Analisys of Perlite Additive as Internal Cure Agent in Cement Concrete System

At the present stage of development of materials science, there are a large number of ways to reduce shrinkage in cement composite systems. However, not every of these methods can be classified as reliable, capable of providing the effect of non-shrinkage under any conditions. This problem becomes especially relevant when it comes to concretes and mortars that are intended for work in difficult conditions, for example, repair mortars. The main methods of curing for freshly molded concrete are analyzed, and the use of perlite sand as an internal maintenance agent to reduce shrinkage in the manufacture of repair mortars is justified. A method for measuring shrinkage using the TEREM 4.0 measuring complex is described. The effect of replacing part of the fine aggregate (quartz sand) with light aggregate (perlite sand) is considered. Graphs of the dependences of the shrinkage value were obtained for different contents of perlite sand and under conditions of low and high environmental humidity. It has been established that the introduction of fine fraction perlite into the cement-sand mortar, as a replacement for part of the sand, in an amount of no more than 5 % by volume is an effective way to reduce shrinkage deformations in dry conditions (φ ≤ 40 %).