Effect Of Supersorbent Polymer On Self-Healing Performance Of Mortar

Concrete structure inevitably produced cracks in the service process,causing the invasion of harmful substances.The durability and structural service life of concrete decreased.The traditional restoration method takes time,labor and money.In recent years,self-healing concrete based on bionics has become a new research hotspot.Among them,there are more and more researches on the use of superabsorbent polymer(SAP)for good water absorption and water retention of micro-cracks in concrete for repeated healing.In this paper,the mechanical and the mass transfer resistance recovery of superabsorbent polymer mortars with different particle sizes and mixing amounts under different damage degrees and cracks healing under different healing ages were studied.The main research contents and results are as follows:(1)Uniaxial compression test and three-point bending test were used to study the changes of compressive strength and flexural strength of specimens before and after healing,and the healing effect of mortar was evaluated.The results showed that SAP could improve the strength recovery effect of mortar specimens,the strength recovery effect of mortar specimens with particle size of 19.7-64.8?m is higher when the content of mortar is 1.0% than when it is 0.5%;The greater the damage degree,the worse the recovery effect of compressive strength;(2)The capillary water absorption coefficient of mortar specimens before,during and after cracking was measured,and the change of mass transfer resistance of mortar specimens was studied.The results show that the capillary water absorption coefficient of mortar specimen decreases and the mass transfer resi stance of mortar specimen recovers after wet-dry cycle,and the greater the damage degree,the worse the recovery effect of mass transfer resistance.With the increase of particle size,the mass transfer resistance of mortar specimen increases first and th en decreases,and the optimum particle size range is 90.9-171.9?m;(3)The healing of cracks on the surface of mortar specimens at different ages was studied by using ultra-depth-of-field stereomicroscope.The results show that the crack width and area on the surface of mortar specimen are reduced to varying degrees after wet-dry cycle.With the increase of healing age,the degree of reduction is greater;(4)Hydration degree and microstructure of specimens without SAP and with 19.7-64.8?m SAP mortar were simulated by HYMOSTRUC software.The results show that SAP can improve the hydration degree of mortar specimens,and the more SAP is added,the more significant the improvement effect will be.