US2783163A

US2783163A - Road making and the like

Info

Publication number: US2783163A
Application number: US432334A
Authority: US
Inventors: Gilman B Mollring
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-05-25
Filing date: 1954-05-25
Publication date: 1957-02-26
Anticipated expiration: 1974-02-26

Description

United States Pate-r1120 ROAD MAKING AND THE LIKE Gilman B. Mollring, Los Angeles, Calif.

No Drawing. Application May 25, 1954, Serial No. 432,334

3 Claims. (Cl. 106-280) This invention relates to a method for building roads in which asphalt or other bituminous substances are employed to coat and bind the mineral aggregate normally used in such construction. The invention particularly relates to an improvement in two of the known methods for building roads by the so-called cold laying process in which the bituminous binding agent is used in the form of a powder; According to the cold laying method described in Radcliffe, U. S. Patent 1,655,240, which has been reissued as U. S. Patent Re. No. 17,985 under date of March 3, 1931, the stone aggregate is first coated with a slow drying liquid binder and then with a powdered bituminous binder and the mixture is later amalgamated on the road by rolling. In this method no heat is employed either to melt the bituminous substance or to effect amalgamation on the road. The solvent liquid binder employed is sufficiently fluid at atmospheric temperatures so that no heat is applied either to liquefy the binder or during admixture with the aggregate. The powdered bituminous binder is of sufliciently high melting point so that when it is commingled with the liquid binder the resultant blend will have a desired melting point sulficiently high to resist summer heat. According to the cold laying method described in the Beckwith U. 8. Patent No. 2,220,670, dated November 5, 1940, the stone aggregate is first coated with a substantially nonvolatile, highly aromatic, non-paraflinic oil which is fluid at atmospheric temperatures and then with a powdered bituminous binder having a high melting point, and the mixture is likewise later amalgamated on the road by rolling.

It is to be noted that both of the :above processes have one thing in common in that the aggregate is first coated with a solvent liquid binder which is fluid at atmospheric temperatures and then with a powdered bituminous binder. Thus a manufacturer of paving material using either of the two above mentioned methods would obviously batch into a suitable mixer three separate components in the following sequence: first, the mineral aggregate; second, the liquid solvent binder; and third, the powdered bituminous binder.

My invention relates to an improvement in the above mentioned cold laying methods for building roads and the like. In the aforementioned methods considerable dimculty has. been experienced in obtaining a uniformly good end product and the following disadvantages are manifest: (l) The paving mixtures are too slow in obtaining initial stability excepting under a considerable amount of pneumatic tired trafiic. (2) The mixtures are highly susceptible to stripping in the presence of water. (3) Longer mixing time is required to make this material because the two bituminous components i. e., the solvent liquid binder and the powdered bituminous binder have to be introduced into the mixer in sequence and not simultaneously, thus the mixer man requires more time to mix a batch of material, (4) Paving mixtures made at atmospheric temperatures of say 50 F. can not be successfully coated with the same quantity of-total binder :as can ice identically graded aggregates made at temperatures of approximately F. This is due to the fact that as the temperature at time of mixing is low the solvent liquid binder deposits a thicker film on each aggregate particle than it would if the temperature were much higher. This temperature variation at time of mixing from time to time results in non-uniform appearing batches of paving material and quite frequently at low temperatures leaves the larger sized aggregate particles partially or totally uncoated. For illustration let us say that a certain aggregate composition by reason of its surface area, porosity, etc., should require a total bituminous binder of say 6% by weight and that the blending chart indicates that by using 3% of solvent liquid binder and 3% of powdered bituminous hinder the composite binder will have a resultant penetration of about at 77 F. If mixing takes place while the atmospheric temperature is around 90 R, we will find that we obtain a uniform and well coated aggregate. However if the mixing takes place at temperatures around 50 F. we will find that a considerable amount Of the larger sized aggregate particles are uncoated. (5) A fairly high percentage of the bituminous binder is completely wasted as it does not come into complete submergence with the solvent liquid binder and it remains in the mixture as just so much inert material. For example 1 have taken samples of paving materials made from the aforementioned process and placed them in a water filled container and after shaking the container found a considerable amount of powdered bituminous binder floating on the surface of the water. It is only fair to relate that paving mixtures made by either of the two aforementioned methods, if manufactured and consolidated on the road bed, under ideal working conditions will provide a highly satisfactory road surfacing material.

It is the object of my invention to provide a simple and effective cold laying process that will completely obviate the disadvantages of the two aforementioned processes and still retain most of their desirable features. Other objects of my invention will appear from the following description of my discovery.

In practicing my invention for building roads I first of all prepare a unique composite liquid bituminous binder. This composite binder may be termed to be an oleosol and may be conveniently made in any suitable mixing chamber preferably provided with power stirrers and a variable speed motor and is made in the following manner: First, a substantially non-volatile bituminous flux oil, hereinafter fully described, in an amount equal to from 20% to 60% of the total composite binder is placed in the mixing chamber. Thereupon a substantially volatile liquid solvent, hereinafter fully described, in an amount equal to from 10% to 50% of the total composite binder is likewise placed in the mixing chamber and the power stirrers operated. This produces a nonviscous solvent liquid flux oil cutback. The making of this liquid flux oil cutback will require but a few minutes. Subsequent to the above operation, a powdered bituminous binder, hereinafter fully described, in anamount equal to from 10% to 50% of the total composite binder is slowly added to the mixing chamber while the power stirrers are kept in continuous operationand the mixing continued until the three :above mentioned components result in a very slightly viscous but still readily pumpable composite liquid containing a fairly high percentage of the powdered bituminous binder particles suspended in the liquid flux oil cutback in a state of solid or semi-solid condition. At this point my composite liquid bituminous I reduce the spread of the power driven stirrers in the mixing chamber. After the stone aggregate material has been thoroughly coated with approximately 4% to 12% by weight, depending of course on the surface area, porosity etc., of the aggregate composition, with my composite liquid bituminous binder the mixture may be taken to the road bed and spread to the desired cross section and thickness and consolidated by rolling.

The above described paving material will exhibit a high initial stability and the composite liquid bituminous binder will, concurrently with the evaporation of the volatile solvent liquid it contains, rapidly amalgamate to provide a substantially homogeneous bituminous binder for the stone aggregate material.

The substantially non-volatile bituminous flux oil I have chosen to use as my first component of my composite liquid bituminous binder may be any one of several grades of asphaltic road oil or bituminous liquid fuel oils. It may be a substantially non-volatile, non-parafiinic, highly aromatic lubricating oil extract as that term is understood in the industry. Preferably this flux oil or liquid binder should have a viscosity S. S. F. of between 30 to 100 at 122 F.

The substantially volatile liquid solvent 1 have chosen to use as my second component of my composite liquid bituminous binder is a petroleum distillate and may be, depending on the type of finished product I wish to produce, a gas, oil or light fuel oil, kerosene, diesel, naphtha etc, it being obvious that each type of solvent has a different evaporation rate and solvent power. Depending on the solvent used, I can produce a composite liquid bituminous binder having, slow, medium or rapid curing characteristics.

The powdered bituminous binder I have chosen as the third component of my composite liquid bituminous binder should preferably meet the following general requirements:

Specific gravity 1.00 Softening point (R. & B.) 250-300 Penetration at 77 F -5 Flash 450 min.

The powdered bituminous binder may be prepared from natural asphalt such as gilsonite or from petroleum asphalt, and can easily be reduced to the desired fineness by means of a suitable impact mill, as for example a #14 Williams Hammer Mill. I have found that I can obtain very good results by reducing the hard asphalt to about the following degree of fineness:

Mesh 100% passing 30 60% passing 80 40% passing 100 20% passing 200 In making my composite liquid bituminous hinder or oleosol it is essential that the components be commingled at or near normal atmospheric temperatures so as to not completely dissolve all of the powdered bituminous binder particles contained in the liquid flux oil cutback as this would produce a material too viscous to pump readily or coat the mineral aggregate particles properly. In actual practice I usually make up just enough composite liquid bituminous binder for the following days mixing operation as it is apparent that the above described composite binder will progressively become more viscous as the powdered bituminous binder is being slowly dissolved by the solvent liquid flux oil cutback.

As specific examples of some of the many composite liquid binders I have made, the following table indicates the percentage by weight of each component, the approximate residue after evaporation of the volatile liquid solvent and the approximate resultant penetration of the residue at 77 F.

T he composite liquid bituminous binder above described provides a binder that is easily pumpablc at normal temperatures and one that is readily miscible with stone aggregate materials without employing any heat whatsoever. When suitable well graded aggregate is fully coated with the above composite binder and the mixture is spread to the desired thickness on the road bed and subsequently consolidated into place by rolling an excellent pavement is obtained. My process difiiers from the two aforementioned methods for building roads in that my powdered bituminous binder is commingled with the liquid solvent binder prior to contact with the stone aggregate and is not introduced into the mixer as a separate component.

As a variant to making a three component composite liquid bituminous binder as hereinbefore described I sometimes use liquid flux oil cutbacks such as slow curing, medium curing or rapid curing types. These grades of cutback asphalt are well known to the industry as SCs, MCs and RC grades of liquid asphalt, and as they con tain a substantially volatile liquid solvent it is necessary to add little if any additional solvent liquid, therefore I introduce any one of these grades of cutback liquid asphalts into my mixing chamber with or without the addition of more liquid solvent and then slowly add to the mixing chamber a quantity of powdered bituminous binder as hereinbefore described, and continue the mixing until I have my composite liquid bituminous binder. I generally prefer to use an 80-0, MC-O or RC-O as these grades have a Furol viscosity of 75-150 at 77 F. and as a consequence are readily pumpable at the normal atmospheric temperatures.

The above description of my invention is not to be considered as limiting my invention but only as illustrative of the invention, as many variations may be made within the scope of the following claims.

I claim:

1. A process for making material for roads wherein stone aggregate is coated with a composite liquid bituminous binder consisting essentially of a pumpable suspension of powdered hard asphalt in a non-viscous flux oil cutback, which comprises blending a substantially non-volatile highly aromatic, non-parafiinic flux oil with a volatile petroleum distillate to form said non-viscous flux oil cutback, mixing therewith at atmospheric temperature said powdered hard asphalt, discontinuing the mixing when the mixture starts to become viscous so as to produce said composite liquid bituminous binder, and mixing said composite liquid bituminous binder with said stone aggregate at atmospheric temperature; the proportions of the various materials being such that the powdered asphalt, flux oil, and petroleum distillate comprise 10 to 50%, 20 to 60%, and 10 to 50% by weight respectively, of the composite liquid bituminous binder, and the composite liquid bituminous binder comprises approximately 4 to 12% by weight of the aggregate composition.

2. A process according to claim 1 in which the nonvolatile liquid is a highly aromatic lubricating oil extract.

3. A process according to claim 1 in which the powdered asphalt comprises a fines fraction which is smaller than 100 mesh and a coarse fraction which is larger than 80 mesh.

References Cited in the file of this patent 5 UNITED STATES PATENTS 6 Richardson Jan. 10, 1911 Berger June 5, 1928 Ferguson Sept. 20, 1932 Fletcher Dec. 19, 1933 Baskin Apr. 30, 1935 Wells Aug. 6, 1935 Swanberg Feb. 9, 1937 Greaves et a1. Apr. 13, 1954

Claims

1. A PROCESS FOR MAKING MATERIAL FOR ROADS WHEREIN STONE AGGREGATE IS COATED WITH A COMPOSITE LIQUID BITUMINOUS BINDER CONSISTING ESSENTIALLY OF A PUMPABLE SUSPENSION OF POWDERED HARD ASPHALT IN A NON-VISCOUS FLUX OIL CUTBACK, WHICH COMPRISES BLENDING A SUBSTANTIALLY NON-VOLATILE HIGHLY AROMATIC, NON-PARAFFINIC FLUX OIL WITH A VOLATILE PETROLEUM DISTILLATE TO FORM SAID NON-VISCOUS FLUX OIL CUTBACK, MIXING THEREWITH AT ATMOSPHERIC TEMPERATURE SAID POWDEREC HARD ASPHALT, DISCONTINUING THE MIXING WHEN THE MIXTURE STARTS TO BECOME VISCOUS SO AS TO PRODUCE SAID COMPOSITION LIQUID BITAMINOUS BINDER, AND MIXING SAID COMPOSITE LIQUID BITUMINOUS BINDER WITH SAID STONE AGGREGATE AT ATMOSPHERIC TEMPERATURE; THE PROPORTIONS OF THE VARIOUS MATERIALS BEING SUCH THAT THE POWDERED ASPHALT, FLUX OIL, AND PETROLEUM DISTILLATE COMPRISE 10 TO 50%, 20 TO 60%, AND 10 TO 50% BY WEIGHT RESPECTIVELY, OF THE COMPOSITE LIQUID BITUMINOUS BINDER, AND THE COMPOSITE LIQUID BITUMINOUS BINDER COMPRISES APPROXIMATELY 4 TO 12% BY WEIGHT OF THE AGGREGATE COMPOSITION.