Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

2nd International Conference on Innovative Materials, Structures and Technologies

Salau, M.A.^1 ; Oseafiana, O.J.^1 ; Oyegoke, T.O.^1

University of Lagos, Department of Civil and Environmental Engineering, Lagos State, Nigeria^1

关键词: Concrete strength;    Demolished buildings;    Elevated temperature;    Heating temperatures;    Optimum temperature;    Peak temperatures;    Recycled coarse aggregate;    Weak interfacial bonds;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/96/1/012078/pdf
DOI  :  10.1088/1757-899X/96/1/012078

来源: IOP

【 摘 要 】

This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.