Abstract
The ceramic properties of test pieces fabricated from the rock-type porcelanite, with the aid of bitumen and a small amount of a low-plasticity clay and high-plasticity clay as binders, have been investigated after sintering in the temperature range 1200-1350 "C. On firing at and above 1225 °C the porcelanite fused, resulting in microstructures characterized by dispersed silica particles embedded in a continuous matrix, predominantly of potassium silicate and mullite composition. Within the firing temperature range, the porcelanite/high-plasticity clay samples exhibited optimum strength (modulus of rupture) of 18 MPa while for the porcelanite/low-plasticity clay and the porcelanite/bitumen samples optimum was of the order of 12 MPa. In addition, for the samples involving the clays optimum strength was combined with both low bulk density and low apparent porosity.Only available as a scanned copy |