Title: Mechanical Characteristics of High Performance Fibre Reinforced Concretes at Elevated Temperatures

Author(s): K. K. Sideris, P. Manita, A. Papageorgiou, and E. Chaniotakis

Publication: Symposium Paper

Volume: 212

Issue:

Appears on pages(s): 973-988

Keywords: concrete; fire resistance; high performance concrete; polypropylene fibres; silica fume; spalling; steel fibres

DOI: 10.14359/12733

Date: 6/1/2003

Abstract:
Mechanical characteristics of High Performance Fibre Reinforced Concrete subjected to elevated temperatures up to 700 C were experimentally investigated in this paper. Three different concretes were prcpared a normal strength concrete (NSC with nominal 28 days strength of 40 MPa) and two High Performance Concretes (HPCI with 28 days strength of 82 MPa and HPC2 with 28 days strength of 94 MPa). Fibre reinforced concretes were produced by addition of steel or polypropylene fibres in the above mixtures at dosages of 40 Kg/m3 and 10 Kg/m3 respectively. A total of 9 concrete mix- tures were produced and fibres were added in six of them. At the age of 4 months specimens were heated to maximum temperatures of 100, 300, 5OO and 700 C. Specimens were then allowed to cool in the furnace and tested for compressive strength, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity. Reference tests were also performed at air temperature (20 C). Residual strength of NSC and HPC1 was reduced almost linearly up to 700 C and 500 C respectively but the latter had an explosive spalling at 700 C. Residual strength of HPC2 was sharply reduced up to 300 C and explosive spalling occurred at higher temperatures. Addition of steel fibres increased the percentage of residual strength up to 300 C hut spalling still occurred in HPC1 and HPC2 at 700 C and 500 C respectively. Such an explosive behavior was not observed when polypropylene fibres were added in the mixtures.