Experimental study on ultra-high performance concrete under triaxial compression

Abstract

Ultra-high strength concrete (UHSC) and Ultra-high performance concrete (UHPC) with high compressive strength and good durability have been increasingly used in engineering structures. In the present study, uniaxial and triaxial compression tests on UHSC and UHPC are carried out by using servo-hydraulic actuators to investigate the mechanical properties of UHSC and UHPC under various stress states. In triaxial compression tests, the confining pressure ranging from 0 to 50 MPa is applied on UHSC and UHPC specimens. The mechanical responses of UHSC and UHPC specimens under various confining pressures, including peak strength, axial and circumferential strain are recorded in the loading process. According to the elastoplastic behavior of UHSC and UHPC specimens in tests, the influence of confining pressure on the compressive strength and plastic deformation performances of UHSC and UHPC are studied. It is found that the compressive strength and plastic deformation capacity of UHSC and UHPC tend to be higher with the increasing of confining pressure. The enhancement of compressive strength of UHPC is slightly lower than that of UHSC However, due to the lateral restraint effect of the confining pressure and the tensile action of the steel fibers inside the UHPC specimen, failure of the cylindrical specimen are delayed more significantly with increasing of confining pressure. Failure surfaces based on Ottosen’s criterion for UHSC and UHPC are identified accroding to test data. By comparing and analyzing the tests results on UHSC, UHPC and previously tested C200, it is concluded the effect of confining pressure on the enhancement of compressive strength of concretes has a negative relationship with the uniaxial compressive strength of concretes.