预湿与附加用水组合处理方式下高红砖含量再生粗骨料替代率对C20混凝土性能影响研究

Study on the effect of high red brick content recycled coarse aggregate replacement rate on the performance of C20 concrete under the combined treatment of pre-wetting and additional water

研究了预湿与附加用水组合处理方式下,高红砖含量再生粗骨料替代率对C20再生粗骨料混凝土流动性能与抗压强度以及界面微观结构的影响。结果表明,在预湿与附加用水组合处理方式下,当高红砖含量再生骨料替代率小于50%时,混凝土流动性能与抗压强度受再生骨料替代率的影响较小;当再生骨料替代率超过50%后,即便采用预湿与附加用水组合处理方式,混凝土减水剂用量仍显著增大,混凝土流动性能受到明显影响,同时混凝土7、28 d抗压强度均显著降低;高红砖含量再生粗骨料对混凝土骨料与浆体界面结构的弱化作用,是其替代率过大时,混凝土抗压强度降低的主要原因。

Under the combined treatment of pre-wetting and additional water,the replacement rate of recycled coarse aggregate with high red brick content affects the flow properties,compressive strength and interface microstructure of C20 recycled coarse aggregate concrete.The results show that under the combined treatment of pre-wetting and additional water,when the replacement rate of high red brick content recycled aggregate is less than 50%,the flow performance and compressive strength of concrete are less affected by the replacement rate of recycled aggregate.When recycled bone after the material replacement rate exceeds 50%,even if the combined treatment of pre-wetting and additional water is used,the amount of concrete water-reducing agent is still significantly increased,the flow performance of concrete is significantly affected,and the compressive strength of concrete 7 d and 28 d is significantly reduced.The weakening effect of high red brick content recycled coarse aggregate on the interface structure between concrete aggregate and paste is the main reason for the decrease of concrete compressive strength when its replacement rate is too high.