Temperature Distribution in a Cement Concrete Slab using Thermocouples and an Experimental Study on Replacement of Fine Aggregate by Manufactured Sand

Concrete is one of the most widely used construction material throughout the world. Usage of concrete is next to the water. Concrete is man-made material produced by the proper mixing of cement, coarse aggregate, fine aggregate (N-sand or M-sand) and an adequate and controlled amount of water, with or without super plasticizers. In this project two slabs were cast with different material properties like one slab cast with N-sand and another slab cast with M-sand. Slab design is largely based on past experience and empirical data. Temperature differential across the depth or thickness of the concrete slab causes the slab to warping and deform resulting in the bending and temperature stresses. The analysis is based on the assumption that the temperature distribution is linear throughout the depth of the slab. This is an approximation because studies have shown that the actual temperature distribution is non-linear. Various researchers have proved that the assumption of linear temperature differential is un- conservative. Therefore, it is necessary to consider non- linear temperature differential instead of linear temperature differential to evaluate the temperature stresses and in the design of slabs when exposed to temperatures. Therefore, an attempt has been made in this study to evaluate the stresses due to the actual temperature distribution across the thickness of the slab. Two slabs of different material properties are cast, instrumented with K-type thermocouples at different levels viz., top, middle and bottom and the actual temperature in the slabs are recorded every hour (8:00 AM - 5:00 PM) for 28 days using a digital temperature recorder. The result obtained from the study clearly shows that the actual temperature differentials are Non-linear. The finding confirmed the importance and the need to account the nonlinear temperature differential in the design of concrete slabs.