The Potential for Achieving Freeze/Thaw Protection in Concrete through the addition of Rubber Crumb

Abstract

This paper evaluates the use of recycled rubber tyres in the form of rubber crumb as a freeze/thaw protection agent when used in concrete. Reusing scrap tyres in the form of rubber crumb, in concrete could benefi t the environment by reducing landfi ll and reducing the chemical usage of air entraining agents. The test procedure involved subjecting concrete to freeze/thaw cycles at 5 days of age. Thawing was conducted in water to ensure full saturation of pores and maximum stress on the concrete samples. Rubber crumb when used at a 0.5% addition by mass provided the optimum freeze/thaw protection whilst maintaining the maximum compressive strength. The practical limitations of the test were time and freezer space so an accelerated test was used, limited to 50 freeze/thaw cycles, which was suffi cient for conclusions to be drawn. This paper contributes to the understanding of the effects of varying doses of rubber crumb in concrete when used as a freeze/thaw protection additive and determines fi nal compressive strength of concrete at normal non freeze/thaw conditions. The compaction of concrete is raised as an area of concern with regard to rubber particle separation within the plastic phase of the concrete’s life