An experimental study on mechanical and thermal properties of structural lightweight concrete using carbon nanotubes (CNTs) and LECA aggregates after exposure to elevated temperature

Abstract

• The effects of high temperature on LWC with carbon nanotubes (CNTs) and structural LECA as coarse aggregates are investigated • The addition of CNTs to LWC brings in an improvement of the tensile properties at high temperature • LWC containing CNTs exhibits a lower thermal conductivity, to the advantage of the insulating power of concrete in fire The effects of elevated temperature on lightweight structural concrete (LWC) containing Carbon Nanotubes (CNTs) and structural Lightweight Expanded Clay Aggregates (LECA) as a substitute for coarse aggregates are investigated. Mechanical properties such as compressive, indirect tensile strength (in splitting and bending) of a 7-day and 28-day structural LWC (with and without CNTs) have been evaluated under different temperature ranges from ambient temperature up to 800 °C. Moreover, in order to capture all aspects, along with characterizing the mechanical response of the concrete, thermal conductivity has also been measured to understand the thermal behavior of structural lightweight concrete. Hereafter, to bring together different results so that the similarities and differences can be seen, each achieved result from present research has been compared to that of literature. Results indicate that all mechanical properties of the structural LWC containing CNTs were improved at different temperatures compared to those without CNTs. The reasons for the improvement were interpreted by Scanning Electron Microscope (SEM). Moreover, thermal test results demonstrate a decrease in thermal conductivity to the advantage of possible high-temperature applications.