reinforced concrete for diffrent temperature

rcc

1. introduction Concrete's mechanical and physical properties are significantly influenced by the environmental conditions during pouring and curing. Extensive research shows that extreme conditions—cold, dry, damp, humid, hot—impact its curing process. Construction may need to be delayed unless precautions like heating or wetting surfaces are taken. The main concern is how cured concrete behaves under varying conditions. Studies indicate that changes in temperature and moisture affect concrete's compressive strength and elasticity. For example, Lawson et al. [12] found a 100°C rise in temperature causes a 50% loss in compressive strength. Proper curing practices are essential for the durability of concrete structures.

2. Procedure  Specimen preparation 137 specimen cylinders were made 71 of them have  diameter 0.15 m(6 in) and height of 0.305 m (12 in.) And others have diameter of 0.10 m (4 in.) and a height of 0.2 m (8 in.) Enivronmental chamber  environmental chamber was designed to be capable of producing temperatures between -30C and 55 C to store the concrete specimens to measure the stress–strain relation of the concrete under different temperatures and moisture levels

3. Concrete Compressive and Tensile Strength Standard concrete cylindrical specimens were tested at various ages to measure strength gains over time, with tests conducted at a constant 20°C. Three specimens were tested for each time interval in both compression and tensile tests. Results show that concrete strength increases rapidly at first and then slows down by day 14, following the typical pattern of concrete strength development. Compression and split tensile tests on day 28 showed that concrete strength decreases as temperature rises. An 80°C increase in temperature reduced compressive strength by 38% and tensile strength by 26%. The strength-temperature data followed linear relationships

4. Modulus of elasticity and Poisson’s ratio Instrumented concrete cylinders were tested in compression at different ages to measure the modulus of elasticity and Poisson’s ratio. To ensure even load distribution, the cylinder ends were smoothed, aligned with the machine axis, and covered with rubber pads. Load was gradually applied and removed from 0 to 45 kN using a 225 kN capacity load cell. The stress-strain data obtained were used to calculate the modulus of elasticity and Poisson’s ratio.

5. RESULTS

6. CONCLUSION Temperature and moisture significantly impact concrete properties. In the study's range of -20°C to +50°C, higher temperatures and moisture levels degraded concrete strength and modulus of elasticity, though Poisson’s ratio was unaffected. Concrete curing initially reduced thermal expansion and strength but eventually increased compressive and tensile strength and modulus of elasticity. These changes should be considered in concrete structure design due to their influence on structural behavior, strength, and stiffness