Method For Bonding Prepared Substrates For Roadways Using A Low-Tracking Asphalt Emulsion Coating

Abstract

A method for bonding together an existing substrate layer and a pavement layer, such that a strong adhesive bond is formed by using a tack coat, provided by an asphalt emulsion, in between the layers as the bond coat. The tack coat layer is a low-tracking coating which cures quickly such that the pavement layer may be applied to the substrate, hours to days after the emulsion is applied to the substrate. The asphalt emulsion comprises at least a first phase of from about 30% to about 70% of an asphalt composition, about 30% to about 70% water, and about 0.1% to about 3.0% emulsifying agent, stabilizer and/or additives, or 0.1% to about 30% if polymeric or other additves are also included.

What is claimed is: 
     
         1 . A method for bonding a layer of pavement material to a substrate of paving materials, soil, clay, sand, shell, cement, limestone, fly ash or mixtures thereof, the steps comprising:
 providing an emulsion with at least a first phase of an asphalt composition, a second phase of water, and emulsifying and stabilizing additives, the asphalt composition selected to provide a coating having a penetration value less than about 40 dmm and a softening point greater than about 140° F. (60° C.) when applied to the substrate and cured;   applying the emulsion to an exposed surface of the substrate at a rate sufficient to provide a coating having an amount of the asphalt composition effective to bond the pavement layer to the substrate;   providing the pavement materials for the paving layer heated to a temperature sufficient to soften the coating an amount effective to form a bonding surface on an exposed surface of the coating;   applying the pavement material to the exposed coating surface to form a pavement layer and to soften the exposed coating surface forming a bond between the pavement layer and the substrate.   
     
     
         2 . The method of  claim 1  wherein the asphalt composition phase comprises a hard pen asphalt composition with a penetration rating less than about 40 dmm and a softening point greater than about 140° F. (60° C.) when applied to the substrate and cured. 
     
     
         3 . The method of  claim 2  wherein the hard pen asphalt has a penetration rating of less than or equal to about 15 dmm, and a softening point temperature of at least about 150° F. (66° C.). 
     
     
         4 . The method of  claim 2  wherein the asphalt composition phase comprises from about 30% to about 70% of the total weight of the emulsion. 
     
     
         5 . The method of  claim 2  wherein the water phase comprises from about 30% to about 70% of the total weight of the emulsion. 
     
     
         6 . The method of  claim 2  wherein the emulsifying agent further comprises stabilizers, additives, and polymers, and comprises from about 0.1% to about 30% of the total weight of the emulsion. 
     
     
         7 . The method of  claim 2  wherein the emulsion is applied to the existing substrate layer in one or more applications having a total application rate of about 0.01 to about 0.20 gallons per square yard. 
     
     
         8 . The method of  claim 1  wherein the emulsion is applied to the existing substrate layer at a temperature of about 140° F. to about 180° F. 
     
     
         9 . The method of  claim 1  wherein the emulsion is applied to the existing substrate layer at temperatures not exceeding about 212° F. (100° C.). 
     
     
         10 . The method of  claim 1  wherein the pavement material is heated to a temperature sufficient to heat the exposed surface of the coating to a temperature greater than about 140° F. (60° C.) when the pavement material is applied to the coated substrate. 
     
     
         11 . The method of  claim 9  wherein the pavement material is a hot mix asphalt heated to a temperature greater than at least about 212° F. (100° C.). 
     
     
         12 . The method of  claim 1  wherein the asphalt composition of the first phase is selected to provide cure time of the emulsion from about 5 to about 60 minutes; and the coating applied to the substrate is allowed to cure for at least the cure time to form a traffic bearing surface before the pavement layer is applied to the substrate. 
     
     
         13 . The method of  claim 2  wherein the emulsion is prepared at a temperature of less than about 212° F. (100° C.). 
     
     
         14 . The method of  claim 1  wherein an emulsion is provided comprising at least a first asphalt composition phase comprising a mid to soft pen asphalt composition having a penetration value greater than about 40 dmm and a softening point less than about 140° F. (60° C.) and additives effective to provide a coating including at least the mid to soft pen asphalt composition and said additives, the coating having a penetration value less than about 40
 dmm and a softening point above about 140° F. (60° C.) when applied to the substrate and cured. 
 
     
     
         15 . The method of  claim 14  wherein the additives are polymeric compositions selected from at least the group of EVA, SBS, SB, SBR, SBR latex, waxes, polychloroprene, isoprene, polybutadiene, acrylic and acrylic copolymers. 
     
     
         16 . A method for forming a low-tracking tack coating capable of bearing traffic without significant loss of bonding strength on a substrate of paving material, soil, clay, sand, shell, cement, limestone, fly ash or mixtures thereof, the steps comprising:
 providing an emulsion with at least a first phase of an asphalt composition, a second phase of water, and emulsifying and stabilizing additives, the asphalt composition selected to provide a coating having a penetration value less than about 40 dmm and a softening point greater than about 140° F. (60° C.) when applied to the substrate and cured;   applying the emulsion to an exposed surface of the substrate at a rate sufficient to provide a coating having an amount of at least the asphalt composition effective to bond the pavement layer to the substrate; and   exposing the coating to the atmosphere for a time sufficient to cure the coating.   
     
     
         17 . The method of  claim 16  wherein the asphalt composition phase comprises a hard pen asphalt composition with a penetration rating less than about 40 dmm and a softening point above about 140° F. (60° C.) when applied to the substrate and cured. 
     
     
         18 . The method of  claim 17  wherein the asphalt composition phase comprises a hard pen asphalt with a penetration rating of less than about 40 dmm, and a softening point temperature of at least about 140° F. (60° C.). 
     
     
         19 . The method of  claim 17  wherein the asphalt composition phase comprises from about 30% to about 70% of the total weight of the emulsion. 
     
     
         20 . The method of  claim 17  wherein the water phase comprises from about 30% to about 70% of the total weight of the emulsion. 
     
     
         21 . The method of  claim 17  wherein the emulsifying agent further comprises stabilizers, additives, and polymers, and comprises from about 0.1% to about 30% of the total weight of the emulsion. 
     
     
         22 . The method of  claim 17  wherein the emulsion is applied to the existing substrate layer in one or more applications having a total application rate of about 0.01 to about 0.20 gallons per square yard. 
     
     
         23 . The method of  claim 16  wherein the emulsion is applied to the existing substrate layer at temperatures not exceeding about 212° F. (100° C.). 
     
     
         24 . The method of  claim 16  wherein after the coating is cured and has been exposed to vehicular traffic, a pavement material is applied to the exposed surface of the coating at a temperature sufficient to heat the coating to a temperature greater than about 140° F. (60° C.) and effective to soften the coating surface to provide a bonding interface between the pavement material and the coated substrate. 
     
     
         25 . The method of  claim 24  wherein the pavement material is a hot mix asphalt heated to a temperature greater than at least about 212° F. (100° C.). 
     
     
         26 . The method of  claim 16  wherein the asphalt composition of the first phase is selected to provide cure time of the emulsion from about 5 to about 60 minutes; and the coating applied to the substrate is allowed to cure for at least the cure time before the pavement layer is applied to the substrate to form a traffic bearing surface. 
     
     
         27 . The method of  claim 16  wherein an emulsion is provided comprising at least a first asphalt composition phase comprising a mid to soft pen asphalt composition having a penetration value greater than about 40 dmm and a softening point less than about 140° F. (60° C.) and additives effective to provide a coating including at least the mid to soft pen asphalt composition and said additives, the coating having a penetration value less than about 40 dmm and a softening point above about 140° F. (60° C.) when applied to the substrate and cured. 
     
     
         28 . The method of  claim 27  wherein the additives are polymeric compositions selected from at least the group of EVA, SBS, SB, SBR, SBR latex, waxes, polychloroprene, isoprene, polybutadiene, acrylic and acrylic copolymers. 
     
     
         29 . A pavement structure comprising a substrate of paving material, soil, clay, sand, shell, cement, limestone, fly ash or mixtures thereof, at least one layer of paving material, as at least one bonding layer between the substrate and the paving material layer, the bonding layer formed from an emulsion having at least a first phase of an asphalt composition, a second phase of water, and emulsifying and stabilizing additives, the asphalt composition selected to provide the bonding layer with a penetration value less than about 40 dmm and a softening point greater than about 140° F. (60° C.) when cured. 
     
     
         30 . The pavement structure of  claim 29  wherein the bonding layer comprises a hard pen asphalt composition with a penetration rating less than about 40 dmm and a softening point above about 140° F. (60° C.). 
     
     
         31 . The pavement structure of  claim 30  wherein the asphalt composition comprises a hard pen asphalt with a penetration rating of less than about 40 dmm, and a softening point temperature of at least about 140° F. (60° C.). 
     
     
         32 . The pavement structure of  claim 30  wherein the asphalt composition phase of the emulsion comprises from about 30% to about 70% of the total weight of the emulsion. 
     
     
         33 . The pavement structure of  claim 29  wherein the emulsion was applied to the substrate layer at temperatures not exceeding about 212° F. (100° C.). 
     
     
         34 . The pavement structure of  claim 29  wherein the bond between the pavement layer and the substrate is formed by heating the bonding layer with the paving layer to a temperature greater than about 140° F. (60° C.) providing a bonding interface between the pavement layer and the substrate. 
     
     
         35 . The pavement structure of  claim 34  wherein the pavement material is a hot mix asphalt heated to a temperature greater than at least about 212° F. (100° C.). 
     
     
         36 . The pavement structure of  claim 29  wherein additional pavement layers are added to said pavement layer, and a bonding coating formed by the emulsion is disposed between each layer to provide a bonding interface as each layer is applied. 
     
     
         37 . The pavement structure of  claim 29  wherein the bonding layer is formed from an emulsion with a first asphalt composition phase comprising a mid to soft pen asphalt composition having a penetration value greater than about 40 dmm and a softening point less than about 140° F. (60° C.) and additives effective to provide a bonding layer, the bonding layer having a penetration value less than about 40 dmm and a softening point above about 140° F. (60° C.) when cured. 
     
     
         38 . The pavement structure of  claim 37  wherein the additives are polymeric compositions selected from at least the group of EVA, SBS, SB, SBR, SBR latex, waxes, polychloroprene, isoprene, polybutadiene, acrylic and acrylic copolymers.