Avoiding spalling of precast HPC & UHPC elements by using a novel layered concept

Abstract

A novel solution for fire protection of concrete based in external protection layer concept is proposed. The solution applies for modifying the granular skeleton of the outer layer but maintaining the interface functionality between both, the structural and the protective, layers as it has the ability to be integrated in the precasting process of UHPC or HPC elements. This solution looks for improving the efficiency of the element in front of fire while preserving the inner outstanding structural properties. Paper focuses on the results of fire response of several approaches of protected layers applied to high performance concrete samples. The solutions are characterised under fire conditions both respect mechanical loss of protective layers and respect temperature gradients evolution under ISO fire test. The results show that for adequate protection respect spalling risk of HPC a smart granular skeleton of the external exposed to fire layer is fundamental. The protective layer to follow the performance requirements of the hybrid system has to assure a physic-mechanical compatibility of both during fire exposure.