The effect of sulfuric acid on eco-friendly concrete containing coal slag and nano silica

Concrete is one of the most widely used materials in the world for various types of structures due to its durability. This paper presents the results of an experimental study on various compressive strength and water absorption tests on concrete containing coal slag and nano silica as partial replacement of cement. For this research work, the tests were conducted for various proportions of coal slag replacement with cement of 0%, 10%, 15%, and 25%, nano silica of 0%, 1.5%, 2.5% and 3.5% and combination of both of them in concrete. The obtained results were compared with those of control concrete made with ordinary Portland cement. In this research, the effect of several amounts of coal slag and nano silica on some properties of concrete were considered in the production of test samples of 5*5*5 cm. After casting the cubes, they were tested for compressive strength and water absorption. Results showed that compressive strength of samples with 10% and 15% pozzolan were increased, but compressive strength of samples with 25% pozollan were decreased more than that of the control sample. Also, application of pozzolan resulted in less water sorption. The use of nano silica increased concrete compressive strength compared to samples without Nanosilica in most samples, and this increase was proportional to the amount of nano silica. Based on the these findings, it is concluded that Pozzolan coal slag is a suitable replacement for cement especially in presence of nano silica.