International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 7, Issue 2, pp: (24-33), Month: October 2019 - March 2020, Available at: www.researchpublish.com
The effect of high and low temperature on the engineering behavior of the reinforced concrete and its impact on resistance Saad khalifa alshahoumi The Public Authority for Applied Education and Training, paaet
Abstract: The objective of the current research is to identify the properties of the structural material (reinforced concrete), to identify the effect of low and high temperatures on the engineering behavior of the reinforced concrete and its impact on resistance, and to make suggestions for controlling changes in concrete due to low or high temperatures. The study found that low and high temperatures affect the behavior of reinforced concrete, as high temperatures lead to heating of concrete elements, so that the level of this heating depends on the value of the temperature, the type of heating, and the type of rebar used. The increase in the temperature of the concrete elements changes the specifications of the components of these elements and affects their behavior when exposed to different loads. This reduces their resistance to carrying loads and increases the size of their elastic deformities. The elasticity coefficient decreases gradually when exposed to high temperatures. The bonding strength of the reinforcing steel to the concrete is reduced. As for the exposure of reinforced concrete to low temperatures; there is no agreement on the behavior of concrete under low temperature, but positive, even for lack of results with these characteristics, so that the concrete in cold weather can be useful for their mechanical performance over the time. Concrete can also be negatively affected when exposed to low temperatures. Low temperatures may contribute to the tendency of the concrete to slow down or even reverse, due to the low melting rate, leading to a reduction in the quality of the concrete structure. In general, there are four main factors that affect the behavior of concrete when exposed to freezing and melting. These factors are the effect of the water content of the cement (c / w), and the effect of the ratio between water and cement (Water Cement Ratio), the concrete content of the rubble, and the temperature. The research recommended that, in order to overcome the problem of low resistance to high temperature concrete and humidity, concrete additives such as fibers can be used to improve many of its engineering properties such as strengthening its durability and resistance to tensile strength and enabling it to withstand thermal shocks. Anti-freeze additives that reduce the freezing point can also be used. In the instructions for quantities to be used from these additives, Keywords: low temperatures, high temperatures, freezing, fire, reinforced concrete, concrete resistance.
1. INTRODUCTION The discovery of reinforced concrete as a construction material has led to significant progress in the building industry and the design of bridges, roads, etc., due to the advantages of this construction material from other materials, as it is characterized by good resistance compared to other materials, and it has high resistance against Water and fire, where the amount of this resistance increases over time due to the continuation of the reactions known as dehydration (the process of flattening) (Zarouk and Ibrahim, 2017). As with other materials, reinforced concrete has a range of defects. The most prominent of these defects is its low resistance to tensile strength. Its resistance to tensile strength is ten times its resistance to pressure, this requires the use of large amounts of reinforcing steel at tensile positions, taking into account the compatibility between the size of stresses generated in both iron and concrete (Ferguson, 1981). Swami (1988) added that one of the deficiencies of reinforced concrete is its problems over time, especially with regard to the problems of crawling and deflation, low resistance to high temperatures, and their susceptibility to humidity.
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