Effect of silica fume and superplasticizer on steel-concrete bond

This paper presents a study on the influence of silica fume and superplasticizer on bond strength. The study included tests of fifty short length pull-out specimens in five series. The effect of silica fume and superplasticizer on bond strength was evaluated separately by tests of specimens made of concretes with similar strengths but different admixtures. Test results showed that the addition of silica fume in the concrete mixture had not a negative effect on bond strength. Also, there was not a considerable decrease in bond strength of specimens made of concrete with superplasticizer. Comparing the measured bond strengths normalized with respect to the square root of the concrete compressive strength, it was seen that the normalized bond strength increased with the concrete strength. This result agrees with the model previously proposed by the author for local bond strength. For the specimens made of high strength concrete including silica fume and superplasticizer, the normalized bond strength did not increase with the concrete strength.