C60机制砂泵送混凝土在两河口水电站木绒大桥悬臂梁的应用研究

Application of C60 machine-made sand pumped concrete in cantilever beam of Murong Bridge of Lianghekou Hydropower Station

以高海拔大温差地区两河口水电站木绒大桥为例,研究粉煤灰、硅粉及引气剂掺量对C60机制砂泵送混凝土工作性能、抗压强度、抗冻性能和微观形貌的影响。结果表明,粉煤灰有利于增加混凝土的坍落度、扩展度和抗氯离子渗透性能,不利于早期7d强度和抗碳化性能,但后期56d强度增加显著;硅粉会增加混凝土的强度,尤其是早期强度增加显著,28d强度达到79.5MPa,还会提高混凝土的抗碳化能力和抗氯离子渗透能力;引气剂可以减少胶凝材料总量,改善和易性,提高抗氯离子渗透能力,大量增加直径20nm以下的无害孔数量,从而有效改善混凝土抗冻融破坏能力。木绒大桥高品质机制砂C60泵送混凝土的抗裂等级为Ⅱ级,抗裂性良好。

The Murong Bridge of Lianghekou Hydropower Station in high altitude and large temperature difference area was taken as an example to study the effects of fly ash,silicon powder and air-entraining agent on the working performance,compressive strength,frost resistance and micro-morphology of C60 machine-made sand pumped concrete.The results show that fly ash is beneficial to increase slump,expansion and chloride ion penetration resistance of concrete,and is not conducive to the early 7 d strength and carbonation resistance,but its later 56 d strength increases significantly.Silicon powder can increase the strength of concrete,especially the early strength,which reaches 79.5 MPa in 28 d strength,and silicon powder also improve the carbonation resistance and chloride ion penetration resistance of concrete.Air entraining agent can reduce the total amount of cementing materials,improve the workability,improve the resistance to chloride ion penetration,and increase the number of harmless holes less than 20 nm in diameter,so as to effectively improve the frost resistance of concrete.The crack resistance grade of high-quality C60 machine-made sand pumped concrete for Murong Bridge is gradeⅡ,and the crack resistance is good.