Mechanical characteristics of pumice-based geopolymer paste

One way to promote sustainability is by using high volume of by-product materials in construction materials, namely by geopolymerization. For that purpose, other studies have focused on the common supplementary cementitious materials (e.g. fly ash and metakaolin) as a precursor. However, there are other potential types of precursor can also be used for geopolymerization purpose. Thus, this study used pumice powder, which is rich in Silica and Aluminium, to produce geopolymer paste. For activation by alkali solution, the ratios of sodium silicate to sodium hydroxide and alkali solution to precursor was fixed at 2.50 and 0.35, respectively. To find optimum molarity, curing temperature and curing period, the pastes made with different alkali concentration (8, 10, 12, 14, 16 and 18 M) and cured at room temperature, 60, 80 and 100 degrees C temperature for 24, 48, 72 and 120 h. The results showed that optimum flexural and compressive strength can be made for the mixes at 60 degrees C of oven curing for 120 h with the alkali solution of 12 M. Additionally, high-strength paste can be obtained at high curing temperatures with less curing time, but when compared to low temperature and more curing time, the flexural and compressive strength gains are less.