Cement hydration and microstructure in concrete repairs with cementitious repair materials

One of the key parameters for the performance of concrete repairs is the quality of the interface between repair material and concrete substrate. To understand the properties of the interface in concrete repairs with cementitious repair materials, cement hydration and microstructure were experimentally studied using non-evaporable water test, mercury intrusion porosimetry, and scanning electron microscopy techniques. The experimental results reveal that the moisture exchange between repair material and concrete substrate results in a change of the moisture content in the repair material and thus affects the cement hydration process and pore structure development. Backscattered electron images demonstrate the existence of an interfacial transition zone of high porosity, since the cement particles of the repair material have a poor packing on the surface of concrete substrate.