Comparison of modulus-elasticity of pavement alkali-activated concrete and normal concrete under high temperature Based on XRD and SEM test

In recent decades, the use of alkaline materials in concrete has found a wide perspective in the concrete industry due to its pozzolanic properties and the presence of aluminosilicate materials with high filling and adhesion properties. The use of this type of concrete (due to its superior advantages over ordinary concrete) in paving roads can improve the strength and increase the useful life of roads. In this laboratory research, a mixture ratio of normal concrete with a cement grade of 450 kg/m3 was made. A mixture ratio was also made of activated alkali concrete based on blast furnace slag to compare and evaluate the modulus of elasticity of concrete under ambient temperature and heat of 500 ℃, at the age of 90 days. Next, X-ray Diffraction Spectroscopy (XRD) and Scanning Electron Microscope (SEM) tests were carried out in order to further investigate and verify the results of the modulus of elasticity test, at the processing age of 90 days at ambient temperature and It was done on concrete samples under the heat of 500 ℃. The modulus of elasticity at ambient temperature was 32 GPa for ordinary concrete and 35 GPa for activated alkali concrete, which had a difference of 8%. By applying heat to concrete samples, the amount of modulus of elasticity drop in normal concrete reached 59% and in activated alkali concrete 42%. The results of the XRD and SEM tests were in agreement with each other and overlapped with the results of the modulus of elasticity test.