A Novel Method of Self-Healing in Cementitious Materials by Using Polyacrylic Hydrogel
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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205
DOI 10.1007/s12205-020-0090-6
Structural Engineering
A Novel Method of Self-Healing in Cementitious Materials by Using Polyacrylic Hydrogel Bo Zhua,b, Qiu Lia, Wei Chena, Wei Zoub, and Wanyu Chenb a
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
b
ARTICLE HISTORY
ABSTRACT
Received 26 January 2020 Revised 29 April 2020 Accepted 7 June 2020 Published Online 28 August 2020
Cementitious materials are the most widely used in the construction. However, cementitious materials have defects such as low tensile strength which is easy to cause the formation of cracks. In recent years, with the research and application of smart materials, intelligent cementitious materials with self-sensing, self-diagnosis and self-healing functions have received extensive researcher’s attention. In this paper, a polyacrylic hydrogel that could be utilized for self-healing of cementitious materials was designed, and the three-dimensional network structure of the hydrogel controlled the release rate of encapsulated repair agent. The phosphate-incorporated hydrogel was filled into cement slurry to prepare self-healing cementitious materials. After the cement sample cracked and water penetrated into the crack, the phosphate was released from hydrogel. Phosphate reacted with the calcium in the pore solution to form hydroxyapatite type minerals which healed the crack. The self-healing cementitious material is in a position to heal cracks of 300 µm in width. After healing for 28 days at 20oC and 95% of RH, the compressive strength of precracked specimens could reach 85% of that of intact ones.
KEYWORDS Self-healing Hydrogel Phosphate Hydroxyapatite
1. Introduction Concrete is a versatile engineering composite material and it is made of cementitious materials, granular aggregates and admixtures in a definite proportion. It is one of the most commonly used building materials because of good compressive strength and favorable price. However, cementitious materials have defects such as low tensile strength which is easy to cause the formation of cracks. The microcracks form easily due to cyclic loading, severe environment and aging, which could result in deterioration of cementitious materials and embedded steel reinforcement. The methods of repairing microcracks and improving durability of concrete infrastructures have attracted researchers’ attention. In general, concrete cracks are repaired by conventional methods after regular inspection, and these methods cannot be successfully implemented due to repairing materials and working environments (Li et al., 1998; Carolyn and Mcmillan, 1999; Yildirim et al., 2015; de Belie et al., 2018). The advantage of self-healing concrete that automatically seals and heals cracks without human intervention has become more apparent than conventional methods (Guo et al., CORRESPONDENCE Wanyu
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