Authors: Ms. Harsha R. Dhabale, Prof. Deepa Telang
DOI Link: https://doi.org/10.22214/ijraset.2023.49123
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The purpose of this study was to provide an overview of the effect of elevated temperature on the behavior of concrete materials. The effects of elevated temperatures on the properties of common portland cement concretes and manufacturing materials are summarized. The effect of elevated temperature on conventional concrete, GGBS concrete and BFS concrete is considered and the performance is compared with the strength of conventional concrete. Concrete in case of an unexpected fire, the properties of the concrete will change after the fire. The building must be designed to withstand high temperatures and also mainly fire. When exposed to high temperatures, such as during a fire, the mechanical properties of concrete such as strength, modulus of elasticity and volume stability are significantly reduced. Concrete structure is exposed to high temperatures, it degrades in many different ways, such as color, compressive strength, elasticity, and high temperature affects concrete density and surface appearance.
The behavior of concrete at high temperatures is influenced by several factors, such as the speed of temperature rise and the type and stability of the aggregate. Sudden changes in temperature can cause spalling and cracking due to thermal shock, and aggregate expansion can also damage concrete . High temperatures also affect the compressive strength of concrete. Above 212ºF, the cement paste begins to dry out (lose chemically bound water of hydration), which gradually weakens the bond between the paste and the paste material. The temperature that concrete often reaches can be determined by observing the color changes in the aggregate. For example, limestone materials turn pink when their temperature reaches about 570º F, which can cause a significant reduction in compressive strength . The thermal properties of concrete are more complex than most materials, because the performance of portland cement-based materials at high temperatures is very difficult, and it is difficult to characterize concrete as a composite material with different properties in its composition, but its properties. also depends on . to ensure moisture and porosity. Exposure of concrete to high temperatures affects its mechanical and physical properties. The changes in properties are due to three processes that occur at high temperatures : phase transformation (eg, loss of free water at approximately 100 ?C, decomposition of calcium hydroxide at approximately 50 ?C, and quartz crystal transformation at 573 ?C. ?C from C temperature - to form), pores structure development (eg, pore volume and surfaces increase to the temperature of an accidental fire, etc.) causes severe damage and undergoes a series of changes and reactions, thus causing a gradual degradation of the cement gel structure, reduced durability, increased tendency to drying and shrinkage, structural cracks and associated overall discoloration .
Fire safety measures of structural parts are measured by fire resistance, which is the time during which a structural part lasts in terms of structural integrity, stability and temperature permeability. Concrete generally offers the best fire resistance properties of all building materials. This superior fire resistance is due to the constituents of concrete (ie, cement and aggregates) which, when chemically combined, form an essentially inert material with low thermal conductivity, high heat capacity, and slower loss of strength with temperature. It is this slow rate of heat transfer and loss of strength that allows concrete to act as an effective fire protection not only between adjacent rooms, but also to protect itself against fire damage .
The behavior of a concrete structural part exposed to fire depends partly on the thermal, mechanical and deformation properties of the concrete from which it is composed. As with other materials, the thermophysical, mechanical and deformation properties of concrete change significantly in the temperature range associated with construction fires. These properties vary with temperature and depend on the composition and properties of the concrete. The strength of concrete significantly affects its properties both at room and high temperatures. The properties of high strength concrete (HSC) vary with temperature unlike normal strength concrete (NSC). This variation is more pronounced in the mechanical properties, which are affected by strength, humidity, density, heating rate, amount of silica fume and porosity .
II. PROBLEM DEFINITION
The objectives of the proposed work are as follows:
V. BLOCK DIAGRAM
The compressive strength of concrete decreases with increasing temperature due to the large dehydration of calcium hydroxide in cement and increased water vapor, which leads to a decrease in strength. In addition, moisture reduces weight when the temperature rises. These are known facts from previous studies. However, the purpose of this study is to obtain a numerical database for Class 0 concrete, which was not included in the previously mentioned work, to guide the design of prefabricated equipment for this class of concrete. For example, at a recommended design age of 28 days for concrete grade 0, a strength loss of 53.7% and a weight loss of .67% at 30 oC were studied. They point to the fact that more research is needed on high-temperature concrete to guide the proper design of facilities where high temperatures are required in places such as nuclear reactor vessels and fire-prone buildings..
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Copyright © 2023 Ms. Harsha R. Dhabale, Prof. Deepa Telang . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Authors : Harsha R.
Paper Id : IJRASET49123
Publish Date : 2023-02-15
ISSN : 2321-9653
Publisher Name : IJRASET
DOI Link : Click Here