Hydrothermal reactions between lime and aggregate fines .2. Experimental conditions for strength improvement using saturated steam at elevated pressure

Investigation into the compressive strengths of various mixtures of indigenous materials consisting lime and aggregate fines such as silica sand, slate and rice husk ash, autoclaved at a temperature of 180 degrees C under a steam pressure of 1.17 MPa for 4.5 hours was undertaken. It was found that me maximum compressive strength of 59.8 MPa could be achieved after 4.5 hours reaction between a mixture of 80.0% silica sand, 15.0% lime and 5.0% slate under the above conditions of temperature and pressure. However, under the same conditions of temperature and steam pressure, lower strengths were obtained for other mixtures of these materials. Thus, for example, when, a mixture of 80.0% silica sand, 15.0% lime and 5.0% rice husk ash and a mixture of 85.0% slate and 15.0% lime were tried, then the respective strengths of 47.6 and 34.7 MPa were achieved.