Durability characterisation of glass fibre reinforced concrete by resistance to freezing and thawing

Abstract

Precast concrete panels are becoming widely used in residential buildings. In this case concrete is acting both as decorative and protective envelope of the whole building. Due to structural and technological reasons, outer skin layer is quite thick-usually 80mm, which can be reduced to 15mm by using innovative and economical composites, such as glass fibre reinforced concrete (GRC). As there is lack of knowledge in scientific literature about this composites behaviour in freeze-thaw conditions, main aim of this article is to investigate freeze-thaw durability of GRC. Silica fume and metakaolin were used as additives, dosing 2,5%, 5% and 7,5% from mass of cement and proved to enhance long term ductility of glass fibre reinforced composite after freeze-thaw tests. Also, flexural stain energy is used as a new concept in concrete freeze-thaw durability to investigate fibre reinforced composites ductile/brittle behaviour. Resistance to freeze-thaw of glass fibre reinforced concrete (GRC) modified with silica fume and metakaolin was tested according to freeze/thaw test method with de-icing salt after 112 cycles. Surface mass loss was obtained, flexural strain energies calculated from load-deformation curves and ductile/brittle behavior of GRC composite explained. SEM micrograph analysis was used to identify possible flaws on the surface of filaments and fiber-matrix contact zone due to freeze-thaw influence.