Experimental and numerical analysis of the thermal and mechanical behaviour of steel and recycled aggregate concrete composite elements exposed to fire

Abstract

Using recycled aggregates in the production of concrete has been a viable alternative for sustainable development. Notwithstanding advanced information on this material at room temperature, its behavior when exposed to fire is still incipient. Thus, based on experimental analyses, the objective of this article is to evaluate the behavior of concrete produced with recycled aggregates for thermal insulation of steel elements, as well as to verify the physical and mechanical properties of these mixtures. For this purpose, eight prototypes, one made of steel and the others coated with different types of concrete, conventional and with recycled aggregates, were inserted in a horizontal oven and heated for 2 h. Based on experimental tests, numerical models were proposed and tested using the ABAQUS computational code, with consistent results when coherent thermal properties were adopted. The experimental results show that recycled aggregate concrete (RAC) has great thermal insulation potential and sustainable benefits, considering that the steel elements coated with this type of material, with the exception of those that underwent spalling, presented temperatures close to or below compared with concrete with natural aggregates. In this regard, it is observed that the thermal conductivity of RACs was inferior to conventional concrete, indicating that this material is a promising strategy for thermal insulation of steel structures.

Residual mechanical properties of recycled aggregate concrete at elevated temperatures

“…If RA are to be used for construction purposes, extensive research must be performed to determine their mechanical properties and durability. Therefore, many studies have investigated the effect of temperature on the residual mechanical properties of RA in the last decade 24–30 …”

“…Therefore, many studies have investigated the effect of temperature on the residual mechanical properties of RA in the last decade. [24][25][26][27][28][29][30] Zhao et al 31 tested the thermal properties of RA concrete at elevated temperatures. They concluded that the thermal conductivity of concrete decreases as the percentage of RA increases.…”

Investigation of Post Fire Mechanical Performance of Recycled Aggregate Concrete Containing Ground Granulated Blast Furnace Slag

“…The exposure of recycled aggregate concrete structures to high temperatures during fire scenarios degrades their mechanical properties [5][6]. A key fire safety design requirement according to European standard, EN 1992-1-2 [7] is that the load bearing capacity of concrete exposed to high temperature due to fire can be assumed.…”