engleski

Short term reduction of mechanical properties of high strength concrete after cooling to ambient temperature

This paper presents experimental study of short-term loss (in time intervals up to 96 hours after initial cooling) of residual mechanical properties of high strength concrete after heating to temperatures 100 – 800°C. Concrete mixture used in the study is specific for the production of hollow core slabs, comprised of standard Portland cement, calcareous aggregate with fraction of 0-8 mm and with 0.33 water/cement ratio. The study comprises residual compressive strength, tensile splitting strength, static and dynamic modulus of elasticity and stress-strain relationship. Experimental results are compared with those obtained from other studies, EN 1994-1-2 and EN 1992-1-2. The results show that compressive strength of concrete has a significant reduction during the first 48 hours, especially at temperatures between 400-800°C. Results of the residual tensile strength show a slight increase at temperatures below 220°C, with a linear reduction at temperatures between 400-600°C. Study of the dynamic and static modulus of elasticity shows that both properties are decreased, but remain constant during the period of 96 hours after cooling. The results presented in this paper were obtained as a part of the ongoing research concerning the behavior of prestressed hollow core concrete slabs in fire.

Concrete; High temperature; Residual mechanical properties; hollow-core slab

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