Composition and method for stabilizing road base

Abstract

A road base made from an existing roadbed material and a coal-combustion by-product comprises: a tilled roadbed soil, a coal-combustion fly ash blended into the tilled roadbed soil at 5 to 50 percent by weight, and a site-specific quantity of an emulsion blended into the tilled roadbed soil after the coal-combustion fly ash. The emulsion includes a resin base, and the site-specific quantity ranges from 0.5 to 2.5 gallons per square yard, depending on a type of the tilled roadbed soil, and further depending on a type of the coal-combustion fly ash.

1 . A road base made from an existing roadbed material and a coal-combustion by-product, the road base comprising:
 a tilled roadbed soil;   a coal-combustion fly ash blended into the tilled roadbed soil at 5 to 50 percent by weight; and   a site-specific quantity of an emulsion blended into the tilled roadbed soil after the coal-combustion fly ash, the emulsion including a resin base, the site-specific quantity ranging from 0.5 to 2.5 gallons per square yard, depending on a type of the tilled roadbed soil, and further depending on a type of the coal-combustion fly ash.   
     
     
         2 . The road base of  claim 1 , wherein the emulsion comprises a petroleum resin. 
     
     
         3 . The road base of  claim 2 , wherein the petroleum resin has a viscosity between 3000 and 5000 saybolt universal seconds at 210 degrees Fahrenheit. 
     
     
         4 . The road base of  claim 2 , wherein the emulsion further comprises a lignin sulfonate at 15 to 45 percent by weight. 
     
     
         5 . The road base of  claim 4 , wherein the lignin sulfonate comprises at least one of an ammonium lignin sulfonate, a calcium lignin sulfonate, and a sodium lignin sulfonate. 
     
     
         6 . The road base of  claim 2 , wherein the emulsion further comprises a surfactant at 6 to 8 percent by weight. 
     
     
         7 . The road base of  claim 6 , wherein the surfactant is a non-ionic surfactant. 
     
     
         8 . The road base of  claim 7 , wherein the non-ionic surfactant is an alkylphenol. 
     
     
         9 . The road base of  claim 1 , wherein the coal-combustion fly ash comprises fly ash from a combustion of coal with limestone added to the coal. 
     
     
         10 . A method for stabilizing a road base using a coal-combustion by-product, the method comprising:
 tilling an existing roadbed soil;   blending an amount of a coal-combustion fly ash into the existing roadbed soil at 5 to 50 percent by weight, the amount depending on a type of the existing roadbed soil; and   introducing a quantity of an emulsion to the existing roadbed soil at 0.5 to 2.5 gallons per square yard, the emulsion including a petroleum resin base, the quantity depending on the type of the existing roadbed soil and a type of the coal-combustion fly ash.   
     
     
         11 . The method of  claim 10 , wherein tilling the existing roadbed soil includes tilling to a depth of approximately 4 to 6 inches. 
     
     
         12 . The method of  claim 10 , wherein a tilling depth depends on an application of the road base or on the existing roadbed soil. 
     
     
         13 . A method for stabilizing a road base using a coal-combustion by-product, the method comprising:
 tilling an existing roadbed soil;   blending an amount of a coal-combustion fly ash into the existing roadbed soil at 5 to 50 percent by weight, the amount depending on a type of the existing roadbed soil, with as little as 5 percent by weight for hard gravel, as much as 50 percent by weight for sand, and approximately 10 to 25 percent by weight for an existing roadbed soil tilled to a depth of approximately 4 to 6 inches; and   introducing a quantity of an emulsion to the existing roadbed soil at 0.5 to 2.5 gallons per square yard, the emulsion including a resin base, the quantity depending on the type of the existing roadbed soil and a type of the coal-combustion fly ash.   
     
     
         14 . The method of  claim 13 , further comprising grading the road base. 
     
     
         15 . The method of  claim 13 , further comprising roller compacting the road base. 
     
     
         16 . The method of  claim 13 , wherein the coal-combustion fly ash is blended dry into the existing roadbed soil before introducing the emulsion. 
     
     
         17 . The method of  claim 13 , wherein the emulsion comprises a petroleum resin. 
     
     
         18 . The method of  claim 17 , wherein the emulsion further comprises a lignin sulfonate and an emulsifier. 
     
     
         19 . The method of  claim 18 , wherein the emulsion comprises a higher proportion of petroleum resin to lignin sulfonate when the existing roadbed soil is a coarse roadbed soil, and a lower proportion of petroleum resin to lignin sulfonate when the existing roadbed soil is a fine roadbed soil. 
     
     
         20 . The method of  claim 18 , further comprising grinding at least the petroleum resin, the lignin sulfonate, and the emulsifier together in a colloidal mill to form the emulsion.