The September 2023 issue (issue 5) of Construction Materials consists of four papers on concrete and geopolymer containing different types of materials including geogrid, fibre, recycled materials and rubber. In general, these materials should either lead to a concrete with better performance in terms of mechanical and durability properties or allow more utilisation of waste materials in construction, thus contributing towards the sustainability of our environment. In addition, the objectives of the journal would be fulfilled.
The first paper of this issue is authored by Al-Hedad et al. (2023) from the University of Wollongong in Australia; they examined the effect of using triaxial geogrid reinforcement on the thermal expansion of reactive powder concrete (RPC). They found that the thermal expansion of RPC is reduced when geogrid is employed and the increase in the number of geogrid layers led to a reduction in the thermal expansion. They went on to develop an equation to determine the thermal expansion strain when geogrid is used in the RPC with a single layer or double layers. This should allow wider utilisation of RPC in construction applications including concrete pavement, where crack control is of importance.
In the second paper, the effect of incorporating recycled aggregate of various sizes on the properties of pervious concrete is investigated by Singh and Singh (2023) of Dr B R Ambedkar National Institute of Technology in India. The recycled aggregate replacement was 100% of natural aggregate. Two sizes (4.75–10 mm and 10–12.5 mm) of recycled aggregate were used in different proportions to produce the pervious concrete. Using 75% of the smaller aggregate size in the pervious concrete was found to produce optimal properties in terms of density, compressive strength, porosity and permeability. The results of this research should lead to the use of recycled aggregate in pervious concrete where sustainable urban drainage and flood control are required. Also, using different layers of geogrid, which was the subject of the first paper, in the production of pervious concrete with recycled aggregate can lead to a better performance.
The third paper is from the National Institute of Technology – Tiruchirappalli in India and is authored by Rathod and Manikandaprabhu (2023), who report on the effect of E-glass and basalt fibres on the characteristics of plain and reinforced concrete. Combining basalt fibre and E-glass fibre led to an increase in compressive strength. The increase in compressive strength was more noticeable when 2% basalt fibre and 1% E-glass fibre were added to the concrete mix. The splitting tensile strength, modulus of elasticity and impact resistance were higher when both types of fibre were present in the mix. Also, the ultimate load-carrying capacity of reinforced concrete beams (RCB) containing basalt and E-glass fibres was higher compared with RCB without fibres.
The fourth and final paper is authored by Yomthong et al. (2023) from Mae Fah Luang University in Thailand, where they investigated the mechanical properties of geopolymer containing two different sizes (0.32 mm and 0.86 mm) of crumb rubber (CR). The rubber replaced the geopolymer matrix by up to 20% (by weight). They found a decrease in density, compressive strength and flexural strength with the increase in CR in the mix. The larger the size of CR, the greater the decrease in strength. The fracture toughness was not affected by the inclusion of CR. However, there was a substantial increase in impact strength due to the presence of CR and this provides an opportunity to use CR in geopolymer concrete in future applications. Cement requires intensive energy to produce and geopolymer often does not include cement; this should pave the way towards more sustainable construction.
This issue should be beneficial to researchers and professionals working in construction materials.
