Abstract: A method of manufacturing cementitious materials. The method comprises combining together approximately 12 parts sand with 1 part lime to form a sand and lime mixture where mixture has a sufficient water content to permit at least partial hydration of the lime. The sand and lime mixture is maintained at a temperature of approximately 60° Celsius for a period of between two and four hours. Thereafter water is mixed into the sand and lime mixture at a weight ratio of from between 5 to 15 percent. Pieces of shredded automobile or truck tires are then added to the sand, lime and water mixture at a weight ratio of between 5 and 15 percent. The combination is then subjected to an autoclave process where it is maintained at a pressure of approximately 16 Bar and at temperatures of between 160 and 180 degrees Celsius for between four and eight hours during which the mixture is allowed to cure and harden.