Dynamic Triaxial Tests of High-Strength Concrete

Dynamic triaxial compression experiments were performed on a limestone-aggregate concrete whose unconfined static compressive strength is about 100 MPa. The axial strain rates ranged from 0.5 s.to 10 s, the confinement levels ranged from zero to 124 MPa, and the peak axial loads ranged from 103 MPa to 393 MPa. The loads were applied with controlled venting of explosive gases, using a new experimental apparatus. The specimens were 150-mm-diameter by 300-mm-long cylinders. The data show no effect of strain rate on the response of this concrete up to at least a strain rate of 0.5 s. However, at a strain rate of 6 s, the elastic modulus increases by about 60% and the unconfined strength increases by about 100% over static values (at a strain rate of 0.0001 s). The triaxial compression data establish an approximate shear failure envelope for strain rates between 1.3 s and 5 s. This envelope is 30% to 40% higher than that for static loading.