Evaluation of silica-fume effect on the mechanical properties of concrete made with coarse masonry recycled aggregates

Document Type : Original Article

Authors

1 Associate professor, department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran

2 Islamic Azad University of Ahvaz

Abstract

The present investigation is studied the effect of the replacement of different levels of silica-fume (SF) on the mechanical properties of recycled concrete made from coarse masonry recycled aggregates. In made concretes, natural aggregates replaced with recycled coarse masonry aggregates at 25%, 50% and 100% levels. For improve the mechanical properties, silica fume replaced by cement at 5%, 10% and 15% levels. In total, 195 standard cubic and cylindrical concrete samples in the 16 mixing designs made and compressive strength tests at 7, 28 and 91 days, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity at 28 days of age evaluated. The results showed that, at replacement levels of 5% and 10% of silica fume, using up to 50% of coarse masonry recycled aggregates, Improvement some mechanical properties of recycled concrete showed relative to conventional concrete without pozzolan. The use of 15% SF replacement rate, in concrete containing 25% coarse masonry recycled aggregates, the mechanical properties of recycled concrete was closed to the conventional concrete without pozzolan, but, in concrete containing 100% coarse masonry recycled aggregates, mechanical properties of recycled concrete was decreased relative to conventional concrete without pozzolan.

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