自密实型超高性能混凝土(UHPC)的优化设计与性能研究

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/m3)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I5、I10、I20分别为7.1,15.6,30.8,均符合UHPC的力学性能指标.

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

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 self-compacting 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/m3) superplasticizer.The strain rate of the produced self-compacting UHPC is 2.5‰, and its toughness index I5 , I10 and I20 are 7.1, 15.6, 30.8 respectively, which meet the mechanical requirements of UHPC .