Mechanical Properties of Concrete with Silica Fume and Coarse Recycled Aggregate Concrete

Recently, there has been an increasing trend toward the use of sustainable materials. Sustainability helps the environment by reducing the consumption of non-renewable natural resources. Concrete – the second most consumed material in the world after water – uses a significant amount of non-renewable resources. As a result, an experimental investigation was conducted to study the hardened properties of concrete constructed with 20% and 50% recycled concrete aggregate (RCA) (coarse) as well as 6% silica fume. This experimental program consisted of six mix designs. Experimental results showed that the compressive and tensile strength of concrete improve by using recycled concrete aggregate (RCA) (coarse) and silica fume in the mix design. For example, the compressive strength of concrete containing 6% silica fume and 20% recycled concrete aggregate at age of 56 days was 14% greater than reference concrete mix, while with increasing percentage of recovered concrete aggregate by 50%, this parameter increased by only 4% which shows the inverse effect of increasing the amount of recovered concrete aggregate on compressive strength. The hardened properties of concrete were compared with the provisions of the international design codes (U.S., Australia, Canada, Europe, and Japan) as well as a database of conventional concrete. Results showed that the RCA has superior hardened properties compared with the reference concrete mix