US2509675A

US2509675A - Treating plastic concrete pavements

Info

Publication number: US2509675A
Application number: US605883A
Authority: US
Inventors: Stephen J Cox
Original assignee: Worthington Pump and Machinery Corp
Current assignee: Worthington Pump and Machinery Corp
Priority date: 1945-07-19
Filing date: 1945-07-19
Publication date: 1950-05-30
Anticipated expiration: 1967-05-30

Description

May 30, 1950 s. J. Cox

TREATING PLASTIC CONCRETE PAVEMENTS Filed July 19, 1945 2 Sheets-Sheet 1 b jg 1 l 2 INVENToR. Y

May 30, 195o s. J. x 2,509,675

TREATING PLASTIC CONCRETE PAVEIMENTS` Filed July 19,` 1945 2 sheets-sheet 2' i IN1/EN TOR.

Patented May 30, 1950 TRETING PLASTIC CONCRETE PVEMENTS Stephen il. Cox, Westfield, J., assigner, `by niesne assignments, to Worthington Pump tand Machinery Corporation, Harrison, N. J., `a corporation of Delaware Application July 19, 1945, =Serial Noif605i883:

(Cl. k9de-46) 5 Claims.

The improvements relate to devices and methods for .making pavements of concrete in 'which hydraulic cement is the bonding element, `and .particularly to devices for mechanically treating and finishing the wet `plastic concrete after it has been mixed, deposited and spread on the subgrade of the roadway and before it Ihas .had time to .set and form the concrete slab providing the linished surface `of the pavement.

The primary objects of the improvements are 1 to provide improved means for compacting `or consolidating the aggregates of 4the ,plastic ,con- `creteusually Portland fcement, sand and small stone or `gravel mixed with a `small percentage of'water-eliminating.excess water `and air from the mass and forming a .firm `body of uniform Amaximum `strength throughout with :a smooth wear and shock `resisting surface, while preserving the intimateand equal mixture and distribution of coarse and i'ine aggregates and without causing deterioration of the .bonding elements or impairing the `action .of entrained air `Where airrentraining cement is used.

VThis is accomplished `in the `present `improvements by subjecting `the surface tof the plastic concrete to the action ofapluralityof relatively `light rollers provided with `uniform `alternately undulating or corrugated surfaces passed over it but not exercisingfsubstantial pressure thereonor ,sinking bodily therein and exercising a mild -Working and agitating or quaking effectrthereon -which extends in `a greater r ilesser :degree through the body thereof.

This action involves a method or process .of A'treating the concrete `for `the purposes stated which may be carried out byother devices than those herein described and shown, but provided with means for `shifting them laterally vatutl'ieend of a stroke or strokes, so that the low ridges fand shallow grooves are `reversedor coi'interactedrby succeeding strokes or reciprocations, .ea-ch ridge being thus succeeded by a groove and vice versa and the aggregates thus being given `a lateral movement alternately in opposite directions.

1In thesaid draWings,Fig. lis a plan of a mechanism embodying the mechanical inventionand adapted to perform the method yorprocess;

Fig. 42 is-a Vertical, medial, longitudinalseetion `oi therst roller, showingthe bottom partfonly;

Fig.` 3 isa like'section of the secondrrollem Fig. 4 is a rear end view .of the mechanism of Fig. l, with one sideframe :member vpartly :in vertical section;

Fig. 5 is a side view ofthe same :with thestrikeoff and screed omitted;

Figs. 6 and 7 are frontand side viewswrespec- 'tively of detached portions `of thesamexshowing strike-oli and screeddevices.

Referring to the said drawings, `l `and 2 `are :hollow l irnperforate` rollers `of relatively: thin sheet meta-1 `weighing `when ,at `ten inches in diameter .and tenveet iniength not substantiallymqrethan ten percent A,of thesamemassaor loulktof concrete, riding .on the .surface of the :plastic concrete as Vthey pass `.over `it and .not sinking into it to ny material extent. They are providedgwith uf `lar corrugations .ornfled by `9110.3BCiQlflS 3 @Elli indentations on land 4 land sirespectively on -2 pf uniform depth, Width and contour, giying their surfaces 4a regular Wave-,like character 1911- ;gitndinally. The depth tof the Hcorrugations exaggerated, .las shown. .Tlue :corrugations of `the two `rollers lare of the same size ,and shape `but uare alternated orstaesercd th respect t0 :each `other -so that the proiecti 111s t3 on roller .4 `are opposite :the `indentations it `.2 and `lille lllpir tions s 4on ,-2 are l opposite the indentations 3f ci The :result ,of rthis `formation 4and errance nt isthat as fthe rollers loesscoller @the surf@ @..Q his, plastic concrete the iirst ,roller fproduces therein .slight longitudinal grooves `or depressions 5 with slight ridges 5 between them .(Eie. 2o ,and ,the second or following roller displaces zand obliterates thesegagrocvestandfridees. and Sllilplnts `thlll with ridges t and grooves 6 respectively(Fig) of itspwnboth rollersmoving the concrete aggregates :at .the surface `laterally 4in these Loperations Aas Wellastoa ce1ztain"`extent.verticallyrand causingagitationlofthe entire mass.

It will :be .observed `that ,the C Qrrugations of1 the rollers l are `such `that-if the `cjollers are :brought together in their longitudinal operating positions their ,corrugations :will `mesh andcoincide` s o-,cthat there will `be anuninterrupted-liineof contact :be: tween ,their opposedfsurfaces. This `duplica n :of .thecorrugations insures .uniform treatinen of lthe concrete throughout Lits zhtire loodyand resulting .uniform cross section of texture and strength. It also ,insuresithe ltunil'crm\ compacting of the mass l and elimination of excess wateraand air pockets. ilihether and in Whatgmanner, ifwat lalLthis duplication can bedeparted from vwithout producing `undesirable lresults can only (be determinedgfby careful tests. `lt A is ;knoWn, hoW1- ever,` that excellent results-arefobtained by adhering to it `and that; some, `at least, l-departuresl, from it `will produce `unsatisfactory results. i

The staggered arrangement of theuridgesfend grooves of the `rollers so `that they .will act alter- `nately on the concrete as the rollers passfbacl; and forth over -itpis Aof :the greatest-importance as "it .produces :a uni for;m"fknead-ing' actipngin which the aggrfegatesfare agitated ,or yibratel verticallyand in :all directions longitud ally and laterally, so that fno portion f of th mass can escape this-action and all partsare subjected ILto:fit-equally. 'JThisqcauses the larger aggregates .to settle to a limited extent. andqtogethertvvith smaller: aggregates to `litA into `the interstices between them, `as `can be obseryedsbythe Lslight shrinkage of the mass when treated and by observing a broken slab so treated after setting.

The corrugations of the rollers are quite shallow and can be from one-half to one quarter inch, from the base of each ridge--or the bottom of the groove separating it from the next-to its apex radially, depending on the character and size of the concrete aggregates to some extent. They are also relatively wide longitudinally of the roller and are from peak to peak a little in excess of the greatest diameter of the largest aggregates, so that these aggregates cannot span them.

The contour of the corrugations is a series of smooth reversed curves on relatively long radii, as shown, and their surfaces are free from sharp edges or abrupt deviations from such curvature.

Two rollers are shown in the illustrative embodiment, but more may be used if desired or found advantageous for the particular use intended. And they are rolled back and forth over the surface of the plastic concrete as many times as may be found necessary to produce the desired finishing and compacting eiect, and the elimination of air voids and excess water. The rollers are spaced apart far enough to give clearance and insure against contact between them, but their exact spacing is not important. They should usually, however, follow one another rather closely, and the strike-off blade preceding the forward roller and the screed following the second roller, hereinafter described, should also.

follow and precede their respective rollers without unnecessary spacing. This prevents the accumulation of liquid or soup in the grooves formed by the rollers and maintains its even distribution over the surface of the concrete The same result may be attained, however, by operating the device at a sufficient speed, regardless of spacing.

The working of the surface of the concrete by the rollers also tends to open up momentarily small crevices between the large aggregates in some places so that the liquid element of the concrete does not exude therefrom to an undesirable extent or form a film of laitance over the surface.

The rollers rotate freely and in unison as they roll over the surface of the concrete but should there be for any reason a small amount of slip` page it will not seriously affect their operation or the performance of their functions. It is therefore not necessary that they be geared together, as by sprockets and chains.

The rollers I and 2 are mounted by axial trunnions I in slotted bearings I I on the side frame members I6 of the carriage running on flanged wheels 8 on side forms 9, and therefore are free to move up and down to a limited extent. This permits them to impose only their own weight on the concrete, the weight of the carriage and other parts carried thereby being borne by the said side forms.

At the forward end of the carriage 1 there is mounted on the carriage a strike-off blade I2 by means of screw bolts I3 passing through adjustment slots I4 and into the end pieces I5 of the carriage frame, This strike-0E is therefore mounted for limited vertical adjustment to accommodate itself to the level of the concrete, and to the bottom of the corrugated rollers. It normally has its lower edge a little above the bottom of the rollers and slightly above the upper edges of the side forms 9 and extends across the strip of pavement to be finished, so that it will strike off the concrete leaving a sufficient margin for shrinkage from the finishing operation and can be positioned intermediate the top and bottom of the corrugations, so that when the rollers are moved backward it will level off the ridges and grooves left by the rollers, shearing off the former and filling in the latter and thus restore the smooth upper surface of the concrete strip. At the rear of the carriage is mounted a screeding blade I9 of the same character as the strike-off I2 and mounted in the same manner, so that when the rollers are moved forward the upper surface of the concrete is leveled by this screed following the roller 2 and as they are moved backward the same function is performed by the strike-oir blade following the roller I. The rollers have end spacing members 2|, extending between their ends and the side frame members and corresponding approximately with the thickness of the flanged wheels 8.

The rollers I and 2, the strike-off and screed I2 and I9 may all be slightly curved or beveled longitudinally to provide the concrete strip upon which they operate with a suitable crown. The frame or carriage is completed by the

top cross strips

23 and 24.

Various changes in the details of construction and arrangement of the exemplary embodiment herein shown and described may be made without departing from the scope of the invention, and various devices for spreading, striking off, screeding, straightedging, belting and final broom finishing may be used in conjunction or cooperation therewith. It will be seen, however, that the invention provides means for consolidating and finishing the plastic concrete, eliminating excess water and air and producing uniform density and compaction without tamping, agitating or vibrating it violently and thus interfering with the arrangement, concrete producing eiciency or uniform texture of the aggregates. This is highly desirable in the finishing of all Portland cement concrete, especially concrete in which air-entraining cement is employed.

The rollers may be rolled crosswise as well as lengthwise of the plastic concrete pavement or one way or the other, if desired, or found necessary or advisable to produce a desired result.

The rollers are also preferably made removable and replaceable by mounting their trunnions in slots formed in outwardly and upwardly inclined side frame members so that the rollers may be lifted out of the upper part of the vertical slots and other rollers then placed in the slots by passing their trunnions down therein'to. In this manner rollers having different weights, form and diameter or different corrugations may be used for different purposes, as to fit the crown of the road or curves or unusual grades. Such a construction is shown at 22.

lt will be understood also that the spacing of the rollers and the instrumentalities preceding and following them may be varied to avoid interference with their action by picked up portions of the concrete, should such a thing occur, and to give full clearance for cleaning. These instrumentalities may be of any suitable form and may operate in any suitable manner to perform their respective functions properly.

On pavements where a slightly corrugated surface is desirable, as at some airports to increase visibility or give greater` braking power and on some unusual road grades to improve traction and drainage, the screeding may be omitted, and

the pavement will be found to be well compacted and finished by the action of the rollers. The main finishing rollers may be followed up by rollers having very shallow grooves and ridges. This may also be done prior to screeding, to reduce the leveling work required of the screed.

I claim:

1. A device for nishing plastic hydraulic cement concrete pavements comprising a plurality of relatively light radially corrugated rolli.

ers mounted to rotate on parallel axes in approximately the same plane, the corrugations of one roller being arranged in staggered relation to those of the next roller so that the ridges of one roller are opposite the depressions of the next and vice versa, whereby the rolling of said rollers successively over the surface of the plastic pavement will thereby form in the surface of the pavement alternating ridges and grooves by displacing the aggregates vertically and laterally with the projecting ridges of the rollers, a carriage on which said rollers are mounted to rotate and bearings thereon for the axes of the rollers, said bearings provided with elongated openings to permit limited vertical movement of the roller axes independent of the carriage.

2. A device for finishing plastic hydraulic cement concrete pavements comprising 4a, plurality of relatively light radially corrugated rollers mounted to rotate on parallel axes in approximately the same plane, the corrugations of one roller being arranged in staggered relation to those of the next roller so that the ridges of one roller are opposite the depressions of the next and vice versa, the corrugations of said rollers extending annular-ly about the rollers and merging each into the adjacent one by arcuate surfaces to present a continuous sinuous surface for contact with the hydraulic cement whereby the rolling of said rollers successively over the surface of the yplastic pavement will thereby form in the surface of the pavement alternating ridges and grooves by displacing the aggregates vertically and laterally with the projecting ridges of the rollers, a carriage on which said rollers are mounted to rotate and bearings thereon for the axes of the rollers, said bearings provided with elongated openings to permit limited vertical movement of the roller axes independent of the carriage and said corrugations forming in effect relatively shallow waves or undulations of uniform size and contour running lengthwise of the rollers.

3. A device for finishing plastic hydraulic cement concrete pavements comprising a plurality of relatively light radially corrugated rollers mounted to rotate on parallel axes in approximately the same plane the corrugations of one roller being arranged in staggered relation to those of the next roller so that the ridges of one roller are opposite the depressions of the next and vice versa, the corrugations of said rollers extending annularly about the rollers and merging each into the adjacent one by arcuate surfaces to provide a continuous sinuous surface for contact with the hydraulic cement whereby the rolling of said rollers successively over the surface of the plastic pavement will thereby form in the surface of the pavement alternating ridges and grooves by displacing the aggregates vertically and laterally with the projecting ridges of the rollers, a carriage on which said rollers are mounted to rotate and bearings thereon for the axes of the rollers, said bearings provided with elongated openings to permit limited vertical movement of the roller axes independent of the carriage, and a strike-olf blade mounted on the carriage in Aadvance of said rollers.

4. A device for iinishing plastic hydraulic cement concrete pavement comprising a plurality of relatively light radially corrugated rollers mounted to rotate on parallel axes in approximately the same plane, the corrugations of one roller being arranged in staggered relation to those of the next roller so that the ridges of one roller are opposite the depressions of the next and vice versa, the corrugations of said rollers extending annularly about the rollers and merging each into the adjacent one by arcuate surfaces to provide a continuous sinuous surface for contact with the hydraulic cement whereby the rolling of said rollers successively over the surface of the plastic pavement will thereby form in the surface of' the pavement alternating ridges and grooves by displacing the aggregates vertically and laterally with the projecting ridges of the rollers, a strike-off mounted on the carriage in advance of the rollers and a screeding device mounted behind the said rollers, said screeding device and strike-olf adjustably mounted on the carriage and adjustable to the surface of the cement being pressed, smoothed and treated.

5. A device for nishing plastic hydraulic cement concrete pavements comprising a plurality of relatively light radially corrugated lrollers mounted to rotate on parallel axes in approximately the same plane, the corrugations of one roller being arranged in staggered relation to those of the next roller so that the ridges of one roller are opposite the depressions of the next and vice versa, the corrugations of said rollers extending annularly about the rollers and merging each into the adjacent one by arcuate surfaces to provide a continuous sinuous surface for contact with the hydraulic cement whereby the rolling of said rollers successively over the surface of the plastic pavement will thereby form in the surface of the pavement alternating ridges and grooves by displacing the aggregates vertically and laterally with the projecting ridges of the rollers, a strike-off mounted on the carriage in advance of the rollers and a screeding device mounted behind the said rollers said strike-off and screeding devices being adjustable to the surface of the cement being pressed, smoothed and treated.

STEPHEN J. COX.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,488,302 Wagner Mar. 25, 1924 1,584,385 Lichtenberg May 11, 1926 1,637,993 Finley Aug. 2, 1927 1,764,963 Laster June 17, 1930 1,831,116 Huntley Nov. 10, 1931 2,152,264 Loft Mar. 28, 1939 2,154,720 Biles Apr. 18, 1939 2,261,893 Wolfard Nov. 4, 1941 FOREIGN PATENTS Number Country Date 366,426 Great Britain Feb. 4, 1932 671,620 Germany Feb. 10. 1939