Effect Of Bulk Density Variation On The Compression Strength Of Clay-Sodium Silicate-Bonded Moulding Sand

Abstract

This paper reports a study conducted to assess the influence of variation of bulk density on compression strength of clay-bonded sand. Five sand mixes containing silica sand, sodium silicate gel (1 wt. % to 5 wt. %), potters' clay (2 wt. %), and about 5 wt. % water were produced. Each mix was divided into three portions to which wood flour (2 wt. %) or charcoal (2 wt. %) or their mixture (1 wt % each). was added to first, second and third portion respectively. Each portion was thoroughly mixed and AFS cylindrical specimens prepared. Thereafter, bulk densities and compression strength of the prepared samples were measured. It was noted that when wood flour, charcoal or their mixture is added, the characteristics of compression strength of clay-bonded sand assume a parabolic form as the bulk density increases. It was inferred that two factors, namely, the number of sand-grain-to-sand-grain contact and the number of pores in the clay-silica gel formed round the surface of sand grains, produce two opposing influences on the compression strength. The compression strength value attains a maximum when these influences are equalized.Journal of Science & Technology (Ghana) Vol. 27 (3) 2007: pp. 141-148