Utilization of lean clay in the development of quality building bricks

Sodium silicate was used as an additive to a mixture composed of three types of lean variety common red burning clays, fly ash and brick powder to ascertain the possibility of the manufacture of common building bricks. Specimens were made by extrusion and subsequently fired at temperatures between 950degreesC to 1100degreesC with 2 hours soaking at the respective peak temperatures. Traditionally, the clay minerals available in the referred region yield low strength porous bricks. Use of sodium silicate resulted in liquid phase formation in the temperature range 1050 to 100degreesC and shows strong adhesion of grains. Specimens made with body mix 6 attained compressive strength 48.3 MPa while water absorption value was 10.96%. Efflorescence property of the specimens was improved. The presence of sodium silicate possibly favoured the formation of complex soluble alkali or alkaline earth salts which are less apt to migration to the surface and thus reducing the efflorescence behaviour of the specimens