Self-healing cementitious materials by the combination of microfibres and superabsorbent polymers

Abstract

Concrete cracks due to its low tensile strength. The presence of cracks endangers the durability as they generate a pathway for harmful particles dissolved in fluids and gases. Without a proper treatment, maintenance costs will increase. Self-healing can prevail in small cracks due to precipitation of calcium carbonate and further hydration. Therefore, the use of microfibres is proposed to control the crack width and thus to promote the self-healing efficiency. In the current research, crack sealing is also enhanced by the application of superabsorbent polymers. When cracking occurs, superabsorbent polymers are exposed to the humid environment and swell. This swelling reaction seals the crack from intruding potentially harmful substances. Mortar mixtures with microfibres and with and without superabsorbent polymers were investigated on their crack sealing and healing efficiency. Regain in mechanical properties upon crack healing was investigated by the performance of four-point-bending tests, and the sealing capacity of the superabsorbent polymer particles was measured through a decrease in water permeability. In an environment with a relative humidity of more than 60%, only samples with superabsorbent polymers showed healing. Introducing 1 m% of superabsorbent polymer gives the best results, considering no reduction of the mechanical properties in comparison to the reference, and the superior self-sealing capacity.