FIRE ENDURANCE OF FIBER REINFORCED CONCRETE SUBJECTED TO DIFFERENT COOLING REGIMES | ||||
| International Journal of Advances in Structural and Geotechnical Engineering | ||||
| Volume 04, Issue 01, February 2020, Page 87-103 PDF (2.36 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/asge.2020.271119 | ||||
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| Abstract | ||||
| Fiber reinforced concrete (FRC) has become a very famous material due to its improved performances under both static and dynamic loads. On the other hand, Fire represent one of the most severe environmental conditions, and therefore, should be properly accounted for in the design of FRC. In addition, there is an urgent need to study and understand the behavior of FRC after exposure to fire. Therefore, this paper investigates the effect of using different types of aggregates and the effect of different cooling regimes on the mechanical properties; compressive strength, splitting tensile strength and flexural strength of FRC after exposure to fire flame. Two types of local aggregates crushed limestone and gravel were used. FRC were produced by addition of steel and polypropylene fibers in the mixtures at a constant content of 0.5% by volume. A total of seven concrete mixtures were produced and fibers were added in five of them. At the age of 28 days. Specimens were subjected to fire flame temperature ranging between (400- 800°C). Three temperature levels (400, 600 and 800°C) where chosen with exposure period of 2 hours after reaching the target temperature. After burning, the concrete specimens were allowed to different cooling regimes namely; air cooling, CO2 powder cooling, 15min spraying water and quenching water cooling. The results obtained from this study indicated that cooling regimes significantly influences residual properties of concrete, such as compressive strength, tensile splitting strength, and flexure strength. The fact that the impact of spraying water for 15 min or more on mechanical properties was almost the same as that of water quenching, indicates that spraying water for 15 min or more could cause thermal shock to a similar degree to water quenching. For each type of concrete under identical target temperature, among the four cooling regimes, CO2 powder cooling maintained a relatively higher value of residual compressive strength. Similar results were also obtained on splitting tensile and flexural strengths. The incorporation of fiber improved the fire resistance and splitting tensile strength of concrete as shown in concrete specimens containing steel fiber. Hybrid fiber (steel fiber and PP fiber) and steel fiber can enhance both residual strength of concrete subjected to thermal shock induced by rapid cooling from elevated temperature up to 800°C. | ||||
| Keywords | ||||
| Fiber reinforced concrete; fire; coarse aggregate; fibers; cooling regimes; residual strength | ||||
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