## 4 Conclusions  
The characteristics of one-part alkali-activated mortars (AAMs) developed from binary (fly ash-C 'FA-C or C' + ground granulated blast furnace slag 'GGBFS or 'S') and ternary (FA-C + fly ash-F 'FA-F or F' + GGBFS) combinations of supplementary cementitious materials (SCMs) with two types of powder-based reagents (calcium hydroxide + sodium metasilicate and calcium hydroxide + sodium sulfate) incorporating silica sand is described. The conclusions drawn from fresh state, rheological, hardened and microstructural properties of the developed eight binary (combinations of C and S) and ternary (combinations of C, F and S) AAMs compared to a control high volume fly ash-based cement counterpart are as follows:  
* The AAM mortars incorporating reagent one (Ca(OH)\({}_{2}\):Na\({}_{2}\)SiO\({}_{3}\) = 1:2.5) obtained higher yield stresses than those with reagent two (Ca(OH)\({}_{2}\):Na\({}_{2}\)SO\({}_{4}\) = 2.5:1) owing to the relatively more significant formation of colloidal complexes (Si-O-H-Na) and Si-Al binding phases. FA-F in ternary (CFS) mixes led to lower yield stress ranging from 51.2 to 77.4 Pa than their binary (CS) counterparts (62.2 to 160.8 Pa). The shear modulus and yield stress were observed to decrease with the increase in the slump flow spread of the mortar mixes. * The slump flow gradually reduced, and the plastic viscosity increased with time from 0 to 60 min after mixing. Lower slump flow/relative slump reductions were noted for mortars with reagent two (250 to 180 mm)/(5.2 to 2.2) than their counterparts with reagent one (245 to 105 mm)/(5.0 to 0.1) after 30 min of mixing. This lower decrease in slump flow spread of mixes with reagent two can be attributed to their higher liquid to solid ratios and the predominant formation of cementitious reaction products having shorter chains than the Si-Al linkages in alkali-activation products formed in mixes with reagent one. * There was no change in the slump flow of cement-based control mortar (FP\({}_{\text{C}}\)M) with time (0 to 60 min after mixing). The high volume (55%) fly ash class F with characteristic round shape particles enhanced the workability, and the formation of shorter C-S-H linkages led to the lowest viscosity, lowest yield stress and highest compressive strength of the control mortar. * All the AAM mixes showed decreased viscosity with an increase in shear rate up to 3.5 RPM depicting pseudoplastic behavior. The mixes with reagent two exhibited slightly lower or similar initial and final viscosities at 0.5 RPM. These binary and ternary mix compositions with reagent two (CSM2, CSM2N, CFSM2 and CFSM2N) also obtained lower viscosities/yield stresses and a higher slump flow spread than their counterparts with reagent one. This rheological behavior of reagent two mixes can be attributed to the dominant formation of cementitious gels (C-A-S-H and C-S-H) with shorter chains or linkages than the polymeric chains associated with geopolymeric products (N-A-S-H and N-C-A-S-H) formed in mixes with reagent one. * The formation of both amorphous and crystalline phases in AAMs is evident from the SEM/EDS analysis. Portlandite formation in the mortars with reagent two is responsible for synthesizing additional binding phases resulting in higher compressive strengths than their counterparts with reagent one. The formation of C-A-S-H/C-S-H and C-A-S-H/N-C-A-S-H as the primary binding phases for binary and ternary mortars is characterized from the SEM/EDS analysis. * The shorter linkages/chains present in the cementitious (C-A-S-H and C-S-H) binding phases and higher liquid to solid (L/S) ratios of mixes with reagent two resulted in a higher flow spread/relative slump, lower plastic viscosities and yield stresses compared to mixes with reagent one with a more significant formation of geopolymeric (N-C-A-S-H and N-A-S-H) products.