Assessment of fracture toughness in strain hardening cement-based composite (SHCC) made from fine and coarse sand

摘要

This paper investigates the effect on fracture toughness of matrices intended for strain hardeningrncement based composite (SHCC), using very fine sand (size up to 0.3 mm, subsequently referred to as FS) andrnlocal coarse sand (size up to 2.36mm and 1.7 mm, CS). ASTM E-399 was followed for measuring fracturerntoughness of the matrices.A series of characterising tests are also reported, including 100mm cube compressivernstrengths, 100×200mm cylinder responses for the E-moduli and flexural strength from 100×100×500mmrnnotched beams tested in three point bending.The matrix fracture toughness K_(IC) was determined from the flexuralrnresponse of the FS and CS beams together with the observed crack propagation in both matrices. The maximumrnvalue for K_(IC) was found to be 1.12MPa.m~(1/2) and 0.95MPa.m~(1/2) respectively for the CS and FS mortar matrices,rncompressive strengths of 32MPa (CS) and 36MPa (FS), and E-moduli of 17 GPa for both FS and CS. Finally,rnby performing direct tensile tests on both FS and CS matrices containing maximum 2.2% and 2% by volume ofrnpolyvinyl alcohol (PVA) fibres, the formation of multiple cracks were verified for both sand types. The purposernof the study was to determine the influence of the particle size on the fracture toughness as well as the relevantrnparameter of the SHCC matrix.The potential of using more realistic sands as aggregate in these high performancerncement-based materials is shown by the results of the research presented in this paper.