粉煤灰掺量对不同骨料混凝土长期强度的影响

试验着眼于C30强度等级混凝土,以不同粗骨料(再生骨料、天然骨料)、粉煤灰掺量(15％、30％、50％)及养护环境(标养、室内自然养护)为变量探究粉煤灰对不同骨料混凝土长期强度的影响.试验结果表明,随着粉煤灰取代率的增加,在龄期较短时表现出对再生混凝土及普通混凝土的强度贡献率都有所下降的趋势,但后期经养护龄期的增加,180 d以后中长期强度贡献率下降幅度有所趋缓;当养护环境为标准养护时,粉煤灰取代率为30％以内试件的强度贡献率在180 d时达到了最大,之后强度贡献率有所下降,粉煤灰取代率为50％时,养护龄期超过180 d其强度贡献率也会有所增加;当养护环境为室内自然养护时,随着养护龄期的增长对不同取代率粉煤灰、不同骨料混凝土的中长期强度贡献率都有所加大.

Effect of Fly Ash Content on the Long Term Strength of Different Aggregate Concrete

The experiment focuses on the C30 concrete with different coarse aggregate(recycled aggregate,natural aggregate),fly ash(15％,30％,50％)and the curing conditions(standard curing,indoor natural curing),exploring the effect of fly ash as volcano ash active mineral admixtures on the long-term strength of the concrete with different coarse aggregate.The experiment results show that with the increase of replacement ratio of fly ash,at an early age the strength contribution of recycled concrete and ordinary concrete rate has declined,but with curing age increasing,the contribution rate of middle and long-term strength has declined slowly after 180 d.When in standard curing,the fly ash replacement rate is within 30％,the strength contribution rate reaches the maximum at 180 d,the strength contribution rate is decreased more than 180 d beyond 30％;but when the fly ash replacement rate is 50％,the strength contribution rate even more than 180 d will increase.When in the indoor natural curing,with curing period increasing,the long-term strength contribution of different replacement ratio of fly ash and different aggregate concrete has been increased.