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

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

The behaviour of superabsorbing polymers in concrete as a sealing agent: absorption kinetics, degradation and water permeability testing

info:eu-repo/semantics/publishe

The use of superabsorbent polymers as a crack sealing and crack healing mechanism in cementitious materials

As concrete cracks due to its low tensile strength and as harmful fluids may migrate into these cracks, the durability of concrete is endangered if no proper treatment or manual repair is applied. To address this need, this research focusses on the use of superabsorbent polymers (1) to seal cracks from intruding potentially harmful substances and (2) to heal the crack due to further hydration and precipitation of calcium carbonate. The first focus relies on hindering the fluid flow by swelling of superabsorbent polymers after they are exposed to a humid environment. The sealing capacity was measured by means of water permeability tests and through visualization of permeability tests by neutron radiography. Superabsorbent polymers are able to seal cracks and thus allow a recovery in water-tightness as a decrease in permeability is noticed. The second focus relies on healing of small cracks in fibre reinforced cementitious materials, restoring the mechanical properties. The regain in mechanical properties was analyzed by four-point-bending tests and the crack closure was microscopically monitored. Cracks close through the combination of further hydration of unhydrated cement particles, precipitation of calcium carbonate and activation of the pozzolanic reaction of fly ash. Desorption of superabsorbent polymers triggers healing in the vicinity of crack faces and cracks up to 130 μm were able to close completely in wet/dry cycles due to the precipitation of calcium carbonate. Mortar samples containing superabsorbent polymers even showed partial healing when stored under a relative humidity of more than 60%. In this way, a smart cementitious material which is reliable and independent from the conditions is acquired

Visualization of water penetration in cementitious materials with superabsorbent polymers by means of neutron radiography

info:eu-repo/semantics/publishe