Thermal Conductivity and Strength Properties of Nanosilica and GGBS Incorporated Concrete Specimens

An important property which affects the heat transfer process in buildings and to minimize the usage of artificial energy in buildings is thermal conductivity. The transfer of heat through walls and roofs determines the amount of artificial energy required in the buildings. The conventional methods used to determine the thermal conductivity of buildings are transient and steady state methods. The objective of this paper is to measure the thermal conductivity of concrete specimens replacing nanosilica and GGBS by weight of ordinary Portland cement. Nanosilica was replaced by weight of cement in different proportions ranging from 1% to 5%. Addition of nanosilica and GGBS in concrete improves the compressive strength and split tensile strength of concrete by around 10%. Improvement in strength properties is mainly due to densification of concrete microstructure by filling pores in concrete specimens. In addition to the strength characteristics, nanosilica incorporated concrete specimens showed better thermal resistance as compared with conventional concrete mix. Lower heat transfer rate is due to the better particle packing nature of nanoparticles in concrete. Nanosilica acts as better heat retarding agent in concrete and thus it minimizes the use of artificial energy in the buildings. It is concluded that utilization of nanosilica reduces the heat transfer rate in to the buildings and the optimum amount of nanosilica was found to be 3% by weight of cement.