Development of self-healing cement pastes by long-term hydration

Optimizing material properties to ensure a minimal risk of service failure has become one of the major goals in construction industry. In situations where maintenance and material replacement is difficult, expensive and requires specialized skills, durability can be extremely important. The preparation process and the curing stage create internal voids in concrete, which can generate microcracks that will propagate during the structure’s life service. When the cracks reach the surface, the rebar will be exposed to water ingress and deterioration. This leads to a potential risk of structural collapse, compromising concrete’s durability. Cement based materials exhibit a natural capability to self-heal because of their long-term hydration process, resulting in some early age cracks to be spontaneously closed. This intrinsic self-healing ability can be boosted by using additives that react and bond chemically with the cement components. The use of fly ash, blast furnace or combinations of expansive agents proved to be effective in achieving long-term hydration. The combination of cement with additives with pozzolanic activity can boost the self-healing by closing microscopic cracks, preventing propagation and subsequent failure. This work investigates the self-healing ability of engineered cement composites using specific additives with high pozzolanic activity, the paper focus on the influence of these additives in their final mechanical properties. Self-healing efficiency was evaluated by assessing the mechanical strength of damaged and healed samples. It has been demonstrated the benefit of using pozzolanic additives to extend cement and concrete durability via crack closure