Experimental investigation of the after fire mechanical properties of both fibre and lightweight concrete

Abstract

ABSTRACT Concrete stands as a fundamental material in the construction industry. However, it encounters challenges such as cracking, crumbling, or disintegration at elevated temperatures, attributed to high thermal stresses and low tensile strength. This study addresses these issues by reinforcing concrete samples with steel and polypropylene fibres, exposing them to temperatures ranging from 25 to 800°C, and conducting mechanical tests. In order to provide a comprehensive examination, a concrete mixture containing lightweight aggregate was also prepared and tested along with other mixtures. The test results showed that adding steel and polypropylene fibres enhanced or maintained compressive strength up to 200°C compared to the control sample. Furthermore, samples containing steel fibres exhibited the highest tensile strength across all temperatures. Notably, at 600°C and above, the lightweight concrete sample demonstrated comparable or superior compressive strength as well as tensile strength compared to the control sample. In addition, it was observed that polypropylene fibres began to melt at 400°C, leading to a decline in compressive and tensile strength in samples containing this fibre type at temperatures exceeding 400°C.