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.

Repeated Autogenous Healing in Strain-Hardening Cementitious Composites by Using Superabsorbent Polymers

“…In other mixtures, a varying amount of SAP expressed as masspercentage (m%) of cement weight was added on top of the reference mixture without SAPs. Two types of SAP from BASF were used: SAP A being a copolymer of acrylamide and sodium acrylate (particle size 100.0 AE 21.5 μm), and SAP B, a cross-linked potassium salt polyacrylate (476.6 AE 52.9 μm) (Snoeck et al 2014b). Both SAPs were produced through bulk polymerization and consisted of irregularly shaped particles.…”

Development of ductile cementitious composites incorporating microencapsulated phase change materials

“…Consequently, much research in recent years has been devoted to developing multifunctional SHCCs which can, apart from their excellent mechanical performance, provide added value to (existing) structures. For increasing long term durability of SHCC repairs, different methods of selfhealing have been proposed, for example addition of bacteria [18] or super absorbent polymers [19]. Furthermore, use of piezoresistive SHCCs for self-sensing of mechanical damage has been recently proposed [20,21].…”

Activation of Pozzolanic and Latent-Hydraulic Reactions by Alkalis in Order to Repair Concrete Cracks

“…Within this research area, different mechanisms are under development. The most common ones use encapsulated polymers (Dry and McMillan 1996;Thao et al 2009;Van Tittelboom et al 2011), calcium carbonate precipitating bacteria (Wiktor and Jonkers 2011;Van Tittelboom et al 2010;Wang et al 2012), or embedded hydrogels (Dennis Lee et al 2010;Kim and Schlangen 2010;Snoeck et al 2013) as healing/sealing agents. The current paper describes a preliminary study to evaluate whether alkaline activators can be used as healing agents in order to obtain self-healing in special types of concrete such as those containing large amounts of unhydrated fly ash (FA) or blast-furnace slag (BFS) particles.…”