聚丙烯纤维高温阻裂机理

通过研究不同纤维掺量自密实混凝土高温情况下的宏微观性能，探讨高温时材料内部的物理化学变化，以及不同温度状况下由微观结构变化所带来的宏观性能变化．试验中，待试样进行不同的高温处理过后，采用汞压力测孔法和扫描电镜对材料进行微观性能研究，并量测了高温后材料的气渗性能．同时，聚丙烯纤维的作用机理也得到了探讨．试验结果表明，纤维熔解能改善材料内部孔隙的连通性能，从而提高材料的气渗性能，降低了材料内部由升温集聚的孔隙压力．进一步，气渗性能的测量能作为评价纤维添加效果的有效手段．同时，研究中还发现熔解过程中聚丙烯纤维的工作机制，将有助于进一步的相关研究．

Mechanism of Polypropylene Fibers on Preventing Spalling of Self Compacting Concrete at High Temperature

This study aims to investigate the evolution of the chemical and physical properties of cement pastes and the change of macro properties caused by the microstructural changes at elevated temperatures of self-compacting cement paste(SCCP) samples.In the experiments,the samples were exposed to a certain high temperature,then mercury instruction porosimetry(MIP) and scanning electron microscopy(SEM) were applied to investigate the microstructure.Gas permeability test was carried out to define the effect of microstructural changes on the permeability of SCCP samples.The influence of polypropylene(PP) fiber was also investigated.Different PP fiber dosages were used to compare both the micro and macro properties.Results show that the melting fibers can be absorbed by the surrounding pores.The total porosity does not show big change due to the melting of the PP fibers.And the connectivity of the pore will be greatly influenced by the melting of the PP fibers.