Mechanical and some durability properties of foam concrete produced using waste rubber and silica fume

This paper presents an experimental study of the effects of cement dosage and waste tire rubber as aggregate on the mechanical, transport and abrasion characteristics of foam concretes subjected to H2SO4 and freeze–thaw cycles. Foam concrete mixtures were made with two percentages 0, and 20 of silica fume as partial substitution of Portland cement and with 100% of waste tire rubber as substitution of fine aggregates. Two groups of mixtures were prepared with silica fume contents of 0% and 20%. At each group of mixtures, three cement contents of 300, 400 and 500 kg/m3 and three foam contents of 20, 40 and 60 kg/m3 were used to produce concretes mixtures having water/binder (w/b) ratio of 0.75. Workability of fresh concretes were assessed by performing slump test. Compressive and flexural strength of the mixtures were determined after 7 and 28 days and transport properties were measured by means of porosity and water absorption after 28 days. Tests for shrinkage, sorptivity, abrasion, acid attack and freeze–thaw cycles of 30 and 60 were also performed in addition to microstructure investigations. An optimization was also performed. The results exhibited that increase in cement dosage resulted in the compressive strength by 204.50% maximum increment at cement content of 500 kg/m3 as compared to the mixture with dosage of 300 kg/m3 at foam content of 20 kg/m3. Based on the results, it was concluded that the lowest and highest shrinkage values of 5032 × 10-6 and 7065 × 10-6 mm/mm were gained for the mixtures with cement dosages of 300 kg/m3 and 500 kg/m3 and foam content of 20 kg/m3 respectively. The results also indicated that silica fume blended mixture with cement content of 500 kg/m3 foam content of 20 kg/m3 showed the best resistance after abrasion, F-T cycles and acid attack exposure. KEYWORDS:Waste tire, Compressive strength, Foam concrete, Sustainability, Thermal conductivity