US1707089A - Apparatus and method for pavement construction - Google Patents

Description

f vMarch 26, 1929. l.. R. MaCKr-:Nzlg 1,707,089

APPARATUS AND METHOD PON PAVEMENT CONSTRUCTION Filed Aug, 2o, '1928 2 sheets-sheet 1 ,M .\A ...H.......... l

March 26, v1929. L.. R. MacKENzlE 1,707,089

APPARATUS AND METHOD FOR PAVEMENT CONSTRUCTION Filed Aug. 20, 1928 2 Sheets-Sheet 2 Patented Mar. 26, 1929.

' UNITED STATES LEON R. MACIUENZIE,V OE DES MOINES, IOWA.

APPARATUS AND METHOD FOR PAVEMENT CONSTRUCTION.

Application led August 20, 1928. Serial No. 300,720.

The object of my invention isv to provide an improved apparatus and method for pavement construction wherein an asphalt-ic road or wear course having a'substantially shallow depth maybe placed upon a concrete base and so united together' that the asphaltic material forming the wear course will be anchored to its base at points arranged at angles to each other and will be constrained against movement from its base and thereby eliminating' ridges and hollows in the surface ofthe wear course;

Still a further object is to provide a novel platform mold adapted to be temporarily supported upon a freshly laidconcrete base and vibrated or rolled over by a roller for compacting the wet concrete and at the same time molding in the upper surface thereof a plurality of specially shaped grooves yar# ranged transversely to each other and in communication with each other. y

It is well known that in the preparation and laying of a concrete-base forasphalt road or street construction, it is desirable to use a large amount of rock aggregate in proportion to the cementnnortar for the reason that rich .mortar mixtures are more susceptible tol com'se, the bond between the top and the base` is ln'olren and the asphaltic wearing surface will break up as a consequence.

Concrete mixtures carrying a large proportion of coarse aggregate will not work easily under ordinary methods. Therefore it is necessary in order to make such mixture applicable for forming a proper and uniformly grooved concrete base to provide especially constructed apparatus in the form of platforms or the like, which are laid upon the mixture andthen subjected to such treatment as will impress the Jlatforms or apparatus finte the concrete an. equally and uniformly distribute the mortar relative to the rock aggregate. i

By providing platform molds havingspecially designed groove forming projections on their under side, I am able to force the platforms downwardly relative to the concrete, and thereby the concrete or plastic material is densitied, and at the saine time there is molded in the concrete surface a substantially Vuniform pattern of projections and grooves.

-Still another object is to provide grooves upon the upper surface of the concrete base, which grooves are arranged in such manner relative to the line of traffic and relative to each other and at the same time are provided with downwardly converging sides, so that a cross section of each groove is substantially V-shaped with the lower half of the V cut ott' to provide a horizontal base in the bottom of each channel groove, wherein the wear course laid thereover is anchored to the base to meet the forces exerted by traliic from any direction. i

Still another object is to provide platforms adapted to be fabricated by use of a plurality of metal sheets preferably of stamped material for forming )Virojections thereon, which when inverted and laid upon the plastic concrete will formthe necessary grooves therein, the corrugated and formed-up plates beingr connected together in sections by stringers, each hollow portion between any pair of the projections being provided with insert cleats for separating the hollow portions into various sections so that when the platform is placed upon a plastic base the surface thereof will be ar 'anged with grooves extending in at least two different directions with the walls of the grooves formed in the plastic .material being inclined upwardly and outwardly from the main body portion of the plastic base.

Another object the formation of a platform mold wherein corrugated metal plate for forming a portion of the platform base is filled with tiller blocks.

More particularly, it is my object to provide a molded top surface on the concrete base having projections and channel grooves therein spaced a sufficient distance apart and so proportioned that when the asphaltic inaterial is `spread thereover and compressed, there will be no shrinkage or increase in the material after the wear' course of asphaltie `materiel het been applied and @empleada Still another object is to arrange the side vwalls of the channel grooves at an angle'sok that when asphaltic material is placed thereover, raked and fluffed land then rolled,.a certain amount of the asphalt-ic` material will be forced into the channel grooves and base and vkthesidewalls of the channelwill impart a f trate-d in the which t downward and sidewise force to the asphaltic material while under compression from above, the inclined side lwalls compensating Vfor the difficulty. inuniformly compressing asphalt of different thicknesses.

lith Vthese and? other objects in view, my

invention consists in the construction, ar-

rangement and combination of the various parts of my apparatus 'and in the practice of mymethod, whereby the objects contemplati?- edV are attained, as hereinafter more fully set forth, pointed Aout in my claims,`and illus-V accompanying drawings, in

Figure 1 is a top plan vie-w of aportion of concrete pavement base with` a plurality of' iolatform molds mounted thereomillustrating the channel-shaped upper surface ofthe base.

Figure 2 is a, perspective sectional'view taken ontheline 2 2 of Figure 1, showing a portion of the concrete base with the groove f forming platform placed thereon, the grooves after. the platform has been removedpand a I. portion of the plastic wear course laidupon y the. concrete, thus illustratingthe,complete cfs upon the sub-base or soil 10.

pavement construction. y

Figure 3 is a transverse, enlarged', sectional Vview through one of` the platforms andthe Figure 7 is a. detail, enlarged', sectional i view takenon the line 7 7 of Figure 6..l

The drawings filed: herewith. illustrate one way in whichmy method for pavement constructionmay be carried out.

In, road .and pavement construction, it is Y usually necessary to prepare the dirt sub-base 10, so that it is in substantially a smooth surface condition adaptable for receiving the concrete base;

A: concrete massi@ forms the concrete buse The hase`12 may vary in thickness dependingr upon the 'strength desired forV the pavement and the particular locationI ofthe road andthe traf-v grooves formed inthe It isfdesirable inE a concretlebaseto provide a considerable amount of rock aggregate. After the mixed cement, sand und rock aggregate forming the mass is laid on the suhsoil or buse 10 and raked and leveled to a true specified contour, I ind that the material may be condensed, and in order to condense the material, I provide platform molds A, which may be of various sizes and shapes, which platforms rest upon the upper surface of the freshly laid leveled concrete mass.

T he platform molds are laid flut upon the upper surface of the mass and may be im pressed into the mixture by the so-called vibrolithic method,-that is operating n. vibratingr machine upon the platform molds over the concrete mass.A

Another way of condensing the concrete mass is to run a roller of suflicient weight vovei' the upper surface of the, platforms and cause them to be impressed. due to the weight so applied, into the concrete mass.

Still another way is to use the impact method of impartingr a downward movement of the platform relative to the concrete muss.

In the drawings, the platform A is fabricated from a plurality of stringers 1li to which may be connected a metallic plate 16 formed into a corrugated sheet, so as to provide raised portions andreccsscs. The corrugated Isheet 16 is secured to the stringers 1+i in any suitable uiianner.

In order to give substantial strength to the metallic plate 1G, I place filler blocks 18 on the under side of the ridges in the plate 1G. The filler blocks also give u smooth upper surface tothe platform molds 'between the stringere, so that mortar accumulation may be readily ,scraped or swept therefrom.

Between the ridges in the corrugated pluie 16, there is neces rily formed a plurality of hollow portions or recesses Qt). These re cesses Q0 run cross-wise of the plate 1G.

It is desirable to have the (,ompletcd coucrcte base uupper surface provided with chunnelshaped grooves running in more than one direction, and I therefore place small cleats 22 atspacedintervals in the hollow portions or recesses 20, so that there is formed a number of individual recesses.

rIhe walls of cach recess are inclined und converge towardsl each other and towards the base or bottom of the recess.

It Ywill be noted that the upper surface, of the plastic material or concrete hase after the platforms are placed thereover with the plate 1G resting thereagainst that each recess in t-he platform will form an upstzinding projection in the concrete base. Each upstunding projection is spaced from the others hy channel-shaped grooves, which grooves in themselves have outwardly inclined side walls.

It thus follows that the distance between the upper edges of the projections in the concrete base is greater than the distance between the lower edges of the projections. Each reloo lll?

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c within the platform A forms a projec tion 24.-. For the purpose of further referonce, the grooves or channels formed in the plastic material have been indicated by the reference numeral 26. The ridges or projections in the plate 16 forni the grooves 26 in the plastic material.

lt will. he noted that in Figures Lil. and 5, the platform inolds are p 'ovidcd with theircnds arranged a.v an angle relative to the stringere proper.

ln Figure (l, which .is a slightly modified forni of structure, the ends of the platform are arranged at substantially right angles to the stringere proper, although in this case, the recess Ys and ridges in the platform are still arranged at an angle relative to the stringere. i

ln the forni of platform as shown in Figures 6 and 'i' of the drawings, l place a sheet metal flat plate 28 `upon 'the stringere and then place thereove a castingl or the like 30, which is fornied with va pair of cross ridges and a number of ridges 3l ar 'ringed to run lengthwise of the entire platform mold. i

rlhc ridges and Se deline recesses 2U which are provided with converging side walls. rluie castings 3() which forni the neces sary grooves and ribs on the platform A are :mchored or fastened to the stringere la by holts, screws or the like.

ln the hottoin of each recess 20, l p roifidc i plurality of small. oiiieningjs 36 through which the water, air and small amounts of excess cement mortar may pass during the process of impressing; the plat/forni in the upper snr face of the concrete mass and formingv in the upper surface of theconcrete mass Athe ncccs sary grooves and rihs as heretofore explained. ln lligures 4land 5, the openings are formed in the plate lo proper7 Whereas in litigare 6, the openingsI 36 are formed in the separate plate 28. Y

'ihe di llcren ce between the structure shouui in Figure il and the structure shown in Fig'- urc resides in che fact that in Figure l the plati is formed of a single piece of n'iaterial and corrugated and lilier hloclqs are used for giving; the device rigidity and strength, whereas in Figure 6, a seoaratellat plate is used, which is connected to the stringere, Vand c; stings of any suitahle kind `are provided e ring); to the platform mold the necessary ,il projections and recesses.

llpon the completed concrete hase7 that is after the formatimi ol' ridges and channels asphaltic material.

and is eo It is fare-her well. known th at asphaltic ma loria-l. `corulenscs more readily near its upper surface upon heine; rolled7 than the lower portion, which in Contact with the hase. lt is dcsirahle, that the asphaltic 'materia as nearly as possible hc compressed to the saine density throughout its depth. lt follows that when the isphaltic material comin-eased7 a cortan ani-:mnt thereof must he forced into the channels 26 in the concrete hase. The fact that asphaltic material compresses more r aadily near its upper surfzuic means that more force is necessary to unifi rinly cond-cinese a thichr section than a shallmrsection. lily wear course is composed of hoth shallow and th i ck sections.

The sido walls of .euch channels heine' arranged on Aan inclined line and converging at their bottoms towards each other 1will tend to compel the asplialtic material which is reccis'ed within such channels to he coiulcnsed so that the inclined walls-or sides of each channel Q6 impart a downward and sidewisc force under con'ipression from ahove to compone-late for the diliiculty of Lmiforinly conipressing asphalt of different tl'iicliief-iscg.

rl `ho opcningfgs or channels 2G in the hase are wider than they are deep.

'lfhe ridges are so arranged relative to the channels in the iilatfm'ni inold, so that the inipreesingr 'i the projections on the platoi form mold into the plastic material is so proportioned that the formino; of the channels in the hase will compensate for the loss of air ind excess wa 'er removed from the mass during` the improwingof the platform niold thowin. vThe Volume in thc hase displaced hy 'the platform projections coiniuaisatcs for ral to the agrureirate .iolumc :auscd [dat-form mold is plz redY upon the liz se and impressed therein hy pressure from ahorc.

il, certain amount of the material is romprcssoiil into Ylhc channels 2li i i l as "allematerialslorccddowuroirdly ii suclichaa nels the inclii'uul side walls of such channels tend to confino and restrict the asphaltic niatcrial so that the same densitT of the a;-z ivihaltic material is ha l at a point where .auch n'mterial actually roes into the channels flo.

The asphaltic material or .rear course 338 when laid over a coi'icrete hase prepared in the manner that lV ha fo just lcscrihcd is preA rented from ri ,ini-r or crcepi hecause of the aiichorinir u1' .rature jui-it mentioned.

rllhe asphaltic material is locked or i nchorcd `to the concrete hase in more than one direction. The channels are arranged at an angle relative to the lineof trailic so that at no time is' "the trailic actually cutting; or crossing; the wear course zt right anales to all of the points of anchorage of the wear course to the ha se.

l find that in the employment of my epm paratus and method herein, descrhad that hy loss of excess water and air, when the i it-is desirable to so space and proportion the proJections on the platforms forming` the channelsin the base and the recesses in the lplatforms forming the project-ions on the ,5j base,lin such a relation to each other, so that there will be a compensation for the elimination of air and water inthe concrete, so that there will be no shrinkage or increase inthe concrete mass after my method has 10.- been employed.

The asphaltic material while it remains in Contact with the concretev base is held against movement` )n the otherhand, when it is desired to cut through the entire pavement g structure for thelaying of sewers or the repair of sewers or the like, l find that after thev asplfialtio wear course has been cut,'1t

, can be. raised from the base comparatively easily. By comparatively easily, I mean with gless hours of labor than would otherwise be required 1f the channels 2G had vertical sides therein instead of inclined sides, I provide. n Y f The term asphaltic as herein used 'is to denote bituminous mixtures, which are commonly used in connection with la ying of pavements and the like. I do not necessarily in tend to limit myself only to asphaltic material.

The term'platforms as herein used is to denote an apparatus that is adapted to lie uponl the wet concrete' for forming and moldmggrooves and projections in the surface l rof the concrete base.

,v ralityof channels and ridges formed therein,

a plurality ef cross cleats mounted within saidfchannels, for separating said channels into a plurality of sections, the walls of said channels being inclined 'from vertical. wherevby the platform mold when. laid upon a plastic base will forni channels therein having inclined walls with a plurality of ridges completely surrounded by said last channels.

VEZ. A platform mold for pavement con struction comprising a plurality of stringers, a plate secured to said stringers having a plurality ofchamielsjand ridges formed therein, a plurality rof cross cleats mounted within said channels for separating'saidchannels into apluralityv of sections, the walls of said channels being inclined from vertical wherebythe plat'lornrmold when laid upon a plastic basewill'form channels therein having inclined Walls with a plurality of ridges completely surrounded by said last channels, and means for allowing the escape of air and water through said plate when the same is laid upon a plastic base.

3. A platform mold for pavement construction comprisingr a plurality of stringersi, a plate secured to said stringers having ay plurality of channels and ridges formed therein, some of the ri dges running at angles relative to others, for separating said channels into a plurality of sections, the walls of said channels beingl inclined from vertical whereby the platform mold when laid upon a plastic base will form channels therein having inclined walls with a plurality of ridges completely surrounded l y said last channels.

Ll. A i platform mold for pavement construction coml'irisingr a. plate, a plurality of parallel ridges on the under surface thereof and cross ridges extending,r between said parallel ridges.

5. A platform mold for pavement con struction conn'nisingr a plate, a plurality of parallel ridges on the under surface. thereof and crossridges extending between said parallel ridges, said plate being,r provided with openings between the ridges.

(i. A platform mold for pavement construction comprising a plate, a plurality of parallel ridges on the under surface thereof and cross ri dgcs extending between said parallel ridges, said plate beingr provided with openings between the ridges, and stringers extending along said plate for reinforcing the' platform mold.

7.`A platform mold for pavement construction comprising stringers, a plate sccurcd thereto7 rid ge members secured to said plate, said. members comprising ridges extendingf in at least two diti'ercnt directions and connected together, the space between adjacent ridges being open, and openings in said plate co-incident with but smaller than the open spaces between said ridges.

8. A platform mold for pavement eonstruction comprising stringers, a plate secured thereto, ridge members secured to said plate on the opposite side from said stringcrs and arranged at an angle relatively thereto, said members having walls, said walls being inclined from vertical, whereby the plat form mold when laid upon a plastic base will forni channels therein having inclined walls, the space between adjacent ridges being open, and openings in said plate co-incidcnt with but smaller than the open spaces between said ridges.

LEON R. MACKENZIE.

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