Abstract: Novel perlite-silicate type insulation materials are provided having improved physical strength qualities. More particularly, such materials are provided having high flexural or transverse strength as measured by A.S.T.M. standard C-203. According to a preferred embodiment, amounts of phosphate within a limited proportioned range are added to insulation mixtures to yield shaped insulating bodies having a flexural strength in excess of about 60 lb./in..sup.2. Addition of clay is made according to another preferred embodiment, whereby substantial reduction in shrinkage is accomplished.

Abstract: An especially high strength, high temperature, economical material useful for insulation is preferably made by making up a mix having the following proportions in parts by weight: 20-50 parts expanded perlite; 0.5-4 parts sodium fluosilicate; 0.2-5 parts fiber material; a water solution having 9.5-19 parts total of solids content of sodium or potassium silicate; 2-9 parts zinc oxide; and water which, along with the water in the sodium silicate solution totals 21.5-67 parts; thereafter storing the mix under cover for less than 21/2 hours, compressing or blowing the mix to a desired form, and curing and drying it by heating.

Abstract: An especially high strength, high temperature, economical material useful for insulation is preferably made by making up a mix having the following proportions in parts by weight: 20-50 parts expanded perlite; 0.5-4 parts sodium fluosilicate; 0.2-5 parts fiber material; a water solution having 9.5-19 parts total of solids content of sodium or potassium silicate; 2-9 parts zinc oxide; and water which, along with the water in the sodium silicate solution totals 21.5-67 parts; thereafter storing the mix under cover for less than 21/2 hours, compressing the mix to a desired form, and curing and drying it by heating.