稻壳灰与混杂纤维对超高性能混凝土的影响作用研究

Study on Effect of Rice Husk Ash and Hybrid Fiber on Ultra-high Performance Concrete

超高性能混凝土(UHPC)具有优异的力学性能、耐久性且能减轻结构自重、降低材料使用量,具有广阔的应用前景。但UHPC中大量采用超细硅灰与钢纤维等材料,成本较高。对此,拟采用稻壳灰取代一定量硅灰,选用聚丙烯纤维、玄武岩纤维与钢纤维混杂,通过测试UHPC的流动度、静动态力学性能、收缩变形与氯离子扩散系数,研究稻壳灰与混杂纤维对UHPC的影响规律。结果表明:稻壳灰用于UHPC是一种性能优良的廉价矿物掺合料,用量适当时能明显改善UHPC流动度、力学性能与体积稳定性;混杂纤维未能使UHPC取得较理想的力学性能和耐久性,但对UHPC抗裂性能有所改善。

The ultra-high performance concrete(UHPC)has excellent mechanical properties,durability,can reduce the weight of the structure and the amount of material used and has a broad application prospect.However,the large amounts of materials,such as ultra-fine silica fume,steel fiber,etc.are used in UHPC,making its cost higher.Therefore,the rice husk ash is proposed to replace a certain amount of silica fume,the polypropylene fiber and basalt fiber are selected to mix with the steel fiber to study the influence rule of rice husk ash and hybrid fiber on UHPC by testing the fluidity,static and dynamic mechanical properties,shrinkage deformation and chloride diffusion coefficient of UHPC.The results show that the rice husk ash is a kind of cheap mineral admixture with excellent performance,and the fluidity,mechanical properties and volume stability of UHPC can be significantly improved when the dosage of rice husk ash is appropriate;the hybrid fiber cannot make UHPC obtain ideal mechanical properties and durability,but improve the crack resistance of UHPC.