Mechanical properties of low-strength concrete at exposure to elevated temperatures
Journal of Structural Fire Engineering
ISSN: 2040-2317
Article publication date: 7 July 2017
Issue publication date: 22 September 2017
Abstract
Purpose
This paper aims to present the results of testing of low-strength concrete specimens exposed to elevated temperatures. These data are limited in the existing literature and do not exist in Pakistan.
Design/methodology/approach
An experimental testing programme has been employed. Cylindrical specimens of 100 × 200 mm were used in the testing programme. These were heated at temperatures which were varied from 100°C to 900°C in increment of 100°C. Similar specimens were tested at ambient temperature as control specimens. The compressive and tensile properties of heat treated specimens were determined.
Findings
The colour of concrete started to change at 300°C and hairline cracks appeared at 400°C. Explosive spalling was observed in few specimens in the temperature range of 400°C-650°C which could be attributed to the pore pressure generated by steam. Significant loss of concrete compressive strength occurred on heating temperatures larger than 600°C, and the residual compressive strength was found to be 15 per cent at 900°C. Residual tensile strength of concrete became less than 10 per cent at 900°C. The loss of concrete stiffness reached 85 per cent at 600°C. Residual Poisson’s ratio of concrete increased at high temperatures and became nearly six times larger at 900°C as compared to that at ambient temperature.
Research limitations/implications
The parameters of the study included heating temperature and effects of temperature on strength and stiffness properties of the concrete specimens.
Practical implications
Building fire incidents have increased in Pakistan. As a large number of reinforced concrete (RC) buildings exist in the country, the data related to elevated temperature properties of concrete are required. These data are not available in Pakistan presently. The study aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members.
Originality/value
The presented study is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of concrete in Pakistan.
Keywords
Acknowledgements
The authors wish to acknowledge the support provided for this research by the laboratory technical staff members. The financial assistance provided jointly by the Higher Education Commission, Pakistan and USAID, USA, under the Grant PGA-2000003665, is gratefully acknowledged.
Citation
Rafi, M.M., Aziz, T. and Lodi, S.H. (2017), "Mechanical properties of low-strength concrete at exposure to elevated temperatures", Journal of Structural Fire Engineering, Vol. 8 No. 4, pp. 418-439. https://doi.org/10.1108/JSFE-11-2016-0017
Publisher
:Emerald Publishing Limited
Copyright © 2017, Emerald Publishing Limited