Spall characteristics of concrete materials

The Hopkinson pressure bar tests were performed to explore the spall characteristics of concrete materials by analyzing the strain waves of the buffer bar. The experimental results, for concretes with different spall strengths at different load rates, indicate that the spall strength of concrete is related with its compressive strength and load rate. An empirical formula was proposed to describe the functional relationship between spall strength, compressive strength and load rate. The rate effect of spall strength mainly results from the different expending paths of crack in concrete at different load rates. Some special efforts, which include the effect of the load compressive wave damage on concrete spall fracture, the results of reduplicate load experiments and the sequences of the multiple spall process, explain that damage plays an important role in the spall fracture of concrete.