Improving thermal and mechanical property of lightweight concrete using n-butyl stearate/expanded clay aggregate with alccofine1203

Abstract

Phase change material (PCM) as n-butyl stearate (n-BS) was immersed in expanded clay aggregate (ECA) by two methods, direct immersion at room temperature and immersion at elevated temperature (30oC, 40oC and 50oC). ECA after 90min of immersion with n-BS at 40oC came to standby in its weight proportion (increased by 24%). After immersion, these aggregates (40oC) were mixed in cement slurry for preventing leakage and homogenous mixture with concrete. Oozing circle a leakage test was conducted on all the ECA with and without cement slury coating (room and elevated temperatures). ECA with cement slurry coating gave a reduction in leakage of ECA-PCM by 45%. Alccofine1203 was partially replaced (10% and 20%) by cement to improve mechanical properties in lightweight aggregate concrete. Compressive, flexural, thermal conductivity, DSC analysis and leakage test on aggregate and concrete specimens were conducted on all the mixes. Compressive strength for 10% replacement gave 31.7 kN/m2 and 32.8 kN/m2 for 7th day and 28th day, respectively. Similarly, flexural strength gave 6.12 kN/m2 for 28 days. DSC analysis of pure PCM (n-BS) gave 30.42oC and 23.25 oC for its melting and freezing temperature with 134.2 J/g and 129.3J/g as enthalpy for its melting and freezing points, respectively. Thermal conductivity for mix-3 (10%PCM-ECA +10% alccofine1203) gave the lowest value of all the mixes i.e, 13% less than the reference mix. There was no leakage or any stain marks were observed on the filter paper till 10% incorporation.