Research on Performance Deterioration of Internally Cured Pavement Concrete under the Coupling Effect of Salt Freeze-Thaw

This paper aims at solving the material durability problem caused by spraying deicing salt on pavement concrete in the northern winter. Super absorbent polymer (SAP) was adopted as an internal curing agent to enhance the durability of pavement concrete. Curing parameters including particle size and dosage of SAP and curing condition were optimized based on mortar tests by means of the grey target decision method. The deterioration rule of durability and mechanical properties of pavement concrete internally cured by different SAP dosages after salt freeze-thaw cycles were explored through rapid freeze-thaw test. Combined with the characteristics of pore structure, hydration and microstructure, the influence mechanism of SAP on the salt freeze-thaw resistance of pavement concrete was revealed. The experimental results showed that: (i) The reduction in mass loss rate and relative dynamic modulus was significantly improved by SAP internal curing with moderate dosage; (ii) The more freeze-thaw cycles the specimen underwent, the greater the increase in strength; (iii) After 75 cycles, the chloride ion erosion depth could be decreased by approximately 23.18%. Moreover, the addition of SAP could refine the pore size, inhibit the generation of shrinkage microcracks, and promote the degree of cement hydration in the late stage, which improved the internal density of the cement concrete structure. Therefore, the deterioration of pavement under the coupling effect of salt freeze-thaw was reduced.

Automated summary

This paper aims to solve the durability problem of pavement concrete caused by deicing salt in northern winter. Super absorbent polymer (SAP) was used as an internal curing agent to enhance its durability. The optimal curing parameters and the deterioration rule of pavement concrete after salt freeze-thaw cycles were explored through experiments. It was found that SAP internal curing significantly improved the mass loss rate and relative dynamic modulus, increased the strength, and decreased the chloride ion erosion depth.