US1409104A - Pavement and process for making the same - Google Patents

Description

G. A. HENDERSON AND H. K. STEPHENSON. PAVEMENT AND PROCESS FOR MAKING THE SAME.

APPLICATION FILED APR. 15,1920. KENEWED JAN. 4. 1922.

Patented Mar. 7 1922.

2 SHEETSSHEET 1- G. A. HENDERSON AND HE K. STEPHENSON. PAVEMENT AND PROCESS FOR MAKING THE SAME- APPLICATION FILED APR. 15,1920. RENEWED JAN. 4, 1922.

1,409, 1 ()4, Patented Mar. 7, 1922.

2 SHEETS-SHEET 2- "AN l ,supplied by the UNITED STATES PATENT OFFICE.

GEORGE A. HENDERSON AND HENSON K. STEPHENSON,

OF ST. ALBANS, WEST VIR- PORATION OF DELAWARE.

PAVEMENT AND PROCESS FOR MAKING THE SAME.

Specification of Letters Patent.

Application filed. April 15, 1920, Serial No. 874,078- Renewed Ianuary 4, 1922. Serial No. 527,056.

To all whom it may concern:

Be it known that we, GEORGE A. HENDER- SON and HENSON K. STEPHENSON, both citizens of the United States, residing at St. Albans, in the county of Kanawha and State of West Virginia, (whose post-office address is St. Albans, West Virgin1a,) have invented new and useful Improvements in Pavements and Processes for Making the Same, of which the followin is a specification.

The invention re ates to improvements in compositions for paving and like structures in which pitch is used as the impregnating and cementing agency of vegetable and mineral matter, and the object of the invention is to produce inherent stability. and density of such roducts as are described in the said Hen ersons United States Patent No. 1,040,321 of Oct. 8, 1912 and his co-pending application for Letters latent, Serial Number 212,194 of 1918, for pavements and process for making the same.

The invention will be best understood by reference to theaccompanying drawings, it being premised that various changes may be made in the apparatus within the scope .of the appended claims. Fig. 1 is a side elevation artly in section, Fig. 2 a cross section and Fig. 3 an end view of apparatus adaptable to the process. F ig. 4 is a detail, sectional view of a compression die; in which drawings A represents the frame work upporting the machine, C a furnace, D an asphalt heating tank heated by the furnace, within the lines of which tank are rigidly hung an impregnating drum (I), H a screw conveyor and its housing, G an aggregate chamber, F a dust ho per, F a gate valve to'chute F to drum in which all of the ingredients are a 'tated under indirect. heat eated bitumen in tank D partially surrounding the drum 1, and by direct heat sucked from the furnace C therethrough by exhaustergK and then discharged in a continuous flow of material under pressure throu h drum-mouth L into vacuum chamber all for the purposes hereinafter described.

In carrying out the invention fibrous particles, preferably that spent hard wood .de-

scribed in said Patent 1,040,321, but while containing water in lieu of sap and cellular tissue removed therefrom, are subjected to the action of bicarbonate of soda in solution to neutralize any remaining pyroligneous acids of such woody particles. These woody particles are then only partially dried while being heated and agitated under the influence of suction in said drum I until their moisture content is reduced to approximately 20% of their solid volume. In this operation the wood dust, when sufliciently dry to float in air suspension, is sucked out of the drum Patented Mar. 7 1922.

by exhauster K before such dust becomes hydro-carbon, and the clean, partially dried woody particles are then taken from the vat, bagged, and weighed in predetermined quantity for use in the process as hereinafter described.

It has been heretofore proposed to mix in excess of fifty per cent. by weight of truly impalpable dust of earthy nature with a bituminous compound of relatively soft consistency,'as tested for penetration, viz., approximately 100-120 penetration, which bi tuminous compound is more of a lubricant permeating such dust than it is a binder such as the heavier bituminous compound of approximately 4050 penetration used in the so-called mixing-method of producing paving structures, as distinguished from the penetration method both known to the trade and prior art. In order to practically agglomerate in colloidal suspension such substantial pro ortion of impalpablemineral dust in suc a heavy bituminous binder,

to act as a filler of voids between, (as distinguished from pores within) particles of larger aggregate sought to be bound thereby, we preliminarily prepare a mixture of such dust of colloidal nature, and of from 5% to 20% pulverized sulfur, of 1%-to 4% sodium chloride, and from 1} of 1%t0 3% 'of sulfate of copper, in proportions'in rela tion to the final product constituents hereinafter described, and in'ect this mixture in air suspension, under t e influence of heat and suction, into a mixture of larger mineral and vegetable aggregate, while agitating the same in a drum, (1), durin dehydration of that mas in the presence 0 molten bitumen.

We have discovered that by this means we obtain temporary fluidity of the bituminous cement and substantial ebullition of the mass, the steam there and then evolved acting as the carrying agent to perfectly agglomerate the bituminous cement uniformly throughout the aggregate and to aid in colloida 1y suspending the dust therein, andfacilitating chemical combination and vulcanization of the ingredients. 1

Depending on the nature of the product of our process, as regards'its consistency, degree of hardness and of elasticity, the proportions of dust and chemicals are varied. In/example, to provide a mastic filler as a matrix within interstices of larger metal of a macadam highway, we prefer the following proportions: the final product shall contain bitumen containing by weight the derivative of one per cent. sodium chloride, copper sulfate one per cent, sulfur five per cent. and 93% pitch cement or bitumen, known to the trade, and the product of this process shall contain, in example, of sulpho-chlorinated bitumen, 30% impalpable mineral dust, 20% woody particles freed from vegetable dust as in the above manner described, and 20%-larger mineral aggregate composed of crushed stone, slag or gravel, containing all dust of fracture, representing in approximate volume the following proportions: viz., of bituminous compound 36%, impalpable dust 20%, vegetable particles, in the absence of dust, 32%, mineral aggregate 12%. In our use of kieselguhr or other light weight impalpable mineral dust, the volume percentages shall be identical with the above, with corresponding changes in proportions by weight.

In operation of said apparatus the vegetable particles, in the absence of dust, are deposited in predetermined measured proportion in mixer E simultaneously with the depositing therein of the predetermined measured quantity of pitch heated to fluidity in tank D, by heat in furnace C supplied by burners C with oil under air pressure throughsupply pipe C from a fuel oil tank carried on traction unit forward of the plant, not shown in the drawings.

Tank D is initially charged from an auxiliary supply, with heated bitumen, through inlet pipe D. By operating threeway cock D the heated bitumen is sucked through pump X, cock D and pipe D to tank D. When charged with hot bitumen the supply to tank D is shut off by closing the inlet through cock D in pipe D, which operation opens suction through pipe D and the pump then operates to suck the heated bitumen up from the bottom of the tank D on one side of drum I and to deposit it at the top of tank D on the reverse side of drum I, which action is designed to (a) furnish a ready supply of heated bitumen through cock D manually operated to 'charge pitch weigh-bucket, not-shown, for

depositing the measured quantity of pitch 'into mixer E, and (b) to cause continuous agitation of the heating bitumen .in tank D, to prevent cokingof the mass therein.

The pitch in excessive quantity in relafinal product if such excess were not taken up by the added dust in the manner hereinafter described, by the action of interdigitating blades E, E anchored to reciprocating shafts E E revolved in the same] direction as each other by cog E on driven shaft E (Fig. 3) operating cogs E, E bearing the blades E E (Fig. 1) aforesaid, connected through driven shaft E with the motive power P in the manner shown.

When the three ingredients just mentioned have been mixed in mixer E one minute, and after each particle of the mineral and the vegetable aggregate has been coated with the pitch, the mass is dumped, by manual operation of lever L (Fig. 1) designed to open the bottom of pug mixer L, in halves, E", E (Fig. 2) (as per known construction,) into aggregate chamber G subjected to suction through pipe G to exhauster K, whereupon the operation in mixer E is repeated.

Simultaneously with the above mixing operation, the aforesaid dust mixed with chemicals, is, in predetermined measured quantity, deposited in hopper F, from which it is gradually fed to chute F through gatevalve F operated by cogged connection F meshing with cog F on driven shaft L and the dustis precipitated by gravity through chute, F in continuous flow to the entrance to drum I at the point shown in Fig, 1 as I At this point the hot air and fumes from the furnace C are sucked into the drum I, carrying said dust thereinto in air suspension by the operation of exhauster K. The number of revolutions per minute of gate-valve F is fixed consistent with the capacity of the entire machine and its connections with driven central shaft I (Fig. 1) and motive power P.

It is designed that the excess pitch in preliminary mixer E shall be partially taken up by the mineral aggregate therein added, and finally such excess exhausted by the addition of the dust in drum I in the manner above described,.so that in the final product the proper percentages of each of the ingredients may be present.

The housing of screw conveyor H forms the bottom of chamber G and that conveyor is designed to be revolved at a speed consistent with the object to move the contents of chamber G, viz., one batch of ingredients from mixer E- from chamber G the length of conveyor E within five minutes time, the mixing operation in mixer E being repeatedly completed every five minutes including the time in which the ingredients are mixing therein, and that time required for dumping mixer E to chamber G, thus providing a continuous flow of mixed and measured ingredients to drum I, for the purpose of providing a continuous flow of material out of drum I into vacuum discharge cham ber M.

The period of agitation within drum I is fixed by the speed of the central shaft I, and

. its blades I, driven by chain I and pulley I connected with the motive power P, and by the number, inclination and dimensions of agitating blades I anchored to the central shaft by sleeves I", which blades are set at such an angle to the centralshaft to form a perfect screw in their operation to move the mass in drum I the entire length of the drum within five minutes. During this period the mass is subjected to agitation, and to such suction by exhauster K as to produce a partial vacuum within drum I,'equivalent to approximately two thirds atmospheric, viz. 466 barometric pressure, at'which pressure the boiling point of water (that residual moisture within the aggregate then being de hydrated) requires a temperature of not exceeding 88 C (190 deg. Fahr.) as compared with 100 deg. C., (212 deg. Fahr.) at atmospheric pressure. In this connection we have discovered that such reduced pressure within the mass inclosure I aids in it's ebullition, as and for the purpose herein;

after described, namely:

The exact temperature of the mass within drum I is essential to be uniformly fixed and registered for the purposes of this process, and this wev accomplish by regulating the degree of heat of the bitumen in tank D, by manually fixing the degree of pressure and quantity of oil supply to the burners G which burners indirectly heat, through the bitumen in tank D, the contents of mixer E, conveyor H, and drum I in the manner shown in Fig. 1. The heat in drumI is further regulated by manually adjusting sliding valve I ('Fig. '1.) through which valve ,air of atmospheiic temperature is admitted and mixed with that hot air from the furnace C. The temperature of the mass in drum I, thus fixed, is registered by a hand thermometer as it emergesfrom drum I, and by the use of fixed thermometers set within the lines of drum I and tank D respectively, at the points shown in Fig. 1 at T T When in drum. I extreme fluidity of the mass (producing a honey-combed effect) is caused by steam in evolution from said residual moisture, escaping from the pores of the woody particles, abnormally enlarging the pores thereof, and entrapping the bituminous cement therein, under the infiu-. ences of said suction and heat, agitation of the mass, and instantaneous action of the chemicals introduced thereto in air suspension with the dust, which action perfectly disseminates the bitumen throughout the mass and .entraps the dust therein while the bitumen is in a state of momentary ebullition sufficient in time and extent for the designed purpose, viz., the colloidal suspension of dust in the bitumen. When the mass is completely dehydrated in this manner, the chemicals are married in a combined state. with the bitumen, at which time the ebullition at once subsides.

The mass in drum I in completing its passage therethrough is subjected to slight compression by the action of blades I ,which compact the same throughdrum mouth L. This compacting aids in the removal of residual gas and air bubbles from the hot mass, by its suction to the atmosphere through exhauster K..

. In the above operation the impalpable particles of dust are separated from their neighboring particles of dust by the thinnest possible film of the heavy bituminous compound (as distinguished from that bituminous binder composed of sulfur and bitumen such as described in Hendersons United States Patents Numbers 1,264,932 and 1,266,261 of 1918.) The combination of the said chemicals with the bitumen, and the entrapping therein in colloidal suspension of said substantial quantity of im palpable mineral matter, is due, in our opinforming a honey-combing effect) which, nevertheless, sets to density and afterwards hardens in the final product to the extent of the predetermined quantity of said dust and chemicals, within the said limits, present inthe o eration. '1

Chamber (Fig. 1) is continuously closed at its mouth and discharge end by the material pressed through them. The action of exhauster K, connected therewith by exhaust stack M produces within chamber M partial vacuum to-wit: that equivalent to'a barometric pressure of 152 mm. or approximately one-fifth normal atmospheric pressure. This condition, in conjunction with the means for compacting the material in chamber M, is designed to free it from any residual gas or air preliminary to final compaction of the mass in the manner hereinafter described. In chamber M the shaft of screw conveyor M driven b the machines motive power by connection as shown, is operated horizontally whereas the bottom of chamber M is'constructed so as to provide an upward grade of approximately ten er cent. toward the compression die Y. he

conveyor M converges in its pitch in ratio fio .Strated in practice, sufiicient resistance to the onward movement of the plastic material in the chamber M toward and through\ die Y to effect substantial compression of the material in chamber M before it reaches the die, to entirely free it of its residual air and gas content within the vacuum influence 1 in chamber M provided. In this manner we and meshing with cogged drums C, bearingaxles C C operate independently of each avoid the entrapping of air and gas in the mass when finally compacted in moulds or otherwise, and inherent stability and density of our product is increased over that of the prior art in this manner.

The degree of compression to be applied to our product of this process is fixed by the dimensions of the die Y in relation to the power applied to compact the material through it. After emerging from the die in a continuous flow the hot, plastic material is compacted in mbulds to shape, or when used as a matrix to fill the voids between the larger stone'of macadam highway, in example, as described in the applicant Hendersons co-pending application Serial Number 212,194,"of 1918, the material consisting of said denatured hardwood chips, impregnated with bitumen in the absence of wood dust, mixed with larger mineral aggregrate precoated with bitumen, and filled with bitumen, colloidally suspending mineral dust chemically treated in the manner hereinabove described, is spread over and compacted within the interstices of larger mineral aggregate, in situ, on a highwa in the followin manner, illustrated in ig.1:

Mu tipedal units 0 0 passing around other to support the machine by connection with its frame work A, in its course forward; and constitute the sides of furnace-C.

to prevent lateral suction of outside air to the furnace C. The ends of furnace G are composed of heavy leather strips C, C, inserted in steel members to scrape over the roads surface, for' like purpose. Scarifiers B suitably attached to the frame work of the machine, by resilient members, not shown, (but known to the trade) are designed to ,plow the road for a depth of from-two to three inches, and to loosen the stone aggregate thereof. Suction through furnace 0,- caused by the operation of exhauster K, is designed to suck up from the interstices and surface of the road, such dust as may be loosened from its aggregate by the scarifiers in combination with the blasts of flame and air, "under pressure, from burners C, C, directed onto said road; and to deposit said dust, in air suspension, into drum I in a continuous operation during the above de-' scribed process in which additional dust, containing the aforesaid chemicals, is likewise earned in air suspension within drum I. We have discovered in practice that,

within relatively close limits, the quantity of v dust removable from the road itself, is sufficient to produce the desired density of our product when added to that dust injected to the mass through chute F In practice we specify and incorporate in the mass considerably more dust than is required to fill all voids between the larger particles when such dust is colloidally suspended in the bituminous compound; and have discovered that when such an excess of this mixture is present the stability and density of the product i is correspondingly increased.

The dust-cleared, loose stone of the highway, heated by said flame-blasts in the course of the machine over it, is then coated with preheated bitumen from an auxiliary supply within a traction unit (not shown), throu h bitumen supply ipe O' and said heated bitumen is forced t rough pipe 0 by air compression, to rotary penetration nozzles O at the rear of the machine, into. the interstices of the scarified surface; As the machine passes over this surface the matrix of the' process hereinabove described, is chuted to place thereover in quantity approximately one inch in thickness, manually raked to shape and compacted into the open, dustcleared, bituminized interstices of the heated stone in situ.

We claim:

1. The herein described process which consists in mixing moist vegetable particles in the absence of vegetable dust with an excess of bitumen preheated to a temperature above, the boiling point of the moisture; then mixing therewith mineral aggregate in relatively large sizes; then agitating the mass in a vat subjected to suction under the influence of suiiicient applied heat to completely dehydrate the same while gradually introducing in air suspension and entrapping thereinimpalpable mineral dust pre- 'mixed with sulfur, sodium chloride and copper sulfate, in quantity suflicient to adsorb the excess bitumen; then subjecting the mass to heat and pressure in partial vacuo and compacting the same to shape.

2. The herein described rocess of treating a metal highway conslsting in vmixing and dehydrating mineral and vegetable ag-, 1

gregate in the presence of an excess of pure bituminous binder in a vat under the influence of sustained heat and sucti n sufficient for the purpose, while adding thereto in air suspension impalpable dust sucked therein from interstitial spaces of the highway created by scarifying the same, and

blowing flame and air there into, simulta-' neously depositing in air suspension within said vat additional dust mixed with sodium chloride, copper sulfate and sulfur suflicient in quantity to adsorb the excess bituminous binder, heating said scarified metal of the highway and causing a bituminous compound to penetrate the same in its dustless loose, heated condition; then spreading said mixed material thereover and compacting the same to shape 3. A bituminous composition comprising mineral and vegetable matter impregnated and coated in the absence of dust with a bituminous binder, the interstices'between which matter representing at least forty per cent, by volume of the final product, being completely filled with a matrix of mineral dust colloidally suspended in sulfochlorinated bitumen.

4. A paving structure consisting of a broken stone bas of relative large sizes of stone coated with a pure bituminous binder the interstices between which are filled with mineral and vegetable matter of smaller sizes nnpregnated and coated in the absence of dust with bitumen the interstices between our hands in the presence of two witnesses this th day of March, 1920.

GEORGE A. HENDERSON. HENSON K. STEPHENSON.

In the presence of- L. J. WHITE,

C. H. ZERKEE.

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