自密实型超高性能混凝土(UHPC)的优化设计与性能研究

Optimaized Design and Performance Evaluation of Self-Compacting Ultra-High Performance Concrete(UHPC)

从配合比的优化设计入手制备了自密实超高性能混凝土(UHPC),并对其性能进行了研究。首先,通过最紧密堆理论确定三种不同粉体组成的基体;分析了减水剂对基体的流动性、强度以及水化放热过程的影响。在上述实验的基础上,优选出一组基体,与相对较低掺量的高效减水剂相结合,制备出自密实UHPC,并对其自密实性能和力学性能进行研究。研究结果表明:优选的水泥粉煤灰基体在减水剂掺量为2.3%(23 kg/m^3)时制备的UHPC,达到自密实混凝土的自密实性能要求;极限拉伸应变为2.5‰,韧性指数I_5、I_(10)、I_(20)分别为7.1,15.6,30.8,均符合UHPC的力学性能指标。

Self-compacting ultra high performance concrete（ UHPC） was produced based on the optimized design ofits particle skeleton and superplasticizer, and its properties were characterized.Firstly,the matrix of three different powders was determined by the optimized particle packing design.The effects of superplasticizer on the fluidity,strength and the hydration process of matrix were analyzed.Then,based on the obtained experimental results,one groups of matrix was selected to produce selfcompacting UHPC combined with the relatively low dosages of superplasticizer,and its workability and mechanical properties were evaluated. The results indicat that a self-compacting UHPC can be produced by cement/fly ash matrix with 2. 3%（ 23 kg/m^3） superplasticizer. The strain rate of the produced selfcompacting UHPC is 2. 5‰,and its toughness index I5,I（10） and I（20） are 7. 1,15. 6,30. 8 respectively,which meet the mechanical requirements of UHPC.