Chemical Shrinkage of High-Strength / High-Performance Cementitious Materials

Abstract

Chemical shrinkage is important property of cementitious materials. It is considered the main cause of autogenous shrinkage of high-strength / high-performance concretes, which are made at low water/cement (w/c) ratio. It is generally assumed that chemical shrinkage varies directly as the degree of hydration and is independent of w/c, since it has its origin in the hydration reaction stoichiometry. The methods of measurements of chemical shrinkage, which include dilatometry, pycnometry and gravimetry (buoyancy), are briefly reviewed. The interpretation of the experimental data on chemical shrinkage of hydrating cement paste is revised in the paper. The chemical shrinkage of cement pastes with w/c ratios of 0.45, 0.33, 0.25 and 0.21 was tested by gravimetry method. The degree of hydration of the pastes was determined by thermogravimetric analyzer (TGA). The effect of water/cement ratio on chemical shrinkage of hydrating cement pastes cured in saturated and sealed conditions was established and compared with the literature data.