Thermal characterization and strength properties of concrete cool roof slab panels integrated with glass wool, rock wool, silica fume and graphene oxide

¹ Department of Civil Engineering, CVR College of Engineering, Hyderabad 501510, India
² Department of Mechanical Engineering, CVR College of Engineering, Hyderabad 501510, India
³ Department of Civil Engineering, R.V.R. & J.C. College of Engineering, Guntur 522019, Andhra Pradesh, India
⁴ Department of Civil Engineering, College of Civil Engineering and Architecture, Adama Science and Technology University, Adama 1888, Ethiopia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 3 August 2026

Abstract

Buildings consume a large share of the energy used for indoor climate control, which raises greenhouse gas emissions and intensifies the urban heat island effect. Improving the thermal performance of roofing elements without reducing their strength is an important goal for sustainable construction. This study evaluates the heat transfer rate, thermal resistance and compressive strength of M20 grade concrete cool roof slab panels made with glass wool and rock wool as insulating materials, silica fume as a partial cement replacement, and graphene oxide as a nano additive. The insulating materials were used in peeled form and as one inch and two-inch-thick pads. Thirty-six panels of size 200 mm x 200 mm x 100 mm were cast and tested. Glass wool panels showed a lower heat transfer rate and lower thermal conductivity than rock wool panels. The top surface temperature dropped by about 15 ºC for glass wool panels and about 10 ºC for rock wool panels, relative to the control. The combined use of silica fume and graphene oxide gave the highest compressive strength, with glass wool outperforming rock wool. Glass wool with silica fume and graphene oxide suits energy efficient cool roof applications.