科研之友
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摘要
The freeze-thaw cycle-damage test was designed and conducted on early-age hydraulic concrete at three freeze-thaw-damage ages (1 d, 2 d, 3 d) and two freeze-thaw cycles (5, 10). The compressive strength growth rate R1 and recovery rate R2 of freeze-thaw-damaged concrete specimens after standard curing to 28 days were used as self-healing indicators, combined with the results of pore-size distribution tests. The effects of freeze- thaw-damage age and freeze-thaw cycles on the self-healing ability of early-age freeze- thaw-damaged hydraulic concrete was investigated. The results showed that when the num-ber of freeze-thaw cycles of early-age hydraulic concrete is <10, the ability of freeze- thaw-damaged concrete specimens to self-heal is improved if standard curing continues. When the freeze-thaw-damage age is 1-3 d, the strength recovery rate R2 increases with freeze-thaw-damage age from 79.23% to 90.81% due to the ongoing hydration reaction of unhydrated cementitious materials within concrete. Additionally, since the freeze-thaw damage in concrete progresses from the surface to the inside, the pore-size distribution test showed that the total pore volume at the surface of the specimen was larger than that at the center of the specimen under the same number of freeze-thaw cycles, with a difference of 0.005813-0.018553 cm3/g. The increase was small in the proportion of harmful and multi-harmful pores in the freeze-thaw-damaged concrete specimens relative to the blank control specimens: 6.06% to 8.81% and 0.14% to 0.68%, respectively.
