US2036379A - Concrete pavement - Google Patents

Description

Amili 79 W3@ 1E. c. WooDm/AHD CONCRETE PAVEMENT Filed June 6, 1952 2 Sheets-Sheet l www@ April 7, fk5? 1E. c. WooDWRD 2031,379

l coNcRETE PAVEMENT Filed Jun@ e, 1952 2 sheets-sheet 2 Patented pr. W, i936 turen sTATEs eATEuT ePrice CONCRETE lPAWIVmN'll poration oi Illinois Application .lune 6, i932, Serial No. 6ll5,6"i2

25 Claims.

This invention is a novel improvement in concrete roads or pavements, and the principal object of the invention is to provide a concrete road or pavement constructed of alternatelong and Short slabs with novel reinforcing anchor' bars and dowels between the slabs to prevent the slabs, particularly the long slabs, from warping at their ends such as takes place in the usual concrete road beds constructed of long slabs of uniform length.

lin concrete road beds as now constructed the slabs have substantial similarity in length, and the warping at the end of one slab is similar and equal to that at the end of the adjoining slab, the amount of warp being dependent upon the length of the slab. The only resistance to this warping is the bending strength of the dowels or anchors which resistance is relatively small. In my invention alternate long and short slabs are used and the ends of the long slabs, if free, Would warp much higher than the ends of the adjoining short slabs; but by anchoring the ends of the long slabs to the ends of the short slabs, the weight of the short slabs will effectively resist the upward warp of the long slabs.

vAnother object of the invention is to provide a novel expansion joint of sinuous form with a view to dove-tailing the slabs on each side of the center line together in order that there may be no tendency for the center joint to open, as no undue stress will be placed on the center'dowels.

Another object of the invention is to provide novel anchor bars at the expansion joints, which bars are so interwoven between the slabs that 5 neither slab will be able to rise above the other without deforming the bars, a suicient number of these .bars being used to carry the load and avoid deformation.

A further object of the invention is to provide novel dummy joints, the adjoining slabs being held at equal elevation by the sheer strength of the longitudinal reinforcement, extra dowel bars being used, and by the resistance to slipping fur nished by the irregular surfaces of the broken slab below the constructed portion of the joint. Said irregular surfaces are held close together by the tensile strength of the dowel bars embedded in the concrete on each side of the dummy joint and passing across the crack which will develop below the dummy joint.

A still further object of the invention -is to provide novel means for waterproong the subgrade Soil and holding the soil at low moisture content, so as to relieve the soil of objectionable excess plasticity, giving the sub-soil ample stability.

l will explain the invention with reference to the accompanying drawings which illustrate one practical embodiment thereof to enable others familiar withv the art to adopt and use the same; and will summarize in the claims the novel features of construction, and novel combinations oi' parts, for which protection is desired.

ln said drawings:

Fig. l is a plan view of a portion of my novel concrete road, illustrating the arrangement oflong and short slabs, expansion joints, dummy joints, and waterprooiing; and showing in dotted lines the reinforcing rods, dowels, and anchor bars at the expansion and dummy joints.

Fig. 2 is an enlarged section on the line t-t, Fig. 1, illustrating the method of waterproonng the sub-soil.

Fig. 3 is a View illustrating the slight warping of the ends of the slabs when using alternate long and short slabs.

Fig. 4 is a view illustrating warping of the slabs of the usual concrete road in which the slabs are all of the same warping being somewhat exaggerated.

Fig. 5 is an enlarged longitudinal section through the expansion joint showing the anchor bars.

Fig. 6 is a perspective View showing the concrete forms adjacent the expansion joints and illustrating the reinforcing members for the concrete adjacent the joints.

Fig. 'l is a top plan View of an anchor bar, detached.

Fig. 8 is a longitudinal section through the expansionand dummy joints.

As shown in Fig. l, my novel road preferably comprises concrete slabs of alternate long and short lengths, the long slabs being indicated by the reference character A, and the short slabs by the reference character B. The long slabs A are preferably substantially three times 'the length of the short slabs, the long slabs being preferably 30 feet, and the short slabs 10 feet, in length.

' At the end of each long slab A is a short slab B separated by a dummy joint C shown more particularly in Fig. 8, each dummy joint C being formed by placing a sinuous plate C (Fig. 6) extending transversely between the side forms D when the concrete is poured, said forms C extending down vinto the linished surface of the road bed a distance of about 2 inches, the width of the forms `C being approximately of an inch.

length, the amount of Between the short slabs B are expansion joints E, preferably conforming with the sinuous curvature of the dummy joints C, as shown in Fig. 6, said joints E being formed between the abutting ends of the short slabs B, and the joints extending entirely through the road bed.

In the abutting ends of the short slabs B, in way of the expansion joints E, are provided a plurality of spaced pairs of opposed anchor bars F (Figs. 1, 5 and 7), which are embedded in the ends of the slabs when the latter are poured, as shown in Figs. 5 and 6, the anchor bars F being bent downwardly as at F (Fig. 5) at the expansion joint, and having flat plates F2, preferably of sheet metal, secured to their lower ends adapted to underlie the adjacent end of the adjoining slab. As shown in Fig. 1 a pair of said anchor bars F are disposed at each side of the road bed, .and a pair of opposed anchors F disposed at approximately one-fourth and three fourths of the width of the road bed respectively, and two pairs of such anchor bars F are disposed at the center of the road bed.

In forming the road bed as shown in Fig. 6, the longitudinal side forms D are laid on prepared grade and spaced apart a width equal to the width of the road, the height of the side forms D being substantially equal to the thickness of the road bed. Extending between the side frames D are the sinuous plates E', Fig. 6, for forming the expansion joints E; also the sinuous plates C for forming the dummy joints C, all properly spaced. Aligned center plates H are disposed between the side frames D, and opposed transversely disposed reinforcing rods G are supported between the plates D and the center plates H so as to be disposed within the thickness of the road when the concrete is poured. Angularly disposed rods K are secured upon the reinforcing rods G extending diagonally inwardly from the ends of the expansion joints E to reinforce the adjacent corners of the short slabs B. Under the dummy joints C are a plurality of spaced pairs of dowels L, one pair being disposed at the center of the road, and other pairs being disposed at approximately 1A and 3A of the width of the road respectively, as shown in Fig. 1. Preferably a pair of longitu dinally disposed bars M extend at each side of the road between each of the expansion joints E and a similar pair of longitudinally disposed reinforcing rods N are disposed at the center of the road.

A length of 30 feet is taken as a length which under normal soil conditions will permit a long slab A (of 30 foot length) having a short slab B (of foot length) attached to each end, to contract after expansion without failure by excessive tensile stress. The elongation of the steel bars L across the crack below the dummy joint C will relieve the long slabs A of some of the load of the short slabs on each end.

Concrete paving slabs with cross-section as at present designed and having a length exceeding 24 feet will curl or warp at each end, as illustrated in Fig. 4, for a distance back from the joint of about 1'2 feet. This distance is both the calculated distance for which the strength of the concrete can lift the slab and is the observed distance at which a crack usually appears. When, therefore, the slabv is 24 feet long there will exist maximum curling with maximum concentration of load on the sub-grade in the central portion of the slab. As rthe slab length increases this base supporting the curled ends becomes greater while the weight of the curled ends to be supported remains constant. Below the 24 foot length with the thickness of the slab remaining constant, the intensity of the warp becomes less and with a slab length of feet this warp is practically negligible. The desirable lengths of slabs, therefore, to minimize the objectionable conditions associated with warping, will be above 24 feet and below about 15 feet. The slab should be as much longer than 24 feet as possible, for the longer the slab the less will be the concentration of load on the sub-grade as the central portion of the sub-grade must support the two free warped ends. However, this length must be limited to the tensile strength of the slab to adjust itself t0 contraction after expansion, or uncontrolled cracks will inevitably appear. In consideration of these facts it is not considered desirable to have the slab longer than about 30 feet.

For the short slab a 10 foot length will be practically free from warping, and its weight combined with the stress set up in the concrete by the offset or longitudinal coordinate joint, will resist the upward warp of the end of the long slab.

The adjoining slabs at the dummy joints C are held at equal elevation by the sheer strength of the longitudinal reinforcements L, M, and N, and extra dowel bars L used, together with the resistance to slipping furnished by the irregular surfaces of the broken slab below the constructed portion of the joint. 'Ihe irregular surfaces are held close together by the tensile strength of the steel bars L embedded into the concrete on each side of the dummy joint, which bars L pass across the crack that will develop below the dummy joint C.

'Ihe anchor lugs F at expansion joints E, and the longitudinal reinforcement L at the dummy joints C will maintain both sides of the joints of either type at equal elevation and therefore resist the upward or downward thrust of the end of the long slab.

The present design for expansion joints provides that all joints shall be straight lines and at right angles to the longitudinal direction of the pavement. This design permits the joint to function as a perfect hinge. In 'the usual expansion joints there is no resistance to this hinge action except the bending strength of dowels used. The surface dummy joints resist this action by the tensile strength of the reinforcement acting through the distance from the reinforcement to the bottom of the slab or the bottom of the dummy joint, as the case may be. The resistance to hinge action in either type of joint is very small in the usual concrete pavement.

In order to strengthen the slab against this hinge action at the transverse joints, I use a sinuous type of joint for the expansion joints E and dummy joints C. 'I'his curve begins at one edge of the road and is normal to that edge. At the one-eighth point it reverses with the same radius and crosses the quarter point of the road normal to the longitudinal axis of the road. The curve crosses the center line of the road normal to the axis and traverses the remaining half of the pavement in a similar and symmetrical manner to that above described.

The alignment of this curve as shown is selected with a View to dove-tailing the slabs on each side of the center line together in order that there may be no tendency for the center joint to open or stress be placed on the center dowels.

The maximum coordinate of the curve measured longitudinal with the pavement will be the shortest distance that will resist the hinge action lil aoaasvo to be encountered. The coordinate should never be so long that the concrete beams formed will break before the reinforcing across the joint will shear.

This curve might be planed as some other curve rather than sinuous or might be made up of a series of straight lines, but however designed the object sought is to resist the hinge action at the joints without exceeding the working strength of the concrete or opening up the center joint.

A joint having a coordinate longitudinal with the pavement will improve the riding qualities of the surface by prescribing an interval of time between Athe passage oi each wheel of .a vehicle across the` joint and thereby minimize the impact to the vehicle from any irregularity that may exist at the joint.

lit is important that the sub-soil under the road bed be well water-proofed. For this purpose the expansion joints E and dummy joints C are waterproofed, the side walls of both joints being treated with cut back asphalt, and illed with pure hot asphalt having a penetration oi not more than 55. Preferably the expansion and dummy joints are first cleaned of dirt, then' the walls are painted with cut back asphalt composed of 50% kerosene and 50% asphalt, and then the joint filled with pure hot asphalt of penetration of not more than 55.

The edge oi' the road is protected from the entrance of water under the slabs A and B by plown ing a furrow P (Figs. l and 2) along the side edges of the slabs A and E to a depth equal to the thickness of the slabs, and iilling the furrow with good road gravel Q. l/'here good road gravel is available, the entire shoulder S should be thus treated, but in all cases the gravel at theedge of the slab should be as deep as the edge of the concrete slabs A and B. Traiiic will keep the gravel at the edge oi' the slab tamped down and maintain a waterproof joint between the shoulder and the concrete.

l claim:

l. A concrete roadway or the like comprising a plurality of integrally formed sections each comprising a long slab and short end slabs partially separated from the long slab by a shallow dummy joint in the upper surface of the section, the joint between ends of adjacent sections being a through expansion joint; metal reinforcements embedded in the section and extending across the lines of the dummy joints, and anchor members in the ends of the sections extending beneath the ei'- pansion joint and the adjacent sections to prevent relative displacement of adjacent sections.

2. A concrete roadway or the like comprising a plurality ci integrally formed sections each comprising a long slab and short end slabs partially separated from the long slab by a shallow dummy joint in the upper surface of the section; the ends of adjacent sections being sinuous and forming a sinuous through expansion joint therebetween, and anchor members embedded in the ends of the sections and extending beneath adjacent sections adapted to prevent relative ver tical displacement of the short slabs at opposite sides of the expansion joint.

3. A concrete roadway or the like comprising a plurality of integrally formed sections each comprising a long slab and short end slabs partially' separated from the long slab by a shallow dummy joint in the upper surface of the section; the meeting ends of adjacent sections being sinuous to form a sinuous through expansion joint therebetween, metal reinforcements embedded in the section -underneath the dummy joints and eirtending across the lines of said joints, and anchor members embedded in the adjacent ends of the sections adjacent the expansion joint and extending beneath said expansion joint and under the lower edge of the end of the adjacent section.

4. A concrete roadway or the like, comprising a plurality of integrally formed sections separated by expansion joints, and anchor members embedded in adjacent sections and bent down below the ends of and extending under the adjoining sections, said members preventing relative vertical displacement of the slabs at such joint.

5. A concrete roadway or the like, comprising a plurality of integrally formed sections, and a series of anchor members alternately embedded in the end of one adjoining section at the joint and projecting beyond the same and bent down below the end oi the adjacent section and extending thereunder, said members preventing relative vertical displacement of the slabs on opposite sides ofthe joint.

6. A road. joint forming device including in combination a load transmitting means comprising a base member, an upright member thereon, and anchoring means projecting from one side only of said upright member in a direction opposite to the base member, whereby the load transmitting means can be anchored in only one of two adjacent road sections permitting the base member to have movable engagement with the other road section.

'7. A metallic joint support, including an arichoring bar and a bracket at one end oi the bar, the bracket havin-g a supporting blade and an abutment member extending perpendicularly to the plane of the blade and to the bar and connecting the two, and the bar and blade extending in generally opposite directions from the abutment member.

8. A joint support, formed from one piece of metal, and including an anchoring bar and a relatively short bracket at one end of the bar, having a supporting blade and an abutment member extending substantially perpendicular-ly to the plane of the bla-de and to the bar, the bar and blade extending in generally opposite directions from the abutment member, and the blade extending laterally away from opposite sides of the bar. y,

9. in construction work having joints, the com bination with a plurality of slabs arranged edge opposite edge, whereby a continuous surface except for the joints between the edges is provided,

of bars embedded in a slab and extending away from one side of a joint, and each bar provided with a blade rigid therewith and extending across such joint to support the slab at the opposite side of the joint.

l0. The combination with a plurality of concrete slabs arranged edge opposite edge to provide a pavement or floor having joints between the edges, of reversed staggered supports embedded in slabs at opposite edges of a joint, and each provided with a member oset therefrom and extending across such joint in supporting relation to the slabs at the sides of the joint.

1l. The combination with a plurality of concrete slabs arranged edge opposite edge to provide a pavement or floor, the slabs being spaced F apart to leave open joints, and expansion llers in the joints, of supporting bars embedded in a slab above the bottom of the slab and at intervals apart at one side of a joint, and each provided with a solid plate member onset downwardly from the bar and extending under the ller in such joint in engagement with the under surface of the slab at the opposite side of the joint.

12. The combination with a. plurality of concrete slabs arranged edge opposite edge to provide a pavement or floor having a joint between the edges, of arched supports embedded in opposite side portions of one slab, and including end plates extending across the joint and bearing on opposite side edges of the adjacent slab to resist its lateral movement.

13. The combination with a plurality of slabs arranged edge opposite edge in spaced relation to provide a pavement or iloor having open joints between the edges, of reversed staggered means alternately anchored in the edge portions of the slabs at each joint for the mutual support of the slabs from the bottoms thereof, and fillers in the joints and supported upon such supporting means.

14. A joint support, formed from one piece of metal, and including an anchoring member and a bracket at one end of the anchoring member, having a supporting blade and an abutment member extending substantially perpendicularly to the plane of the blade and to the anchoring member, the anchoring member and blade extending in generally opposite directions from the abutment member, and the blade extending laterally away from opposite sides of the anchoring member, and means on the anchoring member for resisting longitudinal movement thereof when the support is in use. A

15. In construction work having joints, the combination with a plurality of slabs arranged edge opposite edge, whereby a continuous surface except for the joints between the edges is provided, of supporting bars anchored in a slab at one side of and extending away from a joint, and each provided at its outer end with a member offset therefrom and extending across such joint and directly supporting the slab at the opposite side of the joint from a surface of such slab.

16. In construction Work having joints, the combination with a plurality of slabs arranged edge opposite edge, whereby a continuous surface except for the joints between the edges is provided, of bars anchored in a slab and extending away from one side of a joint, each bar provided with a member extending laterally away from both sides of the bar and extending across such joint to support the slab at the opposite side of the joint.

17. In construct-ion work having joints, the combination with a plurality of slabs arranged edge opposite edge, whereby a continuous surface except for the joints between the edges is provided, of bars anchored in a slab and extending away from one side of a joint, each bar provided with a blade laterally offset therefrom and extending across such joint to support the slab at the opposite side of the joint.

18. The combination with a plurality of concrete slabs arranged edge opposite edge to provide a pavement or floor having joints between the edges, of supporting bars embedded in the concrete of a slab at one side of a joint, and

each provided with a member offset therefrom and extending across such joint in direct supporting relation to the slab at the opposite side of the joint.

19. The combination with a plurality of concrete slabs arranged edge opposite edge to provide a pavement or iloor, the slabs being spaced apart to leave open joints. and expansion llers in the joints, of supporting bars embedded in a slab at one side of a joint, and each provided with a member offset therefrom and extending across the filler in such joint in direct supporting relation to the slab at the opposite side of the joint.

20. The combination with a plurality of concrete slabs arranged edge opposite edge to provide a pavement or floor, the slabs being spaced apart to leave an open joint, and an expansion ller in the joint, of an anchorage member embedded in a slab at one side of the joint, and extending down to the bottom of such slab which is at the sub-bed, and a member at the lower end of the anchorage member and formed therewith of one piece of metal, such lower member extending across the iiller in engagement with the bottom of the slab at the opposite side of the joint.

21. A metallic joint support, including an anchoring bar, rigid means on the bar and extending perpendicularly from its middle portion, and a pair of supporting members offset from the bar and extending in opposite directions from the rigid means.

22. 'I'he combination with a plurality of concrete slabs arranged edge opposite edge to provide a pavement or floor having a joint between the edges, of supporting bars embedded in the adjoining slabs and each provided with depending rigid means, and a pair of supporting members extending in opposite directions from the rigid means in supporting relation to the adjoining slabs.

23. The combination with a plurality of slabs arranged edge opposite edge to provide a pavement or floor having joints between the edges, of alternately arranged means rigidly anchored in the edge portions of one of the slabs at each joint and projecting across the joint beneath an opposite slab for the mutual support of the slabs from the bottom thereof.

24. The combination with adjacent slab members placed side by side, of staggered alternately reversed load transmitting means each alternately supporting one slab and embedded in an adjacent slab whereby the load impressed upon such adjacent slabs is transmitted from one slab to the other.

25. A load transmitting device for use at the joints of concrete roadways and the like comprising a plurality of members respectively supporting the roadway at opposite sides of the joint with the members on opposite sides of the joint being independent of one another and respectively embedded in the roadway structure at sides of the joint opposite the points of support.

EDWIN Ci WOODWARD.

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