The emission of CO₂ and energy requirement in the production of Ordinary Portland Cement (OPC) causes the continuous depletion of ozone layer and global warming. The introduction of geopolymer concrete (GPC) technology in the construction industry leads to sustainable development and cleaner environment by reducing environmental pollution. In this article, constituents of GPC and their influence on properties of GPC has been reviewed critically. Fresh and hardened properties of GPC as well as the factors influencing these properties are discussed in detail. Flow charts have been proposed to show which factors have higher/lower impact on the fresh and hardened properties of GPC. A comprehensive review on the mix design of GPC, nanomaterial-based GPC, 3D printing using GPC, reinforced GPC and Global warming potential (GWP) assessment was conducted. Finally, the practical applications of GPC in the construction industry are provided.

This research aimed at exploring the effects of a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH) activators in a sugar cane bagasse ash (SCBA)-based geopolymer cement paste. Bagasse ash replacement was 20% of cement by weight. The mixture of NaOH and KOH comprised 4, 8, and 12 M solutions with mixing percentages of 0%, 20%, 40%, 60%, 80%, and 100% for all possible combinations. A pH test was performed on each possible combination of solutions. A Chapelle’s test, XRD, X-ray fluorescence (XRF), and SEM analysis were used to check whether the SCBA exhibited pozzolanic reactivity. Subsequently, the SCBA geopolymer cement paste was tested for compressive strength, water absorption, permeable porosity, and sorptivity. It was estimated that the geopolymer cement paste exhibited higher absorption and sorptivity values than control mixtures when molarity increased. However, the samples prepared with combinations of the 8 M activator solution exhibited consistent absorption, sorptivity, and compressive strength values when compared to the control and other geopolymer mixtures with 4 and 12 M activator solutions. Thus, the two activator solutions G8N₄₀8K₆₀ and G8N₂₀8K₈₀—where GxN_ayK_b represents the geopolymer concrete sample prepared by adding solutions of two bases, i.e., ‘xN_ayK_b’ showing an ‘a’ percentage of ‘x’ molar NaOH and a ‘b’ percentage of ‘y’ molar KOH—were obtained as the optimum molar ratio of the activator in geopolymer concrete. The geopolymer cement pastes, along with the optimum and control samples, were further tested for concrete durability, SEM, and TGA tests. The G8N₂₀8K₈₀ sample exhibited a better mechanical and durability performance than the G8N₄₀8K₆₀ sample. The durability performance of the geopolymer concrete was also superior to ordinary concrete. Moreover, the geopolymer concrete achieved a 21% reduction in global warming potential compared to the control mixture. Thus, it can be concluded that the use of SCBA in geopolymer concrete can address the ash disposal and CO₂ emission problems with enhanced durability.

Bentonite clay is widely used as a hydraulic barrier in geosynthetic clay liners (GCLs) due to its low hydraulic conductivity, but in an aggressive environment, such as interaction with electrolytic solutions and higher temperature variations and number of wet and dry cycles, the performance of bentonite deteriorates. Polymerised bentonite clay (hyper clay) has shown better performance than untreated bentonite under these conditions, possibly due to better water retention, thus highlighting the need to investigate the water retention capacity. Therefore, the water retention behaviour of hyper clay GCLs was studied and compared with that of untreated clay GCLs. This paper presents the soil water retention curves of untreated bentonite GCL and hyper clay GCLs treated with 8% carboxymethylcellulose measured by filter paper tests. Different electrolytic solutions were used as permeation fluids along with deionised water to represent a more aggressive environment. The results showed that a hyper clay GCL has 7% higher water retention capacity near the air entry value than an untreated clay GCL in deionised water. In other words, a hyper clay GCL can be considered a potential alternative to conventional bentonite GCLs due to its improved water retention capacity.

Geosynthetic clay liners are widely used as hydraulic barrier due to their low hydraulic conductivity but bentonite in the liners loses its effectiveness due to significant thermal fluxes by both diurnal and seasonal heating and cooling cycles. Modified sodium carboxy methyl cellulose-based bentonite clay (HYPER clay) has shown better hydraulic performance in both situations. A possible reason for this improved performance of HYPER clay based geosynthetic clay liner is the improvement in the suction under changing thermal conditions. Thus, the relationship between soil suction and moisture content, also called the soil water retention curve, needs to be estimated. Therefore, we investigated the soil-water retention curve of the HYPER clay based geosynthetic clay liner and compared it with the untreated clay based geosynthetic clay liner. The article presents the suction test results on wetting path conducted on geosynthetic clay liner prototypes containing HYPER and untreated clay assessed by the contact filter paper method and the relative humidity sensor. The results showed that the geosynthetic clay liner containing HYPER clay has a high volumetric water content and thus, high water retention compared to untreated bentonite at a given suction value. In other words, the HYPER clay can be considered as a potential alternative to conventional bentonite due to its improved water retention capacity.