An Experimental Study On Spalling Of High Strength Concrete Elements Under Fire Attack

Abstract

The spalling of high strength concrete under f i e attack is discussed in this paper. Two series of f i e tests on reinforced concrete elements were carried out in order to investigate the spalling behavior and effect of spalling on the fire endurance of reinforced concrete elements. The results of the f i e tests on 30 specimens can be summarized as follows: a) the spalling is significantly affected by the water-cement ratio of the concrete, the permeability of the concrete, the amount of steel reinforcement, the f i e intensity and the age of the concrete at f i e exposure, b) the addition of polypropylene fiber into concrete is a good measure for the prevention of spalling and can improve the f i e endurance of reinforced concrete elements, c) the addition of polypropylene fiber into concrete at a ratio of Ikg polypropylene fiber per lm3 concrete reduces the depth of spalling by about 18mrn.

Experimental analysis of the spalling phenomenon in precast reinforced concrete columns exposed to high temperatures

“…It is observed that there is a direct relation between average crosssection loss with the increase of concrete cover thickness. These results agreed with those presented by Morita et al [17], who report that the increase of concrete cover thickness implies in the increase of concrete spalling. Figure 9 shows the relation between compressive strength and average cross-section loss.…”

“…Thereby, Sanjayan [15] shows that the concrete properties are not the main factors influencing spalling degree. Studies conducted by Ali [14], Kodur [16] and Morita et al [17], using full-scale samples, demonstrated that several design parameters, such as dimensions and shape of cross-section, presence and configuration of the reinforcement, intensity and mode of loading, influence the spalling phenomenon. Kodur and Raut [18] verified that stirrup configuration and spacing can contribute to the spalling occurrence.…”

Is high strength concrete more susceptible to explosive spalling than normal strength concrete in fire?

“…1,2,3,5,6,8À10,12,16À19, 23,25 These studies identified several distinct categories of spalling including surface spalling, corner spalling, aggregate spalling and explosive spalling. Although the different types of spalling vary in their severity, they each can cause unfavourable damage and deterioration of concrete structures in fires and can limit the application of fire resistant concrete design.…”

“…High concrete density stops the water vapour inside the concrete from escaping out of the concrete mass, which increases the susceptibility of spalling in fire. Many researchers, including Hertz and others, 2,3,4,7,11,12,14,15,20,23,26 studied high strength concrete exposed to fire, but most of these studies focused on specific types of high strength concrete (concrete of different ingredient and mix proportions). Some of the results of this research were used to reform guidelines of fire concrete design.…”

An experimental evaluation to determine the required thickness of passive fire protection layer for high strength concrete tunnel segments

“…Thermal behaviors of ingredients that constitute the aggregate and the binding paste of concrete are different. This difference could lead to relative deformations under heat exposure that can initiate the development of stress levels surpassing the direct tensile capacity of concrete [9,10]. Research also suggests a rapid increase of the internal pressures with lower temperatures due to lower porosity levels of higher strength concrete [10][11][12][13].…”