Evaluation of self-healing in reactive powder concrete with urea-formaldehyde/epoxy microcapsules

The use of microcapsules as a preservative agent for healing materials has led to a great revolution in the repair of materials. Microcapsules have been used in medicine, agriculture, metallurgy, and mechanics. In civil engineering applications, microcapsules are usually used for the self-healing of concrete, asphalt and cementitious materials. Concrete and cement are widely used in civil engineering and they are distinguished as the predominant construction materials worldwide. The objective of this study is to design and produce urea-formaldehyde microcapsules for the recovery of reactive powder concrete (RPC). The obtained results demonstrated that the RPC specimens containing microcapsules exhibit different behaviors, compared to RPC specimens without microcapsules. For all RPC specimens containing microcapsule, measured values of strengths were lower than specimens without microcapsules. The minimum reduction in the compressive strength was observed in specimens with microcapsules content ranging from 4% to 6% by cement weight. The healing ratio of the compressive strength increased by increasing the weight percentage of microcapsules. Scanning electron microscope (SEM) imaging and energy dispersive spectroscopy (EDS) analysis were used to observe the process of crack healing. The SEM/EDS results showed that cracks are filled by healing products.