US2288924A - Bituminous emulsion - Google Patents

Description

Patented July 7, 1942 are ,aszi

i ops reminslon Frederick s. Scott, Los Angeles, cane, assignor to Union Oil Companyoi California, Los Angeles, (Jalifi, a corporation of California,

No Drawing. Application March 6, 1939,

Serial No. 260,10?

2 Claims.

Thepresent invention relates 'toimproved aqueous emulsions of bitumen or asphalt or other bituminous substances of natural or artificial origin and to a process for making the same. The invention relates particularly. to emulsions of asphalts which are similar to so-called cutback asphalts.

It is generally recognized that there are at least When the asphalt is applied in an emulsified state, that is, as a dispersion in water and an emulsifying agent, the emulsion may either be mixed with the road building material until the emulsion. is thoroughly distributed throughout the aggregate and then spread on the road bed, or it may be blade-mixed with the aggregate on the road bed. For this purpose, a so-called slow breaking or -mixing type emulsion is employed which doesnot break rapidly and thus permits the proper admixture with theaggregate. In other cases, the road is built by the so-called penetration method which consists essentially in spraying, pouring or pumping the asphalt emulsion upon the mineral aggregate on the road bed. For this purpose, a so-called quick breaking emulsion is employed. In either case, the emulsion breaks, allowing water to evaporate to the atmosphere and permitting the asphalt to bind the aggregate particles.

When a cut-back asphalt is employed as the binding agent for the aggregate, the cut-back asphalt which generally consists of a blend of the relatively hard asphalt and a volatile solvent is mixed with'the aggregate or spread on the aggregate placed on the road-bed and as the volatile solvent evaporates to the atmosphere, the road hardens or takes a set as it is commonly called.

The use of road oils, which are generally reduced petroleum residua, is quite similar to the cut-back asphalts, the diluent is a relatively low viscosity distillate such as gasoline, naphtha or kerosene, whereas in the case of the residual road oils, the diluent consists of naturally occurring heavy gas oil and lubricating oil fractions. 0b-

viously, the road oils are very markedly slower in obtaining their set.

It is also recognized to. us'e an emulsified cu back asphalt as a cementing agent for aggregate in road building construction. The cutback asphalt -as generally produced by mixing the hard asphalt, which is desired to remain on the road bed, with 10 to by volume of a volatile solvent, such asgasoline or kerosene, is emulsified with an aqueous solution containing an emulsifying agent by merely mixing the two liquid materials in the cold, i. e. at atmospheric conditions. The gasoline solvent generally has an end point of 437 F. and the kerosene has an initial point of 325 to 375 F. and an end point of .500 to 550 F. and an average boiling point of 4.25 to 450 F. Usually, the type of emulsion produced when employing such cut-back asphalts is one of the semi-quick-breaking type, that is, it breaks relatively rapidly. In such cases, the rapid breaking down of the emulsion and the rapid evaporation of the volatile solvent causes the asphalt to harden prematurely and thus prevents the asphalt from penetrating deeply into the road bed or into the soil when the product is employed for the stabilization of soil, clay and the like. Myinvention relates to an improvement in this type of emulsidn and is particularly directed to the production of an emulsion of cut-- back asphalt which does not break as rapidly as the heretofore known emulsified cut-back asphalt's. us, 'it is possible with the use of the emulsified cut-back asphalt forming the subject matter of my invention to constructfroads by mixing the emulsified cut-back asphalt with the road building material and thus obtain an even distribution of the asphalt throughout the aggregate without premature breaking down of the emulsion or in the case where the product-is use of cut-back asphalts and probably antedates Y residual road oils, may be considered as bein a mixture of a hard bituminous component and a less viscous solvent. In the case of the volatile used in the stabilization of soil, clay and the like by spraying the emulsion on the surface of soil, etc., the emulsion is permitted to penetrate deeper into the formation before the emulsion breaks and the asphalt hardens.

I have discovered that if a certain'garoportion of a gas-oil fraction is incorporated into the cutback asphalt before it is compounded into an emulsion, that the emulsion for some reason or In general, the composition which I have found to be particularly suitable for the purposes herein mentioned comprises an emulsion of water, an emulsifying agent and an asphalt composition comprising a mixture of approximately 10 to 30% by volume of gasoline having an end point of about 437 F., 10 to 30% by volume of a petroleum fraction having a boiling range of approximately 450 to 720 F. with an average boiling point of about 550 to 600 F. and the remainder of an asphalt crude oil residuum having a penetration of about 100 to 300 at 77 F. or approximately 90 to 99% of 80 penetration asphalt at 77 F. The petroleum fraction having a boiling range of approximately 450 to 720 F. will be hereinafter referred to as gas-oil or gas oil fraction. It will be noted that I intend to employ approximately 20 to 60% by volume of vaporizable constituents, i. e., gasoline and gas-oil. It is possible and within the scope of my invention to use a greater proportion of the gas-oil fraction and a correspondingly less amount of the gasoline fraction. In fact, I may delete the gasoline fraction entirely and add a greater amount of the gas-oil fraction. However, I prefer under normal atmospheric drying conditions to have in my cut-back asphalt at least a small proportion of solvent boiling between 350 and 500 F. which may be obtained either by the use of gasoline or by the selection of a gas-oil having low boiling components. This fraction has the purpose, during curing on the road, of helping to lift the heavier boiling fractions in order to obtain the desired hard asphaltic residue as rapidly as possible. It is preferable, however, to employ a sufficient amount of either the gasoline-gas-oil solvent mixture or the gasoil fraction alone to produce a cut-back asphalt having a viscosity of approximately 100 to 120 seconds Furol at 122 F.

The emulsion forming the subject of my invention may be produced by first compounding the bituminous cement or cut-back asphalt and subsequently emulsifying this bituminous cement with an aqueous solution containing a small amount of emulsifying agent. The bituminous cement may be compounded by merely agitating and stirring the mixture of gasoline or naphtha, gas-oil fraction and the hard asphalt. Preferably, the asphalt is first heated to above its melting point and the gas-oil fraction is stirred into the melted asphalt until a homogeneous mixture is produced. Finally the gasoline or naphtha fraction is stirred into the blended asphalt-gas-oil mixture. The gasoline or naphtha fraction may be added while the asphalt-gas-oil mixture is at a somewhat lower temperature in order to prevent substantial amounts of the gasoline fraction from evaporation.

In some cases, my cut-back asphalt may be produced by carrying out the topping of the asphaltic crude oil under such controlled conditions as to retain the proper amount of gasoil fraction in the asphalt residuum where the character or composition of the crude oil is such as to make this possible. The asphalt distillation bottoms may then be blended with the proper amount of gasoline or naphtha fraction. In fact, it is possible that certain asphalt base crude oils may be of such a composition that they contain the proper proportions of gasoline, gas-oil and asphalt as to provide a proper cut-back asphalt which may be emulsified directly. In some cases, it may be possible to produce a proper cut-back asphalt by merely removing part or all of thegasoline fraction contained in the crude oil to leave a residue which contains substantially only 20 to 60% of a gasoline-gas-oil fraction or gas-oil fraction alone and an asphalt having a penetration of 100 to 300 at 77 F. In some cases, it may be possible to add to an untopped or partially topped crude, a suitable quantity of gasoline or gas-oil to obtain a cutback asphalt having the characteristics described in the preferred embodiment of my invention. Whether this is possible will, of course, depend upon the characteristics of the crude oil. Most crude oils, however, do not contain the requisite proportions of gasoline and gas-oil fractions or gas-oil fraction alone to make this possible. The ordinary crude oils generally contain considerable amounts of lubricating oil fractions which do not evaporate when they are applied on the road and thus these crude oils are generally too soft after the lighter oil fractions have been evaporated to the atmosphere to make them suitable for high quality road laying purposes wherein the binder sets to a tough binding medium which is intended by my invention. However, it is within the scope of my invention to use natural crude oils which contain proper proportions of gasoline and gas-oil fractions, or gas-oil fractions alone which will volatilize when applied to the road or other places of use and which will leave as a residue, an asphalt which will set up as a hard bituminous cement. It is generally preferred that the residue upon evaporation of the volatile gasoline and gas-oil frac-- tions to the atmosphere have a penetration of about 100 to 300 at 77 F. or that it contains from 90 to 99% of penetration asphalt at 77 F.

The emulsification of the cut-back asphalt, that is, either the synthetically produced product or the naturally occurring product, is accomplished by simply mixing the fluid bituminous material in the cold with an aqueous solution containing an emulsifying agent which results in the formation of an oil-in-water type emulsion. If. desired, either the bituminous Inaterial or the aqueous solution or both may be heated somewhat; however, it is one of the advantages of using cut-back asphalts in emulsions that it is unnecessary to heat any of these ingredients to effect the proper emulsification.

As emulsifying agents'to effect the emulsification of the cut-back asphalt with the water, I may employ an alkaline material such as sodium hydroxide or potassium hydroxide, sodium or potassium carbonate and the like, or I may employa soap such as sodium or potassium oleate, resinate, stearate, palmitate. When employing the alkali hydroxide or carbonates, the emulsification of the asphalt is eifected through a saponification of the natural saponifiable ingredients in the asphalt itself. In general, the emulsions produced with alkali alone as the emulsification agent are of the quick breaking type. However, with the presence of the gas-oil fraction in the bituminous cement, these emulsions do not break as rapidly as do the emulsions produced with melted hard asphalt or with the ordinary cut-back asphalts which do not contain substantial amounts of the gas-oil fraction. The amount of emulsifying agent will, of course, depend upon the proportions of ingredients employed and upon the characteristics of the asphalt. In general, I have been able to produce satisfactory emulsions of the oil-in-water type by employing about 0.1 to 0.2% by weight of sodium hydroxide when using approximately equal parts of the bituminous cement and water. 'When employi'ng a snap as the emulsifying agent, it is generally necessary to use a greater amount of this material than in the case of the caustic alkali alone.

materials as starch, gum acacia, agar agar, gum.

targacanth, pectin, Irish moss and the like. It is also possible to stabilize the emulsion with the use of small amounts-of certain alkaline salts or salts of weak acids such as sodium borate, sodium phenate, sodium cresolate and the like.

When employing certain of these stabilizing agents, it may be desirable to also add a preservative such as formaldehyde, cresol, phenol, sodium benzoate and the like. However, if the emulsion is to be applied reasonably soon after its formation, it may not be necessary to add a preservative to the stabilized emulsion.

It is thus an object of my invention to produce an aqueous bituminous emulsion from cut-back asphalts containing substantial amounts of a gasoil fraction.

It is ainore specific object of my invention to emulsify a bituminous cement containing from to 30% by volume of a gasoline fraction of 437F. end point and from 10 to 30% of a gasoil fraction having a boiling range of 450 to 720 F. and the remainder of an asphalt having a high degree of" cementitiousness and hardness. It is another specific object of my invention to emulsify a bituminous cement containing a greater proportion of said gas-oil fraction and a correspondingly less amount of gasoline, said bituminous cement to have a viscosity approximately 100- 120 seconds Furol at 122 F.

It is a still further object of the invention to produce an oil-in-wate'r type emulsion by mixing a cut-back asphalt containing a substantial amount of a gas-oil fraction with an aqueous soobject to effect such admixture at atmospheric temperatures.

It is a specific object of the invention to emuL- sifya cut-back asphaltcontaining a substantial amount of a vaporizab gas-oil fraction having a boiling range of 450 to1720 F. and anasphalt having a penetration of 100 to 300 at 77F., the cut-back asphalt having a viscosity of 100 to 120 seconds Furol at 122 F.

Various'other objects, features and advantages of my invention will appear to those skilled in the art from the following example of one embodiment of-my invention which is given herein for the purpose of illustrating and explaining the invention and which is not to be considered as limiting;

Approximately 59.4% by volume of a petroleum residuum obtained as distillation bottoms in the distillation with steam of .a California asphalt base crude oil and having a viscosity of 980 seconds Furol-at 122 F., apenetration of lution and an emulsifying agent. It is another 200 at 77 F. and approximately 95% of an penetration asphalt at 77 F. was heated to a temperature of about 200 F. to melt the same. Then approximately 18.6% by volume of a gasoil fraction was added and mixed with the melted asphalt. This gas-oil fraction had an initial boiling point of 462 F. and a maximum boiling point of 720 F. and an average boiling point of 589 F. Then approximately 22% by volume of a gasoline fraction having an end point of 437 F.

were added to the mixture and the mixture was agitated for a sufiicient period of time to thoroughly blend the asphalt with the added diluents. The final'blend was a readily flowable mixture at atmospheric temperature having a viscosity of 119 seconds Furol at 122 F.

The blended bituminous cement was then agitated at atmospheric temperature with approximately an equal quantity of water containing about 0.12% of sodium hydroxide for a sufficient period of time to thoroughly disperse the bituminous cement in the aqueous solution.

While some of the common uses to which my,

emulsified cut-back asphalt or bituminous cement may be put comprise road building and repairing roofs, I have found that the emulsion'is specially adapted for the stabilization of loose soils, such as fairly sandy soils or mounds oftailings dump of copper and other mines to prevent erosion of the soil or mound by windand rain. I have found by spraying approximately 0.15 gallon per square yard of the surface, the. emulsion will penetrate a relatively greater distance into the top surface of the soil without breaking and that after the emulsion has broken and the water and diluent evaporated'the top surface is hard and waterproof and is not damaged by subsequent re-emulsification in wet weather.

It is to be understood that the above description is merely illustrative of a preferred embodiment of my invention of which many variations may be made within the scope of the following claims by those skilled. in the art without departing from the spirit thereof.

I claim:

1. An aqueous bituminous emulsion comprising a mixture of water, an emulsifying agent and a bituminous cement comprising a blend of 10 to 30% of gasoline having an end point of about 437 F., 10 to 30% of a gas-oil fraction having a boiling range of approximately 450 to 720 F. and 80 to 40%of an asphalt having a penetration of approximately 100 to 300 at 77 F.

2. An aqueous bituminous emulsion comprising amixture of water, an emulsifying agent and a bituminous cement comprising a blend of ap-.

proximately 59.4% by volume of an asphalt containing of 80 penetration. asphalt at 77 F, and havin a penetration of approximately 200 at 77 F., ap roximately 18.6% by volume of a gasoil fraction havingan initial boiling point of approximately 462 F., a maximum boiling point of 720 F. and an average boiling point of approximately 589 F. and 22% by volume of a gasoline fraction having an end point of 437 F., said blend of asphalt, gas-oil and gasoline having a viscosity of approximately 119sec0ndsFurol at FREDERICK S. SCOTT.