large pores in dry-mix glass concrete which can accommodate the ASR gel. Through the in-situ observation using 3D X-ray μCT, no new cracks were generated in the dry-mix glass concrete during the progressive development of ASR. On the contrary, new cracks which were filled with ASR gel were densely distributed in the wet-mix glass concrete, which led to failure of the concrete matrix. This is because the expansive ASR gel formed could not be accommodated by the limited pore space in the wet-mix glass concrete, and the swelling pressure of ASR gel induced new cracks in the wet-mix glass concrete.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.027
  • Effect of mix design inputs, curing and compressive strength on the
           durability of Na2SO4-activated high volume fly ash concretes
    • Authors: Diego F. Velandia; Cyril J. Lynsdale; John L. Provis; Fernando Ramirez
      Abstract: Publication date: Available online 3 April 2018
      Source:Cement and Concrete Composites
      Author(s): Diego F. Velandia, Cyril J. Lynsdale, John L. Provis, Fernando Ramirez
      This paper aims to advance research on the use in concrete of a high volume of fly ash, with a high loss on ignition value, aiding in sustainable low carbon footprint construction. To this end, the work explores the benefits that may be achieved in terms of long-term concrete performance from the incorporation of fly ash along with a chemical activator. Durability tests are performed on concrete with an activated hybrid cementitious system: Portland cement (PC) and high volume fly ash with sodium sulfate. The chloride diffusion coefficient significantly decreased over time for the activated system (50% PC - 50% fly ash with added sodium sulfate) compared to the control samples (100% PC and 80% PC - 20% fly ash) at the same water to cementitious material ratio. This behavior is particularly evident in samples cured under controlled laboratory conditions (100% RH and 23 °C). However, outdoor curing increases the permeability for all concretes. Long term carbonation is also investigated under natural exposure conditions, and samples that are cured outdoors exhibit a significant carbonation depth. The compressive strength is correlated with the durability parameters: the durability performance improves as the compressive strength increases, indicating that as is the case for Portland cement (but not always for alkali-activated binders), the microstructural factors which yield high strength are also contributing to durability properties.

      PubDate: 2018-04-16T01:53:18Z
      DOI: 10.1016/j.cemconcomp.2018.03.028
  • Improvement of early-age properties for glass-cement mortar by adding
    • Authors: Jian-Xin Lu; Chi Sun Poon
      Abstract: Publication date: Available online 24 February 2018
      Source:Cement and Concrete Composites
      Author(s): Jian-Xin Lu, Chi Sun Poon
      Poor early-age performance (e.g. lower early strength, longer setting time) is an important technical challenge for the application of blended cementitious materials containing low reactivity or high volumes of supplementary cementing materials. In this study, the mechanism of using nanosilica (NS) to improve the early-age properties for cement mortars blended with glass powder (GP) and glass aggregates has been investigated. The results indicate that the addition of NS into glass-based cement mortar largely improved the early stiffening which was dependent on high specify surface area of the NS rather than cement hydration. Combining the use of NS and GP was conducive to compensate the delayed setting times and the strength losses caused by the incorporation of GP. These beneficial behaviors were associated with the physical, acceleration, pozzolanic and pore refinement effects of NS. In terms of heat of hydration, the inclusion of NS intensified and accelerated the appearance of the third exothermic peak (AFt to AFm) due to the absorption of sulfate ions by the increased C-S-H formation. Also, the total hydration heat liberated was found to correlate linearly with the corresponding early-age compressive strength. Microstructural analysis suggest that NS significantly helped to densify the microstructure of the GP blended cement matrix and improved the interface between the GP particle and the binder matrix. This was verified by the contribution of NS on refining the coarse pore size caused by the use of GP as a replacement of cement.

      PubDate: 2018-02-26T02:40:07Z
      DOI: 10.1016/j.cemconcomp.2018.02.010
  • Mineralogical and microstructural characterization of biomass ash binder
    • Authors: Piyush Chaunsali; Hugo Uvegi; Rachel Osmundsen; Michael Laracy; Thomas Poinot; John Ochsendorf; Elsa Olivetti
      Abstract: Publication date: Available online 21 February 2018
      Source:Cement and Concrete Composites
      Author(s): Piyush Chaunsali, Hugo Uvegi, Rachel Osmundsen, Michael Laracy, Thomas Poinot, John Ochsendorf, Elsa Olivetti
      While the incineration of biomass residues is gaining traction as a globally available source of renewable energy, the resulting ash is often landfilled, resulting in the disposal of what could otherwise be used in value-added products. This research focuses on the beneficial use of predominantly rice husk and sugarcane bagasse-based mixed biomass ashes, obtained from two paper mills in northern India. A cementitious binder was formulated from biomass ash, clay, and hydrated lime (70:20:10 by mass, respectively) using 2M NaOH solution at a liquid-to-solid mass ratio of 0.40. Compressive strength of the biomass ash binder increased linearly with compaction pressure, indicating the role of packing density. Between the two mixed biomass ashes used in this study, the one with higher amorphous content resulted in a binder with higher strength and denser reaction product. Multi-faceted characterization of the biomass ash binder indicated the presence of aluminum-substituted calcium silicate hydrate, mainly derived from the pozzolanic reaction.

      PubDate: 2018-02-26T02:40:07Z
      DOI: 10.1016/j.cemconcomp.2018.02.011
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