## 1 Introduction  
Geopolymers or alkali-activated materials are classified as novel sustainable construction materials developed through geopolymerization or an alkali activation reaction between alkaline activators and aluminosilicate rich source materials, mainly supplementary cementitious materials (SCMs) [1]. These cement-free alkali-activated materials having better fresh state and hardened properties are found to be more sustainable than the currently available green eco-friendly blended cements and concretes in the market incorporating industrial wastes and natural pozzolans such as fly ash, volcanic ash, volcanic pumpice and other underused natural materials [1, 2, 3]. The alkali-activated materials are generally developed using a conventional two-part wet mixing technique incorporating solution-based reagents. The aluminosilicate-rich materials (precursors) and the alkaline solutions (reagents) are first separately prepared and mixed to obtain a wet mix. Various factors associated with this technique limit the commercial application or large-scale production of these materials. The first factor is using highly alkaline solutions and the heat curing of specimens to achieve desired mechanical and durability characteristics comparable to cement-based systems [4; 5; 6]. Additionally, preparing large quantities of these corrosive and viscous solutions creates a hostile environment for workers. The requirement of elevated temperature curing is energy-intensive, increases production costs and hinders construction applications [5; 6]. In contrast, a one-part geopolymer development technique incorporating s solid/powder form of reagents to improve the reaction process of aluminosilicate-rich materials provides a sustainable solution to the issues associated with the two-part system. These one-part geopolymers developed in ambient curing conditions by adding water to the pre-blended dry mix of precursors and reagents can obtain comparable mechanical and microstructural characteristics to cement-based systems [7; 8]. Moreover, the powder form reagents are required in significantly lesser quantities than their counterpart alkaline solutions typically used in the two-part system, which would reduce the production costs of the binders, making them commercially viable [6; 7; 8]. Understanding the influence of the ingredients of the alkali activation process on the workability, rheological, thixotropic and strength characteristics are crucial for developing alkali-activated materials from the point of view of their applications in construction industries. The effect of the SCMs, type and molarity of the alkaline reagents and the aggregate content on the workability and rheological characteristics of alkali-activated slag (AAS) and fly ash (AAFA) mortars in comparison with ordinary Portland cement (OPC) mortars was investigated by [PERSON] et al. [9]. The slag-based mortars activated with water glass (WG) exhibited lower static yield stress at all the liquid to solid (L/S) ratios than the AAS-based mortars with NaOH due to WG's better fluidizing characteristics. The percentage decrement between the first two static yield stress values for these mortars was consistently between 75-80%. The static yield stress in OPC mortars reduced with the increase in the L/S ratios. This was attributed to the reduction in inter-particle frictional forces because of the decrease in solid concentration with the additional water causing a decrement in mortar's resistance to flow. A 74% reduction in static yield stress was seen in OPC mortars on increasing the L/S ratio from 0.13 to 0.15. The AAFA-based mortars observed lower values for initial static yield stress than OPC or AAS-based mortars due to the insignificant activation of fly ash. This, in turn, would also nullify the influence of fluidization by WG on the initial yield stress values. The percentage reduction between the first two static yield stress values for both the AAFA mortars was 80%.