JournalTOCs

Materiales de Construcción
Journal Prestige (SJR): 0.903

Citation Impact (citeScore): 2
Number of Followers: 2

This is an Open Access Journal

Open Access journal
ISSN (Print) 0465-2746 - ISSN (Online) 1988-3226
Published by CSIC

[33 journals]

Influence of different sources of coal gangue used as aluminosilicate
powder on the mechanical properties and microstructure of alkali-activated
cement
- Authors: B. J. Frasson, R. C.A. Pinto, J. C. Rocha
  First page: 199
  Abstract: Coal mining wastes are associated with serious environmental problems; they have potential as building materials, including alkali-activated cement. In this study, the effect of different coal mining wastes on the mechanical properties and microstructural development of alkali-activated materials (AAMs) was evaluated through XRD, SEM and FTIR spectroscopy. Different alkali-activated compounds were produced; the alkaline solution was composed of NaOH+Na2SiO3. The results obtained using the calcined coal sludge showed excellent mechanical performance, with compressive strength higher than 60 MPa. However, addition of metakaolin and ordinary Portland cement was necessary to increase the mechanical performance of calcined coal gangue materials. The formation of N-A-S-H gel and the incorporation of iron ions into the cementitious matrix were evidenced. Ultrasonic pulse velocity indicated the early polymerization during the reaction processes. The study verified that the different characteristics of the wastes influence the performance of alkali-activated materials.
  PubDate: 2019-09-20
  DOI: 10.3989/mc.2019.12618
  Issue No: Vol. 69, No. 336 (2019)
Effect of different PVA and steel fiber length and content on mechanical
properties of CaCO3 whisker reinforced cementitious composites
- Authors: M. Cao, C. Xie, L. Li, M. Khan
  First page: 200
  Abstract: In this paper, calcium carbonate (CaCO3) whisker as a fiber reinforcement is mixed with steel and PVA fiber to form a multiscale hybrid fiber reinforced cementitious composites (MHFRCC). ASTM standard and post-crack strength techniques are performed to evaluate the mechanical properties of MHFRCC. The 1.25 % long steel fiber, 0.55 % short PVA fiber and 2.0 % CaCO3 whisker specimens showed the best flexural behavior before L/600 deflection. However, 1.5 % long steel fiber, 0.4 % long PVA fiber and 1.0 % CaCO3 whisker specimens presented better crack resistance after L/600 deflection. It is revealed that flexural parameters increase as comprehensive reinforcing index increase. The result showed that the CaCO3 whisker and short PVA fiber provided crack resistance effect at micro-scale and mainly play a dominate role in inhibiting micro-cracking. However, long steel fiber and long PVA fiber showed a better bridging effect of macro cracks at a large deflection.
  PubDate: 2019-09-25
  DOI: 10.3989/mc.2019.12918
  Issue No: Vol. 69, No. 336 (2019)
Assessment of mechanical properties of fibrous mortar and interlocking
soil stabilised block (ISSB) for low-cost masonry housing
- Authors: F. Qamar, T. Thomas, M. Ali
  First page: 201
  Abstract: Walls of Interlocking Stabilised Soil Blocks (ISSBs) have been considered in low-cost houses around the world especially in developing countries. These were reported to be very weak in resisting the lateral load (e.g. wind or earthquake) without special considerations. In this paper, mechanical properties (compressive strength, elastic modulus, pre/post crack energy absorbed and toughness index) of ISSBs with three configurations and seven combinations of plain and fibrous mortar cubes are experimentally evaluated. Sisal fibre and rice straw (2% and 5%, by cement mass) were considered for fibrous mortar. Empirical equations were developed to predict elastic modulus. It was found that ISSBs had reasonable strength to be considered for masonry. The failure load and toughness index of 2% sisal fibre samples was improved by 10% and 16%, respectively, whereas 2.21 times enhancement was found in elastic modulus. Thus, 2% sisal fibre in plaster (i.e. reinforced coating) would likely improve the lateral resistance of interlocked masonry walling.
  PubDate: 2019-09-25
  DOI: 10.3989/mc.2019.13418
  Issue No: Vol. 69, No. 336 (2019)
Acoustic behavior of porous concrete. Characterization by experimental and
inversion methods
- Authors: M. Pereira, J. Carbajo, L. Godinho, P. Amado-Mendes, D. Mateus, J. Ramis
  First page: 202
  Abstract: The use of porous concrete solutions with lightweight aggregates has become increasingly common in noise control due to their versatility in exterior and interior applications. In this work, samples of porous consolidated concrete with aggregates of expanded clay were produced, in order to study the influence of the grain size, thickness and water/aggregate/cement ratio on the sound absorption. Experimental techniques were used to obtain the surface impedance and sound absorption coefficient. In addition to experimental characterizations, an inverse method was used (based on a genetic algorithm) to obtain the macroscopic parameters capable of representing the materials studied through the theoretical model of Horoshenkov-Swift. Using the theoretical Horoshenkhov-Swift model it becomes possible to represent these materials in numerical models as equivalent fluids.
  PubDate: 2019-10-07
  DOI: 10.3989/mc.2019.03619
  Issue No: Vol. 69, No. 336 (2019)
Self-activation of slag-cements with glass waste powder
- Authors: M. A. Trezza, V. F. Rahhal
  First page: 203
  Abstract: The aim of this study is to evaluate the behavior of glass powder waste as alkaline activator of slag when both are used in blended cement. The slag blended cement was prepared with 70% slag, and then the slag was replaced with 10-20% glass powder by mass. The self-activation concept is here introduced. Ground glass releases alkalis through dissolution in a slow and sustained way over time. This would activate slag. Ground glass improves fluidity of mortars and the compressive strength overcomes dilution and increases with age due to the combined pozzolanic action of slag and glass. The proposed blended cement has better mechanical properties than slag-cement. The proposed blended cement has better mechanical properties than slag-cement and due to less use of slag, it becomes more sustainable and it contributes to waste management.
  PubDate: 2019-09-26
  DOI: 10.3989/mc.2019.13618
  Issue No: Vol. 69, No. 336 (2019)
Study of the suitability of a new structural concrete manufactured with
carbon fiber reinforced lightweight aggregates sintered from wastes
- Authors: J. M. Moreno-Maroto, A. L. Beaucour, B. González-Corrochano, J. Alonso-Azcárate
  First page: 204
  Abstract: The suitability of three new lightweight aggregates containing carbon fiber residues (CAs) as components in structural lightweight concrete has been studied. Prismatic concrete specimens were prepared using these CAs as a coarse fraction. Additional specimens of normal-weight aggregate, commercial lightweight aggregate and mortar were prepared for comparison. The CA-concrete samples (CACs) have yielded compressive strength values between 35 and 55 MPa as well as low density and thermal conductivity results. Furthermore, the CACs have displayed the highest ratios of mechanical strength over density and the thermal conductivity, which means that there is a better balance between their mechanical and physical properties than in the other samples studied. These results indicate that the new CAs could have great potential for use in structural lightweight concrete, also complying with the principles of the Circular Economy.
  PubDate: 2019-10-01
  DOI: 10.3989/mc.2019.05719
  Issue No: Vol. 69, No. 336 (2019)
Comparison between wet and dry timber visual strength grading according to
the Spanish (UNE 56544) and German (DIN 4074-1) standards
- Authors: D. F. Llana, F. Arriaga, M. Esteban, G. Íñiguez-González
  First page: 205
  Abstract: Visual strength grading is widely used to estimate mechanical properties of structural timber. National visual grades are allocated to strength classes according to European standard EN1912. The recent discussion about the proper function of visual strength grading standards and the assignment of strength classes shows the need for further research in this field. Spanish-sourced radiata, Scots, Salzmann and maritime pine timber samples were visually graded in wet and dry condition according to the Spanish UNE56544 (2011) and German DIN4074-1 (2012) standards. Rejection was far higher dry due to distortion (warping) parameters. However, this rejection could be significantly mitigated by adopting a higher twist limit (2 mm / 25 mm width). UNE 56544 is more suitable for visually grading these species because it was specifically designed for them and a Spanish source. However, both standards underestimated the Scots pine rejection pieces which mechanical properties fulfill the MEG and S10 grades.
  PubDate: 2019-09-26
  DOI: 10.3989/mc.2019.03319
  Issue No: Vol. 69, No. 336 (2019)