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  Subjects -> ENGINEERING (Total: 2431 journals)
    - CHEMICAL ENGINEERING (210 journals)
    - CIVIL ENGINEERING (203 journals)
    - ELECTRICAL ENGINEERING (112 journals)
    - ENGINEERING (1271 journals)
    - ENGINEERING MECHANICS AND MATERIALS (402 journals)
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    - INDUSTRIAL ENGINEERING (77 journals)
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CIVIL ENGINEERING (203 journals)                  1 2 | Last

Showing 1 - 200 of 203 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: 39)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 32)
Agregat     Open Access   (Followers: 1)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 34)
Architectural Engineering     Open Access   (Followers: 5)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 3)
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     Open Access   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 10)
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: 20)
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: 22)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 12)
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: 282)
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     Open Access   (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: 18)
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: 3)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 30)
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: 2)
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 Applied Research in Water and Wastewater     Open Access  
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: 6)
Journal of Civil Engineering     Open Access  
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 15)
Journal of Civil Engineering and Management     Open Access   (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: 5)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites     Open Access   (Followers: 78)
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: 9)
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: 8)
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 Structural Mechanics     Open Access  
Journal of Structures     Open Access   (Followers: 4)
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  
Journal of Water and Wastewater / Ab va Fazilab     Open Access  
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil     Open Access  
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)
Media Komunikasi Teknik Sipil     Open Access  
Mokslas – Lietuvos ateitis / Science – Future of Lithuania     Open Access  
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: 14)
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)
Recent Trends In Civil Engineering & Technology     Full-text available via subscription   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 6)
Resilience     Open Access   (Followers: 1)
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: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 11)
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  
Territorium : Revista Portuguesa de riscos, prevenção e segurança     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)

        1 2 | Last

Journal Cover
Cement and Concrete Composites
Journal Prestige (SJR): 3.146
Citation Impact (citeScore): 6
Number of Followers: 20  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0958-9465
Published by Elsevier Homepage  [3162 journals]
  • Carbonation depth predictions in concrete bridges under changing climate
           conditions and increasing traffic loads
    • Abstract: Publication date: Available online 17 July 2018Source: Cement and Concrete CompositesAuthor(s): Chao Jiang, Xianglin Gu, Qinghua Huang, Weiping Zhang This paper first introduced a numerical carbonation model (NCM) for fatigue-damaged concrete. Then, based on the NCM, a simplified carbonation model (SCM) for fatigue-damaged concrete was established, comprised of a non-damaged concrete contribution term and a fatigue damage contribution term, through Monte Carlo simulations. Both the NCM and SCM were verified by experimental results reported in the literature. Subsequently, an incremental method was proposed to consider the time-variant fatigue damage and exposure conditions. Finally, a case study was conducted, which determined that cumulating fatigue damage could have a big influence on carbonation depth evolution. Meanwhile, differences in the cumulating fatigue damage could lead to noticeable differences in carbonation depth evolution among different points in the same concrete bridge. Moreover, drastic increases of CO2 concentration and temperature could induce relationships of carbonation depths with square roots of service times to remarkably deviate from the proportional laws widely accepted under a time-invariant environment.
       
  • Durability performance of high-performance concrete made with recycled
           aggregates, fly ash and densified silica fume
    • Abstract: Publication date: October 2018Source: Cement and Concrete Composites, Volume 93Author(s): D. Pedro, J. de Brito, L. Evangelista This study intends to analyse the effects of the incorporation of recycled aggregates (RA) and densified silica fume (SF) on the durability of high performance concrete (HPC). Considering that the mortar adhered to the RA strongly influences the behaviour of the concrete made with it, the source of these aggregates was restricted to precast mixes with target compressive strengths of 75 MPa and subjected to a primary plus a secondary crushing process. With regard to SF, a certified commercial product was used, which was incorporated in the concrete as an additional material to cement. The experimental campaign included the production of 12 types of concrete, which were evaluated by means of water absorption by immersion, water absorption by capillarity, resistance to carbonation, resistance to chloride penetration and permeability to oxygen tests. The results show that it is possible to produce HPC with significant quantities of fine and coarse recycled aggregates (FRA and CRA) as replacement of traditional fine and coarse natural aggregates (FNA and CNA). Ultimately, considering the properties analysed, it seems possible to produce HPC without incorporating natural aggregates (NA). The incorporation of densified silica fume contributed to an increase of concrete's performance through the use of a mixing process developed by the authors that minimized the previously endured dispersion difficulties associated with this product.
       
  • Flexural behaviors of fiber-reinforced polymer fabric reinforced
           ultra-high-performance concrete panels
    • Abstract: Publication date: October 2018Source: Cement and Concrete Composites, Volume 93Author(s): Weina Meng, Kamal Henri Khayat, Yi Bao The use of fiber-reinforced polymer (FRP) fabrics as reinforcement in concrete offers several advantages, such as high tensile strength, corrosion resistance, and light weight. This paper presents experimental and mechanical studies on the flexural behaviors of FRP fabric reinforced ultra-high-performance concrete (UHPC) panels. Glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) fabrics were investigated. Mechanical properties of GFRP and CFRP fabrics, high-strength mortar, and UHPC containing micro steel fibers were experimentally evaluated. The interfacial properties between the FRP fabric and cementitious matrix were characterized using push-pull tests. The flexural performance of panels with different reinforcement configurations was experimentally evaluated. The use of GFRP or CFRP fabric enhanced the flexural properties of UHPC panels, but did not lead to any increase in the flexural strength for the panels made with high-strength mortar. A mechanical analysis is performed to understand and predict the flexural behavior of the FRP fabric reinforced UHPC panels. The proposed fabric reinforced UHPC panel is demonstrated to be promising for the development of lightweight, high-performance permanent formwork system. Such formwork can be potentially used in accelerated construction of critical infrastructure with enhanced crack resistance and extended service life.
       
  • Improved mesoscale segmentation of concrete from 3D X-ray images using
           contrast enhancers
    • Abstract: Publication date: October 2018Source: Cement and Concrete Composites, Volume 93Author(s): P. Carrara, R. Kruse, D.P. Bentz, M. Lunardelli, T. Leusmann, P.A. Varady, L. De Lorenzis Obtaining the mesostructure of concrete from X-ray computed tomography (CT) requires segmentation of the data into distinct phases, a process complicated by the limited contrast between aggregates and mortar matrix. This paper explores the possibility to add baryte or hematite into the concrete mixture to enhance the contrast between cement paste and aggregates in CT, thus allowing for a semi-automatic segmentation. Raw and segmented CT images of plain and modified concrete mixtures are obtained and compared to assess the validity of the proposed approach. Characterization tests are also performed in order to ensure that the concrete characteristics are not appreciably affected by the presence of the enhancers.
       
  • Properties of recycled aggregate concrete prepared with scattering-filling
           coarse aggregate process
    • Abstract: Publication date: October 2018Source: Cement and Concrete Composites, Volume 93Author(s): Gelong Xu, Weiguo Shen, Bingliu Zhang, Yongxin Li, Xiaoli Ji, Yongxin Ye RAC produced with crushed recycled aggregate (RA) is regarded as an environmental friendly material, while its high water demand, high mortar content and low modulus have restricted its application. Scattering-filling coarse aggregate (SFCA) process was applied to prepare the recycled aggregate concrete with promoted performance. With the reference of conventional concrete and the scattering-filling natural aggregate (SFNA) concrete, the influences of ratio, type, size and moisture state of RA on mechanical and durable properties of scattering-filling recycled aggregate (SFRA) concrete were investigated. The results indicate that SFCA process could improve the compressive strength, elastic modulus, and reduce the drying shrinkage and chloride penetration. The frost resistance of SFRA is comparable with the conventional concrete. With 10–20 mm scattering-filling aggregate of RA, SFCA concretes get more significant improvement on elastic modulus and anti-permeability; Higher water content of RA worsen the performance of recycled aggregate concrete (RAC) for water in the RA weakening ITZ; Furthermore, image processing analysis and microhardness indicated that SFCA process improve the properties by increasing the homogeneity of aggregate distribution and improving ITZ between the aggregate and cement paste in RAC. SFCA process provides an economic method to produce high-quality recycled aggregate concrete and an efficiently approach to the utilization of recycled concrete aggregate from Construction and Demolition waste.
       
  • Experimental investigation of compressive strength and compressive
           fracture energy of longitudinally cracked concrete
    • Abstract: Publication date: October 2018Source: Cement and Concrete Composites, Volume 93Author(s): Hikaru Nakamura, Takahiro Nanri, Taito Miura, Sushanta Roy In this study, compression tests of longitudinally cracked concrete were conducted to clarify the effect of existing crack on reduction of compressive strength and compressive fracture energy. In the specimens, one or two longitudinal cracks were introduced mechanically before compression loading. The experimental parameters were set to specimen shape, size, height to diameter ratio, coarse aggregate size, number of existing crack and the width. Based on experimental evidences, it was clarified that the reduction of both compressive strength and compressive fracture energy due to existing crack was dependent on crack width and those reduction tendencies are clearly influenced by coarse aggregate size without the effect of other parameters. Moreover, in order to discuss the reduction mechanism, compression tests focused on the effect of crack shape such as wave height and length were also conducted. In the specimens, imitation of existing cracks were embedded for neglecting the effect of damage near crack. As a result, it was found that the crack shape was significant for the reduction of concrete strength and compressive fracture energy. Finally, compressive strength reduction model in association with maximum crack width and maximum coarse aggregate size was proposed.
       
  • Superabsorbent polymers to mitigate plastic drying shrinkage in a cement
           paste as studied by NMR
    • Abstract: Publication date: October 2018Source: Cement and Concrete Composites, Volume 93Author(s): D. Snoeck, L. Pel, N. De Belie At early ages, a problem of plastic shrinkage can arise when a cement paste is subjected to harsh drying conditions during hardening. SuperAbsorbent Polymers (SAPs) are a promising admixture to mitigate shrinkage in cement pastes. By introducing internal curing by means of the stored mixing water in the SAPs, the plastic shrinkage can be partially mitigated, next to the mitigation of autogenous shrinkage during setting of the cement paste. The kinetics of water release by the SAPs towards the cementitious matrix have been studied in detail to understand the mechanism. Nuclear Magnetic Resonance (NMR) is an effective technique to non-destructively monitor the effects induced by the SAPs during this plastic period and hardening as a function of time. The SAPs are able to protect the cement paste internally from the harsh ambient drying conditions and are able to sustain the internal relative humidity. The plastic settlement was reduced and there was less plastic shrinkage measured. Below 5 mm of the surface in SAP specimens, the specimens were hardening as if put in sealed conditions.
       
  • A self-healing cementitious composite with mineral admixtures and built-in
           carbonate
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Xianfeng Wang, Cheng Fang, Dawang Li, Ningxu Han, Feng Xing In this study, experimental investigations were conducted on the self-healing potential of concrete. Sulfoaluminate based expansive agents (CSA), crystalline admixture (CA), and calcium hydrogen phosphate were used as part of cementitious materials, and porous ceramsites served as the carrier for sodium carbonate solution. The quantification of the widths/areas of the cracks was performed to examine the feasibility of the approach and optimize mix proportions. A gas permeability test was conducted on two preferred mixes to investigate the change in the gas permeability of pre-cracked samples. After curing in still water for 28 d, the pre-cracked specimens with ceramsites containing sodium carbonate, and appropriate dosages of additives exhibited considerable efficiency in surface crack closure and healing in gas permeability. The SEM results indicated the deeper formation of healing products (CaCO3) in the cracks of the suggested mix when compared to that in the control mix. A healing mechanism was discussed based on the experimental results.
       
  • Dry-processing of long-term wet-stored fly ash for use as an addition in
           concrete
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): M.J. McCarthy, L. Zheng, R.K. Dhir, G. Tella The paper describes a study carried out to explore the potential for recovery of fly ash from wet-storage areas for use as an addition in concrete, and involved drying and processing material to achieve finer fractions/reduce particle size. Three relatively coarse fly ashes with medium/high carbon contents (loss-on-ignition; LOI) were obtained from two UK lagoons and a stockpile. Initially, drying (105 °C) and screening (600 μm) were carried out, giving acceptable handling properties. Thereafter, processing using (63 μm) sieving, air classifying or grinding was investigated. The methods gave increased fineness levels (greatest with grinding), with some reductions in LOI also found after sieving and air classifying. Assessment of fly ash reactivity indicated improvements with processing, and most noticeable effects by grinding. Tests on concrete found that both consistence (slump) and compressive (cube) strength increased with processing and tended to follow fly ash fineness. Further analysis showed that strength could be related to the sub 10 μm particle level in fly ash. This appeared to be irrespective of processing method, with progressive increases (in strength) up to sub 10 μm contents of about 60% (maximum in the study). Concrete tests for water absorption and intrinsic (air) permeability, carbonation and chloride diffusion showed that these were also influenced by fly ash sub 10 μm content. The factors affecting behaviour are discussed and practical implications of the research considered.
       
  • Chemical forms of lead immobilization in alkali-activated binders based on
           mine tailings
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Qian Wan, Feng Rao, Shaoxian Song, Ricardo Morales-Estrella, Xian Xie, Xiong Tong The present work studies the immobilization forms of lead in alkali-activated cementitious binders (AACBs) based on mine tailings. Through deconvolution of Pb 4f XPS spectra of the mine tailings-based binders, the immobilization forms of lead in network, and lead in silicate glass of PbO·3SiO2 and PbO·7SiO2 were first quantitatively presented. The 29Si NMR spectra of the binders synthesized with Pb(NO3)2 additions from 0 to 6% give the ratios of silicates involved in the formation of lead silicate glass, ranging from 0 to 10.56%. In addition, images of scanning electron microscope (SEM) equipped with X-ray microanalytical mapping and results of zeta potential measurements confirmed the immobilization forms in the mine tailings-based binders. It not only gives fundamentals for the solidification/stabilization (S/S) of mine tailings through alkaline activation process, but also enriches the understanding on the immobilization of heavy metals in AACBs.
       
  • The influence of different aggregates on the behavior and properties of
           gypsum mortars
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Jitka Krejsová, Magdalena Doleželová, Radka Pernicová, Petr Svora, Alena Vimmrová The structure, behavior and properties of gypsum mortars with different types of fine aggregates were studied. Investigation by scanning electron microscopy shows that the presence of aggregate particles significantly influences the shape and size of gypsum crystals in the interfacial transition zone. The porosity of the gypsum matrix in mortars is greater than the porosity of pure gypsum paste and the pore size distribution shifts towards smaller pores. The shape and size of crystals in the transition zone depends on the surface roughness of the aggregate particles. The grain surface roughness was measured by confocal laser scanning microscopy. The properties of mortars also depend on the grain surface roughness. The workability, setting times and thermal conductivity decrease with increasing grain surface roughness, while the strength and water vapor resistance increase.
       
  • Enhanced passivation of alloy corrosion-resistant steel Cr10Mo1 under
           carbonation — Passive film formation, the kinetics and mechanism
           analysis
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Zhiyong Ai, Jinyang Jiang, Wei Sun, Xianglin Jiang, Bo Yu, Kai Wang, Zhifeng Zhang, Dan Song, Han Ma, Jianchun Zhang It has been repeatedly reported that Cr-series alloy steels have enhancing passivation under carbonation (within alkalinity range), which is diametrically opposed to plain carbon steel. This work investigated the composition and structure depth profiles of passive film formed on alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions of different pH (13.3, 12.0, 10.5 and 9.0) by X-ray photoelectron spectroscopy (XPS), and analyzed the kinetics of the passive film growth and formation influenced by the pH through current transient analysis. The results stated that the growth and formation process of passive film on the steel could be explained using dissolution-precipitation reaction mechanism. When exposed to an alkaline medium, the metal first incurs rapid anodic dissolution and releases metallic cations into the electrolyte before the passive oxides/hydroxides precipitation. Decreasing pH promotes excessive anodic dissolution of the metal and more metallic cations are released into the solution, resulting more Cr species enriched in the film layer for their high stability insensitive to lower pH although Fe species become soluble under carbonation. This contributes to the formation of a thicker passive film with higher corrosion resistance, providing the steel enhanced passivity in less alkaline environments.Graphical abstractImage 1
       
  • Efflorescence and subflorescence induced microstructural and mechanical
           evolution in fly ash-based geopolymers
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Zuhua Zhang, John L. Provis, Xue Ma, Andrew Reid, Hao Wang This paper reports the effects of efflorescence on the microstructural and mechanical properties of fly ash-based geopolymers. Geopolymer pastes manufactured by sodium hydroxide and sodium silicate activation of three Class F fly ashes exhibit varying efflorescence behaviour. The geopolymer derived from sodium silicate activation of fine fly ash, which has a compact microstructure, shows a relatively slow efflorescence rate and low efflorescence potential. The efflorescence occurring on the surface of the geopolymer specimens does not change their mineralogical characteristics. However, the compressive strength development and compressive modulus of geopolymers can be affected through processes related to the loss of alkalis, and also to subflorescence. The phenomenon of subflorescence can be regarded as an extended efflorescence taking place under the surface of the material, leading to crystallisation pressure, which may exceed the tensile strength of hardened binders and generate structural damage.
       
  • Sounding of subsurface concrete defects using frequency response of
           flexural vibration
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Sean Blaney, Rishi Gupta Standard sounding procedures such as hammer percussion and chain drag can be used to locate subsurface concrete defects, but are often subject to the individual judgement and ear of trained inspectors. However, defect depth information can be difficult to gauge by ear alone. By recording audio and analyzing the frequency content of sounding via hammer percussion, a single- and triple-link chain drag, and a novel speaker-based excitation procedure, simulated defects in concrete test slabs were detected. The speaker-based method shows the capacity to detect a similar number of defects as chain drag methods, though it is slightly less effective than the hammer method. The duration and type of the acoustic signal used by the speaker to induce vibration are important factors in performance of the speaker-based method. The detectability of a defect via all methods tested depended largely on the ratio of defect depth to defect lateral dimensions; defect detectability was shown to drop after this ratio exceeded about 0.35.
       
  • Dispersion of graphene oxide agglomerates in cement paste and its effects
           on electrical resistivity and flexural strength
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Xiangyu Li, Linhao Wang, Yuqing Liu, Wengui Li, Biqin Dong, Wen Hui Duan Actual dispersion of graphene oxide (GO) in cement paste was investigated by using both X-ray computed tomography and X-ray photoelectron spectroscopy. It was found that GO nanosheets are mainly agglomerated, as an individual phase, with platelet-like morphology and little GO being absorbed onto surfaces of cement particles and hydration products. By performing an electrical resistivity test, GO agglomerates are found to be more electrically insulative than cement paste. Therefore, it is not possible to develop self-sensing cement composites by incorporating GO directly without resolving its dispersion issue. However, GO agglomerates enhance the flexural strength of cement paste because of their special morphology and intrinsic strength. Results showed that the flexural strength of cement paste was increased by 83% with incorporation of 0.04% GO by weight of cement.
       
  • Development of conductive cementitious materials using recycled carbon
           fibres
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): G. Faneca, I. Segura, J.M. Torrents, A. Aguado Conductive cementitious materials have gained immense attention in recent years owing to the possibility of achieving multifunctional materials. The usual approach has been to incorporate carbonaceous nanomaterials and/or virgin carbon fibres into cementitious matrices. This paper presents the first research devoted to the development of conductive cementitious materials using recycled carbon fibres (rCFs). Four different types of PAN-based rCFs were studied, by varying the aspect ratio and supplying characteristics, in two concrete dosages: conventional and ultra-high-performance concrete mixes. Two mixing methods—dry and wet—commonly used to fabricate fibre-reinforced concrete were considered. The results obtained in our result have shown that wet mix method achieves better workability of the mixes and good dispersion of the fibres. Furthermore, electrical resistivity values in the range of 3–0.6 Ω m were obtained for rCF contents ranging from 0.2 to 0.8% in vol. The obtained results demonstrate the possibility of using rCF to develop multifunctional cementitious materials and thus enhance the possibility of using these materials from an industrial point of view. Furthermore, new possibilities are created for the recycling of carbon fibre composites to obtain high-added-value products.
       
  • The influence of fiber orientation on bleeding of steel fiber reinforced
           cementitious composites
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Hui Li, Ru Mu, Longbang Qing, Huisu Chen, Yanfeng Ma The bleeding of steel fiber reinforced cementitious composites influences the durability and mechanical properties of hardened composites, fiber orientation affects the bleeding of the composites. This paper focuses on the influence of fiber orientation on the bleeding of cementitious composites. A simplified mathematical model based on fluid mechanics is proposed to investigate the influence of fiber orientation on bleeding, and a series of experiments are carried out to assess the difference in bleeding between aligned and non-aligned (randomly oriented) fibers in steel fiber reinforced cementitious composites. The research results indicate that the bleeding characteristics of the composites are greatly affected by the inclination angle of fibers in the matrix. The bleeding content increases as the inclination angle of fibers increases, and the bleeding content of horizontally aligned steel fiber reinforced cementitious composites (ASFRCC) is much less compared to non-aligned (randomly oriented) steel fiber reinforced cementitious composites, vertical fiber ASFRCC, and plain concrete.
       
  • Electrochemical behaviour of a novel alloy steel in alkali-activated slag
           mortars
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Jinjie Shi, Jing Ming, Wei Sun The present paper aims to investigate the passivation capability and accelerated chloride-induced corrosion behaviour of a novel alloy steel (00Cr10MoV) and a conventional low-carbon steel (20MnSiV) in ordinary Portland cement (OPC) and alkali-activated slag (AAS) mortars. Both steels were embedded in mortars with intact mill scale. Compared with OPC mortar, AAS mortar resulted in the formation of less protective passive film for both 20MnSiV and 00Cr10MoV steels after passivation due to the presence of reducing sulphides. Despite this, the initial negative effect of AAS mortar on 20MnSiV steel can be well compensated by its denser interfacial microstructure after the occurrence of active corrosion induced by chlorides. As for 00Cr10MoV steel in AAS mortar, however, this compensating effect was less pronounced. Moreover, unexpected low passivation capability and corrosion resistance can be confirmed for 00Cr10MoV steel in both OPC and AAS mortars due to the presence of defective and Cr-depleted mill scale.
       
  • Visualized tracing of rebar corrosion evolution in concrete with x-ray
           micro-computed tomography method
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Biqin Dong, Guiyun Shi, Peng Dong, Weijian Ding, Xiaojuan Teng, Shaofeng Qin, Yuqing Liu, Feng Xing, Shuxian Hong A X-ray micro-computed tomography (XCT) imaging method is proposed to measure and analysis the corrosion behavior of rebar in a marine environment. The experimental results reveal that the time-dependent corrosion morphology of rebar in the three-dimensional configuration can be clearly visualized and certain corrosion parameters can be determined. Based on the characteristics analysis of XCT image, the time point of the initial rust and corrosion-induced crack are estimated. Moreover, the whole corrosion process can be divided into three phases as corrosion initiation (chloride penetration), free expansion and cracking, which agrees with the frequently used corrosion model.
       
  • A novel test setup for the characterization of bridging behaviour of
           single microfibres embedded in a mineral-based matrix
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Majid Ranjbarian, Viktor Mechtcherine The mechanical performance of fibre-reinforced, mineral-based composites, such as strain-hardening cement-based composites (SHCCs), is determined to a great extent by the bonding between dispersed fibres and matrix and the corresponding bridging action of fibres crossing cracks. To characterize such interactions between fibre and matrix, single fibre pull-out tests in a single-sided configuration are usually performed. Such tests are relatively simple and straightforward, but they have some major limitations. To overcome these limitations, a novel setup is suggested in the article at hand. First, setting up, preparation of specimens, testing procedure and data evaluation are described in detail. Then, the results obtained in the quasi-static monotonic tests on individual PVA microfibres embedded in a fine-grained, cement-based matrix are presented and discussed under consideration of corresponding results gained by conventional single-sided fibre pull-out tests on specimens made of the same constituents. Next, the experiments with the new setup are performed at a higher displacement rate so that the rate effect on the pull-out force-crack opening behaviour can be investigated. Finally, the applicability of the new setup for testing fatigue behaviour of the composite on the micro-scale is demonstrated by means of cyclic tests in tension-compression regime. Such tests cannot be performed using conventional fibre pull-out tests.
       
  • Effect of shrinkage reducing admixture on early expansion and strength
           evolution of calcium sulfoaluminate blended cement
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Iman Mehdipour, Kamal H. Khayat This research examines the influence of presence of shrinkage reducing admixture (SRA) on expansion, hydration, and strength evolution of calcium sulfoaluminate-based expansive agent (CSA-based EX) blended with ordinary portland cement (OPC) in the absence of initial moist curing. The performance of inclusion of SRA in OPC-CSA system and without moist curing was compared to the moist-cured OPC-CSA system made without any SRA. The investigation uses the measurements of cement hydration from isothermal calorimetry, autogenous and drying volume changes, internal relative humidity, X-ray diffraction (XRD), and thermogravimetry, as well as compressive strength to characterize the expansion and hydration of OPC-CSA mortar systems. The results indicate that under unsealed conditions, the expansion and strength evolution of OPC-CSA system is significantly sensitive to the presence of moist curing. Mortar containing 15% CSA-based EX resulted in no expansion and had comparable magnitude of total deformation to that of the plain OPC system when no moist curing was adopted. This is linked to the: (i) reduced ettringite formation; and (ii) decreased stiffness which translates to the lower resistance to deformation. Analysis of calorimetry, XRD pattern, and thermogravimetry indicates the synergistic effect of using SRA in OPC-CSA system, which contributes towards higher early-age expansion and increased later-age strength compared to the similar system made without any SRA. In the absence of moist curing, the OPC-CSA system containing SRA exhibited 20% higher non-evaporable water content than OPC-CSA system alone, confirming the effect of SRA addition on hydration reaction progress of OPC-CSA system. The outcomes of this research provide insights into formulation of CSA-based suspensions with the aim of reduced shrinkage, when insufficient initial moist curing is applied.
       
  • The early hydration of metakaolin blended cements by non-contact impedance
           measurement
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Rongjin Cai, Zhen He, Shengwen Tang, Tao Wu, E Chen This paper aims to study the early-age hydration process of metakaolin blended cement pastes. The hydration characteristics of different stages, i.e. first dissolution, acceleration, second dissolution and hardened stage, are analyzed by non-contact impedance measurement (NCIM), X-ray diffraction (XRD), derivative thermogravimetric analysis test (DTG), and Fourier transform infrared spectroscopy (FTIR). Through the comprehensive investigation, the second dissolution stages corresponding to the plateau segments appearing in impedance modulus curves for metakaolin blended cement pastes, seem to be associated with the dissolution behavior of metakaolin in alkaline condition. The larger amount of metakaolin in the paste results in the more distinct plateau or descent segment. Furthermore, 15% metakaolin replacement is most favorable to enhance the hydration rate and broaden the range of pore size distribution of blended cement paste. Meanwhile, the compressive strength, water requirement of normal consistency and setting time of blended pastes are examined to study their macro-physical performances.
       
  • Gamma-ray attenuation coefficients and transmission thickness of high
           consistency heavyweight concrete containing mineral admixture
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): H.Süleyman Gökçe, Buket Canbaz Öztürk, N.Füsun Çam, Özge Andiç-Çakır In the study, high consistency heavyweight concrete mixtures containing barite aggregate were produced by using some common mineral admixtures (viscosity modifier, silica fume and fly ash) at various water/binder ratios and binder contents. Gamma-ray linear attenuation coefficients of the concrete mixtures were determined by using gamma sources of 137Cs and 60Co in NaI(Tl) gamma spectrometry system. The relationship between specimen thickness and transmission of the rays was constituted by emphasizing their mean free path, half-value layer, and tenth-value layer. Moreover, experimental mass attenuation coefficients of the concrete specimens were determined and compared with theoretical mass attenuation coefficients calculated by XCOM software depending on elemental fractions of these concrete in equivalent energies (662 keV, 1173 keV and 1332 keV). As a result, the replacement of the aforementioned admixtures with ordinary cement negatively affected the linear attenuation coefficients of the heavyweight concrete. A relative change of up to 25% was observed between the least and the highest attenuation thickness values at a certain gamma-ray transmission. A good regression relationship has been established between density and linear attenuation coefficients, density and mean free path, and density and half- or tenth-value layers of the heavyweight concrete. Theoretical (XCOM) mass attenuation coefficients were found similar to the experimental mass attenuation coefficients of the heavyweight concretes. Although there is a good linear regression relation between the theoretical and experimental mass attenuation coefficients at 662 keV energy of gamma rays, the relations were disappeared at 1173 and 1332 keV energies of gamma rays.
       
  • Development of advanced plasters for insulation and renovation of building
           constructions with regard to their hygrothermal behaviour
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Jitka Peterková, Jiří Zach, Martin Sedlmajer Thermal insulation and renovation plasters are in still greater demand for the insulation and renovation of existing as well as new buildings. The main reason is the need for thermal protection with the purpose of reducing the energy consumption of existing buildings and the construction of near zero energy buildings. Suitable thermal insulation brings considerable savings in terms of energy costs and reduction of pollutants and emissions generated during heating. Protection of the environment and human health is also very important. Another reason is the need for the materials to be able to withstand increased humidity, which is a problem in older buildings.Research is aimed at developing materials which would be ecological, exhibit capillary activity, have an optimal ratio of thermal insulation and mechanical properties, high porosity, and low diffusion resistance.This paper describes the results of the development of plasters useable for thermal insulation and renovation of buildings and the study of their hygrothermal behaviour including a simulation of thermal and humidity conditions of a selected construction detail.Measurements and simulations showed that the newly developed mixtures had similar or better properties than the reference lime-cement plaster. The optimal mixture in terms of physical, thermal insulation, and mechanical properties was mixture 7 made with lime hydrate and fly ash 2. Simulations were run in the software THERM and WUFI so as to calculate the lowest surface temperatures for 3 different implementations of a jamb. The results showed that the newly developed plasters delivered markedly higher surface temperatures than the reference plaster, i.e. Mixture 1. All the new plasters tested in jamb detail 3 showed a surface temperature above 12.94 °C based on a determination of the dew point according to ČSN 73 0540–2 at a temperature of +21 °C and relative humidity of 60%.
       
  • Rammed earth blocks with improved multifunctional performance
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Hannah Porter, Joshua Blake, Navdeep Kaur Dhami, Abhijit Mukherjee Rammed earth is a traditional construction technology that has proven to be sustainable. This paper explores further improvement of its multifunctional performance by increasing the strength, reducing moisture permeation and increasing the thermal resistance. Surface application of microbial cementation was found to increase the strength by 25%. The water permeability and erosion of the blocks also reduced by 24% and 62% respectively, due to surface application of microbial cementation. The thermal test showed that addition of crumb rubber resulted in a temperature difference of around 30 °C even after 6 h. However, the addition of crumb rubber also reduced the strength. This research demonstrates that significant improvement of overall performance of rammed earth materials can be achieved through various treatments. However, the overall performance requirements are specific to the engineering application and synergistic and antagonistic interactions must be considered to obtain an optimal performance.
       
  • Squeeze flow coupled with dynamic pressure mapping for the rheological
           evaluation of cement-based mortars
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Franco A. Grandes, Victor K. Sakano, Andressa C.A. Rego, Fábio A. Cardoso, Rafael G. Pileggi The squeeze flow test provides relevant information about the macroscopic rheological behavior of mortars. Nevertheless, the identification and characterization of micro and meso physical phenomena is necessary for a more thorough analysis. This work presents an experimental methodology that combines the squeeze flow test with a pressure mapping system for the rheological evaluation of cement-based mortars. Two compositions were analyzed, with and without viscosity modifying cellulose ether based admixture, and the liquid phase migration was quantified to support the interpretation of the results. The developed pressure mapped squeeze flow (PMSF) method allowed for reliable measurement of the evolution of the pressure distribution on the whole area of the squeezed sample, and the results were compared with theoretical models for different flow types and rheological behaviors. The presence of the cellulose ether admixture resulted in more homogeneous flows, which enabled bigger displacements and generated less fluctuations in the pressure distributions.
       
  • Nano-silica and silica fume modified cement mortar used as Surface
           Protection Material to enhance the impermeability
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Bingliu Zhang, Hongbo Tan, Weiguo Shen, Gelong Xu, Baoguo Ma, Xiaoli Ji In corrosion environment, corrosion ions can easily penetrate from the surface into the inside of the concrete due to the porous structure of the surface; in this case, concrete can inevitably suffer from the damage. In this study, an attempt to use nano SiO2 (NS) and silica fume (SF) modifying cement mortar as a Surface Protection Material (SPM) was made, in order to promote penetration resistance of the whole system. SPM was coated on the surface of matrix, and then interfacial bond strength between matrix and SPM was measured; shrinkage consistency was also considered; the chloride penetrability of the system was examined as well. To reveal the mechanism, effect of NS and SF on pore structure, Interfacial Transition Zone (ITZ), hydration process, and compressive strength of SPM were investigated. The results show that matrix coated with SPM on the surface has a good integrity, with excellent interfacial bond strength and little difference in shrinkage, and chloride diffusion coefficient of the system was considerably declined, in comparison with the matrix, showing an excellent penetration resistance. The mechanism behind is that SPM, which was modified with SF-NS, shows the excellent impermeability, and this kind of material existing on the surface can noticeably obstruct the chloride ions penetrating into the inside. In cement hydration process, SF and NS can not only consume a large amount of CH to form dense C-S-H, but also exert the grading filling effect, resulting in the decline in porosity, the increase in density, the improvement in microstructure of ITZ, and the enhancement in mechanical performance. The findings can provide useful experience for the design of the cement-based materials servicing in high corrosion environment.
       
  • Electromagnetic wave absorbing cement-based composite using Nano-Fe3O4
           magnetic fluid as absorber
    • Abstract: Publication date: September 2018Source: Cement and Concrete Composites, Volume 92Author(s): Yongjia He, Linnu Lu, Keke Sun, Fazhou Wang, Shuguang Hu The idea of preparing electromagnetic wave absorption cement-based composite using nano-Fe3O4 magnetic fluid as electromagnetic wave absorber is proposed. Nano-Fe3O4 magnetic fluid with obvious superparamagnetism is synthesized based on the co-precipitation method. When 5% nano-Fe3O4 magnetic fluid is added into cement, the composite prepared shows excellent electromagnetic wave absorption properties, e.g. the absorption bandwidth with reflection loss lower than −10 dB and lower than −15 dB is about 9.5 GHz and 6.3 GHz respectively, much better than that of the composite prepared with nano-Fe3O4 powder and bulk Fe3O4 powder. As well, nano-Fe3O4 magnetic fluid accelerates the early hydration of cement and improves its early age compressive strength obviously. Due to the advantages of easy processing, cheap cost, non-toxic and high electromagnetic wave absorption, cement-based composite prepared with nano-Fe3O4 magnetic fluid shows the huge potential application in construction of electromagnetic wave interference shielding buildings.
       
  • On the size effect of interfacial fracture between concrete and fiber
           reinforced polymer
    • Abstract: Publication date: Available online 10 July 2018Source: Cement and Concrete CompositesAuthor(s): Kyungsu Ha, Habeun Choi, Moochul Shin, Kyoungsoo Park In this study, the size effect of the nominal interfacial strength between concrete and fiber reinforced polymer (FRP) is investigated by integrating fracture tests and computational simulations. Three-point bending fracture tests are performed with geometrically similar specimens to demonstrate the size effect, and to measure fracture parameters for mode-I. Based on the measured fracture parameters, the crack-growth behavior is predicted using the finite-element-based cohesive zone model. Computational results predict accurately the experimental results of the load versus crack mouth opening displacement (CMOD) curves. Furthermore, both the computational and experimental results illustrate that the nominal interfacial strength decreases with increases in the specimen size, i.e., the size effect of the interfacial fracture. Because of the size effect, fracture parameters, such as the fracture energy, should be measured and evaluated to predict the interfacial fracture between concrete and FRP.
       
  • Carbonation activated binders from pure calcium silicates: Reaction
           kinetics and performance controlling factors
    • Abstract: Publication date: Available online 10 July 2018Source: Cement and Concrete CompositesAuthor(s): Warda Ashraf, Jan Olek This paper presents a study on the carbonation activated binders prepared from pure calcium silicate phases, which included tricalcium silicate (3CaO.SiO2, [C3S]), β-dicalcium silicate (β-2CaO.SiO2, [β-C2S]), γ-dicalcium silicate (γ-2CaO.SiO2, [γ-C2S]), tricalcium disilicate (rankinite, 3CaO.2SiO2, [C3S2]), and monocalcium silicate (wollastonite, CaO.SiO2, [CS]). The overall study consisted of three experimental parts, with individual focus on the following issues: (i) reaction kinetics, (ii) mechanical performance at the microscale, and (iii) mechanical performance at the macroscale. Carbonation of calcium silicate phases was found to occur in two distinct stages, namely: phase boundary controlled stage and product layer diffusion controlled stage. Theoretical solid-state reaction approach, including contracting volume model and Jander's equations were used to determine the carbonation rate constants for the calcium silicate phases. Phase boundary controlled stage was found to be dominantly dependent on the type of the starting calcium silicate phases. On the other hand, during the diffusion controlled stage the reaction rate constants were found to depend on the type of carbonation products (in this case Ca-modified silica gel and calcium carbonate). The mechanical properties of the individual microscopic phases were evaluated using nanoindentation test whereas the overall strength of the carbonated paste was evaluated using macroscale three-point bending test. Correlations between the mechanical performances and microstructural characteristics revealed the performance controlling factors of the carbonation activated binders. The higher bound water contents of the carbonated matrix tend to increase the short-term (up to 3 h) creep deformation of the matrix when subjected to constant stress. The presence of a higher proportion of poorly-crystalline forms of calcium carbonates (i.e., aragonite, vaterite and amorphous calcium carbonate) were observed to increase the flexural strength but decrease the elastic modulus of the carbonated matrix.
       
  • Enhanced dynamic mechanical properties of cement paste modified with
           graphene oxide nanosheets and its reinforcing mechanism
    • Abstract: Publication date: Available online 6 July 2018Source: Cement and Concrete CompositesAuthor(s): Wu-Jian Long, Jing-Jie Wei, Feng Xing, Kamal H. Khayat The effect of graphene oxide (GO) nanosheets on the static and dynamic mechanical properties and microstructure of cement paste has been investigated. The results of dynamic mechanical testing revealed that loss factors of the pastes containing 0.05, 0.10, and 0.20 wt.% of GO were improved by 31%, 58%, and 77%, respectively. The maximum storage modulus of 52% was observed at a GO content of 0.1 wt.%, while the 28-d flexural and compressive strengths of the cement pastes with GO contents of 0.05 and 0.2 wt.% exceeded those of the control pastes by 12%–26% and 2%–21%, respectively. TGA analysis and microstructural analysis of the hardened cement pastes showed that the added GO could promote cement hydration, refine the capillary pore structure, reduce the air voids content, and improve the density of pastes. Dynamic mechanical properties reinforced mechanisms of paste incorporated with GO were also revealed based on the internal contact surfaces, porosity, and non-uniform stress distribution analysis.
       
  • Hydraulic clinkerless binder on the fluid sulfocalcic fly ash basis
    • Abstract: Publication date: Available online 5 July 2018Source: Cement and Concrete CompositesAuthor(s): František Škvára, Rostislav Šulc, Roman Snop, Adéla Peterová, Martina Šídlová Sulfocalcic fly ash (mostly called FBC fly ash) is formed when a dry process of limestone injection is applied to the desulfurization of flue gases. The hydration of sulfocalcic fly ash results in the formation of an expanding low-strength body. Its volume instability prevents its use as an admixture to the concrete. The mixing of sulfocalcic fly ash, PCC fly ash and Ca(OH)2 in a presence of a plasticizer gives the possibility to obtain a ternary binder possessing strength values comparable to those of Portland cement (PC). The ternary binder is characterized by a long-term volume stability thanks to the presence of the plasticizer based on polycarboxylates that modifies the habitus of ettringite crystals; the expansion stresses due to the ettringite modification are thus eliminated. The SEM/EDX analyses have revealed that the composition of the amorphous parts does not correspond to that of the C-S-H phase because even Al is present in this phase. It was found, the hydrated ternary binder contains an amorphous C-A-S-H phase, a crystalline ettringite phase as well as residues of crystalline phases (as mullite, quartz, hematite) from the fly ashes. The C-A-S-H phase in the hydrated ternary binder can also be characterized by 21Al MAS NMR as a geopolymer formed by alkaline activation of amorphous parts of ashes under the action of Ca(OH)2. The hydrated ternary binder is obviously similar to the Roman concrete because it contains an amorphous C-A-S-H phase. The ternary hydraulic binder would be a promising perspective for the use of the sulfocalcic fly ash that is nowadays predominantly deposit in the ash landfills.
       
  • Effect of concrete rheological properties on quality of formed surfaces
           cast with self-consolidating concrete and superworkable concrete
    • Abstract: Publication date: Available online 26 June 2018Source: Cement and Concrete CompositesAuthor(s): Wael A. Megid, Kamal H. Khayat An experimental program was undertaken to evaluate the effect of rheology of self-consolidating concrete and superworkable concrete on formed surface quality. In total, 31 mixtures with different workability and rheological properties were cast in a specially designed Z-shaped column without any mechanical consolidation. Surface defects, including surface air voids, signs of bleeding, segregation, and low filling ability were evaluated using a proposed image analysis methodology. The proposed method was successfully compared to other approaches that mainly target the detection of surface voids. Statistical models were developed between surface defect characteristics of formed surfaces cast with self-consolidating concrete and superworkable concrete and the rheological properties of the concrete. Concrete mixtures with yield stress lower than 25 Pa were found to develop superior surface finish. It was also observed that a prolonged delay in cement hydration of mixtures with yield stress lower than 50 Pa could lead to surface defects associated with bleeding. Mixtures with yield stress greater than 100 Pa exhibited considerable surface defects caused by insufficient filling ability of the concrete in the absence of mechanical consolidation. Finally, surface defects resulting from segregation were found with flowable concrete with plastic viscosity lower than 10 Pa s and yield stress lower than 100 Pa.
       
  • Multi-scale strategy for modeling macrocracks propagation in reinforced
           concrete structures
    • Abstract: Publication date: Available online 27 April 2018Source: Cement and Concrete CompositesAuthor(s): Christian Nader, Pierre Rossi, Jean-Louis Tailhan This paper introduces a new approach to model cracking processes in large reinforced concrete structures, like dams or nuclear power plants. For these types of structures it is unreasonable, due to calculation time, to explicitly model rebars and steel-concrete bonds. To solve this problem, we developed, in the framework of the finite element method, a probabilistic macroscopic cracking model based on a ulti-scale simulation strategy: the Probabilistic Model for (finite) Elements of Reinforced Concrete (PMERC).The PMERC's identification strategy is case-specific because it holds information about the local behaviour, obtained in advance via numerical experimentations.The Numerical experimentations are performed using a validated cracking model allowing a fine description of the cracking processes.The method used in the inverse analysis is inspired from regression algorithms: data on the local scale would shape the macroscopic model.Although the identification phase can be relatively time-consuming, the structural simulation is as a result, very fast, leading to a sensitive reduction of the overall computational time.A validation of this multi-scale modelling strategy is proposed. This validation concerns the analysis of the propagation of a macrocrack in a very large Double Cantilever Beam specimen (DCB specimen usually used in the framework of Fracture Mechanics studies) containing rebars. Promising results in terms of global behaviour, macrocracking information and important reduction in simulation time are obtained.
       
  • A printability index for linking slurry rheology to the geometrical
           attributes of 3D-printed components
    • Abstract: Publication date: Available online 1 April 2018Source: Cement and Concrete CompositesAuthor(s): Sabrina Ketel, Gabriel Falzone, Bu Wang, Newell Washburn, Gaurav Sant While the field of 3D-printing (3DP; formally known as additive manufacturing) has increasingly matured, its use in large-scale applications, e.g., building and infrastructure construction, remains limited. Although layer-wise slurry deposition/extrusion (LSD/E) methods are amenable to scale-up and offer versatility in terms of the materials that can be printed (i.e., “inks” that can be used), there is a lack of quantitative metrics to assess the geometrical attributes of printed components vis-à-vis their 3D-CAD (computer-aided design) inputs. To address this limitation, we present an original method to assess the external geometrical attributes of 3D-printed components using laser triangulation-based 3D-scanning. Significantly, a printability index (0 ≤ Ip ≤ 1, unitless) is presented which compares the overall geometric fidelity of the printed specimen to its CAD input. By adjusting the rheology of a model silicate-based slurry, we examine the relationships between slurry rheology, shrinkage and printability. The printability index offers a quantitative basis for assessment and quality control of 3D-printed components, while helping to develop an improved understanding of how slurry behavior, and optimizations therein can maximize printability.
       
  • Robust production of sustainable concrete through the use of admixtures
           and in-transit concrete management systems
    • Abstract: Publication date: Available online 11 January 2018Source: Cement and Concrete CompositesAuthor(s): Elise Berodier, Larry R. Gibson, Elizabeth Burns, Lawrence Roberts, Josephine Cheung The production of sustainable building materials, such as concrete, has drawn more and more attention in the last decade. Breakthroughs in the development of new admixtures, new mix designs, new concrete management systems, together with deeper understanding on the best-mode usage of admixtures with different cementitious materials have resulted in production of sustainable concrete with better performance at a lower cost. This paper reviews the latest mechanistic understanding on how admixtures interact with cement and cementitious materials, real-world examples on current practical challenges faced by concrete producers, and an example on the advances allowed by the use of transformational technologies for improved concrete management systems. We also highlight new technical challenges and conditions to investigate these gaps in hope to better coordinate research efforts critical to the industry.
       
 
 
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