Investigate the influence of expanded clay aggregate and silica fume on the properties of lightweight concrete

Abstract

This study concentrated on the formulation of self-flowing and an energy efficient lightweight aggregate foamed concrete (LAFC) to be employed as thermal insulation, thermal mass and structural material. Low density concrete mixtures (for the density values from 800 to 1300 kg/m3) were prepared by changing the volume of lightweight expanded clay aggregate (ECA) from 49.4% to 20.1%. Flowing properties of concrete mixtures were improved with the help of stable foam. Ordinary Portland cement (OPC) was replaced by the 5% and 10% silica fume (SF) to examine the influence of SF on the properties of LAFC. Compressive strength and tensile strength of LAFC mixtures were respectively enhanced from 6.5 MPa to 24.30 MPa and 0.52 MPa to 1.63 MPa by reducing the volume of ECA from 49.4% to 20.1%. LAFC mixture (800-0SF) with the lowest density exhibited highest porosity and sorption coefficient value of 70.63% and 2.56 kg m−2 min−0.5. Thermal conductivity, volumetric specific heat capacity and thermal diffusivity of LAFC mixtures were in the range of 0.23–0.45 W m−1 K−1, 1136–1631 kJ/m3.K and 0.20–0.275 mm2/s respectively. SEM analysis revealed that reduction in the volume of ECA and addition of SF densified the microstructure of LAFC. Finally, LAFC mixtures were classified into Class-I, Class-II and Class-III grade concretes for the structure and insulation purposes as per functional classification of RILEM.