粉煤灰在超高性能混凝土中的应用技术研究

Study on application technology of fly ash in ultra-high-performance concrete

水泥用量大、成本高,限制了超高性能混凝土(UHPC)的发展。以Ⅰ级粉煤灰和粉煤灰微珠为主要掺合料制备了环保型UHPC,探究了其对工作性能、力学性能及收缩性能的影响规律,并分析了其协同作用效果。结果表明,20%掺量下,Ⅰ级粉煤灰和粉煤灰微珠体系UHPC的工作性能均优于矿粉体系。低掺量条件下,UHPC的工作性能、力学性能和自收缩性能均随粉煤灰微珠掺量的增加而提高,且各项性能优于矿粉体系。但当粉煤灰微珠掺量大于15%时,不利于UHPC的工作性能和力学性能发展。Ⅰ级粉煤灰和粉煤灰微珠掺量均为10%时,UHPC的工作性能最佳,力学性能可与矿粉体系持平。

The development of ultra-high performance concrete(UHPC)was restricted due to the large consumption and high cost of cement.In this study,Ⅰclass fly ash and fly ash microsphere were used as main mineral admixture to produce UHPC.The effect ofⅠclass fly ash and fly ash microsphere and their synergy effect on the workability,mechanical property and autogenous shrinkage of UHPC were evaluated.The results show that the workability of UHPC withⅠclass fly ash and fly ash microsphere is better than that with slag when the dosage is 20%.The mechanical properties and autogenous shrinkage increase with the increasing fly ash microsphere content,and the performance is better than that of slag blended UHPC under low mineral admixture dosage.However,when the content of fly ash microsphere is higher than 15%,it is not conducive to the workability and development of mechanical properties.When the content ofⅠclass fly ash and fly ash microsphere are both 10%,the workability of UHPC is the best,and the mechanical properties can be equal to that of mineral powder system.