Title: Thermal Conductivity Studies for Self-Consolidating Concrete with Sand and Fly Ash Variation

Author(s): Abhijeet S. Gandage, V. Vinayaka Ram, A. B. Yaswanth, P. Kumar Thota, and Sankalp Gupta

Publication: Materials Journal

Volume: 112

Issue: 6

Appears on pages(s): 709-721

Keywords: crushed sand; fly ash; natural sand; self-consolidating concrete (SCC); thermal conductivity

DOI: 10.14359/51687976

Date: 11/1/2015

Abstract:
The thermal properties of self-consolidating concrete (SCC) influence its durability performance. Thermal properties (specific heat, coefficient of thermal expansion, and thermal conductivity) of concrete are governed by the thermal properties of the constituent materials. Fine aggregates have a significant role in fresh as well as hardened state properties of the concrete mixture. The availability of natural sand (NS) is limited due to environmental regulations. Crushed sand (CS) is an emerging alternative to NS for concrete preparation. An experimental study was undertaken to measure thermal conductivity (k) values for an M-40 grade SCC mixture, with varying fly ash dosage, prepared with NS and CS. The k values were determined for normal service temperature range of 86 to 176°F (30 to 80°C) using the steady-state method. The experimental results were analyzed and empirical relations between the k value and the density, as well as with temperature, were developed. The 28-day compressive strength for SCC mixtures with CS was 18% and 35% more than the NS concrete mixtures at 0% fly ash and at 40% fly ash addition level, respectively. The k value for the SCC mixtures with CS was 6.25% and 2.38% more than the SCC mixtures with NS at a temperature range of 86 to 104°F (30 to 40°C) and 158 to 176°F (70 to 80°C), respectively, without any fly ash addition. At 40% fly ash addition level, the k value for the SCC mixtures with CS was 26.39% and 4.12% more than NS-based mixtures at 86 to 104°F (30 to 40°C) and at 158 to 176°F (70 to 80°C), respectively. Durability and sustainability of concretes may be enhanced by using CS instead of NS.