EFFECT OF LIMESTONE IN CEMENT ON THE STRUCTURE AND MODULUS OF ELASTICITY OF CONCRETE

Abstract

The beginning of the 21st century in Russia was marked by the intensification of activities aimed at adapting Russian construction standards to European ones. In this connection, they cancelled the decision taken in the Soviet Union not to introduce limestone additives into binders in the new GOST 31108 “Cements for general construction. Technical conditions”. Moreover, in 2003 the Russian GOST allowed the production of CEM II/A-I with limestone content from 6 to 20%, and in 2016 – introduced also CEM II/B-I with limestone content from 21 to 35%. However, earlier, the studies of V.V. Timashev’s school proved that the use of limestone additive in the dosage up to 5% positively affects the phase composition of cement stone and makes only a stabilizing effect when it is increased to 10%. The introduction of limestone admixture in cement above 10% starts to significantly affect the phase composition of hydrates, elastic modulus and Poisson's ratio of concrete, therefore it should be used in cement composition above 5% only after additional tests of concrete composition intended for operation in strictly specified conditions.