US 1727258 A
Description (OCR text may contain errors)
Sept. 3, 1929. E. A. TUCKER ROADWAY OR PAVEMENT Filed Jan. l0, 1924 Patented Sept. 3, 1929.
Unirse STATES EDWARD A. TUCKER, r0E WINoHEsTEE, EinsehenUsEr'iJs.` ,d
yE'oAirwAY yon PAVEMENT.
' Application filed 4January 10, 1924. Serial No.y 685,370.
This invention relates to roadways or pavements, more particularly to concretesurfaced i'oadways or pavements, and consists in improvements which are designed to lengthen the life thereof.
A concrete surfaced road tends to deteriorate in part because of theincapacity of the surface to yield and adapt itself without fracture to changes 'either permanent `or temporary and seasonal in the position of the underlyingroadbed. Vnder the action of frost, or due to a natural settling o'r upheaval of the roadbed, certain parts thereof are apt to become relatively depressed and others elevated. k,This compels the surface to bend more or less, and dueto its inability to flex sufficiently' to adapt itself to the changed position of the underlying bed without fracture7 a crack starts where ythe bending or flexing ris the greatest. yOnce started this crack soon opens and grows into a large fissure under the travel which the roadbed carries. u
The object of the present invention is to produce a roadway or pavement having a hard, durable, concrete surface, with sufli* cient exibility to enable itto adapt itselfy without fracture or theformation of surface cracks to the changes in the underly? ing roadbed which are commonly incident to a well built roadway. In the illustrative embodiment of the invention this saccoin plished by providing the roadway with a surface composed preferably of individual, pre-cast, concrete units of relatively great length as compared with the lesser transverse dimension, each unit being so reinforced, and preferably by a multiplicity of longitudinal reinforcing members distrib- 'uted with substantial uniformity through'j` by employing suitable ineans toy hold the pre-cast, surface units in'fplace," they may be utilized in connection with ak roadbed prepared withoutfa concretefbase, yor with' portions onlyy formed of concrete. f
The invention will be best understood by reference to the/following description when taken in connectionr with the accompanying illustration L'of one specific" embodiment thereof, while its f 'scope will be'more par ticularly pointed out in the appended ci aims. In the drawings i;k f Fig. l` is a cross sectionshowing "a roadway provided with a concrete 'basef and a i concrete surface 'constructed in accordance with'one form of the'invention;
Fig. 2 is a longitudinal 'section of axporr` tion of the roadway illustratedin Fig. l;
Fig. 3 is a perspective on a larger scaley showing one endypartly broken away, of
a pre-cast, concrete, surfacing unit ,rein-f forced to provide angabnormal amount yof flexibility; y y f Fig. 4 is a cross section taken through one ofthe surfacing units illustrating one 'form of `an anchoring device;y n*
Fig. 5 is a cross sectionof a roadway 'uti'- lizing. precast', surface' units slightly modified from the construction'showii in Fig. ly
and applied to a roadbed'phaving other than aconcrete base;` ff y Fig. 6 sliows'in detail one means of holding the endsof the pre-cast, surfacingunits n along the edge of they roadway shown in Fig.5;` V` f Fig. 7 is a longitudinalsection of a portion of the roadway shownin 5; and
Fig. 8 is a detail illustrating the usefof ay preferably pre-cast yjointfor the center of the roadway,rwhere a roadbed ofthe type shown in Fig. y5 is employed. f
Referringto the drawings and more particularlyto the illustrative embodiment 'of the invention shown in Figs. l to finclusive, I have there showna roadway inwhich I there is utilized for theconcr'ete Vsurfacea series of precast, concrete, plank-likemembers y1l which maybe laid transversely on thel upper surface of the `concrete bed` 1.3, the latter being Vpoured in place and resting on the underlyingfbed 15.'L The lattermay be' constructed fof broken stone with suitable g lling, or may havey any other' usual andy desired formationv according to requirements, and the concrete base 13 may be of any desired depth or thickness. The bed having been thus prepared the precast, surfacing units are laid on the pouredfconcrete top thereof while the latter is still soft andy adapted to have embedded therein `suitable anchoring devicesf presented by the under side of the surface units 11.
Any suitable anchoring means may be employed, but herein there are. provid-edV for that purpose a series of wire loops 17 depending, from the bottomfof each planky likeunit and having their ends held within the body of the unit by the pre-casting operation and preferably, though not necessarily, anchored or securedtothe reinforcement thereof.k Y f l In the case of a narrow roadway or pavement the individual surfacing units may extend entirely across the same, butin the illustrative form ofthe invention thev roadway, bothas to ythe concrete base and the surface, is divided transverselyy into two longitudinal sections, the individual surfacing units extendng; across yeach section and having their ends separated atthe center of the roadway by a. ,small space which is filled with cement or,` other suitable substance to form a continuous center joint 19 between thetwo sections. The two sections of the concrete bed 13 may be united at intervals by dowel pins 21 (see Fig.,1) or other re- ;jinforcing means adapted to tie them together. 1
The surfacing unitsvmay be laid with their sides in contact, butV preferably they are located to leave narrow intermediate gaps fwhich, after the units are laid, are filled with cement to form, transverse jointsy23 between individual. units, so that the entire top `forms a smooth, unbroken. surface Acom- I prising the individual pre-castk members united to the top of the poured concrete bed and separated by the narrow,longitudinal and transverse-joints referred to.
f mate required height so as to permit the unitsl to be worked down into the bed to provide `a smooth, finished top surface of the j required `contour and height. This process will result in forcing more or less cement Vup between theunits and will result in partly or wholly fillingthe intermediate, joints.
The individual surfacing units are preferably pre-cast with a system of reinforcement such as that described in my Patent No. 1,530,630 dated March 24, 1925. Thisv vtransversewires, but herein I have shown the same in the form of successive layers of longitudinal wires 25 whichl are separated atl intervals by the interposed transverse bars or members of a grid or netting 27. Such a grid or netting may be employed at intervals lengthwise the unit, but its function is primarily to relatively space and locate the rods in the mould during the casting operation and itis not essential as a matter of reinforcement.
.While the invention is not restricted to the dimensional limits of the reinforcing unit, by way bf illustrative example the member may be assumed to have a cross section S x 1% inches.l the longitudinal reinforcing members being formed of approximately No.. 12 wire and arranged in six layers, theV reinforcement in adjoining layers being preferably in staggered relation to better distribute the vreinforcement and successive layers in the illustrative example having respectively five `and six members each.` In t e illustrative example, furthermore, the longitudinal reinforcing members of successive layers are spaced apart on centers by a distance equivalent to about two diameters of the wire, so that each layer of the concrete considered from the top to the bottom of the unit will be within the effective Vbonding region of one of said longitudinal reinforcing members. To achieve this result the layers of reinforcement should preferably be separated by an amount equivalent to not more than five diameters on centers. It iszunnecessary that the spacing ofthe longitudinal rods of each layer in the direction at right angles to the least dimension (or crosswise the plank) be less than a distance equivalent to three diameters. It will be understood that these dimensional examples given are illustrative merely.
In arranging the reinforcement in the mould and in pouring the concrete, there is preferably allowedonly a slight covering of the concrete over the upper and lower layers of reinforcement so as to give the necessary embedment thereof.
The effect of this disposition of the relill) llO infor-cement is to distribute the steel or other metallic 'reinforcing strands throughout the entire cross section ina series of planes or layers and symmetrically with reference to the axis, but spaced closely enough sothat the concrete in any plane or layerat right angles to the least dimension is held together and rendered capable of greatly increased elongation in the same manneras in concrete immediately surrounding f a reinforcement member.
In the usual method of reinforcement, where the latter is concentrated and placed unsymmetrically with relation to the axis of the concrete member, only those portions of the concrete near such reinforcement, and ordinarily near the outer surface, are made capable of inci'eased elongation, Whereas in the illustrative embodiment of the invention all portions are made similarly capable of increased elongation because yof the substantially uniform distribution of the steel throughout they entire cross section. Furthermore, the capacity for elongation of the outer surface is further increased because of the fact that these portions are helped out or relieved of some ofthe strain by the concrete and strandsin each adjacent layer which, being of the same capacity and under less strain because nearer the neutral axis, will help hold the outer fibres or strands from rupture and at a higher strainthan such fibres or strands would' stand if only the surface of theconcrete were reinforced. A surfacing unit reinforced in the manner described is qualified to withstand anabnormal deflection without detriment.
In a concrete unit reinforced'fas in the present case by a multiplicity of small strands or other ysimilar reinforcing members, it is sometimes diiiicult to eliminate voids and provide a dense, 'homogeneous body of concrete.y It is important to maintain the separation and spacing of the reinforcing members and to eliminate all voids. In practice this'niay be attained by fixing in the mould a series of separating grids 27 orftheir equivalent, closely fitting the strands and qualified to hold them in fixed relative positions, and then agitating the moulds during and following Lthe pouring of the concrete, 'thus causing thel concrete to settle down and completely fill all spacesy between the reinforcement while at the saine time avoiding displacement of the strands from their assigned positions.
rlhe application yof the pre-cast concrete cast. y f
The surfacing units 33 f are preferably and also, in a dependable yway, the full tensile strength of thecoiic'retm-both acting together. The method of distributing the strands of steel in the pre-cast member also'produces, when the member is bonded to the base, a unit having greater flexibility than would be obtained if reinforced with the same amount of steel in a single layer. This permits a relatively small amount of steel to be used for road reinforcement, giving the required flexibility to the surface, and at the same time the required lstrength to the entire road section yconsidered as a beam.
Referring to Figs. 5 to 8 inclusive, I have there shown the use of pre-cast, surface members in connection with a roadbed other than of concrete formation. In this case the roadbed 29 may be specially constructed for the purpose or maybe the bed of an existing roadway which it is desired to have surfacedor rebuilt. This is covered with a levelling or filling surface 31 yof gravel, sand, tar `or other material, the' top of which is brought to a uniform level orgrade, and has applied thereto the surfacing units 33. rlliese units are laid with their outer edges resting on the tops of concretebeams 35 and secured thereto by `the concrete edge strip 37 and the bolts 39 set at rintervals in the `beams 35 and arranged to pass through 'perforations in the surfacing units and the strip 37. The edge beams 35 may be pre-cast but are preferably poured in place With the aid of forms. The edge strip 37 is preferablypreformed with the system vof reinforcement alreadydescribed, which imparts a high a double section roadway as illustrated in the drawings, the abutting edges of the units may be united by any suitable kind of a joint. f In the illustrative `form of the invention the inner ends of each section are grooved or flanged," as illustrated, so that preferably, as in the case of the roadway 'il` lustrated in Figs'. lfto l inclusive, they are laid with small' intermediate spaces which are cement filled to provide transverse oints While I have herein `shown and described for' the purposes of yillustrz'uzion `one rspecific eiifibodiment lof the invention, it is yto be understood that the same is notv limited'to" the dimensional characteristics ysubmitted by,
way of example, or to the form or relative arrangement of parts, or to the speciiicapplicationhereinv made thereof, but that-ex- Aen tensive deviations may be made from the illustrative embodiment of the invention all without departing from the spirit thereof.
I claim: f i l; In a roadway or pavement, the combination with a roadbed, of a surface comprising a series of reinforced concrete units laid thereon and secured thereto, each unit consisting of a member vofy relatively great length compared to its least transverse dimension, and having longitudinal reinforcing members sol distributed throughout its cross sectionas tobring each concrete layer lying transverse to the direction of said least dimension within the eective bonding region of one of said reinforcing members to provide thereby a member adapted to undergoy abnormal defiection.
2. In a roadway or pavement, the combination with a roadbed, of a surface comprising al series of reinforced concrete units laid thereonand secured thereto, each unit consisting of a member of relatively great length as compared to its leasttransverse dimension, and having a multiplicity of longitudinal reinforcing members distributed with substantial uniformity throughout its cross section to provide thereby a unit reinforced throughout and adapted to undergo Y e abnormal deiiection and elongation.
3. In a roadway or pavement, the combinationfwith a roadbed, of a surface comprising a series of reinforced concrete units laid thereon and secured thereto, the reinforcement for each unitv comprising longitudinal reinforcing members arranged in a series of layers, and the spacing of each layer in the direction of least dimension of each unit being not greater than live diameters of the reinforcing member.
4. In a roadway or pavement, the combinationv with al roadbed having a concrete body, of a surface comprising a series of reinforced concrete units laid thereon and bonded thereto, each unit consisting of a member having longitudinal reinforcing elements distributed throughout the cross section thereof.
`5. In a roadway or pavement, the combination with aroadbed having avconcrete body, of a surface comprising a series of precast, reinforced concreteV units laid thereon and bonded thereto, each unit consisting of a member having longitudinal reinforcing elements so distributed throughout its cross section as to bring each concrete layer of said unit within the effective bonding region of one of said reinforcing elements to provide thereby a member kadapted to` undergo abnormal delection, and anchoring means for said members embedded in the concrete body of the roadbed. l
6. 11n a. roadway or pavement, the combination with a roadbed having a concrete body, lof a surfacefcomprising ya series of precast', reinforced, concrete units laid thereon and bonded thereto, eachunit consisting of a memberhaving longitudinal reinforcing elements sok distributed throughout its cross section as to provide a member capable of taking, elongation in each component layer in a manner resembling that characteristic of a homogeneous beam.
;7. Inafroadway or pavement, the combination with a roadbedv having a concrete body, of a surfacecomprising a series of precast, reinforced, concrete units laid thereon and: bonded thereto, each unit being of relatively great length as compared with its thickness and consisting of a member having distributed throughout substantially the entire cross section a series of reinforcing membersin amultiplicity of layers, not less than four in number, serially arranged transverse the thickness of the surface unit whereby there is provided a surface with a roadbedcapable of having elongation in each component layer thereof in. al manner resembling that characteristic of a homogeneous beam.
8. A roadway or pavement having a concrete base, a series of precast surfacing units each of relatively great length as compared with the thickness, said units being reinforced by a. multiplicity ofy longitudinal reinforcing members arranged in a series of planestransverse to the thickness of the unit, the distance between successive planesofreinforcement being not greater than five diameters of the reinforcing members, andy said surfacing units being secured to the concreate base by bond and anchorage to form a combined sectioncapable of developing a beam action.
9. A construction memberhavinga concrete body and a precast, reinforced, concrete unit laid `thereon and bonded thereto, said unit being of great length as compared with its thickness and consisting of a member having a multiplicity of longitudinal reinforcing elements so distributed throughout its cross section as toprovide a member capable of taking elongation in each component layer in a manner resemblingthat characteristic of a homogeneous beam, said construction member providingy a section capable of developingv a beam action in its wholecross section.
l0. A concrete roadway or pavement characterized by a concrete body having reinforcement concentrated closely adjacent to the surface ofthe roadbed but comprising reinforcing members arranged in a multiplicity of layers, not less than four in number, serially arranged transversely relative to the thickness of the roadbed.
InV testimony whereof, I have signed my name to this specification.
EDWARD A. TUCKER.`