Spalling of concrete: A synthesis of experimental tests on slabs

Nicolas Taillefer,Dhionis Dhima,Pierre Pimienta,P. Pimienta,F. Meftah

doi:10.1051/matecconf/20130601008

Nicolas Taillefer, Dhionis Dhima + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/20130601008

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Abstract

The article reviews the results of many commercial or research tests carried out in CSTB on middle size concrete slabs. They concern 22 concrete slabs, made of normal and high strength concrete, for a rather wide range of thickness and compressive strength classes. Test procedures and a synthesis of main results are presented in order to provide deeper understanding of near-reality conditions of concrete structures. The tests concerned both new and existing tunnels. Results are detailed in relation with main parameters that are identified as impacting spalling in previous studies, such as concrete composition, concrete properties and specimen size.

Highlights

When dealing with safety of structures, the assessment of fire resistance in severe thermal conditions often requires an assessment of concrete spalling
Since slabs are quite large and show a significant zone of quite homogeneous spalling, and measuring step (15 cm) provides about 60 usable values, authors recommend characterizing spalling by the mean value of measures
It appears clearly that edge effect should be taken into account properly, but the size of the slab provides an interesting zone of “uniform spalling”

Summary

Introduction

When dealing with safety of structures, the assessment of fire resistance in severe thermal conditions often requires an assessment of concrete spalling. Recent catastrophic events enlightened the need for a deeper understanding on concrete mechanical characteristics changes when structures are submitted to high temperatures. On a structural point of view, spalled concrete depth is one of the essential parameters to be known, because it can directly impact the behavior of the structure. Various factors impact the physical phenomena leading to spalling and many studies aiming at better understanding them have already been undertaken. There still is a demand of experimental results in order to validate models and establish proper design methods taking into account the risk of concrete spalling due to fire exposure. Several research institutes have already released experimental data to feed research, and this article is intended to be a contribution to the process

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