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.