Microstructural response of polypropylene fibres at high temperature to protect concrete from spalling

Abstract

The microstructural analysis of the interfacial transition zone (ITZ) and the interaction of polypropylene fibres (PPF) with mortar in the temperature region 170 to 300 °C have been considered. The results confirm a mixed mechanism: The presence of the PPF alters the ITZ and favours an initial cracking formation. After melting, PPF diffuses in the surrounding cement paste closing micropores while, simultaneously, macro pores are increased as consequence of the free space leaved and the growing of microcracks.