USRE17985E - Certificate of correction - Google Patents

Description

Reissued Mar. 3, 1931 UNITED STATES PATENT OFFICE JOHN RADCLIIB'FE, OF SHERLOCK ROW, NEAR TWYFORD, ENGLAND, ASSIGNOR TO GOLPROVIA LIMITED, OF LONDON, ENGLAND, A CORPORATION OF GREAT BRITAIN ROAD MAKING AND THE LIKE 80 Drawing. Original 110. 1,655,240, dated January 3, 1928, Serial N'o. 758,265, Med December 26, 1924,

and in Great Britain January 2, 418,979.

This invention relates to roads which are composed of aggregate material bound together with oiLpitch, coal tar pitch and other bitumens and similar materials.

The efficiency of roads requires that they do not unduly soften in summer temperature. The binder should therefore have a melting point high enough to resist too much softenlng when exposed to the sun. The coated stone should therefore be laid down warm or it will be too stifi to handle. Binders having the requisite temperature stability are well known, but difiicult to apply for the reason stated.

y invention consists in a process of road making by which this may be avoided, and

at the sametime a higher technical efiiciency may he arrived at, that is to say, the road may have a good temperature stability in hot and in cold weather, and comprises a method of employing binders by which roads may be either laid down cold or at lower temperatures than hitherto necessary, and at the same time using the desirable higher melting-point inder.

According to one application of my invention, the stone is first coated with a liquid of semi-liquid part of lower melting-point than ultimately required, which need not be done near the roa'd to be made, the resultant mix being of an oily, freely movable nature at temperatures below summer heat. Such a coated stone cannot get wet and perfect coating and perfect adhesion will be secured.

Secondly, at a suitable time before or while this coated stone is being laid down, I'add, in any form, but preferably as a dust, a suitable proportion of another binder part of higher melting-point than ultimately required. The resultant mix is com osedpf aggregate particles coated with a rst oily coating and a second exterior dustllke coa ing of powdered bitumen, the aggregate particles being thus separated from each other by the dustlike coating and therefore freely movable with respect to each other.

This may be done manually or mechanically.

Before the incorporaton of the liquid part or part of too low melting-point which is on 1924. Application for reissue filed January 8, 1980. Serial No.

the stone, with the part of too highmeltingpoint afterwards added, sufficient time will have elapsed so as to allow of proper handling and placing of the mass in position in consolidation, but the powdered part is preferably applied shortly after the incorporation of the liquid part, as the oiled a gregate if stored for considerable periods 0' time would be likely to get covered with dust and to oxidize somewhat, thus interfering with proper adhesion thereto of the powdered binder when added. Where powdered binder is promptly added, however, the material can be successfully stored for considerable periods of time and subsequently laid and consolidated by means of pressure.

By rolling and short lapse of time, the binding parts will incorporate and amalgamate to form a composite and consolidated binder of the requisite temperautre stability, the liquid part being a ve slow solvent or blending agent for the pow cred high melting point art. a p The binder dust added may contain fine mineral or organic matter.

I find the mixtures of the kind above described are useful in making orfor strengthening roads made from tar and similar materials. Natural mixtures of bitumen and mineral matter. have been ground up finely and used for the above purpose.

I find that better and cheaper mixtures can be made containing any required proportion of pitch by grinding together in an impact mill pitch, preferably high melting point oil pitch, for example, that melting at 230 F., and mineral matter, preferably sand.

to a fine condition by any form of rubbing is useless for the above purpose, as the effect is simply to roll up or ball up the pitch or bitumen.

A. mixture of this kind is not onl useful as an enricher, but provides a suitable proportion of filler, thus avoiding the use of the ex ensive Portland cement.

he material for the construction of roads by my process can be conveniently prepared in a mixer of the type of a concrete mixer.

The variables are the size of the stone, which determines the viscosity of the liquid, which in turn determines the ropertion of the hi h melting powder and t e proportion of tota binder. The general principles under which these may be easily determined are as follows y The smaller the stone, li uid part should be.

rge stones of size 1 inches to 1 inch, rapidly rotate in a mixer, can be easily coated with the requisite amount of liquid or semi-liquid, while smaller material, for example, one-eighth inch, would simply ball up, part of it having too much and part too little. The larger stone would coat without sticking together, which is the correct the more fluid the condition. Sand on the other hand, requires quite a thin oil, for example, a fuel 011.

The character and quantity of the liquid part determine the proportion of hi h melting powder to he used. This will e made clear from the example below, which relates to the use together of a fuel oil derived from crude petroleum as a liquid non-volatile flux oil and a high melting-point, e. g. 230 F., residue pitch from distillation.

In the case of fine sand, fuel oil alone may be used for the liquid part. In the case of larger material, part of the solid binder portion would be first dissolved in the fuel oil, thus thickening it. This procedure would facilitate operation of crude oil distillation, as distillation could be carried further. and the more valuable lubrication oils saved, the less valuable high melting-point pitch used for roads, and transported as pitch without ack es, which would save money. A ratio of 30 uel oil of 3. gr. 0.95 to of pitch of melting-point 230? F. will in general give a correct binder.

In hot climates, however, the proportion of oil will be less, and in tro ical climates, roads without oil can be made i desired, when using finel ground mineral matter with ground pitc as will afterwards he mentioned. The proportion of ground high melting-point pitch can be greatly increased, and in this case the excess makes and acts as a filler with the advantage that rolling will consolidate it. In fact, at a temperature of 70 F., ground pitch of melting-point 230 F. can be mixed with fine mineral matter, and it will consolidate by rolling, although not making as strong a compound for roads as when mixed with a liquid softener.

A ound binder of melting-point 212 F. will, dibwever, give a usable compound with fine mineral matter, such as fine sands.

I have found that a suitable fineness for the ground pitch is such that 60% will pass a mesh of 100 to the linear inch, and 30% a mesh of 200. These figures are obtained with a pitch of 230 F. melting-point, but the process is workable with considerable variations from these fi ures. In general, if the pitch alone with ne sand will bind in the iplroportions of 90 sand to 10 pitch, it will be ne enough.

The grinding and handling of the pitch is facilitated by grinding with mineral matter, for example, sand, and this serves a double object, as material fine enough to act as a filler can be produced, replacing Portland cement sometimes used. It can also be transported without caking. Thus if a-mixture of 90 sand to 10 pitch he passed through a mill of the kind described, it maybe ground to the following Per cent Passing 20 to linear inch Passing 40 to linear inch 4.0 Passing 50 to linear inch 15.0 Passing 70 to linear inch 27.0 Passing 100 to linear inch 29.0 Passing 200 to linear inch 24.0

the pitch being relatively more finely ground than the sand.

The binder ratios having been determined according to the principles stated, that is to say. in accordance with the size of the mineral matter, the climatic conditions, the character of the oils available, the character of the pitch available, and the proportion of total binder economically desirable, I use them preferably in the following manner, which may be taken as an example Stone of to 4 inch is placed in a mixer. the liquid part added, and the mixer rotated until the said stone is covered, forming an oily mix the aggregate particles of which are free- 1y movable on one another at temperatures below summer heat. The powder part is then added while the mixer rotates and adheres to the liquid coating of the aggregate as a dust.

The mixing is continued only long enough to.

properly distribute the powdered binder throughout the mass forming a freely movable mass of particles cushioned and separated from each other by said dustlike coating. Mixing for longer periods tends to make the mass too sticky and viscous and hinders the removal of the mass from the mixer and the spreading of it on the road. This may ,be used at once, as the binder course of the road. I prefer, however, to add a proportion of finer mineral matter from one-eighth inch down to sand which has been previously treated with its proportion of liquid part and binderpowder added. 'This may contain a proportion of sand adheres to the arger mineral matter and aids in forming a separating dustlike cushionbetween the aggregate particles.

ound up with pitch. This It is better, however, that the stone, large and small, made to carry its own proportion of the binders. Made in this manner, my road material consists of separate nuclei of stone carrying its binders and surrounded with the proper pro ortion of finer material also having its bin er. This can be transported and rolled down without any more preparation at ordinary or low temperature, and a strong dense roadmade, as the material for filling the interstices is part of the mass of which the stones form nuclei.

Wearing surfaces composed of the usual fine material, consisting as a rule largely of sand, are made in the same manner. These may contain a total of 11% binder.

Alternatively, the larger stone, after being wetted with liquid part, may have the whole or part of the powder binder added, which has been ground up with mineral matter, as described. This will allow of transport and storage of powder without any danger of caking.

This material may also contain liquid part.

The operations may be carried out on the spot, and the mixing done continuousl the pitch dust or pitch dust and ground mineral matter being blown directly by the fan from the mill to the mixer. The material may be prepared in any simple apparatus of the type of a concrete mixer.

In most cases I contemplate mixing and laying at ordinary temperature, but the advantages of the invention are part1 realized with mixtures which require a mo erate degree of heat, particularly in the case of a thick oil which may require warming to make it run.

As stone may tion, I ma dry be delivered in a wet condimoist aggregate has been dried by heating rior to use, it should preferabl be cooled efore the powdered binder is ad ed.

In this manner I can construct roads without necessarily warming, binders having the desired physical properties can be used without difficulty, efficiencies improved by ensuring the perfect first coatin which, by its nature, is not likely to be detached, and a cushion placed, if required, between each stone by increasing the amount of organic or mineral part.

I am aware that as halt pavement is made by mixing powdered sand or other fine ag regate, then heating the mixture to a relative y high temperature sufficient to make the bitumen or asphalt fluid or at least semi-liquid and then spreading and rolling the mixture on the road while hot. The resulting pavementhas the desired density, but it lacks uniformity of distribution of asphalt binder and particles of aggregate, y reason of the fact that the squeezing it by adding a proportion of dry lime efore adding liquid portion. If.

dust added to the pulverized binder itumen or asphalt with down of the aggregate particles in the hot, soft asphalt, by rolling, results in squeezing up of the asphalt toward the surface of the road, so that the finished pavement has somewhat less than the desired proportion of binder to aggregate in its lower part and somewhat more than the desired proportion in its upper part and may be covered with a thin skin of asphalt. This makes the road undesirably slippery at first. And whereever the top surface wears through, it permits rapid disintegration of the lower portion of the pavement which has not the desired proportion of binder asphalt.

With my invention, on the contra the powdered bitumen or asphalt is still su stantially in solid phase when laid. In this condition, it not only has greater specific gravity than when amalgamated with the liquid binder, but the physical state of the dry hard asphalt is such that it cannot squeeze upward to the surface of the road under the pressure of the roller. Hence the distribution of the asphalt through the pavement is better in the case of my process than in the case of the hot asphalt process described. Furthermore the amalgamation of the liquid and powdered binder under pressure in m process forms a consolidated or composite binder which retains for some time a rather glutinous consistency allowing the particles of aggregate to arrange themselves under the pressure of trafiic to positions of ultimate compactness without disturbing the uniformity of rela-- tion of aggregates and binder in the avement and without distortion of the roa surface. This feature is of great practical importance, and it is not possible in any type of hot asphalt construction because once the pavement has cooled off the asphaltic binder is too hard to permit further movement of the aggregate particles init.

An additional advantage of my invention over ordinary asphalt roads is b reason of the more erfect distribution 0 the composite asp altic binder from top of the pavement. And as this Is composed of correctly proportioned oil and hard asphalt, it has the the pavement for longer periods than is possible in hot asphalt.

I am also aware that certain asphaltic avements are laid cold. The materials or such pavements are prepared by first coating the aggregate with a volatile solvent oil and then mixing in the asphalt at a relatively high temperature (about 270 F The volatile solvent oil partially dissolves the asphalt and renders it semi-fluid and workable at ground temperatures so that it ma be laid and rolled at the works, provided su cient time has not clasped to permit evaporation of the solvent. Such cold asphalt pavements are hardened by evaporation of the solvent.

property of keeping alive But it will be readily understood throu that the evaporation takes place first at the surface of the pavement, thereby hardening the surface and tending to prevent evaporation from lower portions of the avement, and thus if a dense upper surface is formed the lower portion remains too soft and the upper surface is permitted to creep and roll, forming undesirable corrugations. To avoid this, such pavements have to be made less dense than is otherwise desirable in order to permit evaporation of the solvent from the whole body of the pavement. Even then undue softness of the lower ortion of the pavement is not entirely avoidiad and the smoothness and wear of such avements is notably inferior to hot aspha t pavements or to those resulting from the use of my invention.

As no evaporation of a volatile solventis required in laying pavements b my process and pavements so made consoli ate at a substantially uniform rate throughout, my invention constitutes a great practical improvement over prior cold asphalt pavements of the type described, by permitting uniform distribution of aggregate and binder throughout the pavement while retaining the desired density of the resulting pavement. By my invention, the amount of voids in the finished pavement may be controlled by the selection, sizes and proportions of stone, sand or other aggregate and of the filler and binder materials used therewith without sacrificing uniformity of the mixture throughout the pavement. Accordingly, I am enabled to provide a avement having the desired characteristics 0 density and to vary the same to the requirements of the pavement to be constructed, whether it be a stonefilled or sand-filled base course or hinder course or sheet pavement, while at the same time maintaining uniform distribution of asphalt and aggregate and the desired density hout these courses.

Di culty has been encountered heretofore in incorporating into the aggregate material in the finished road the esired proportion of bitumen, when using as a binder hot asphalt alone or asphalt mixed with a liquefier, for in such road buildin it is found that only a limited amount of itumen will adhere to the surface of-the aggregate particles and be incorporated into the road as laid. This is due to the fact that when the bitumen is sufficiently fluid to be workable in the mixer,

drains off the surface of .the aggregate parmost of the bitumen subsequently ticles. This difliculty is encountered particularly in coating coarse aggregate material, as coarse material has less surface area in proportion to its bulk than fine material to which the bitumen in fluid condition may adhere. Frequently it is desirable to increase the proportion of bitumen in a road beyond the amount of fluid bitumen which will adhere to the aggregate, to make the road more firmly and permanently bonded. It has been found for example that when hot bitumen used alone or with a iiquefier is used in connection with coarse aggregate, the laid road can be made to contain only about 5% bitumen. To make up the deficiency in bitumen, hot bitumen has been heretofore sprayed upon the surface of the laid road but it is obvious that this does not accomplish uniform distribution of the added bitumen.

According to this invention, aggregate may be coated with a flux oil which corresponds in amount to the quantity of hot bitumen, used either alone or with a liquefier, which could have been made to adhere to the aggregate particles by methods heretofore used.

hen powdered bitumen me. be added to any additional amount desire which adheres as a dust to the aggregate particles and becomes uniformly distributed in the road when laid where it amalgamates with the flux oil to produce a binder of proper consistency. Thus coarse aggregate, for example, may be coated with 5% of flux oil and then an additional 5% or more of owdered bitumen added, thus producing a nished road containing 10% or more of binder uniformly distributed.

In practice, my invention has provided roads which are admirably adapted to heavy traffic and which have a toughness combined with resiliency and'long life that make them a substantial improvement over pavements heretofore known.

The invention may be used not only in making the road surface adapted tobe laid on ex1sting surfaces of' concrete water-bound macadam, tar-spread roads, wornout roads of bituminous materials and the like, *but in addition, it may be used for making the foundations as well as the top surface.

While I have described my process particularly in relation to road makin it is apparent that my process is applicab e generally to the coating of a 'gregate materials with a bituminous binder y coating the aggregate with a liquid binder having a meltmg point lower than is necessary to resist summer heat, applying to the lirhuid coating of the aggregate a powdered bin ing having a melting point higher than is necessary to resist summer heat, and amalgamating the said liquid and powdered binders as a composite and consolidated binder for the aggregate having a melting point sufficiently high to resist summer heat by pressing and coniolidating the mix without the-application of eat.

What I claim and desire to secure by Letters Patent is:--

1. A process of making material for roads wherein stone aggregate is coated with bituminous materials, characterized by coatin the aggregate with a slow solvent liqui binder avmg a melting point lower than is necessary to resist summer heat, and subsequently before or during drying applying to the coated aggregate while relatively cold a powdered bituminous binder having a melting point higher than is necessary to resist summer heat and capable only under applied pressure of amalgamating while cold with the liquid binder to form a substantially homogeneous composite binder.

2. A process of making material for roads wherein stone aggre ate is coated with bituminous materials, characterized by coating the aggregate with a slow solvent liquid binder having at a melting point lower than is necessar to resist summer heat, and subsequently libforeor during drying applying to the coated aggregate while relatively cold a powdered bituminous binder having a melting point higher than is necessary to resist summer heat and capable only under applied pressure of amalgamating while cold with the liquid binder to form a substantially homogeneous composite binder, said latter binder being mixed with a powdered filler.

3. A process of making material for roads, comprising coating aggregate material with a binder which is liquid at temperatures below summer heat to form a freely movable oil mix, and then applying to said aggre ate tius coated a powdered bituminous iiinder having a melting point higher than is necessary to resist summer heat as an adhering exterior dustlike coating for the aggregate particles to form a freely movable mass of particles cushioned and separated from each other by said dustlike coating and adapted to be laid and consolidated in place on roads.

4. A process of making material for roads comprising coating aggregate material with a binder which is liquid at temperatures below summer heat to form a freely movable oily mix, and then applying to said aggre ate thus coated a powdered bituminous inder having a melting point higher than is necessary to resist summer heat and a powdered mineral substance as an adhering exterior dustlike coating for the aggregate particles to form a freely movable mass of particles cushioned and separated from each other by said dustlike coating and adapted to be laid and consolidated in place on roads. 1

5. A process of making roads wherein aggregate material coated with a bituminous binder having a melting point sufficiently high to resist summer heat is used, characterized by coating the aggregate with a slow solvent liquid binder having a melt ing point lower than is necessary to resist summer heat to form an oily mix the particles of which are freely movable on one another at temperatures below summer heat, applying to said liquid coating of the aggre- 1gate as an adhering dust a powdered binder aving a melting point higher than is necessary to resist summer heat, and capable only under applied pressure of amalgamating while co d with the liquid binder to form a substantiall homogenous composite binder, and therea ter substantially amalgamating said liquid and powdered binders as a composite consolidated binder for the aggregate by means of pressure and consolidation of the mass while in place without the application of heat.

6. Process of road making which comprises first preparing the pavement material by drying the aggregate, mixing a filler with the drie aggregate, coating the aggregate and filler with a substantially nonvolatile oil which is liquid at temperatures below summer heat, and coating the oiled aggregate and filler with a powdered hard asphalt at normal temperature.

. Process of road making which comprises first preparing the pavement material by dr mg the aggre ate, mixing a filler withthe dried aggrega e, coating the aggregate and filler with a substantially non-volatile oil, which is liquid at temperatures below summer heat, coating the oiled aggregate and filler with a powdered hard asphalt at normal temperature, and then la ing'the pavement material so repared an amal amating the oil and pow ered hard asphalt y pressure and rolling to form a composite binder having a. melting point sufliciently high to resist summer heat, substantially uniformly distributed with the aggregate throughout the resulting pavement.

8. A process of making roads wherein aggregate material is coated with a bituminous binder having a melting point sufliciently high to resist summer heat, characterized by coating the aggregate with a substantially non-volatile binder which is liquid at temperatures below summer heat, applying to said liquid coating of the aggregate as an adhering dust a powdered bitummous binder having a melting point higher than is necessary to resist summer heat, laying the aggregate as thus coated with said liquid binder and with said adhering powdered binder, and substantially amalgamating the liquid and powdered binders by rollin and consolidating the ma terial in place wit out the application of heat.

9. A process of coating aggregate material with a bituminous binder, characterized by coating the aggregate with a binder which is liquid at temperatures below summer heat to form a freely movable oily mix applying to the liquid coating of the aggregate a. powdered binder having a melting point higher than is necessary to resist summer heat, and amalgamating said liquid and powdered binders as a composite and consolidated binder for the a gregate having a melting point sufficiently high to resist summer heat by preslaf:

sure and consolidation of the mix without the application of heat.

10. A' process of road making wherein aggate material is coated with a bituminous Eider havinga melting point sufliciently high to resist summer heat, comprisin coating t e aggregate at a temperature be ow summer heat with a non-volatile liquid oily binder to form a freely-movable oily mix, applying to said aggregrate thus coated at a temperature not above summer heat a powdered bituminous binder having a melting point higher than is necessary to resist summer heat as an adhering exterior dustlike coating for the aggregate particles to form a freely-movab mass of particles cushioned and separated from each other by said dustlike coating, laying the aggregate unheated as thus coated with said liqui binder coating and with said powdered binder coating, and substantiall amalgamatin the liquid and powdered bin ers by conso idating the material in place without the application of heat.

11. A process of coating aggregate material with a bituminous binder, comprising coating the aggregate with a binder which is liquid at tem eratures below summer heat to form a free y movable oily mix, applying to the aggregate thus coated at a tem erature not above summer heat a powdere binder having a melting point higher than is necessa to resist summer heat as an adhering extenor dustlike coating for the aggregate particles to form a freel movable mass of particles cushioned and separated from each other by said dustlike coating, and then amalgamating said 1i uid and sai powdered coatmgs by means 0 pressure and consolidation of the mix without the application of heat to form a composite and consolidated binder for the aggregate having a melting point suflic ently high to resist summer heat.

In testimony whereof I aflix m s' ature.

a, JpHN nandn m rn.

CERTIFICATE OF CORRECTION.

Reissue Patent No. l7,985. Granted March 3, 1931, to

IOHN RADCLIFFE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 70, for "temperautre" read temperature; page 4, line 106, after "surface" insert "Moreover, my invention is also adapted to the making of paving blocks composed of aggregate coated and bound together by bitumen, simply by taking aggregate material coated with a first coating of flux oil and a second adhering dustlike coating of powdered bitumen and pressing said material into suitable forms, thus consolidating and amalgamating the binders and forming blocks of desired shapes and dimensions.

Page 4, line 115, for "binding" read binder, and page 5, line 14. claim 2, strike out the word "at"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 14th day of April, A. D.. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.