Influence of Aggregate Rock Type, Water to Cement Ratio on Thermal Conductivity of Structural Concrete

Abstract

Concrete is used in slab and also in walls forming envelope of building. Energy efficiency and thermal performance of building plays a major role in sustainable building as total operational energy consumed during the life of building is several times greater than embodied energy. Envelope plays a major role in cooling and heating energy load of building and thus thermal properties especially conductivity of envelope material such as concrete is very important Thermal conductivity of concrete depends on rock type of aggregate and porosity which is governed by water to cement ratio used in concrete. In this paper first data on thermal conductivity with various rock types are presented and using model, conductivity of solid is estimated from the information on porosity. The porosity of concrete as a function of water cement ratio is estimated and thermal conductivity of concrete as function of rock type and water to cement ratio is presented. Concrete have been used in slabs for a long time, of late, with the advent of tunnel form, insulating form, sandwich wall, modular concrete 3-D box construction and other industrialized construction practices, concrete is also used in walls in the envelope. Such concrete is usually multi-functional, not only bears structural loads but also contributes to thermal insulation. Thus the outcome of the work presented in this paper would enable estimation of thermal conductivity of such concrete material and help in estimating the additional insulation requirements.