The behaviour of fibre reinforced concrete (SHCC) under biaxial compression and tension

[摘要] ENGLISH ABSTRACT: Strain hardening cement‐based composites (SHCC) are fibre‐reinforced composites designed to formmultiple fine cracks under tensile and flexural load. The cracks are controlled to small widths, wherebysignificant toughness, or energy dissipation, is realised on the one hand, and high resistance to gas andliquid ingress is maintained on the other hand. These two physical phenomena define application fieldsof SHCC, i.e. for instance elements of buildings and infrastructure for enhanced earthquake resistance,and protection of steel bars under service loads which lead to crack formation. Also exploiting thepotential protection offered by SHCC to existing structures, thin overlays have been applied to existingdam faces, reinforced concrete retaining walls, water channels and RC road pavements. The layers varybetween 20 and 40 mm in thickness. Considering the fibre length, usually 8 or 12 mm, as well as theapplication method, such thin layers may have dominantly two dimensional fibre orientation, with littleor no component in the layer thickness direction. While several research groups have performeduniaxial tensile tests and flexural tests on SHCC specimens, little or no information is available on SHCCresponse to biaxial loading, as is to be expected in road pavement repair layers, or other repair layers.This paper reports the results of biaxial testing of 20 mm thick SHCC specimens produced in such a wayto have dominantly two‐dimensional fibre orientation, and another group of specimens produced bycutting from larger specimens, whereby three‐dimensional fibre orientation was preserved in theresulting 20 mm thick specimens. Biaxial tests were performed in three quadrants, i.e. compressioncompression,compression‐tension, and tension‐tension. A clear fibre orientation‐related difference inthe failure patterns involves out‐of‐plane splitting under biaxial compression of specimens with twodimensionalfibre orientation, at significantly lower load, as opposed to in‐plane tensile splitting ofspecimens containing three‐dimensional fibre orientation.

[发布机构] Stellenbosch University