Geopolymer-based cementitious materials known for their robust durability and lower environmental impact make them an ideal choice for sustainable construction. The main focus of this study is to understand the influence of chemical admixtures which plays a pivotal role in improving the properties of geopolymer mortar (GM). This research integrates various chemical admixtures, including calcium chloride, sodium sulphate, sodium hexametaphosphate, and MasterGlenium SKY 8233 (SKY) which falls under the category of either accelerators, retarders, or superplasticisers. Assessments were conducted on the fresh and hardened states of flyashbased GM mixes with varying proportion of river sand (RS), laterite soil (LS) and copper slag (CS), encompassing flowability, setting times, compressive strength, durability study in aggressive environmental conditions and microstructural analyses after 56 days of ambient curing. Findings reveal that calcium chloride and sodium sulphate efficiently decrease the initial and final setting times of the geopolymer paste, highlighting their roles as accelerators, with calcium chloride showing greater efficacy than sodium sulphate. On the other hand, sodium hexametaphosphate serves as a retarder, substantially extending the initial setting time of the geopolymer paste. Introducing the modified polycarboxylic ether (PCE) based superplasticiser SKY into the mortar matrix caused the initial setting time to be extended and resulted in a slight drop in compressive strength compared to the other mixes. Durability tests confirmed the superior resistance of GM mixes to harsh environments like acid, sulphate, and marine water exposure. These findings highlight the potential for tailoring geopolymer blends to achieve desired properties under ambient curing conditions using chemical admixtures.

Foam concrete has been used in various real-life applications for decades. Simple manufacturing methods, lightweight, high flowability, easy transportability, and low cost make it a useful construction material. This study aims to develop foam concrete mixtures for various civil and geotechnical engineering applications, such as in-fill, wall backfill and soil replacement work. A blended binder mix containing cement, fly ash and silica fume was produced for this study. Its compressive strength performance was compared against conventional general purpose (GP) cement-based foam concrete. Polypropylene (PP) fibre was used for both mixtures and the effect of various percentages of foam content on the compressive strength was thoroughly investigated. Additionally, two types of foaming agents were used to examine their impact on density, strength and setting time. One foaming agent was conventional, whereas the second foaming agent type can be used to manufacture permeable foam concrete. Results indicate that an increase in foam content significantly decreases the strength; however, this reduction is higher in GP mixes than in blended mixes. Nevertheless, the GP mixes attained two times higher compressive strength than the blended mix's compressive strengths at any foam content. It was also found that the foaming agent associated with creating permeable foam concrete lost its strength (reduced by more than half), even though the density is comparable. The compressive stress-deformation behaviour showed that densification occurs in foam concrete due to its low density, and fibres contributed significantly to crack bridging. These two effects resulted in a long plateau in the compressive stress-strain behaviour of the fibre-reinforced foam concrete.