冻融环境下沙漠砂再生混凝土的轴心抗压力学性能试验研究

Experimental study on the axial compressive mechanical properties of desert sand recycled concrete under freeze-thaw environment

为了研究沙漠砂再生混凝土(DSRC)在冻融环境下的耐久性能,探明沙漠砂(DS)和再生粗骨料(RCA)替代率对其冻融后力学性能的影响规律,并为DSRC在新疆等寒冷地区构件和结构设计提供数据支撑,对DSRC进行冻融后轴心抗压强度试验,分析冻融循环作用下DSRC质量损失率、动弹性模量损失率和应力-应变曲线的变化规律。结果表明:在冻融循环次数相同时,DSRC动弹性模量损失率、极限应变和弹性模量均小于普通混凝土,峰值应力大于普通混凝土;随着冻融循环次数增加,DSRC质量损失较小,动弹性模量损失率、峰值应变和极限应变均增加,峰值应力和弹性模量均减小;DS和RCA替代率分别为40%时,DSRC质量损失率和动弹性模量损失率分别为0.25%和27.50%,其抗冻性能最优;采用普通混凝土本构模型对DSRC应力-应变曲线进行拟合,相关控制参数表明曲线预测能力良好,可对冻融后DSRC的力学性能进行分析。

In order to study the durability performance of desert sand recycled concrete(DSRC)in freeze-thaw environments,explore the influence of desert sand(DS)and recycled coarse aggregate(RCA)substitution rate on its mechanical properties after freeze-thaw,and provide data support for the design of components and structures of DSRC in cold regions such as Xinjiang,the axial compression test of DSRC after freeze-thaw was carried out to analyze the change rules of mass loss rate,dynamic modulus loss rate and stress strain curve of DSRC under freeze-thaw cycles.The results show that the loss rate of dynamic elastic modulus,ultimate strain and elastic modulus of DSRC are lower than those of ordinary concrete,and the peak stress is higher than that of ordinary concrete at the same freeze-thaw cycles;With the increase of freeze-thaw cycles,the mass loss of DSRC is small,the loss of dynamic elastic modulus,peak strain and ultimate strain increase,and the peak stress and elastic modulus decrease;When the DS and RCA substitution rate are 40%,the DSRC mass loss rate and dynamic elastic modulus loss rate are 0.25%and 27.50%,respectively,which indicates the optimal frost resistance performance;The ordinary concrete constitutive model is used to fit and analyze the stress strain curve of DSRC,and the relevant control parameters show that the curve has good prediction ability,which can be used to analyze the mechanical properties of DSRC after freezing and thawing.