机制砂UHPC轴拉性能试验研究

Experimental study on axial tension performance of mechanical sand UHPC

基于传统UHPC制备技术,优化原材料组分和配合比,配制出强度等级为120MPa的机制砂UHPC,开展不同材料掺量与配比对机制砂UHPC轴拉性能试验研究。结果表明:钢纤维的掺入能较好地约束机制砂UHPC变形和内部微裂纹的扩展,提高抵抗开裂能力和增强抗拉强度和拉伸应变,效果随钢纤维体积率的增加而逐渐增强,但在钢纤维掺量超过2%后增幅明显趋缓;机制砂UHPC抗拉性能随水胶比的增大呈先增大后减小的趋势,在水胶比0.18时,其抗拉强度和峰值应变最大分别为9.7MPa、2745.6με;适当增加机制砂UHPC中部分粗颗粒质量分数和石粉的掺量可以提高机制砂UHPC的抗拉性能。根据上述结果,机制砂UHPC的优选配合比设计为水胶比0.18,细度模数3.0,石粉含量5%,钢纤维体积掺量2%,可为后续机制砂UHPC力学性能深入研究与推广应用提供参考。

Based on the traditional UHPC preparation technology,the composition and mixing ratio of raw materials were optimized,and the strength grade of 120MPa machined sand UHPC was prepared,and different material dosage and ratio were carried out to test the axial tensile properties of machined sand UHPC.The results show that the incorporation of steel fiber can restrain the deformation of UHPC and the propagation of internal microcracks,improve the cracking resistance and enhance the tensile strength and tensile strain.The effect gradually increases with the increase of steel fiber volume ratio,but the increase obviously slows down when the steel fiber content exceeds 2%.The tensile properties of UHPC increased first and then decreased with the increase of water-binder ratio.When the water-binder ratio was 0.18,the tensile strength and peak strain of UHPC were 9.7MPa and 2745.6με.The tensile properties of UHPC can be improved by appropriately increasing the mass fraction of coarse particles and the content of stone powder in UHPC.According to the above results,the optimal mix design of machined sand UHPC should be 0.18 water binder ratio,3.0 fineness modulus,5%stone powder content and 2% steel fiber volume content,which can provide a reference for further research and application of machine-made sand UHPC mechanical properties.