US1220680A - Process of forming a paving material. - Google Patents

Description

- MICHAEL A. POIPKESS,

SAS CITY, MISSOURI, ASS IGNOR .TO BITUMINIZED ROAD COMPANY, A COBPORATION'OF ARIZONA.-

IPROCESS 0F FORMING A PAVING MATERIAL.

LQQUMBMI".

No Drawing.

To all whom it may concern:

Be it known-that T, MICHAEL A. PorKEss, a citizen of the United States, residingat Kansas City, in the county of Jackson and State of Missouri, have invented new and" useful Improvements in Processes of EOE-m ing a Paving Material, of which the follow: ing is a specification. Y 5

he present invention relates to the production of a substance, suitable for paving purposes and the like, the main ingredient of which is a material which has heretofore been considered quite unsuitable for such purposes. a

There exist, in most localities, deposits of sand, gravel and earthy material, .or stone in a more or less decomposed or disintegrated state, sometimes called rotten stone or dirty sand and gravel. Such material, in its natural state, cannot be easily mixed with a bituminous binder so as to form a durable product. The reason ap-' pears to be that the fine or earthy material forms a coating or shell around and adherent to the larger stony particles, which coating or shell prevents the bitumen'from coming into contact with said stony particles and, therefore, from cementing them together. v 7

Consequently, such deposits have never come into practical commercial use, as an ingredient of paving material, and, therefore, at the present day it is always required that the mineral aggregate for asphalt pavements shall consist of clean, hard, sharp particles of graded sizes. Dirty sandor gravel is not permitted.

Where attempts have been made to use deposits, such as described-above, the plasticity and colloidal qualities of the earthy material were destroyed, owing to the high temperatures used, whereby it was caused to fiocculate or form lumps which absorbed Water but not the bituminous binder.

, Specification of Letters Patent. v Patented Mar. 2?, 11ml '2'. Application filed April 1t),

1916', Serial in. 90,244.

results as possible, it is necessary that the mineral aggregate be practically free from earthy material and graded so that there is .an interlocking of theseparticles. The stabilityof the pavement'is governed by this ...interlocking, and, for that reason round particles are not satisfactory,-but, as above stated, clean, hard, sharp and" irregular particles are demanded, the idea in this type of I pavement being-to have the. aggregate support the trafic by. the stony particles rest,- ing on each other and with the bitumen merely cementing said particles together.

In actual construction'work where large quantities of different sized materials are us ed, the interlocking of the different sizes of material is imperfectly attained on ac- Count of the fact that the large particles separate .more or less from the fine particles in the-road making operation and the difl'erent sizes tend to segregate into. clumps in the mixing thereof, which prevents the interlocking and close com acting action.

tion of-holes; it also causes creeping, which makes the pavement unevenand wavy.

Also, the gradual. crushing of the minerali aggregate in asphaltic pavements, as ordinarily constructed, produces mineral parti-f cles which are not coated with bitumen, thus destroying the cementation and allowing the pavement to erode and wear into holes.

When a sheet asphalt or asphaltic concrete pavement becomes hot, the bitumen be:

comes thinly liquid and ceases to act as a cement and its only value then is that it par-v tially water-proofs the mineral aggregate,

to the extent that it fills part of the large voids with .too much bitumen and the small voids with too little. As a result, all of the load on the surface must be borne' by the' mineral aggregate, which transfers the load directly downward to the base, and on account of the lack of tensile strength in the mineral aggregate which' -constitutes the wearingzsurface, a rigid base of concrete or the like is considered necessary.

Heretofore, in making bituminous pavements,composed of a mineral aggregate and asphalt, the high temperatures used in heating the aggregate preparatory to mixing it with the asphalt, which was necessarily a hard asphalt of low penetration, made the mixture too hot and tended to coke the latter asphalt, which therefore, lost most of 'its cementing property, causing the pavement to disintegrate and the formation of holes therein.

The present invention is a development of that covered by my Patent No. 1,008,433, and was conceived or discovered in the experimental use of the machine which is disclosed in myapplication of April 4, 1914, Serial No. 829,549, the object being to meet the demand for a cheaper kind of, material.

Said machine is designed to deliver fine dry dust produced by drying, disintegrating and sifting ordinary earthy material; and it comprises a slowly rotating drum, within which is a rapidly revolving pulverizer, while between the latter and said drum is a screen cylinder, attached to the latter, the purpose of said cylinder being to separate out the dust from the larger particles as fast as it is formed.

While this machine was designed for the treatment of earthy material, substantially free fromsand and gravel, such as that used 'in practising the process of my said patent,

tests were made with earthy material such as described above, containing more or less gravel, dirty sand, disintegrated rock and the like. Naturally, the larger particles were not disintegrated into dust and did not pass through the screen but were delivered out at the rear end thereof, and were then mixed with the dust and binder. I then discovered that by the action of the pulverizer and the screen andthe heat, the said solid stony particles though not disintegrated had been thoroughly cleaned from all adhering dirt and, indeed, were fractured and polished, and that, in that condition, the mixture of binder and earth would adhere to and coat them, and that the product, consisting of such cleaned stony particles, and of the combined earthy dust and binder, after being compacted, either to form a pavement in situ or into blocks, was practically as coherent and possessed almost as much tensile strength as my previous product made from earthy material substantially free from sand, gravel and stone.

The present process and the resulting productpresent several advantages, one of which is the fact that material can be used which is found nearly everywhere and has heretofore had no commercial value as an ingredient of a paving or the like; another is that the gravel and stony particles act as a filler, thereby reducing the amount of bituminous binder required, and reducing the cost, where paving specifications call for a cheaper grade of pavement. I

Any type of pulverizing machine can be used for the purposes of the present invention provided it be run in such a way that the harder bodies or particles are not materially disintegrated but are merely cleaned or cleaned and fractured.

In the present invention the decomposed and disintegrated earthy material, mixed with the bitumen, completely fills the voids and acts as a cushion between the clean and fractured solid particles and constitutes itself a malleable wearing material, which that described herein, because it rapidly fractures and wears away under the conditions of modern trafl'ic, which demand a different kind of supporting surface from that which was fairly satisfactory under old traffic conditions.

I have also found that, when the hard particles crack and grind away, or come out of the surface of my pavement, this wear resisting substance, consisting of bitumen and earthy material will actually iron out and fill the voids left by the stony particles, so that, eventually, the wearing surface comes to consist. entirely of the wear-resisting binder, which is not the case with the binders heretofore used in other bituminous pavements. The sand and gravel particles act more as a filler than as a wearing aggregate, thereby reducing, as above stated, the amount of bitumen required. Furthermore, the present process requires no grading or sizing of the mineral aggregate because the stability of the pavement does not depend upon the interlocking of the particles of stony material.

While the process is very advantageously carried out by the machine of my said application, it does not necessarily require the use of that or any other particular machine, since obviously various means may be employed to clean the gravel, etc., or free it from adhering earthy material before it is mixed with the binder and the fine material.

While the use of heat seems to be' advantageous it is not essential in all cases, and particularly where if a natural liquid asphalt is used.

Whereas, in some cases, it is better to with, it is not essential to the successful op-,

eration of my process.

It is immaterial, as faras the present process is concerned, what the relative percentages of stony and earthy or soft material are, or whether the particles of stony material are sharp or rounded. The resulting product varies in its composition according to the percentage of fine dust, from a pave: ment similar to an ordinary sheet asphalt to that now clai ed in my application, Serial No. 92,704 April 21, 1916.

In cases Wherefthe natural earth does not contain the amount of sand, gravel or crushed rock required or desired, it is obvious that more can be added.

What I claim is:

1. The process of preparing a sulbstance suitable for paving and surfacing purposes, which consists in subjecting dirty gravel and sand to a disintegrating, cleaning and polishing treatment and intimately mixing the resulting material with a bituminous binder.

2. The process of producing a homogeneous wear resisting substance for paving or other surfacing purposes, which consists in simultaneously pulverizing friable earthy material and cleaning hard stony particles and mixing the same with a bituminous binder.

3. The process of forming a paving material, which consists in subjecting, natural mixtures of stony and earthy material to a disintegrating action which partially pul verizes and partially cleans and fractures the same, and thoroughly mixing a bituminous binder with the resulting material.

4. The process of producing a paving material, which consists in taking natural mixtures of stony and earthy material, subjecting them to a treatment whereby the softer or earthy ingredients are reduced to dust and the harder stony ingredients are freed or cleaned from the adhering softer mate rial, and impregnating and mixing the resuiting material with asphalt.

5. The process of producing a homogeneous wear resisting substance for paving purposes and the like, which consists in impregnating disintegrated earthy material with bituminous binder, incorporating a mineral aggregate with similar binder, and mixing both materials together.

6. The process of producing a homogeneouswear-resisting substance which comprises comminuting-earthy material to a high degree of fineness, thoroughly impregnating the comminuted material with a bituminous binder, cleaning a hard mineral aggregate and incorporating it with a bituminous binder and thoroughly mixing the resulting materials.

7. The process of preparing a substance suitable for paving and surfacing purposes, which consists in subjecting natural mix tures of stony or rocky and earthy matter,

' to a mechanical treatment by which the friable and finer material is comminuted and separated out from the coarse and solid material, and the latter is cleaned and polished, and intimately mixing and impregnating both said materials with a bituminous binder.

8. The process of preparing a substance suitable for paving and surfacing purposes, which consists in subjecting natural mixtures of stony or rocky and earthy matter to the action of heat and of mechanical means, whereby the friable and finer material is comminuted and separated from the remainder, and mixing both the comminuted and the remaining material together with a bituminous binder.

9. The process of preparing a substance suitable for paving and surfacing purposes, which consists in subjecting natural mixtures of stony or rocky and earthy 'matter to a separating treatment whereby the larger solid particles of mineral matter are cleaned and separated from the friable and finer matter, impregnating the latter with a bituminous binder, and mixing it with said larger particles.

10. The process of preparing a substance suitable for paving and surfacing purposes, which consists in subjecting mixtures of solid-and friable mineral matter to a treatment whereby the friable matter is comminuted and the solid matter is cleaned, polished and fractured, and mixing the comminuted and cleaned particles with a bituminous binder, whereby, when the product is compacted, it will possess unusual tensile strength, be malleable and yet resilient and possess great durability.

11. The process of preparing a substance suitable for paving and surfacing purposes, which consists in subjecting natural mixtures of stony or rocky and earthy matter to a separating treatment whereby the larger solid particles of mineral matter are cleaned and separated from the friable and finer matter, impregnating the latter with a bituminous binder and stirring into said mixture said larger cleaned particles.

12. The process of forming a paving material, which consists in subjecting mixtures of hard and soft stones and earthy material to a disintegrating action which pulverizes the soft stones, disintegrates the earthy material and fractures and cleans the hard stones, and mixing the resulting material with a bituminous binder.

13. The process of producing a homogeneous wear-resisting substance adapted for pavement and other purposes which com-v comminuting soil, loam or clay to a high degree of fineness, thoroughly impregnating the comminuted material with a bituminous binder, the proportion of such comminuted soil, loam or clay relative to such bituminous binder being such as to give a malleable, coherent wearing material capable of withstanding traflic, incorporating mto the mixture a clean hard mineral aggregate, and thoroughly mixing the re- 10 my hand.

MICHAEL A. POPKESS.