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.

To achieve value-added recycling of slurry -like mud (MS) and resolve the shortage issue of construction fill materials, physicochemical combined methods (PCCMs), which integrate flocculation, solidification, and vacuum preloading (optional), have been proposed to enhance the engineering properties of MS. The optimization of chemical admixtures, which consist of solidification and flocculation components, is crucial in ensuring the effectiveness and cost -efficiency of PCCM in practical application. In this study, a number of solidification model tests are performed to optimize the solidification components for PCCM via determining the optimal mixing ratio in each of the two GGBS-based binders. Subsequently, surcharge preloading deposition tests and vacuum preloading model tests, with different types/dosages of flocculant, are conducted to determine the appropriate flocculation components. The results indicate that OPC-GGBS exhibits remarkable effectiveness in strength improvement, and the use of a combination of organic and inorganic flocculant, particularly CaO-PAM, can significantly enhance the efficiency of PCCM. Moreover, increasing the dosage of the composite flocculants enhances the dewatering process, but the benefit becomes less significant when the dosage exceeds a threshold value of 0.16%. Additionally, this study provides a preliminary understanding of the key mechanism involved in synergizing flocculation, solidification and preloading to enhance the performance of MS. These findings contribute to the optimal design and application of PCCM for the treatment of MS.