机制砂在山区高速公路桥梁高性能混凝土中的应用

Application of machine-made sand in high-performance concrete of highway bridges in mountainous areas

结合具体工程,通过遴选机制砂替代天然砂、优化水泥供应质量、控制原材料带入混凝土中碱含量等措施,进行混凝土配合比优化设计和试验。结果表明:所配制的C55混凝土碱含量总体受控,在水胶比和砂率不变的条件下,采用天然砂与亚甲蓝值≤0.5、石粉含量5%~7%的机制砂试配混凝土7 d及28 d抗压强度相当且增长正常,满足配制强度和工作性能要求,而当机制砂亚甲蓝值超过0.5,达到0.8、1.0和1.2时,混凝土碱含量增加明显,7 d后强度几乎不增长,甚至出现倒缩。

Combined with specific engineering application examples,through the selection of machine-made sand to replace natural sand,optimizing the quality of cement supply,and controlling the alkali content of raw materials brought into the concrete,the optimal design and test of the concrete mix ratio are carried out.The results showed that the alkali content of the prepared C55 concrete is generally controlled.Under the condition of constant water-binder ratio and sand ratio,the concrete of natural sand and machine-made sand with methylene blue value≤0.5 and stone powder content of 5%~7%,which the 7 days and 28 days compressive strengths are equivalent and the growth is normal,which meets the requirements of formulation strength and work performance.While the methylene blue value of machine-made sand exceeds 0.5 and reaches 0.8,1.0 and 1.2,the alkali content of concrete increases significantly,and the strength is almost unchanged even shrinkage after 7 days.