地聚物再生砖骨料混凝土与钢筋黏结-滑移试验研究

Experimental investigation on bond-slip behaviour between geopolymer recycled brick aggregate concrete and rebars

为解决地聚物再生砖骨料混凝土与钢筋的协同工作问题,进行了96个地聚物再生砖骨料混凝土与变形钢筋的中心拉拔试验,分析了再生砖骨料取代率(0、25%、50%、75%、100%)、矿渣掺量(25%、40%)、水胶比(0.45、0.5、0.55)、钢筋直径d(12~22 mm)、相对保护层厚度(2.63、4.19、5.75)、黏结长度(1d~8d)、养护条件(常温、80℃养护24 h)对黏结性能的影响。试验结果表明:提高保护层厚度、减小钢筋直径或减小黏结长度都可以提高黏结强度,有效防止地聚物再生砖骨料混凝土发生劈裂破坏;增大矿渣掺量、减小水胶比或采用80℃养护,都提高了地聚物再生砖骨料混凝土的抗压强度、抗拉强度和与钢筋的黏结强度,峰值滑移增大,但更容易发生劈裂破坏;随着再生砖骨料取代率的增大,黏结强度不断下降,再生砖骨料取代率50%时黏结强度下降19.77%~30.6%,再生砖骨料取代率100%时黏结强度下降37.0%~49.63%。根据试验结果,提出了地聚物再生砖骨料混凝土与变形钢筋的黏结-滑移模型,模型预测结果与试验结果吻合良好。

To solve the problem of collaborative work between geopolymer recycled brick aggregate concrete(GRBC)and rebars,pull-out tests were conducted on 96 specimens of GRBC with deformed rebar in this paper.The effects of parameters such as recycled brick aggregate(RBA)replacement ratio(0,25%,50%,75%,100%),slag content(25%,40%),water-to-binder ratio(0.45,0.5,0.55),rebar diameter d(12-22 mm),relative concrete cover(2.63,4.19,5.75),bond length(1d-8d)and curing conditions(ambient temperature,80℃for 24 h)on bond performance were investigated.The test results show that higher concrete cover,smaller rebar diameter or smaller bond length can increase the bond strength and effectively prevent splitting failure.With the increase of slag content or the decrease of water-to-binder ratio or using 80℃curing,the compressive strength,tensile strength and bond strength of GRBC are improved,and the slip at peak bond stress increases,but the specimen is more prone to splitting failure.Increasing RBA replacement ratio results in the decline in bond strength,and the bond strength reduces by 19.77%-30.6%when RBA replacement ratio is 50%,and reduces by 37.0%-49.63%when RBA replacement ratio is 100%.Based on the test results,the bond-slip model for GRBC with deformed rebar was developed,and the predicted results agree well with the test results.