Failure criteria and triaxial behaviour of HPFRC containing high reactivity metakaolin and silica fume

In this paper, the triaxial compressive behaviour of high performance fibre reinforced concrete (HPFRC) containing two types of pozzolans namely high reactivity metakaolin (MK) and silica fume (SF) is studied. Standard triaxial tests with four different confining pressure levels were performed on 75 × 150 mm cylindrical concrete specimens containing 2% steel fibres by volume. Companion uniaxial direct tensile tests are also performed on dog-bone shaped specimens to ascertain the strain-hardening behaviour of these composites. The results show that an increase in confining pressure leads to an increase in the peak additional axial stress in both SF and MK specimens, and the increase is about the same for the two types of composites. However, the peak additional axial stresses of MK specimens occur at higher axial strains thus showing a more ductile behaviour with higher energy absorption capacity. To establish an empirical relation for prediction of axial strength as a function of confining pressure, three constitutive models i.e. Mohr–Coulomb two-parameter, Hsieh–Ting–Chen four-parameter and William–Warnke five-parameter models are used and calibrated with the test results.