## 3 Fresh and Hardened Properties of GPC
### Workability  
Generally, the workability of geopolymer mortar is controlled by flowability. Depending on the concentration of activators and their respective ratios, the workable flow ranges from \(110\pm 5\%\) (mm) to \(135\pm 5\%\) (mm). The workability of GPC influences its hardened properties [51]. [PERSON] et al. [105] found that the flowability further depends on the fly ash/alkaline solution ratio and Na\({}_{2}\)SiO\({}_{3}\)/NaOH ratio. The increase of the mentioned ratios results in more water demand to produce workable mix due to the higher viscosity of Na\({}_{2}\)SiO\({}_{2}\). It is reported that workability decreases with an increase in the molarity of NaOH [81; 106; 107]. [PERSON] et al. [108] studied the effect of the alkaline solution on HCWA geopolymer mortars and observed that by increasing Na\({}_{2}\)SiO\({}_{3}\)/NaOH ratio or NaOH molarity, the workability decreases owing to a substantial influence of NaOH concentration on the flowability of geopolymer mortar. [PERSON] et al. [109] concluded while studying the type of activator, Ca/Si ratio, and temperature effect on geopolymer mortar that the addition of Na\({}_{2}\)SiO\({}_{3}\) with no percentages of NaOH reduces the workability due to its higher viscosity. [PERSON] and [PERSON] [110] noticed that GPC with NaOH as an activator exhibits significant improvement in workability than the mixes containing the blend of NaOH and Na\({}_{2}\)SiO\({}_{3}\)[110]. According to [PERSON] and [PERSON] [111], the workability depends on the fineness of the aluminosilicate particle and SiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) ratio [111] present in GPC. The more value of fineness, the higher the slump value of GPC and vice versa [83]. Several researchers studied the effect of superplasticizers and nanoparticles on the workability of geopolymer pastes. [PERSON] et al. [112] found that with the use of naphthalene-based superplasticizer, the workability of FA-based geopolymer increases. However, the use of water significantly improved the workability than that of naphthalene-based superplasticizer but with a small reduction in strength [113]. According to [PERSON] et al. [114], the flowability of geopolymer mortar is reduced with the use of high content of GGBFS due to the increase of non-spherical particles in FA. [PERSON] et al. [115] investigated that the use of silica nanoparticles decreases the slump value due to accelerated reaction and high demand of nanoparticles. Figure 9 shows the effect of activator concentration and water to ash ratio on the flow of geopolymer samples. It is clear that with the increase of water to ash ratio, the workability increases while with a rise of NaOH concentration the workability decreases, due to an increase of viscosity. In addition, a strong relationship can also be visualized between flow and water/ash ratio with the coefficient of determination (R\({}^{2}\)) of 0.96. It is also observed that with the increase in silicates to hydroxide ratio, flow decreases, and the decrease drops with the rise in hydroxide concentration. The linear dependence exists between flow and hydroxide molarity with R\({}^{2}\) of 0.91 and 0.87 in case of higher and lower silicate/hydroxide ratio, respectively. From Table 5, it is observed that GPC has the highest workability when retarder is added. According to [PERSON] et al. [52], also retarder affects the initial and final setting time along with an insignificant change in strength development of GPC. [PERSON] and [PERSON] [53] reported that increasing alkaline content increased the workability and the flow value. However, the GPC mix containing OPC reduces workability and setting time and thus enhances compressive strength [53]. According to [PERSON] et al. [66], the aggregate grading, type, and packing influence the workability of GPC. The authors also found that GPC exhibits segregation when the coarse aggregate to sand ratio becomes higher, while it exhibits excessive bleeding when the ratio becomes lower.