Mechanical properties and sulfate resistance of concrete incorporating foundry sand, silica fume, metakaolin

Abstract

Sand has been used for centuries as a moulding material in ferrous and non-ferrous metal casting industries because of its thermal conductivity. Foundries successfully recycle and reuse the sand many times in a foundry. When the sand can no longer be reused in the foundry, it is removed from the foundry and is termed as foundry sand. Use of foundry sand in various engineering applications can solve the problem of disposal of foundry sand and other purposes. This waste foundry sand has been used in this study by replacing the fine aggregates (ordinary sand) with 10% of waste foundry sand in all concrete mixes. The primary aim of this study is to investigate the strength properties (compressive strength and splitting tensile strength) and sulphate resistance of concrete incorporating foundry sand mixed with Silica fume and Metakaolin. For this purpose cement is replaced by weight in three different proportions of 5%, 10% and 15% by Silica fume and Metakaolin separately. Specimens are tested for compressive strength, splitting tensile strength and sulphate resistance. Testing is done at age of 7, 28 and 56 days. Concrete made in this work by replacing 10% foundry sand with fine aggregates and mixing Silica fume and Metakaolin passes all the plastic stage tests. Furthermore hardened stage tests (compressive strength and splitting tensile strength) results were also positive. There was increase in compressive strength and splitting tensile strength with incorporation of Silica fume and metakaolin. Also there was increase in sulphate resistance of SCC when cement is replaced by Silica fume and metakaolin.