Investigating activation of expanded perlite with different grain size of nanometric and micronized particles

Approximately two-thirds of perlite, which has approximately 6700 million tons of reserves in the world, is found in our country. Perlite, which is of volcanic origin, expands in volume after heat treatment and then it is called as Expanded Perlite. Expanded perlite, containing high proportions of silica and alumina, is a construction material with pozzolanic properties that can be replaced by cement. Due to the substitution of pozzolanic materials for cement in high volumes, early-age strength development problems occur. It was thought that it would be important to examine the early-age fresh and hardened properties of expanded perlite with nano and micronized calcites having high reactivity and high specific surface area/volume ratio. In addition, it was understood that the studies on the substitution of perlite for cement and the publications of the State Planning Organization were insufficient and thus the necessary R&D studies should be carried out. For this reason, a detailed experimental study has been carried out on the effects of perlite and nano technology on the fresh and hardened properties of cement mortars in order to make our domestic resources with high reserves more subject to scientific research. For this purpose, nine different mortar mixtures containing 0%, 6% and 18% expanded perlite and 5% nano and micronized calcite were prepared. For mortar samples containing expanded perlite at different rates and modified with nano and micronized calcite, tests/analyses for mini-slump flow, consistency, initial and final setting times, dimensional stability (Le Chatelier Method), unit weight, and also compressive strength and ultrasound wave velocity tests for the curing ages of 7, 28 and 120 days were carried out. Experimental results showed that perlite adversely affects the early and hardened properties of mortars and improvements were, in general, obtained with nano/micronized calcite substitution. Since nano calcite has a relatively higher surface area, more contribution is made to the fresh and hardened properties compared to micronized calcite.