Explosive spalling behavior of restrained concrete in the event of fire

Title: Explosive spalling behavior of restrained concrete in the event of fire
Author(s): Toru Tanibe, Mitsuo Ozawa, Dantas Rafael Lustoza, Kouetsu Kikuchi, Hiroaki Morimoto
Paper category : conference
Book title: 2nd International RILEM Workshop on Concrete Spalling due to Fire Exposure
Editor(s): E.A.B. Koenders and F. Dehn
ISBN: 978-2-35158-118-6
e-ISBN: 978-2-35158-119-3
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 319 - 326
Total Pages: 8
Nb references: 10
Language: English

Abstract: Recent papers have shown the explosive spalling of concrete occurred in the event of fire.
Such spalling results mainly from two processes: a thermo-mechanical process in which stress builds up in thermal deformation gradients within the material, and a thermo-hydraulic process in which stress accumulates due to the pressure of vapor in the concrete’s porous network. Many engineers and researchers have studied the addition of synthetic fiber to concrete to prevent explosive spalling in the event of fire, and this approach has proven successful in reducing such spalling caused by vapor pressure. However, it cannot directly reduce explosive spalling that stems from thermal stress.
A number of studies have also analytically demonstrated that the influence of thermal stress on explosive spalling is greater than that of vapor pressure. However, few papers have outlined actual experimental studies on the influence of thermal stress.
This paper reports on an experimental study regarding the behavior of restrained concrete in the event of fire. The study aimed to estimate thermal stress from restrained steel ring strain and vapor pressure in restrained concrete under the conditions of a RABT 30 rapid heating curve.
The specimens were made from high strength concrete (Fc: 90MPa) that were restrained by steel ring. The size of specimen was φ300×100mm. In the result, explosive spalling was seen from 4 minutes to 10 minutes (in heating time). Then, the thermal stress was greater than the vapor pressure value of 0.1 MPa at a point 10 mm from the heated surface at 5 minutes.
The maximum depth was about 61 mm, and the depth of the center part was greater than that of the outer part. The specimen was severely damaged. Spalling behavior caused by thermal stress may become predominant under restrained conditions.

Online publication: 2012-01-17
Publication type : full_text
Public price (Euros): 0.00