The evaluation with anova of the effect of lime admixture and thermal cure time on fly ash paste activated with sodium silicate solution

Class F fly ash obtained from Kütahya Seyitömer (Turkey) thermal power plant was used as raw material in this study. Fly ash was activated with sodium silicate solution (water glass) and quenched calcium lime was substituted to the mixture at rates ranging from 10% to 30%. Then, samples were formed in 4 × 4 × 16 cm metal molds by means of the vibration method. The samples were subjected to thermal curing in a laboratory type oven at +105 °C for 12, 24 and 48 h in order for them to acquire resistance. After the curing process, the physical properties such as apparent porosity, apparent density, bulk density, water absorption by weight and linear shrinkage, and the mechanical properties such as flexural strength and compressive strength of the samples were determined by the three samples for each mixture. After the physical and mechanical tests, a two-factor analysis of variance (ANOVA) and a comparative analysis of the mean values were carried out in order to investigate the effects of the variables used in the production and the preparation of the samples on the values. Consequently, it was determined that in the fly ash-lime mixtures, 24 h curing for the samples with 20% lime substitution is very efficient and that these samples yield the best compressive strength.