US2299318A - Form for paving blocks - Google Patents

Description

Oct. 20, 1942. w, FQ SB RG j 2,299,318

FORM FOR .PAVING BLOCKS v Filed Jan. 6, 1940 I IN VEN TOR;

ATTORNEY Patented Oct. 20, 1942 UNITED STATES PATENT OFFICE FORM FOR, PAVING BLOCKS George W. Forsberg, Albany, Calif.

Application January 6, 1940, Serial No. 312,695

3 Claims.

The present invention relates to forms for paving blocks, and particularly to forms adapted for use in casting blocks in place directly upon the surface to be paved.

It is the object of the invention to provide forms that may be used in the building of pavement to create a paved surface of separate but interlocked blocks of relatively small dimensions in order to overcome the ill effects of warping, expansion, and cracking which occur in large slabs, and to provide forms which remain in place after the paving material is poured between them to function as expansion joints for the blocks.

A further object is to provide forms for casting paving blocks in place which will serve as ideal receptacles for concrete or the like to be poured into them, and which will serve to induce proper curing of the concrete and to provide a suitable expansible material between adjacent blocks after they are cured.

Further objects and advantages of the invention will be made apparent in the following specification, wherein the invention is described in detail with reference to the accompanying drawmg.

The drawing and description relate to forms particularly adapted for laying pavement on a street or highway, and the material of which the pavement is formed will be referred to as concrete. It will be understood, however, as the description proceeds, that the forms are adapted to other uses, such, for example, as laying floors in large buildings, lining water canals, and many other uses where it is otherwise common practice to cover a surface with a paving material.

Furthermore, the word concrete as used herein is intended to refer to any cement-like or plastic material capable of being poured in forms to provide a pavement or similar surface.

In the drawing- 7 Fig. 1 is a perspective view of a small portion of a surface to be paved, showing the forms of the present invention in place to receive the paving material;

Fig. 2 is a vertical sectional view taken on the line II-II of Fig. 1;

Fig. 3 is an enlarged section taken on the line IIIIII of Fig. 1 and illustrating a modification of the form shown in Fig. 1;

Fig. 4 is an enlarged vertical transverse section of the upper edge of any one of the form members illustrated in Fig. 1, showing details of construction thereof;

Fig. 5 is a similar section of the lower edge of the same number; and

Fig. 6 is a horizontal section taken on line VIVI of Fig. 1.

Referring first to Fig. I, the forms of the invention are shown as comprising a plurality of parallel spaced elongated form members II] with short form members I I extending between adjacent members III at spaced intervals in a manner to divide the elongated spaces between the members I0 into courses of staggered reticules for the reception of concrete which, when poured in these spaces and leveled off to the tops of the forms, will provide individual paving blocks separated from each other only by the material of which the forms are made.

The form members I!) and II are disposed at an angle to the vertical, as shown in Figs. 1 and 2, and angularity of the members [0 is alternately reversed. The angularity of the members II is likewise alternately reversed, the result being that all of the blocks cast in the form will have inclined side walls, each wall being parallel to the adjacent walls of abutting blocks. The inclination of the forms is such that the blocks when cast and cured will have a tendency to lie together as though they were formed of a single slab, although they are sufficiently separated to prevent cracking or warping as a result of stresses which may be set up, for example, as by expansion and contraction or slight settling of the base upon which they are cast. This slight inclination of the side walls is such that the overhang of the upper edge of the blocks with inwardly sloping side walls will not be sufiicient to induce breaking off of the upper edges of the blocks when they are subjected to a load, and any tendency toward cracking of the blocks at their edges due to this incline is also overcome by the construction of the upper edges of the form members, presently to be described in detail.

The construction of the form members is shown in cross section in Figs. 4 and 5, wherein each member is shown as comprising outer layers of flexible moisture resistant material I2, and an inner layer I3 of compressible material adapted to compensate the Variation of the space between the blocks upon expansion and contraction which may result from temperature variations. The material forming the layers [2 is preferably pasteboard impregnated with a water resistant material such as paraffine, varnish, or any suitable composition that will retain or supplement the rigidity of the pasteboard and prevent its absorbing any material amount of moisture from the concrete which is poured against it. The layer I3 of material which is placed between the layers I2 may be a thick paper-like material of bituminous base or other semi-plastic substance, preferably bituminous, suitable for the formation of an expansion joint. As the blocks of which the pavement is formed are of relatively small dimensions, the expansion possibilities for any single block are very small and the combined thickness of the layers I2 and I3 may .be as thin as it is practical to make them and still retain sufiicient rigidity for the casting of the concrete.

Each of the form members is provided with a base member as shown in Fig. 5, which member is formed by bending the layers I2 outwardly to a plane parallel to the ground and then reinforcing them with a strip I4 of similar material which is preferably curved upwardly and inwardly and pressed or crimped into position with its :edges I5 overlying the outwardly extending portions of the members I2. .This-base.-serves:as a support for the members and H in their slightly inclined position, and the =members l'l are preferably of slightly less height than the members I'Il'so that their base members willoverlie :the basemembers of the members -I lastshown in Figs. 1 and 2. The base members of the members 1:0 and 1 I combine to provide inwardly projecting flanges in each of the spaces in 'which concrete is to be poured, soithat if desired a bottomimay be provided for the forms, which .bottom may bea rectangular sheet of paper impregnated' with a material to resist moisture .and of a size to fit within the .castin'gspace with its edges overlying the base flanges of the .form members. The useaof such a bottomamember will prevent .undesiredabsorption .of .moisture or cementpaste from the .concrete by the .underlying grade surface before the concrete hasbeen properly cured. V

.The upper edges of the form members Haredesigned -.as illustrated in Fig. .4 to .form :rounded edges on the blocks to .prevent crushing or crackinglof their edges .due'to the load thatwill be imposed upon them'by wtraiific, and also incorporate means to prevent the .expansible' material I3 from exuding upwardly 'onto the surface of the pavement, as frequently occursin other pavements in warm weather, and with means to serveas aguide in surfacing the blocks after they are poured. .As shown in Fig. 4,:the "two layers of paper-like material I.2 are "flared outwardly as at I6 .to .serve as forms for rounded corners on adjacent blocks. Afilleriof rubber orother similar resilient materialmay .be inserted between the outwardly flared portions I6 and "may consist of 'aflat strip bentupon itself to form a tubelike member I! with a projecting flange 'I'8 of double thickness which may be secured between the members I2 by rivets .or clips I9. A'molded rubber strip may be used for this purpose "if desired. The rivets or clips I9 also serve to retain the upper edges of the form members I2" and I3 against separation, and while thesemembers may be pressed or rolled together and will normally adhere to each other sufficientlyto prevent. separation "throughout the greater part :of their :surfaces, rivets or other fastening meanssuchasindica-ted at I9 may be used at intervals furtherto insure against .their'separatiomif :desired.

.Apasteboard strip 2!] preferably .caps the form member and has its edges bent downwardly'and inwardly-as indicated at 2I to. retain .it :in place and to brace and protect the outwardly flaredportion I6 of the members I2. When the forms are assembled in the manner illustrated in Fig. 1, metal screeds shown at 22 in Fig. 4 may be used to protect the upper edges and serve as guides for leveling off the tops of the blocks and insure a uniform pavement surface. The screeds 22 may be placed at necessary intervals, and being of channel-shaped cross section, will be easy to place and remove. After the blocks have been cast, the screeds 22 may be pulled off and will leave, adjacent the edges of the blocks, a slight downward step and then a gradual curve which will lend an appearance that is neat and provide a surface that has enough roughness to prevent skidding without producing bumps noticeable to the ordinary rubber tired vehicle.

The upper outwardly flared portion I6 of the members I2 may remain in place or may be worn away by weather and traffic, but the rubber member I1 will remain in place and prevent the plastic material I3 from being exuded, onto the surface of the pavement.

In order that the blockswvill be securely interlocked with relation to each other and in a manner to prevent longitudinal sliding or twisting movement between adjacent courses, the forms are provided with recesses 25 in their walls, adapted to produce complementary tongues and grooves in the abutting side walls of adjacent blocks. The recesses 25, which are preferably largest in cross section at their lower ends and tapered upwardly to a point short of the .top edges of the blocks, are preferably formed asillustrated in Fig. 6 by cutting away a portion-of the form wall and projecting a channel-shaped form member 26 therethrough. Themember 26 is provided with flanges 2'! along its sideand top edges, which flanges are secured to the form wall by means of rivets 28 or any other suitable means for securing them in place. The members 25 are preferably formed of the same material as the form walls, so that the small space between the registering tongues and grooves formed in the blocks will be filled with expansible material.

'The short form members II are retained .in place between the longer form members! by means of elongated clips 30 of metal, impregnated pasteboard, or other suitable material (see Figs. 1 and 3), which clips are secured to the form members II] by means of prongs 3I piercing the members and bent over at their ends. The clips 30 are formed of strips with their outer edges bent inwardly to form resilient retaining flanges 32 adapted to engage opposite sides of the form members II. The form members II have flanges 33 pressed outwardly from their edges to engage under the clips 32 and positively prevent their removal from the clips.

The members 25 and clip members 30 will lend rigidity to the forms so that they may be made of very thin material and yet stand up during the pouring of concrete or other material of which the paving blocks are to be made. If it is desired further to supplement the rigidity of the .forms, stiifeners 35, as shown in Figs. 1 and 6,

may be used. These stiifeners may be formed of light metal strips with a central longitudinal crease 36 to prevent them from bending and with prongs 31 adapted to pierce the walls of the forms and to be bent over to retain the strips in place. Other means for stiffening the forms may be used, and one such means is shown in Fig. .3, wherein the material of the forms is corrugated as at 40, the corrugations running in a vertical direction on the form members I0 and I I. These,

corrugations could be used throughout the entire length of the form members, but it is preferable that they be provided in spaced groups so that the major portion of the side wall surfaces of the blocks will be formed on flat planes. The vertical corrugations also serve to make the forms sufficiently flexible to conform to slight curves such as may be encountered in a highway profile.

In use of the forms for paving a highway or the like, a suitable subgrade is prepared in the usual manner. A blanket of sand or any other cushioning material should preferably be laid over the subgrade and finished to the desired profile. The forms are then laid upon the profile and asesmbled in the manner illustrated in Fig. l, the longer forms l being placed preferably transversely to the longitudinal center line of the highway, and the shorter forms ll being secured in place by means of the clips 30, as described above. The forms may then be anchored to the subgrade by spikes or similar means driven through the bottom flanges of the forms. If it is desired to reinforce the blocks, any suitable reinforcing means may be placed within the individual block forms. Reinforcing members bent to required shape from steel wire will, for example, serve this purpose, and if the wire shapes are made of a size to contact the side walls of the form, they will serve as additional support for the forms as the concrete is being poured and will also strengthen the blocks after the pouring. It is to be undertsood, however, that reinforcement of the blocks is not considered essential but is optional, and that any preferred shape of reinforcing members may be used.

The forms having been set up and secured in place as described, they may be filled with concrete, which is poured approximately to the level of their uppermost edges and thereafter trowelled smooth to the level of the tops of the screeds 22. The screeds are removed and, after the concrete has cured and attained sufficient strength, a weighted roller may be run over the top of the highway to provide a firm contact between the blocks and the surfacing material on the subgrade.

Due to the very small expansion joints between the blocks, the possibility of moisture leaking through them is reduced to a minimum. They are free to expand and contract the maximum amount possible without danger of cracking, and a durable highway is provided at a low cost, as the blocks may be made considerably thinner than large concrete slabs and may be placed with considerably less cost than bricks or other small blocks which are pre-cast and then have to be transported to the site of the highway and handled a great deal before they are finally laid in place.

Blocks may be differently colored for ornamental purposes or to provide markers for the direction of traffic, and any repairs to the highway or to underlying pipes or conduits may be readily effected, as the blocks may be removed one at a time and are capable of being replaced in their original positions, it being necessary usually to cast but one or two new blocks where a section of pavement has been removed.

Although the blocks have been illustrated and described as of a generally rectangular shape, it should be understood that the form walls of which they are made are adaptable to arrangements for the provision of various shapes and designs. Furthermore, it is not essential that the form walls be arranged at an angle to the vertical, as shown in the accompanying drawings, as, while this angularity has certain advantages in highway construction, vertical walls may be used to advantage in some cases.

The particular manner in which the form walls are constructed may be varied in several ways. For example, the upper portion of the wall, as illustrated in Fig. 4, may be formed without the added cap 20 with the flanges 2| thereon by producing the outer members [2 is a single piece and bending or rolling them to the general shape shown, incorporating the rubber strip 11 in the rolling operation and, if desired, incorporationg reinforcing members in this, as well as other parts of the form, wherever they may be required. It is to be understood that the foregoing description and accompanying drawings are for illustrative purposes and are not intended to limit the invention which may be varied as to the materials employed and the particular construction and arrangement of the several parts shown Within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In forms for paving blocks or the like, a form wall comprising spaced sheets of paperlike material and an intermediate layer of ex pansible material, said sheets being flared outwardly adjacent the upper edge of the wall to provide rounded edges on blocks cast on opposite sides of the wall, and a filler member of resilient material incorporated in the form between the outwardly flared upper edges to prevent said expansible material from exuding from the joint between adjacent blocks.

2. A form wall for paving blocks, comprising spaced sheets of paper and an intermediate layer of expansible material, said sheets being flanged oppositely outwardly at the bottom of the wall to provide a base for supporting the wall in an upright position, and a strip of paper underlying the outwardly flanged portions and bent upwardly over their edges to provide a seal for preventing escape of the expansible material.

3. A form wall of the character described, comprising parallel spaced sheets of water-resistant material bent outwardly adjacent their top and bottom edges to provide longitudinal rigidity, a layer of compressible material between said sheets, and a resilient sealing member disposed between the upper outwardly bent edges of the sheets to prevent the compressible material from exuding.

GEORGE W. FORSBERG.

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