Title: Fibers, Percolation, and Spalling of High-Performance Concrete

Author(s): Dale P. Bentz

Publication: Materials Journal

Volume: 97

Issue: 3

Appears on pages(s): 351-359

Keywords: concrete; cement ratio. fibers; high-performance concrete; spalling; water-

DOI: 10.14359/9878

Date: 5/1/2000

Abstract:
While the strength and durability of high-performance concretes (HPCs) are often greatly superior to conventional concretes under ambient conditions, their failure is sometimes rapid and dramatic during exposure to afire, characterized by the explosive spalling of layers from the exposed concrete surface. This failure mode is rarely encountered in conventional concretes of higher w/c ratios. In these concretes, it is suggested that the interfacial transition zones (ITZS) surrounding each aggregate particle provide a convenient escape route for the vapor built up during the thermal exposure. In HPC, these IT2 regions are thinner and notpercolated, but can be repercolated by the addition of just a few (0.2 to 0.5% by volume) fibers. Here, simulations are conducted to determine the relative efficiency of different length fibers in creating a percolated network, and to investigate the effects of aggregate volume fraction and gradation on IT2 percolation.