Fracture Properties of High-Strength Concrete

The fracture behaviors of normal strength concrete (NSC) are well understood after about 20 years of worldwide research. As the strength of concrete increases, its fracture properties become more important, because on the one hand high-strength concrete (HSC) is more often used in complicated structures that are vulnerable to damage by external loads, and on the other hand concrete becomes more brittle as its strength increases. And as the strength of concrete increases, the internal damage pattern changes greatly, so it is not proper to transfer knowledge of the fracture properties of NSC directly to HSC. The test results of fracture properties of HSC as well as NSC are presented and compared with the empirical formulas of CEF-FIP Model Code 1990 (MC90) in the paper. It is found that (1) tensile strength and elastic modulus of HSC match MC90's formulas, as well as NSC, and (2) fracture energy and characteristic length of HSC are lower than predictions from MC90's formulas, while those of NSC are slightly higher than predictions from MC90's formulas.