Colloidal sealant composition

Abstract

The present invention relates to the addition of biocidal agents to colloidal silicate coating compositions, the compositions being useful for coating structures prepared from Portland cement compositions.

1 . A substantially water impenetrable gelled film for permanently hydrostatically sealing a substrate that employs Portland cement as binder, the film prepared by a process comprising the steps of:
 (1) obtaining a composition comprising:
 (a) a colloidal silica composition substantially free of alkali metal and alkaline earth metal cations, and substantially free of organic compounds; 
 (b) a water-soluble or water-dispersible additive composition that is a member selected from the group consisting of fluorescent dyes, nonfluorescent dyes, biocides, bactericides, fungicides, microbicides, pesticides, perfumes, deodorants and mixtures thereof; and 
 (c) water; 
   (2) contacting the composition with the substrate; and   (3) drying the substrate for a time of at least about 1 hour, whereby the composition gels as by contact with alkali metal and alkaline earth metal cations present in the substrate to obtain an impenetrable gelled film and whereby the film is situated at least about ¼ inch below the surface of the substrate, and whereby the additive composition is situated between the surface of the substrate and the impenetrable film.   
     
     
         2 . An impenetrable gelled film according to  claim 1  that is amorphous in the presence of water. 
     
     
         3 . An impenetrable gelled film according to  claim 1  that is noncrystalline in the absence of water. 
     
     
         4 . An impenetrable gelled film according to  claim 1  wherein the substrate that employs Portland cement as the binder is a member selected from the group consisting of unreinforced concrete, reinforced concrete, cast-in-place concrete, precast concrete, post-tensioned concrete, pavers, concrete block, concrete pipe, grouts, stucco, shotcrete, gunnite, pool plaster, concrete siding and products made from concrete that mimic natural stone. 
     
     
         5 . A permanently sealed substrate that employs Portland cement as binder, the substrate being permanently sealed by a process comprising the steps of:
 (1) obtaining a composition comprising:
 (a) a colloidal silica composition substantially free of alkali metal and alkaline earth metal cations, and substantially free of organic compounds; 
 (b) a water-soluble or water-dispersible additive composition that is a member selected from the group consisting of fluorescent dyes, nonfluorescent dyes, biocides, bactericides, fungicides, microbicides, pesticides, perfumes, deodorants and mixtures thereof; and 
 (c) water; 
   (2) contacting the composition with the substrate; and   (3) drying the substrate for a time of at least about 1 hour, whereby the composition gels as by contact with alkali metal and alkaline earth metal cations present in the substrate to obtain an impenetrable gelled film and whereby the film is situated at least about ¼ inch below the surface of the substrate, and whereby the additive composition is situated between the surface of the substrate and the impenetrable film, to obtain the permanently sealed substrate.   
     
     
         6 . A composition according to  claim 5  wherein the substrate that employs Portland cement as the binder is a member selected from the group consisting of unreinforced concrete, reinforced concrete, cast-in-place concrete, precast concrete, post-tensioned concrete, pavers, concrete block, concrete pipe, grouts, stucco, shotcrete, gunnite, pool plaster, concrete siding and products made from concrete that mimic natural stone. 
     
     
         7 . A composition according to  claim 5  wherein the colloidal silica composition is present in an amount of about 20 weight % solids to about 70 weight % solids. 
     
     
         8 . A composition according to  claim 7  wherein the colloidal silica composition is present in an amount of about 40-50 weight % solids. 
     
     
         9 . A process for preparing a substantially water impenetrable gelled film for permanently hydrostatically sealing a substrate that employs Portland cement as binder, the process comprising the steps of:
 (1) obtaining a composition comprising:
 (a) a colloidal silica composition substantially free of alkali metal and alkaline earth metal cations, and substantially free of organic compounds; 
 (b) a water-soluble or water-dispersible additive composition that is a member selected from the group consisting of fluorescent dyes, nonfluorescent dyes, biocides, bactericides, fungicides, microbicides, pesticides, perfumes, deodorants and mixtures thereof; and 
 (c) water; 
   (2) contacting the composition with the substrate; and   (3) drying the substrate for a time of at least about 1 hour, whereby the composition gels as by contact with alkali metal and alkaline earth metal cations present in the substrate to obtain an impenetrable gelled film and whereby the film is situated at least about ¼ inch below the surface of the substrate, and whereby the additive composition is situated between the surface of the substrate and the impenetrable film.   
     
     
         10 . A process according to  claim 9  wherein the substrate that employs Portland cement as the binder is a member selected from the group consisting of unreinforced concrete, reinforced concrete, cast-in-placed concrete, precast concrete, post-tensioned concrete, pavers, concrete block, concrete pipe, grouts, stucco, shotcrete, gunnite, pool plaster, concrete siding and products made from concrete that mimic natural stone. 
     
     
         11 . A process according to  claim 9  wherein the colloidal silica composition is present in an amount of about 20 weight % solids to about 70 weight % solids. 
     
     
         12 . A process according to  claim 11  wherein the colloidal silica composition is present in an amount of about 40-50 weight % solids. 
     
     
         13 . A process according to  claim 9  wherein said composition is gellable, nonthixotropic and viscous. 
     
     
         14 . A process according to  claim 9  wherein the impenetrable gelled film is noncrystalline in the absence of water. 
     
     
         15 . A composition for formation of a barrier on a substrate that employs Portland cement as binder, the composition comprising a subsurface layer having a thickness up to about 4 inches, an intermediate layer and a surface layer. 
     
     
         16 . A composition according to  claim 15  wherein the subsurface layer comprises: a colloidal silica composition substantially free of alkali metal and alkaline earth metal cations, and substantially free of organic compounds, wherein the colloidal silica composition, upon curing, pushes all contaminants into the volumetric space between the cured colloidal silica composition and the upper surface of the substrate that employs Portland cement as binder. 
     
     
         17 . A composition according to  claim 15  wherein the intermediate layer comprises a water-soluble or water-dispersible additive composition that is a member selected from the group consisting of fluorescent dyes, nonfluorescent dyes, biocides, bactericides, fungicides, microbicides, pesticides, perfumes, deodorants and mixtures thereof; and
 (c) water. 
 
     
     
         18 . A composition according to  claim 15  wherein the surface layer comprises an epoxy topcoat. 
     
     
         19 . A composition according to  claim 18  wherein the epoxy topcoat contains sand. 
     
     
         20 . A composition according to  claim 18  wherein the epoxy topcoat is a member selected from the group consisting of a nonglossy topcoat and a glossy topcoat.