Fracture properties of cement paste and mortar: An experimental investigation

Three-point bending beams of cement paste and mortar with different sizes and strengths were tested. A complete load versus crack mouth opening displacement ( P-CMOD) curve was directly obtained, and double-K fracture parameters could subsequently be determined. An apparent stable crack propagation preceding unstable failure was observed in cement paste, but this stable stage shortens with the increases in the compressive strength and the size lessening, furthermore the influence of specimen size on the stage was more obvious than that of strength. The experimental results show that resistance to crack propagation in matrix is enhanced due to aggregate in the matrix, though the grain size used was very small. The double- K fracture parameters https://www.w3.org/1998/Math/MathML" display="inline"> K I c i n i and https://www.w3.org/1998/Math/MathML" display="inline"> K I c u n of cement paste are size-independent. For cement paste and mortar, due to the influence of shrinkage crack, the divergence of the unstable fracture toughness https://www.w3.org/1998/Math/MathML" display="inline"> K I c u n is more evident than initial fracture toughness https://www.w3.org/1998/Math/MathML" display="inline"> K I c u n .