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Structural Engineering and Mechanics Volume 72, Number 3, November10 2019 , pages 339-354 DOI: https://doi.org/10.12989/sem.2019.72.3.339 |
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Effect of pozzolans on mechanical behavior of recycled refractory brick concrete in fire |
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Mahdi Nematzadeh, Ardalan Baradaran-Nasiri and Mehdi Hosseini
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| Abstract | ||
| Reusing building materials and concrete of old buildings can be a promising strategy for sustained development. In buildings, the performance of materials under elevated temperatures is of particular interest for determining fire resistance. In this study, the effect of pozzolan and aggregate type on properties of concrete exposed to fire was investigated. In doing so, nanosilica with cement-replacement levels of 0,2, and 4% as well as silica fume and ultrafine fly ash with cement-replacement levels of 0, 7.5, and 15% were used to study effect of pozzolan type, and recycled refractory brick (RRB) fine aggregate replacing natural fine aggregate by 0 and 100% was utilized to explore effect of aggregate type. A total of 126 cubic concrete specimens were manufactured and then investigated in terms of compressive strength, ultrasonic pulse velocity, and weight loss at 23 degree celcius and immediately after exposure to 400 and 800 degree celcius. Results show that replacing 100% of natural fine aggregate with recycled refectory brick fine aggregate in the concretes exposed to heat was desirable, in that it led to a mean compressive strength increase of above 25% at 800 degree celcius. In general, among the pozzolans used here, silica fume demonstrated the best performance in terms of retaining the compressive strength of heated concretes. The higher replacement level of silica fume and ultrafine fly ash pozzolans in the mixes containing RRB fine aggregate led to a greater weight loss rate, while the higher replacement level of nanosilica reduced the weight loss rate. | ||
| Key Words | ||
| recycled refractory brick; concrete; pozzolan; elevated temperatures; ultrasonic pulse velocity; weight loss; silica fume; nanosilica; ultrafine fly ash | ||
| Address | ||
| Mahdi Nematzadeh, Ardalan Baradaran-Nasiri: Department of Civil Engineering, University of Mazandaran, Babolsar, Iran Mehdi Hosseini: Department of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran | ||