Diatomite and pumice replaced cements investigation of hydratation reactions and surface properties byspectroscopic methods

Environmental pollution and global warming, increasing both in our country and worldwide, have boosted new product development studies in cement technology. One of the studies covers the possibility of replacing cement with natural or artificial pozzolanic materials. In this study, have used diatomite and pumice, which are abundant in our country. Former studies have revealed the positive effects of pozzolanic materials on the physical, chemical, and mechanical properties of concrete and cement. Furthermore, with the use of pozzolanic materials in production, environmental pollution is reduced, and energy resources are secured. Examining the literature, it has been detected that the use of pumice and diatomite which have a thinner structure than cement in cement production and concrete technology reduces permeability and therefore improves strength and durability properties, thanks to its pozzolanic quality. In this context, first of all, the physical, chemical, mineralogical and micro-structural properties of the raw materials were determined in the study. Then, for reference, CEM I 42.5 R type Portland cement, 10% and 20% diatomite and pumice separately; 7 different cements were obtained by substituting 5% and 10% pumice and diatomite together. The compressive strength of the cement mortars produced with these on the 2nd, 7th, 28th and 90th days, as well as the water requirement, setting times and expansion values of the prepared cement pastes were determined. Besides, XRD, FT-IR, DTA-TGA, and SEM were used to detect the reaction rates of the prepared cement mortars on the 2nd, 7th, 28th, and 90th days. In addition, the surface properties of the raw materials were determined and zeta potential measurements were carried out to understand the compatibility between them. As a result of all data, reactions occurring from the substitution of diatomite and pumice for cement, separately or together, have been detected. Among these analyses, XRD, FT-IR and DTA-TGA results show that cements containing sole pumice, diatomite and diatomite and pumice have a high hydration rate on the 90th day, and this hydration would continue. Furthermore, it has been detected that the chemically bound water contents of these cements are the same as, and even a little more than, the PÇ on the 90th day. In addition, SEM footages reveal that these cements get a denser microstructure as their hydration age increases. The results showed that pozzolanic materials reduced the compressive strength of mortars at an early age.However, on the 28th day, the compressive strength was reached above the minimum strength values of the PÇ 42.5R type cement, and on the 90th day, it was determined that the compressive strength values of both 10% pumice substituted and 5+5% pumice and diatomite substituted mortars were higher than the reference mortar. Keywords: Diatomite, Pumice, Hydration, Thermal analysis, Microstructure.