US3495509A

US3495509A - Apparatus and method for creating a joint-intersection region in concrete slabs

Info

Publication number: US3495509A
Application number: US664457A
Authority: US
Inventors: Arthur I Lusk
Original assignee: IND ENG DEV Inc
Current assignee: IND ENG DEV Inc
Priority date: 1967-08-30
Filing date: 1967-08-30
Publication date: 1970-02-17
Anticipated expiration: 1987-02-17

Description

Feb. 17, 1970 A. l. LUSK 3,495,509

APPARATUS AND METHOD FOR CREATING A JOINT-INTERSECTION Filed Aug. 30, 1967 REGION IN CONCRETE SLABS v 4 Sheets-Sheet l A INVENTOR. men/me L 03K nrroeue'ys'.

Feb. 17, 1970 A. l. LUSK 3, 9

APPARATUS AND METHOD FOR CREATING A JOINT-INTERSECTION 4 Sheets-Sheet 2 REGION IN CONCRETE SLABS Filed Aug. 50, 1967 INVENTOR. 42 77/08 I. L034 M fa Feb. 17, 1970 A. l. LUSK 3,495,509

, APPARATUS AND METHOD FOR CREATING A JOINT-INTERSECTION REGION IN CONCRETE SLABS Filed Aug. 30, 1967 4 Sheets-Sheet 3 INVENTOR. 14/? T1402 1 0.26

TTOQ/VE/S'. E

Feb. 17, 1970 .A. l; LUSK 3,495,509

- APPARATUS AND METHOD FOR CREATING A JOINT-INTERSECTION REGION IN CONCRETE SLABS Filed Aug. 30, 1967 4 Sheets-Sheet 4 FZU/D sol/eascom-e04 INVENTOR. Aer/we 1. 0.96

4 7' TOENE/S.

United States Patent 3,495,509 APPARATUS AND METHOD FOR CREATING A .ggggg-lNTERsECTlON REGION IN CONCRETE Arthur I. Lusk, Santa Ana, Calif., assignor to Industrial Engineering Developments, Inc., Little Rock, Ark., a corporation of Arkansas Continuation-impart of application Ser. No. 623,638, Mar. 16, 1967. This application Aug. 30, 1967, Ser. No. 664,457

Int. Cl. E0lc 11/06 U.S. Cl. 94-39 26 Claims ABSTRACT OF THE DISCLOSURE A means and method for creating a joint-intersection region, in concrete slabs, by embedding a transverse jointforming tape or strip in Wet concrete wherein a longitudinal joint-forming tape has previously been embedded. The longitudinal tape is severed, during laying of the transverse tape, by the combined action of a saw blade and the tape-laying blade. In another embodiment, an elongated horizontal prow and associated knife are employed, in place of the saw blade, to sever the longitudinal tape.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application Ser. No. 623,638 (now Patent No. 3,413,901), filed Mar. 16, 1967, for Apparatus and Method for Inserting a Continuous and Solid Joint Strip into Plastic Concrete, which application is a continuation in-part of Ser. No. 468,381, filed June 30, 1965, for Apparatus and Method for Inserting a Continuous and Solid Joint Strip into Plastic Concrete, and Joints Formed Thereby, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to the art of forming joints in concrete highways by introducing tapes or strips therein prior to the time that the concrete has hardened.

Description of the prior art It is conventional practice to embed a longitudinal joint strip or tape along the center line of a highway during extrusion or laying of the concrete which forms the highway. Because the longitudinal joint strip is present prior to introduction of the transverse tapes or strips which are employed toform transverse joints at spaced points along the highway, it is necessary that such longitudinal joint strip be severed. Such severing should be effected with a minimum of disruption of the location of the longitudinal joint strip, and must be effected without crushing or moving the longitudinal joint strip downwardly into the wet concrete. The problem of effectively severing the longitudinal joint strip has been very difiicult of solution, particularly since severing should be effected not only without substantially disturbing the longitudinal joint strip, and causing the severed ends thereof to become inclined or out of alignment, but also without damaging the concrete therearound.

3,495,509 Patented Feb. 17, 1970 SUMMARY OF THE INVENTION Applicant has discovered that the same apparatus which lays or embeds the transverse joint strip into the plastic concrete may be employed to sever the longitudinal joint strip, thereby forming the desired joint-intersection,re-

gions in the concrete. Such severing of the longitudinal joint strip is effected by an apparatus provided on or in advance of the tape-insertion blade which is utilized in laying the transverse strip, it being a feature of the invention that the vibrator for the tape insertion blade serves additionally to aid in the strip-severing operation. In accordance with one major aspect of the present apparatus and method, a saw blade is oriented at a predetermined angle relative to the horizontal and is adapted to saw through only a predetermined portion of the longitudinal tape. The remainder of the tape is severed by the transverse tape-inse'rtion blade which trails behind the saw blade. In accordance with another embodiment, the longitudinal tape is first penetrated by an elongated horizontal prow and is then severed by a knife mounted in advance ofthe transverse tape-insertion blade.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is an isometric view illustrating a tapeinsertion mechanism for a transverse tape, such mechanism having mounted thereon a first embodiment of a severing means for the longitudinal tape;

FIGURE 2 is a fragmentary transverse vertical sectional view which illustrates, in schematic manner, the vibrator means which vibrates the transverse tape-insertion blade and also the severing means for the longitudinal p FIGURE 3 is a fragmentary side elevational view illustrating the tape-severing means during a severing operation; I

FIGURE 4 is a fragmentary front elevational view of the apparatus portion shown in FIGURE 3, but omitting an illustration of the longitudinal tape or strip;

FIGURE 5 is an enlarged fragmentary side elevation of a second embodiment of the severing means for the longitudinal tape, showing thesarne in theactof severing only a predetermined upper portion ofsuch longitudinal p f r FIGURE 6 is a vertical sectional view taken online 66ofFIGURE5;

' FIGURE 7 is a fragmentary side elevational view illustrating the severing of the remaining or lower portion of the longitudinal tape, such severing being effected by the blade which inserts the transverse tape into the concrete;

FIGURE 8 isa fragmentary longitudinal sectional view illustrating a third embodimentof the severing means for the longitudinal tape, such third embodiment incorporating a saw which is retractably mounted in advance of the insertion means for the transverse tape;

FIGURE 9 is a sectional view on line 9-9 of FIG- URE 8; and I FIGURE 10 is a fragmentary plan view of the surface of the highway, illustrating the longitudinal and transverse tapes in the intersection region thereof, which tapes create the joint-intersection region in the concrete slab.

DETAILED'DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGURE 1 in particular, this view illustrates the lower portions of an apparatus for inserting or embedding a tape or strip transversely into the upper region of a slab of wet (plastic) concrete'. The portions of the apparatus not shown in actual form are represented schematically by the box 10, which is denoted suspension and actuating means. The entire apparatus is shown and described in detail in the above-cited copending patent application Ser. No. 623,638.

As set forth at length in the patent application referred to, the suspension and actuating means includes a movable beam or track which is mounted across the highway in a manner of a bridge, being spaced above the upper surface of the concrete. The means further comprises the upper regions of a carriage which moves along the beam or track, from one side of the highway to the other. Additionally, the apparatus 10 includes means to supply strip or tape downwardly to the transverse tape-insertion blade or head 11 which forms one of the most critical components of the described apparatus. The tape or strip which is fed from means 10 to blade or head 11 is indicated at 12 in FIGURES 2-4, being denoted the transverse tape in order to distinguish it from the longitudinal tape or strip which is discussed at length below.

The direction of movement, during a strip-insertion traverse over the concrete, is from left to right as viewed in FIGURES 1, 3, 5, 7 and 8. Thus, parts shown to the right of blade 11 may be stated to be in advance thereof, whereas parts to the left of blade 11 are to the rear thereof.

The components shown in actual form in FIGURE 1, as distinguished from being represented schematically by the box 10, comprise vertical shafts or connectors 13 which extend downwardly from the suspension means to a support plate 14 adapted to support various components of the apparatus. As best shown in FIGURE 2, one of the elements supported by plate 14 is an undercarriage 16 having a suitable vibrator mounted thereon. The vibrator is represented schematically at 17 and is adapted to effect vertical vibration of the undercarriage 16 and associated parts. The vertical vibratory movement is made possible by helical compression springs 18 which are mounted around bolts 19 and seats against the upper and lower surfaces of the undercarriage.

The above-indicated blade or head 11 is suitably mounted on undercarriage 16 for vertical vibratory movement therewith, and for simultaneous longitudinal movement (longitudinally of the blade 11, but transversely of the highway) due to the operation of the suspension and actuating means 10. The means to shift the carriage (and thus blade 11) along the beam is part of suspension and actuating means 10.

The tape-insertion blade 11 is hollow (so that tape may pass therethrough), and has a curved lower edge 21 and a scalloped upper edge region 22. One of the functions of the latter edge region is to bend the transverse tape 12 in a generally vertical plane in order to cause the axis of the tape to be horizontal as the tape emerges from the rear or trailing edge of the blade 11. As described in detail in the cited copending patent application, the tape passes from a real (contained in suspension and actuating means 10) downwardly to tapedrive rollers contained in a housing 23 (FIGURES 3 and 4), thence rearwardly through the hollow blade 11 and into the plastic concrete through which the blade is moving.

In passing from the suspension and actuating means 10 to the drive-roller housing 23 and thence to and through blade 11, the tape passes through or adjacent various guide means as described in the cited patent application. One such guide means is a stationary guide mounted on housing 23 and indicated at 24 in FIGURES 3 and 8. The mounting portion or means which is connected to the undercarriage 16 (FIGURE 2), and which supports not only the blade 11 but also housing 23 and thus stationary guide 24, is denoted by the reference numeral 25.

Proceeding next to a description of other elements suspended from the support plate 14 and thus from the means 10, a sensing shoe 27, preferably having a relatively large area, is mounted in advance of the blade or head 11 and is adapted to engage the upper surface of the plastic concrete in order to determine the elevation thereof. Shoe 27 is connected to the arms 28 of a U-shaped yoke, the base of the yoke being shown at 29 in FIGURES 4 and 8. Arms 28 are pivotally connected at 30 to support plate 14, thus permitting the shoe 27 to pivot upwardly and downwardly relative to plate 14. Such vertical movements of the shoe are transmitted through a linkage 31 to control means (described in detail in the cited patent application) which serve to adjust the elevation of blade 11 and associated elements relative to the concrete surface.

Finishing elements are provided to the rear of blade 11 in order to fill in the groove formed thereby and to finish over the concrete in order to place the same in substantially the same condition it was in before traverse of the blade therethrough. Such means, as described in detail in the cited application, comprise a set of chevron trowels 33 and 34 and a finishing float 35. Elements 33-35 are supported from support blade 14 by struts 36, springs 37, etc. Means, not shown, are provided to vibrate the finishing float 35.

To indicate briefly the operation of the apparatus as thus far described, such apparatus being described in detail in the cited application, the suspension and actuating means 10 operate (during a tape-insertion traverse) to shift the apparatus transversely of the highway at a region where it is desired to form a transverse joint. The sensing shoe 27 and linkage 31 cooperate with other unshown apparatus to determine the elevation of the blade 11 and finishing means 33-35 relative to the highway surface. The relationship is caused to be such that the blade 11 is, as shown in FIGURE 2, largely immersed in the plastic concrete, which is shown at 39. On the other hand, the sensing shoe 27 and finishing elements 33-35 ride along the upper surface of such plastic concrete.

The means 10 and the tape-feed rollers within housing 23 cooperate to effect feeding of the strip or tape 12 into the forward (right) end of blade 11 and thence through such blade out the trailing (left) end thereof into the concrete 39. The rate of tape feed out the rear end of blade 11 is caused to be equal and opposite to the rate of blade movement through the concrete. Accordingly, there is no resultant movement between the tape and the concrete into which it is introduced.

As an illustration, the tape 12 may be a strip of plastic (for example, impact polystyrene) two inches wide and about 0.020 inch thick. Such two-inch strip is caused to be substantially completely embedded in the upper surface of the concrete 39, which concrete is conventionally (in a highway) on the order of nine inches thick. After the concrete cures, and due to the presence of the tape 12 in the highway, the contraction of the concrete in the highway causes formation of a crack directly beneath the tape. The crack and the associated tape form a transverse joint in the highway.

As previously indicated, it is conventional in laying a concrete highway to include therein a plastic joint tape or strip which extends longitudinally of the highway at the center line thereof. Such a tape or strip is indicated at 40, being conventionally a strip or tape two inches wide and embedded in the upper region of the concrete. The center tape may be thin, for example a strip or tape of polyethylene about 0.004 inch in thickness. The longitudinal tape 40 is flexible and normally elastic, being frequently under tension since it is conventionally laid by being pulled out of a roll provided on the concrete extruder or paving machine.

In accordance with a first embodiment of a means and method for severing longitudinal tape 40, there is provided on blade or head 11 a point element, com

prising an elongated dowel 41 oriented parallel to the direction of blade motion and adapted to penetrate strip or tape 40 at a region spaced a substantial distance beneath the surface of the highway. In the present example, the dowel 41 is shown as engaging the tape 40 at a distance spaced one inch beneath the surface of the concrete (namely, at the center line of the twoinch tape). Because of the substantial downward spacing of the dowel, there is suflicient aggregate adjacent the upper portion of the tape 40 that it will not be bent over in response to pressure exerted by the dowel. Instead, the dowel will penetrate the tape 40 and prepare the same for complete cutting by a knife blade or keel 42 having cutting edges 44.

Stated more definitely, the dowel 41 is a cylinder having a conical point, and is welded or otherwise suitably secured at the front end of the metal blade or keel element 42. Blade 42 is, in turn, welded to the lower edge 21 of head 11. Such blade or keel 42 lies in the vertical plane of the portion of tape 12 which has been inserted into the concrete. The forward (cutting) edges 44 of the blade or keel 42 are inclined (forwardly convergent) as illustrated, in order to augment the cutting action. The dowel 41 may be about one-fourth inch in diameter, whereas blade 42 may be one-eighth inch thick.

The described apparatus cuts the longitudinal tape or strip 40 cleanly and effectively, and is aided by the vibration action indicated relative to vibrator 17 (FIGURE 2). The dowel 41 and blade 42 are relatively immune to loss of effectiveness as a result of the highly abrasive action of the concrete. Furthermore, the indicated dowel 41 and blade 42 have been found to provide little or no increased resistance to passage of the strip-insertion blade or head 11 through the concrete.

Once the longitudinal strip 40 has been cut as described, the transverse strip or tape 12 deposited in accordance with the present invention may pass between the severed ends of strip 40 and thus create four corner joints or regions where cracking will occur upon curing of the concrete.

As best shown in FIGURE 1, the sensing shoe 27 should be cut out in a region 46 above the dowel 41. This is because such dowel creates some swelling of the concrete immediately in advance of the blade or head 11, which swelling may cause elevation of the shoe 27 and consequent spurious upward actuation, if no cut-out is present.

EMBODIMENT OF FIGURES 5-7 The tape-severing means described above and illustrated in FIGURES l and 3-4 is operable, and is relatively satisfactory in numerous types of concrete. It has been found, however, that the longitudinal tape-severing means described below is more satisfactory, particularly in concrete containing relatively large aggregates.

The tape-severing apparatus of FIGURES 5-7 comprises a saw blade 52 having teeth 53 on the leading edge thereof. The blade is disposed in a vertical plane which is coincident with or closely adjacent the vertical plane in which the lower edge 21 of tape-insertion blade 11 is disposed. In the illustrated form saw blade 52 is pivotally mounted on tape-insertion blade 11 as by means of a horizontal stud 54 (which is perpendicular to the plane of the saw blade) and nut 55 provided at the forward region of the tape blade 11. The trailing region of saw blade 52 nests in a generally U-shaped saddle 56 which is welded or otherwise suitably secured to the lower edge region 21 of tape blade 11.

Saddle 56, which prevents rearward pivoting of the lower end of saw blade 52 beyond a predetermined point as the apparatus moves through the concrete 39, is so related to the stud 5-4 that blade 52 (or, more specifically, the cutting edge thereof) lies at a predetermined angle tothe horizontal, with teeth 53 facing generally downwardly as well as forwardly. Stated more definitely,

saw blade 52 is so oriented that the angle between such blade and a horizontal plane is less than the angle b..- tween such blade and a vertical plane (which vertical plane is perpendicular to the plane of the saw blade). Preferably, the angle between the saw blade and a horizontal plane is on the order of 30 degrees.

The forward or leading end of saw blade 52 is at a higher elevation than the lower or trailing end thereof, causing the blade to initially contact the upper edge of the longitudinal tape.

Because teeth 53 face generally downwardly, when the blade 52 moves through the concrete and is simultaneously vibrated by the vibrator means 17 (FIGURE 2), the saw blade tends to force the aggregates down into the concrete 39 instead of moving them forwardly in a horizontal direction. In addition, the aggregates are pushed laterally-that is to say in directions perpendicular to the plane of the blade. The above is to be contrasted with what would occur if blade 52 were vertical, for example, in which event the aggregate would be pushed horizontally in advance of the blade and would create undesired results including (as one example) interfering with the operation of the sensing shoe 27.

A particularly effective saw blade 52, having long wearing characteristics, has about six teeth per inch, each tooth being a substantially equilateral triangle one altitude of which is perpendicular to the axis of the saw blade.

From the above it will be understood that one important aspect of the embodiment of FIGURES 5-7 comprises providing the saw means 52 in advance of the tapeinsertion blade 11, and moving the saw blade 52 through the concrete in order to effect sawing or severing of the longitudinal tape 40. In accordance with another important aspect of the present apparatus and method, the positioning of saw blade 52 is such that only the upper region of the longitudinal tape 40 is severed, not the entire tape 40. It is preferred that approximately the upper twothirds of the tape 40 be severed by the operation of blade 52, leaving the remaining one-third in unsevered condition. Thus, for example, if the longitudinal tape 40 is two inches Wide, the saw blade 52 is caused to penetrate to a depth of approximately one and thre'e-eighths inches.

The reason why only the upper region of the longitudinal tape 40 is severed will next be described. Referring to FIGURES 5 and 7 in particular, it is pointed out that the longitudinal tape 40 is originally in a substantially vertical plane as shown at a. However, the sawing operation tends to effect a slight tilting of the tape to the position shown at b in FIGURES 5 and 7. It is an important feature of the method and apparatus that the tape 40 is then caused to re-assume a vertical relationship due to operation of the tape-insertion blade 11 itself. Thus, even though the tape-insertion blade 11 has a relatively dull bottom edge, when it passes through the tape 40 it will not only complete the severing thereof but will also tilt the same to the substantially vertical position indicated at c in FIGURE 7. It is pointed out that once the cutting of the tape is initiated by the saw blade 52, the relatively dull tape-insertion blade 11 becomes operative to complete the operation.

The saw blade 52 should cut through more than half of the tape 40, leaving the remaining (minor) portion to be severed by tape-insertion blade 11. One reason for this is that the relatively sharp saw blade tilts the tape, during sawing of the upper two-thirds, through about the same angle that the relatively dull (in comparison to the saw blade) tape blade tilts it in the reverse direction during severing of the remaining one-third. The desired vertical orientation is thus achieved as shown in FIGURE 7.

Referring to FIGURE 10, which is a plan view of a joint intersection region, a transverse joint strip or tape is indicated at 12, being that tape passed through the tape-insertion blade 11 and embedded in the concrete as described above. A longitudinal joint strip is shown at 40 and is severed prior to laying of the transverse tape 12 between the severed ends. There is frequently a slight gap between the severed ends of the longitudinal tape 40, due to the fact that such tape is under tension and therefore, after severing, tends to contract somewhat. Also, the ends of the tape 40 are offset laterally away from the main body of the tape 40 due to the action described above relative to the letters a, b and c in FIG- URE 7. Such offset is shown in exaggerated form in FIG- URE 10, and is found to be not harmful to the joint intersection region. A crack forms in the concrete beneath each of the

tapes

12 and 40, thus completing the intersection region.

It is a very important feature of the invention that the severed ends of the tape 40 are directly in line with opposite each other as illustrated in FIGURE 10. Such alignment is aided by the fact that the saw blade 52 does not cut completely through the tape. Instead, the unsevered lower region of the tape 40 maintains the alignment of the partially severed tape ends until after substantially all of the tape-insertion blade 11 has passed thereover. It follows that there is only very little disturbing of the concrete after complete severing of the tape, with consequent maintaining of the fully-severed tape ends in substantial alignment as desired. Stated otherwise, severing of longitudinal tape 40 is not completed until substantially after the upper tape region is severed, and just before the transverse tape is inserted.

EMBODIMENT OF FIGURES 8 AND 9 It has been found that the amount of wear on the above-described saw blade 52 (which is formed of steel) by the abrasive concrete is surprisingly little. Nevertheless, the wear can be further minimized if the blade 52 is caused to be immersed in the concrete 39 only during the relatively short portion of travel which occurs adjacent the longitudinal tape 40. The embodiment of FIG- URES 8 and 9 provides one form of apparatus for maintaining the tape-cutting blade above the concrete 39 at all times except when it is necessary to sever the longitudinal tape 40.

In the apparatus illustrated in FIGURES 8 and 9, a saw blade 58, which may correspond exactly in construction and angular position to the above-indicated saw blade 52, is inserted downwardly through an opening 59 in sensing shoe 27. The upper end of the blade 58 is connected rigidly to the piston rod 61 of a cylinder 62, the latter being suitably mounted on the shoe 27 as by means of a bracket 63 welded thereto.

When a suitable pneumatic or hydraulic fluid is introduced through a line 64 into the left or lower end of cylinder 62, from a suitable fluid source and control 65, the piston 66 within cylinder 62 is shifted upwardly from the left end of the cylinder to the right end thereof. This operates through piston rod 61 to retract blade 58 through opening 59 and thus out of the plastic concrete 39.

Conversely, when fluid is introduced from source 65 through a second line 67 into the right or upper end of cylinder 62, piston 66 is shifted downwardly to the left end of the cylinder, thus operating piston rod 61 to inject blade 58 to the desired depth into the concrete 39.

The fluid source and control 65 may be automatically or manually operated, automatic operation being possible through actuation of a limit switch (contained within suspension means when the carriage is adjacent the center of the highway. It is to be understood that the fluid source and control may include suitable venting means for venting fluid through one of the lines 64 and 67 when fluid is introduced through the other.

In the operation of the apparatus shown in FIGURES 8 and 9, the cylinder 62 is operated in such manner that blade 58 is injected into the concrete just slightly before the time when the shoe 27 passes over longitudinal tape 40. The blade is injected to the full depth shown in FIG- URE 8 before the tape 40 is engaged, and remains at full depth until after the tape is cut. The blade 58 then severs the upper region of tape 40 during passage of the shoe thereover. Thereafter, and as described above relative to FIGURES 5 and 7, tape 40 is caused to assume a vertical position when the lower region thereof is severed by the lower edge of the tape-insertion blade 11. As soon as the blade 58 has passed through the tape, the blade is retracted (as described above) through operation of cylinder 62.

The severing of the upper region of tape 40, by blade 58, is indicated in FIGURE 9, such figure also indicating (as does FIGURE 6) that the partially severed ends of the tape 40 tend to pull apart, in many instances, due to the fact that the tape 40 is often under tension when in the concrete.

In conclusion, it is emphasized that the relatively slow speed (for example, about one to two feet per second) at which the insertion means for transverse tape 12 moves through the concrete is one factor making it highly diflicult to sever the longitudinal tape 40.

It is further emphasized that even if the longitudinal tape 40 were pre-severed, at the correct point and prior to commencement of the insertion operation for the transverse tape, there would remain a severe problem relative to dislocation, disruption, and excessive separation of the severed ends of the longitudinal tape and as an incident to insertion of the transverse tape. Such problem is solved by maintaining the partially-severed ends connected (by the unsevered lower portion) until after the disturbing of the concrete is substantially completed. Stated otherwise, the final severing operation is not effected until after the saw blade and the forward portion of the tapeinsertion blade 11 have substantially ceased disrupting the aggregates in the concrete.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

What is claimed is:

1. Apparatus for laying transverse joint strips in the upper region of a highway of plastic concrete, said upper region of said highway having previously embedded therein a longitudinal joint strip, which apparatus comprises:

means to lay a transverse joint strip in said upper region of said highway at generally the same elevation as said longitudinal joint strip previously laid therein, and

means to sever said longitudinal joint strip to permit passage of said transverse joint strip therethrough without bending over or otherwise adversely affecting said longitudinal joint strip,

said severing means comprising a point element adapted to penetrate said longitudinal joint strip at a region spaced a substantial distance below the upper edge of said longitudinal joint strip,

said severing means further comprising cutting means operative after said penetration to enlarge the hole formed by said point element until said longitudinal joint strip is severed,

said severing means further comprising means to effect movement of said point element and said cutting means in advance of said means to lay said transverse joint strip.

2. The invention as claimed in claim 1, in which said means to lay a transverse joint strip comprises an elongated head adapted to move through the upper region of said concrete, said head being generally aligned with the direction of movement thereof through said concrete, and in which said cutting means comprises a cutting blade mounted on said head and lying in a generally vertical plane parallel to the direction of movement of said head through said concrete, said blade having said point element provided at the forward end thereof.

3. The invention as claimed in claim 2, in which the forward edge of said blade comprises forwardly-converging cutting edges arranged at an acute angle relative to each other, and in which said point element comprises an elongated dowel mounted at the extreme forward portions of said cutting edges and having a generally conical pointed end remote from said cutting edges, said dowel being generally horizontal and aligned with the direction of movement of said head through said concrete.

4. Apparatus for creating a joint-intersection region in a concrete highway while the concrete in such highway is in plastic condition, said plastic concrete having embedded therein at the upper region thereof a longitudinal tape disposed in a vertical plane and adapted to form a longitudinal joint in the highway, which apparatus comprises:

a tape-insertion means adapted to move transversely of the highway and to embed therein at the upper region thereof a transverse tape disposed in a vertical plane and adapted to form a transverse joint in the highway,

a saw blade adapted to saw through at least a substantial portion of said longitudinal tape, and

means to move said saw blade through said concrete in advance of said tape-insertion means and through at least the region of said highway wherein said longitudinal tape is embedded,

said last-named means maintaining said saw blade positioned at an acute angle relative to the horizontal and with the teeth of said saw blade positioned to initially engage said longitudinal tape at an edge thereof.

5. The invention as claimed in claim 4, in which the cutting edge of said saw blade is at an angle to the horizontal which is substantially smaller than the angle of said cutting edge relative to the vertical.

6. The invention as claimed in claim 4, in which said cutting edge is so oriented that the saw teeth thereon face generally downwardly, and in which the upper end of said cutting edge is in advance of the lower end thereof whereby said blade initially engages said longitudinal tape at the upper edge thereof.

7. The invention as claimed in claim 4, in which the cutting edge of said saw blade is at an angle to the horizontal which is substantially smaller than the angle of said cutting edge relative to the vertical, in which said cutting edge is so oriented that the saw teeth thereon face generally downwardly, and in which the upper end of said cutting edge is in advance of the lower end thereof whereby said blade initially engages said longitudinal tape at the upper edge thereof. 1

8. The invention as claimed in claim 7, in which the angle of said cutting edge relative to the horizontal is on the order of 30 degrees.

9. The invention as claimed in claim 7, in which said tape-insertion means includes a transverse tape-insertion blade which penetrates into the concrete at least to the depth of the lower edge of said longitudinal tape, in which said saw blade penetrates into the concrete to a depth substantially less than the depth of the lower edge of said longitudinal tape, and in which said tape-insertion blade is adapted to sever the lower region of said longitudinal tape after the upper region thereof is severed by said saw blade.

10. Apparatus for creating a joint-intersection region in a concrete highway while the concrete in such highway is in plastic condition, said plastic concrete having embedded therein at the upper region thereof a longitudinal tape disposed in a vertical plane and adapted to form a longitudinal joint in the highway, which apparatus comprises:

a hollow tape-insertion blade adapted to have tape passed therethrough for embedding in the upper region of the plastic concrete in said highway, whereby said tape will form a transverse joint in said highway,

severing means mounted in advance of said tape-insertion blade during the tape-embedding operation thereof and adapted to cut at least a major part of the way through the longitudinal tape present in said plastic concrete,

said severing means being a toothed saw blade inclined at an angle to the horizontal in such relationship that the teeth of said saw blade face generally downwardly,

the forward end of said saw blade being dis posed at a higher elevation than the rear end thereof, said saw blade being adapted to cut through at least the upper portion of said longitudinal tape, and actuating means to move said tape-insertion blade and said severing means transversely of said highway and at least partially immersed in the upper region of the plastic concrete,

said tape-insertion blade being oriented longitudinally of the direction of movement thereof but transversely of said highway.

11. The invention as claimed in claim 10, in which said saw blade only penetrates into the concrete a distance sutficient to result in cutting of the upper region of said longitudinal tape, and in which said tape-insertion blade is shaped and positioned to effect cutting of the lower region of said longitudinal tape after cutting of the upper region thereof by said saw blade.

12. The invention as claimed in claim 10, in which said saw blade is pivotally and removably mounted on said tape-insertion blade, and in which the lower end of said saw blade rests in a saddle which is provided on said tape-insertion blade to prevent excess rearward pivoting of the lower end of said saw blade.

13. Apparatus for creating a joint-intersection region in a concrete highway while the concrete in such highway is in plastic condition, said plastic concrete having embedded therein at the upper region thereof a longitudinal tape disposed in a vertical plane and adapted to form a longitudinal joint in the highway, which apparatus comprises:

transverse tape-insertion means to introduce tape into the upper region of the plastic concrete in said highway whereby said tape will form a transverse joint in said highway, sensing means disposed in advance of said tape-insertion means during a tape-insertion traverse across said highway,

said sensing means being adapted to sense the elevation of the upper surface of said highway and to operate control means whereby the elevation of said tape-insertion means relative to said upper highway surface is regulated, and tape-severing means mounted on said sensing means and adapted to sever at least the upper portion of the longitudinal tape in said highway during said tapeinsertion traverse.

14. The invention as claimed in claim 13, in which said sensing means is a sensing shoe which floats along the upper surface of said highway, said shoe having an opening therein, in which said severing means is a saw blade mounted in said opening and extending downwardly into the concrete during a tape-insertion traverse, and in which means are mounted on said sensing shoe to retract said saw blade out of the concrete during periods when said sensing shoe is not in the vicinity of said longitudinal tape.

15. The invention as claimed in claim 14, in which said saw blade is inclined at an angle to the horizontal of approximately 30 degrees, the upper end of said saw blade being in advance of the lower end, the teeth of said saw blade being downwardly facing.

16. The invention as claimed in claim 14, in which said saw blade extends downwardly into the concrete a distance less than the width of said longitudinal tape, whereby only the upper region of said longitudinal tape is severed by said saw blade, and in which said transverse tape-insertion means is a blade adapted to complete the severing of said longitudinal tape.

17. In an apparatus for embedding a transverse tape in the upper region of a concrete highway while the concrete forming said highway is in plastic condition, said concrete having therein a longitudinal tape adapted to form a longitudinal joint in the highway, which apparatus comprises:

means to introduce into the upper region of said plastic concrete forming said highway a tape adapted to form a transverse joint therein,

means to move said transverse tape-insertion means transversely of said highway during embedding of said tape in said highway, and

cutting means mounted in advance of said tape-insertion means during embedding of a tape transversely in said highway and adapted to cut through at least a substantial portion of the longitudinal tape present in said highway whereby an intersection region may be formed between the longitudinal and transverse tapes,

said cutting means being inclined from the horizontal and facing generally downwardly whereby aggregates engaged by said cutting means will be moved generally downwardly and laterally relative to the direction of movement of said tape-insertion means instead of being pushed forwardly ahead of said tape-insertion means, said cutting means being an inclined saw blade having teeth on the lower edge thereof.

18. The invention as claimed in claim 17, in which means are provided to effect generally vertical vibration of said tape-insertion means and of said cutting means to thereby aid in effecting movement thereof through the plastic concrete and despite the presence of aggregates in said concrete.

19. In an apparatus for forming a joint between longitudinal and transverse tapes present in the upper regions of a concrete highway prior to the time that the concrete in said highway hardens, an apparatus for severing the longitudinal tape present in said highway and for laying a tape transversely of said highway, said apparatus comprising:

severing means to sever only the upper region of the longitudinal tape present in said highway,

said severing means being a saw blade adapted to sever substantially more than one-half of the way through said longitudinal tape, and means operable subsequent to severing of the upper region of said longitudinal tape by said severing means to sever the lower region of said longitudinal tape and thereby complete the severing of said longitudinal tape whereby the transverse tape may be laid between the severed ends,

said last-mentioned severing means comprising a transverse tape-insertion blade having a lower edge region which penetrates into the plastic concrete to a depth lower than that of the lower portion of said first-mentioned severing means and at least to the depth of the lower edge of said longitudinal tape,

said tape-insertion blade being adapted to sever the lower region of said longitudinal tape.

20. Apparatus for laying transverse joint strips in the upper region of a highway of plastic concrete having a longitudinal joint strip therein, comprising:

a transverse strip-insertion mechanism to insert transverse joint strips into said plastic concrete highway at generally the same elevation as that of the longitudinal joint strip therein,

said strip-insertion mechanism including a stripinsertion head and means to move said head through said concrete in a direction transverse to the highway,

cutting means incorporated in said strip-insertion mechanism to sever said longitudinal joint strip prior to completion of passage of said head therethrough,

said cutting means including a saw blade mounted on said mechanism in advance of at least a portion of said head for movement transversely of the highway at substantially the same speed as that of said head,

said saw blade having thereon a substantial number of individual cutting teeth disposed to engage and out said longitudinal joint strip, and means to retract said cutting means, to a region above the upper surface of the plastic concrete, except during periods when said cutting means is adjacent said longitudinal joint strip.

21. The invention as claimed in claim 20, in which said saw means is a saw blade having coarse teeth.

22. The invention as claimed in claim 21, in which the number of saw teeth in said blade is on the order of about six per inch.

23. In an apparatus for forming a joint-intersection region in the upper surface of a concrete highway prior to the time that the concrete hardens, said concrete having provided therein in the upper region thereof a longitudinal tape adapted to form a longitudinal joint in the highway, apparatus for embedding a transverse tape in the upper region of said highway prior to hardening of the concrete and at the same elevation as said longitudinal tape, said apparatus comprising:

tape-insertion means to move through the upper region of the concrete forming said highway prior to hardening thereof and to embed a transverse tape in said upper region at the same elevation as that of said longitudinal tape,

means to cut through said longitudinal tape prior to the time that said transverse tape is laid whereby said transverserse tape may pass between the severed ends of said longitudinal tape to form a jointintersection region,

said cutting means including a toothed saw blade the teeth of which are disposed to engage and cut at least a major portion of said longitudinal tape, and means to maintain said cutting means retracted above the upper surface of the highway at all times except when said cutting means is in the general vicinity of said longitudinal tape. 24. A method of severing a longitudinal tape which is present in the upper surface of a concrete highway and at a time prior to hardening of the concrete forming said highway, said longitudinal tapelying generally in a vertical plane, said severing being incident to formation of an intersection region between longitudinal and transverse tapes to thereby provide a joint-intersection region in the concrete highway said method comprising:

laying a transverse tape in the upper region of said highway in generally the same elevation as said longitudinal tape therein whereby to form a joint-intersection region,

effecting severing of the upper region of said longitu dinal tape at a time prior to said laying of the transverse tape in the vicinity of said longitudinal tape, and

effecting severing of the lower region of said longitudinal tape after severing of said upper region thereof and just prior to laying of said transverse tape.

25. The invention as claimed in claim 24, in which said first-mentioned severing step is effected by moving a severing means generally longitudinally of the direction of movement of an insertion means for the transverse tape, whereby said severing step tends to tilt said longitudinal tape somewhat, and effecting righting of said longitudinal tape to cause the same to be in a substantially vertical plane and as an incident to said severing of said lower region of the longitudinal tape.

26. The invention as claimed in claim 24, in which said method further comprises laying said transverse tape by moving a tape-insertion means through the concrete and transversely of said longitudinal tape, and effecting said severing of said lower region of the longitudinal tape after at least the leading portion of said tape-insertion means for the transverse tape has passed by the partiallysevered tape region, whereby to minimize disturbance of the fully-severed tape ends by aggregates in the concrete.

References Cited UNITED STATES PATENTS Heltzel 94-45 Heltzel 94-51 XR Beesley 9439 Worson et a1. 94-39 Atkinson 9445 XR JACOB L. NACKENOFF, Primary Examiner