EXPERIMENTAL INVESTIGATION ON THE COEFFICIENT OF THERMAL EXPANSION AND CONRACTION OF CONSTRUCTION MATERIALS

Low-temperature thermal cracking is one of the most prominent failures of flexible pavement. To quantify the stresses caused by abrupt temperature changes, thermal contraction and thermal expansion coefficients must be known. This attribute is difficult to assess in materials with complex behaviour, such as asphalt concrete, and no systematic methods are currently available for determining it in laboratory experiments. The thesis’ fundamental goal is to provide a research procedure for calculating the coefficient of thermal contraction and expansion of asphalt concrete. More precisely, the operation must be as effective as possible, with as little operator interference. The instrument used for this purpose was a dynamic shear rheometer (DSR), which is generally used for the rheological characterization of materials like bitumen. With the methodology developed using the DSR, it is possible to calculate the variation in height along with the temperature change more precisely. Mainly three methods have been compared in this study to quantify CTC and CTE. Out of 3 methods, the first method was already developed in previous work by another researcher. In this thesis, we analyzed this methodology and checked its reproducibility. The key factors in this methodology are that the DSR makes the measurements at given target temperatures only after the specimen reaches thermal equilibrium and the measuring plate (PP08) enter into the measuring cell only to take measurements at target temperatures. The temperature range used is 40 °C to -10 °C with a 20 °C/h temperature gradient. Concerning the second method, two different techniques were applied. The first technique’s procedure is that we didn’t consider the thermal equilibrium of the specimen, and the measurements are taken instantly at target temperatures. Even in this technique, the measuring plate enters the measuring cell only to take measurements at target temperatures. The temperature range chosen is 20 °C to -10 °C with a 10 °C/h temperature gradient. While discussing about the second technique, everything is the same as the previous one, apart from the thermal ramp. Here we use a 5 °C/h thermal ramp. Finally, in the third method, the temperature range and thermal ramp (5 °C/h) are the same as the second method, but here we use the invar bar of 8 mm diameter as a measuring plate instead of PP08, and the vital factor in this method is that the measuring plate will be inside the measuring cell for the entire test and make the measurements. Approach one will be beneficial as we cope with extensive temperature ranges, and the second and third approaches will be ideal with a shorter temperature gap. From the second and third methods, we get more reliable information regarding the deformation of the specimen between two consecutive temperatures.