Experimental Study of Ultra-High-Strength Concrete under Triaxial Compression

This article presents experimental results of ultra-high-strength concrete with uniaxial strength over 200 MPa (29 ksi) subjected to triaxial compression, hydrostatic pressure, and uniaxial compression. Various confining pressures from 25 to 400 MPa (3.6 to 58 ksi) were applied in the tests to investigate the confinement effect on ultra-high-strength concrete. A brittle to ductile failure transition phenomenon was observed between confining pressure of 100 and 200 MPa (14.5 and 29 ksi). Based on the test data, failure surface was developed to describe the constitutive behavior of the ultrahigh- strength concrete under multiaxial stress status. Comparing the ultra-high strength concrete with high-strength concrete and normal-strength-concrete, it was found that the effect of confining pressure on the enhancement of compressive strength has a negative relationship with the uniaxial compressive strength. The tests show that the confinement pressure has the lowest enhancement effect on the compressive strength of ultra-high-strength concrete as compared to high-strength concrete, which in turn is lower than that of the normal-strength concrete.