SEM Image-based Porosity Analysis of Fire Damaged High Strength Concrete

Abstract

The porosity of concrete affects the durability of reinforced concrete structures, wherein high levels of porosity are linked to a shorter service life. Recent works have noted that high porosity levels naturally exist in the aftermath of a fire exposure – especially when concrete is classified as high strength concrete (HSC). To shed more light into this phenomenon, this paper showcases a method for measuring the porosity of HSC under elevated temperatures through scanning electron microscopy (SEM). In this method, SEM-based images were examined to quantify the surface porosity of fire-affected HSC. Detailed image analysis was performed for HSC exposed to various heating durations. The study concludes that the surface porosity obtained via the SEM processing method is in good agreement with that from the SEM-based method (with a minor average difference of 3.8%). As such, the proposed method is expected to be reliable for the porosity analysis of fire-damaged concrete.