关键词: 再生混凝土;粉煤灰;力学性能;抗冻性;衰减模型

Abstract: Effect of fly ash admixture amount and recycled coarse aggregate substitution rate on the flexural strength and compressive strength of recycled concrete was studied,and compressive strength and mass loss rate of recycled concrete under 4 stages of freeze-thaw cycle were measured. It's shown that with the increase of fly ash content,the compressive strength of recycled concrete firstly increases and then decreases. The maximum compressive strength of recycled concrete is reached when the fly ash content is 15% and the replacement ratio of recycled coarse aggregate is 30%. The flexural strength is increased, but lightly when the fly ash is included. When the freeze-thaw cycle is lower than 50 times,the compressive strength of the test block decreases slowly,and then the rate of decline is accelerated. When the freeze-thaw cycle reaches 150 times,the strength loss is the largest. The substitution rate of recycled coarse aggregate is higher than that of fly ash content. The prediction model of compressive strength of recycled concrete under freezing and thawing cycles is established considering the replacement ratio of recycled coarse aggregate and the amount of fly ash.

Key words: recycled concrete;fly ash;mechanical property;frost resistance;degradation model