再生砂超高性能混凝土力学性能研究

Mechanical Properties of Ultra-high Performance Concrete with Recycled Sand

将废弃混凝土制成再生砂后,以不同掺量替代天然河砂,按标准试验方法制备了再生砂超高性能混凝土(UHPC),通过测试其各项力学性能,探究用再生砂制备UHPC的可行性.结果表明:再生砂在UHPC中的优选替代率为40%~60%,当再生砂替代率为60%时,再生砂UHPC具有较好的力学性能,其抗压强度、抗折强度、劈裂抗拉强度和弹性模量依次为170.26、19.45、12.17MPa和50.65GPa,比再生砂替代率为0%的对照组分别提高了1.88%、12.88%、8.27%和5.65%;随着再生砂替代率的增加,再生砂UHPC中的毛细孔占比呈现出先增大后减小趋势,表明掺入再生砂可以在一定程度上优化UHPC的孔径结构.

Processing waste concrete into recycled sand,and using recycled sand to produce ultra-high performance concrete(UHPC),different mechanical properties of UHPC were investigated by the standard test method by replacing natural river sand with recycled sand in different substitution rates.For the different mechanical properties of UHPC,the optimal substitution rate of recycled sand was in the range of 40%60%.The UHPC displayed high mechanical performance when the substitution rate of recycled sand was 60%.The compressive strength,flexural strength,splitting tensile strength,and elastic modulus of UHPC were 170.26MPa,19.45MPa,12.17MPa,and 50.65 GPa,respectively,which suggested that the compressive strength,flexural strength,splitting tensile strength,and elastic modulus of UHPC with recycled sand was 1.88%,12.88%,8.27%,and 5.65%,higher than control group of UHPC.With the increase of substitution rate of recycled sand,the content of capillary pores in UHPC increased firstly and then decreased,which suggested that pore structure of UHPC with recycled sand was improved to some extent due to the addition of the recycled sand.