Chemically active glasses for steel enamels

Abstract

A corrosion resistant steel reinforcing rod system, including a steel reinforcing rod having a coefficient of thermal expansion of between about 14 ppm/° C. and about 17 ppm/° C. and a vitreous shell substantially encapsulating the steel reinforcing rod. The vitreous shell has a composition selected from the group consisting essentially, in weight percent, of about 40-45% SiO 2 , 3-5% Al 2 O 3 , 5-15% B 2 O 3 , 3-15% K 2 O, 5-20% Na 2 O, 4-7% CaO, 1-2% ZrO 2 , 0-2% NiO, 0-2% CoO, and 5-20% P 2 O 5 . The vitreous shell has a coefficient of thermal expansion between about 12.5 ppm/° C. and about 13.5 ppm/° C.

We claim: 
     
         1 . A corrosion resistant steel reinforcing rod system, comprising:
 a steel reinforcing rod; and   a vitreous shell generally encapsulating the steel reinforcing rod;   wherein the vitreous shell has a composition selected from the group consisting essentially, in weight percent, of about 40-45% SiO 2 , about 5-25% B 2 O 3 , about 5-25% Na 2 O, and about 5-20% P 2 O 5 .   
     
     
         2 . The system of  claim 1  wherein the vitreous shell has a P 2 O 5  content of between about 9 and about 18 weight percent. 
     
     
         3 . The system of  claim 1  wherein the vitreous shell is enveloped in a cementitious matrix; wherein there are apertures in the vitreous shell exposing the portions steel rod to the cementitious matrix; wherein phosphate is released from the vitreous shell; and wherein hydroxyapatite is deposited onto exposed portions of the steel reinforcing rod. 
     
     
         4 . A composite structural material comprising in combination:
 a cementitious matrix;   a plurality of steel reinforcing rods positioned in the cementitious matrix; and   a plurality of vitreous shells, each respective vitreous shell generally covering a respective steel reinforcing rod;   wherein each respective steel reinforcing rod has a coefficient of thermal expansion of between about 14 ppm/° C. and about 17 ppm/° C.; and   wherein each respective vitreous shell has a composition selected from the group consisting essentially, in weight percent, of about 40-45% SiO 2 , 3-5% Al 2 O 3 , 5-25% B 2 O 3 , 3-15% K 2 O, 5-25% Na 2 O, 4-7% CaO, 1-2% ZrO 2 , 0-2% NiO, 0-2% CoO, and 5-20% P 2 O 5 ; and   wherein each respective vitreous shell has a coefficient of thermal expansion between about 12.5 ppm/° C. and about 13.5 ppm/° C.   
     
     
         5 . The composite structural material of  claim 4  wherein there are apertures in the vitreous shell exposing the portions of the steel rods to the cementitious matrix; wherein phosphate is released from the vitreous shell; and wherein hydroxyapatite is deposited onto at least some of the exposed portions of the steel reinforcing rods. 
     
     
         6 . The composite structural material of  claim 4  wherein the bond strength of the steel reinforcing rods in the cementitious matrix increases over time. 
     
     
         7 . A method of reinforcing concrete, comprising:
 coating a plurality of steel reinforcing members with phosphate-rich glass layers for emplacement into a cementitious matrix, wherein the respective steel reinforcing members have a first coefficient of thermal expansion and wherein the respective glass layers have a second coefficient of thermal expansion substantially matching the first coefficient of thermal expansion; and   forming a cementitious matrix around the plurality of steel reinforcing members;   releasing phosphate from the glass layers; and   forming a hydroxyapatite layer on steel surfaces not coated with glass.   
     
     
         8 . The method of  claim 7  wherein the glass layers have a composition selected from glasses consisting essentially, in weight percent, of about 40-45% SiO 2 , 3-5% Al 2 O 3 , 5-15% B 2 O 3 , 3-15% K 2 O, 5-20% Na 2 O, 4-7% CaO, 1-2% ZrO 2 , 0-2% NiO, 0-2% CoO, and 5-20% P 2 O 5 . 
     
     
         9 . The method of  claim 7  wherein the glass layers have a coefficient of thermal expansion between about 12.5 and 13.5 ppm per degree Celsius. 
     
     
         10 . The method of  claim 7  wherein the glass layers contain about 9 to about 18 weight percent P 2 O 5 . 
     
     
         11 . A steel reinforcing rod system, comprising: a steel reinforcing rod having a coefficient of thermal expansion of between about 14 ppm per degree Celsius and about 17 ppm per degree Celsius; a vitreous shell generally encapsulating the reinforcing rod; a plurality of metal particles distributed throughout the vitreous shell; wherein the vitreous shell has a composition selected from the group consisting essentially of about 40-45% SiO 2 , 3-5% Al 2 O 3 , 5-25% B 2 O 3 , 3-15% K 2 O, 5-25% Na 2 O, 4-7% CaO, 1-2% ZrO 2 , 0-2% NiO, 0-2% CoO, and 5-20% P 2 O 5 ; and wherein the vitreous shell has a coefficient of thermal expansion between about 12.5 ppm per degree Celsius and about 13.5 ppm per degree Celsius. 
     
     
         12 . The system of  claim 11  further comprising a cementitious matrix adjacent to and generally surrounding the vitreous shell; wherein there are apertures in the vitreous shell exposing portions of the steel rods to the cementitious matrix; wherein phosphate is released from the vitreous shell; and wherein hydroxyapatite is deposited onto at least some of the portions of the steel reinforcing rods exposed to the cementitious matrix.