Mechanism of frost damage of concretes with especially low permeability

According to the results of many studies and the provisions of standards, it is recommended to make frost-resistant concrete only on the basis of Portland cement with obligatory air entrainment. However, the recent research has shown that a  high degree of water content reduction with modern superplasticizers can also be used to produce Portland slag cement-based concretes with high frost resistance without the need for air entrainment. Environmental, economic and operational characteristics of such concretes are higher than those of concretes based on Portland cement. But until now the mechanism of frost damage and the role of air entrainment in such concretes have been insufficiently studied. In this connection, studies of concrete based on Portland slag cement with especially low permeability (W/C ratio < 0.3) have been carried out in the present work. All characteristics of the concrete mix and concrete have been determined according to the standards effective in Russia. Specifics of cement hydration products formation in concrete and their changes during cyclic freezing and thawing were investigated using X-ray diffraction, simultaneous thermal analysis and electron microscopy.
It has been established that the structure of the cement matrix of the developed concrete is formed with low porosity and mainly from weakly crystallized hydrated calcium silicates of tobermorite

Author: I.M. Ivanov, L.Ya. Kramar, K.V. Shuldyakov

Section: Waste utilization

Keywords: freeze-­thaw resistance, frost fracture mechanisms, ground granulated blast­furnace slag, Portland blast­furnace slag cement, water­-cement ratio, cement matrix, structure, calcium hydrosilicates, durability