Flexural Strength Deterioration of Steel Fiber Reinforced Concrete Due to High Temperature.


 Mohammed R. A. Kadir & Ismail H. Musa

University of Sulaimani



Abstract
    There are important cases in which concrete is exposed to high temperatures such as fire, chimneys and refractory structures, etc. exposing concrete to high temperature causes strength deterioration, increase in drying shrinkages, and the reduction in bond strength with reinforcement.
This investigation is carried out to study the effect of steel fiber addition on flexural strength deterioration of concrete exposed to high temperatures in the range of 20o to 800o C. The following variables are taken in to account: type of mix, fiber content and aspect ratio, heating duration and type of cooling. Test results have shown that the inclusion of steel fibers in concrete reduces the amount of strength loss due to heating, the degree of strength deterioration depends on the fiber content and high temperatures, and the bulk flexural strength lose occurs within two hours of heat exposure.

References:
1- Purkiss, J.A. , 1984, "Steel Fiber Reinforced Concrete at Elevated Temperatures", The International Journal of Cement Composites and Lightweight Concrete, Vol. (6) , No. 3, P.179-184.
2-Faiyadh, F.I. and M.A. Al-Ausi, 1986, "Effect of Elevated Temperature and Methods of Re-cooling on the Cmpressive Strength Plain and Fiber Reinforced Concrete", Third Rilem Intenational Symposium, UK. , P. 255-230.
3- Austin, S.A. and P.j. Robins, 1986, "Toughness Testing of Steel Fiber Refractory Concrete After Cyclic Heating", Third Rilem International Symposium, UK , P. 363-370.
4- Lankard, D.R. and H.D. Sheets, 1971, "Use of steel Wire Fibers in Refractory Castables", Bulletin Am. Cer. Soc. , Vol. (50), No. 5, p. 497-500.
5- Strevanck S.D. and R.H. Herran, 1980, "High Temperature Mechanical Properties of Stainless Steel Fiber Reinforced Castables", Bulletin Am. Cer. Soc. , Vol.(59), No. 7, P. 742-745.
6- ACI Committee 544, 1984, "Measurements of Properties of Fiber Reinforced Concrete", International Symposium on FRC Sp-81, Michigan, P. 433-440.
7- British Standards Institution, 1972, "Fire Tests on Building Materials and Structures", BS 476, Part 8 London.
8- Mohamed Bhai, G.T.G, 1986, "Effect of Exposure Time and Rates of Heating and Cooling on Residual Strength of Heated concrete", Magazine of Concrete Research, Vol.(38), No. 136, P. 151-168.