Inorganic adhesive composition

An adhesive composition comprising:

• (a) an aqueous silica sol having a mean particle size of from 5 to 200 millimicrons and a molar ratio of SiO.sub.2 /M.sub.2 O (where M represents an alkali metal atom, an amine molecule or a quaternary ammonium group) of from 30 to 2,000 in an amount of 100 parts by weight as SiO.sub.2 ;
• (b) an inorganic refractory powder having a particle size of from 0.5 to 1,000 microns in an amount of from 100 to 100,000 parts by weight;
• (c) a fine powdery silica in amorphous form having a particle size of from 5 to 200 millimicrons in an amount of from 0.5 to 500 parts by weight, said fine powdery silica remaining in particle form in said composition,
• (d) an aqueous solution of an alkali silicate having a molar ratio of SiO.sub.2 /M'.sub.2 O (where M' represents Na, K, Li, an amine molecule or a quaternary ammonium group) of from 1 to 30 and having an alkali silicate concentration of from 1 to 60% by weight in an amount of from 0.1 to 500 parts by weight as the alkali silicate component;
• and
• (e) one or more coupling agents selected from the group consisting of a silane compound of a general formula (I):
• R.sup.1 Si(OR).sub.3 (I)
• where OR represents an alkoxy or acyloxy group having from 1 to 3 carbon atoms, and R.sup.1 represents a monovalent organic group having from 2 to 9 carbon atoms, or a hydrolysate thereof, and a silane compound of a general formula (II):
• R.sup.1 SiCH.sub.3 (OR).sub.2 (II)
• where OR and R.sup.1 have the same meanings as defined above, or hydrolysate thereof, in an amount of from 0.05 to 100 parts by weight, said composition has a viscosity of from 1 to 10,000 poise at 20.degree. C. and a solids content of from 40 to 95% by weight.