Abstract:

Polypropylene fibers are widely used in high-performance cement-based materials to reduce the high-temperature damage of structures. However， the calculation and prediction of thermal transfer parameters for polypropylene fiber reinforced concrete at high temperature still lack an effective model. Based on the homogenization method of composite materials， a refined multiscale calculation model was proposed to estimate the equivalent thermal conductivity of polypropylene fiber reinforced concrete at high temperature， which fully considered the influence of the volume change of polypropylene fiber at high temperature and the relaxation effect after fiber melting. As verified by experimental results， the proposed calculation model can accurately predict the thermal conductivity of polypropylene fiber reinforced concrete as a function of temperature. In addition， the thermal transfer properties and shape of polypropylene fiber have little effect on the equivalent thermal conductivity， while the fiber content is the main influence factor through model parameter sensitivity analysis. The analysis results provide a reference for the thermal design of fiber reinforced concrete.

Key words: fiber reinforced concrete, heat transfer properties, high temperature, homogenization method, relaxation effect