Abstract: A process for producing an inorganic compound-containing urea resin, which comprises adding an acidic gelling agent to an aqueous urea-formaldehyde precondensate solution to prepare a urea resin-containing product, and either(1) mixing the product with a reactant which reacts with the gelling agent to form inorganic particles substantially insoluble in water, or(2) separating the urea resin from the product, mixing the resin-freed mother liquor with such a reactant as stated above, and mixing the resulting inorganic particles with the separated urea resin.

Abstract: An improved grout impregnation method which uses an injection tube for contacting and mixing different kinds of materials supplied thereinto separately to prepare a grout and impregnates the grout into the earth through an injecting opening provided at a tip end of the tube.

Abstract: A slow release nitrogen fertilizer comprising a hydrous cured product of urea-formaldehyde condensate in which the total methylol content is 0.1 to 1.0% by weight (based on the weight of hydrous product) and the hot water-dissolution percentage [percentage of the cured product dissolved in hot water at 80.degree. C. when the product has been immersed therein for 30 minutes (based on the weight of anhydrous product)] is 10% by weight or less.

Abstract: In the stabilization of soil which comprises injecting into soil a mixture of (A) an aqueous sodium silicate solution and (B) at least one compound selected from the group consisting of chlorides, sulfates and nitrates of aluminum, magnesium and iron, and then gelling the injected mixture in soil, the formation of a large amount of the metal hydroxide precipitate on mixing the components (A) and (B) can be prevented by adding (C) at least one oxy acid selected from the group consisting of citric acid, tartaric acid and lactic acid to any one of the components (A) and (B).