Compression behavior in correlation with morphological findings of fly ash grout material

The ordinary Portland cement (OPC) is the function as a binder for grout material. However, a massive used of OPC had caused pollution to the environment. Thus, the earlier research proposed the environmental friendly binder known as geopolymer. This new binder needs to be mixed between alkaline liquids and materials rich in silica and alumina. In this paper, fly ash class C was used as source material with alkaline activators such as sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). This paper concluded that the concentration of NaOH solution and sodium silicate-to-sodium hydroxide (Na2SiO3/NaOH) ratios have a significant effect on compressive strength. The different concentration of NaOH solution (10 M and 12 M) and sodium silicate-to-sodium hydroxide (Na2SiO3/NaOH) ratios (1.5, 2.0, 2.5 and 3.0) were used in the production of geopolymer. The parameters such as curing and solid-to-liquid (S/L) ratio were controlled in this paper. The main evaluation techniques in this study were compressive strength and optical microscopy (OM). The optimum compressive strength obtained was 15.5 MPa for 28 days resulted from 12 M of NaOH concentration and Na2SiO3/NaOH with ratio 2.5.