Effect of healing agents on the rheological properties of cement paste and compatibility with superplasticizer

Abstract

Self-healing concrete is considered as a new generation of concrete with the ability to heal cracks without human intervention. The healing agents are incorporated into the concrete to activate the healing mechanism and to improve the healing efficiency. While both lab- and large-scale projects have shown that the addition of healing agents can have a possible positive effect on the hardened concrete properties (e.g. compressive strength), unfortunately, the evaluation of fresh properties of self-healing concrete mixes is often neglected. In the current study, the effect of healing agents is clearly identified starting from the paste level. Different techniques were used to study the effect of healing agents on the consistency, viscosity and adsorption behaviour of PCE-based superplasticizer in cement paste. A crystalline admixture and bacteria were used as healing agents, and CEM III/A was used as the binder component of the paste. The results showed that the inclusion of bacteria did not influence the rheological properties of the cement paste and no incompatibility issues were found with the superplasticizer. On the other hand, the presence of the crystalline admixture in the paste interfered with the rheological properties of the cement paste as a reduction of workability, an increase of paste viscosity, and an increased adsorption of superplasticizer.