Production of Sustainable concrete brick units using Nano-silica

Concrete bricks or blocks are the most commonly used as construction materials over the world. They are used extensively in buildings due to the raw materials availability and the main binder of concrete is Portland cement which is well known manufactured. Cement is a major contributor to climate change; cement manufacturing is a significant source of CO2 emissions, the primary greenhouse gas of concern. So, the use of a locally available solid waste materials or industrial by-products depends on availability of the local materials such as glass powder and steel slag as partial replacements of cement in concrete which are considered as a viable strategy for reducing the cement proportion use. This research aims to produce sustainable and economic bricks using glass powder and steel slag powder as replacements of cement and study the effect of the added Nano-silica to concrete brick mixes to improve the properties of bricks. Two different curing methods were included to investigate the effect of curing regime on some fundamental mechanical and physical properties (compressive strength and flexural strength, ultrasonic pulse velocity and drying shrinkage) of concrete bricks. The first curing method was the normal curing method at 23 ± 2°C and the second curing method was the boiling water method at 100°C. Different six mixes were cast and cured under different curing conditions before testing. From the test results, it has been found that the use of 2.5 % or 3.5 % of Nano-silica in concrete brick mixes can significantly increase the compressive and flexural strengths at early and late ages. Also these strengths of bricks exhibited better performance due to boiling curing compared with normal curing. However, the results of drying shrinkage with boiling curing's specimens at all ages showed that the values of drying shrinkage were slightly higher than these of specimens shrinkage at normal curing method.