US 2323848 A
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Description (OCR text may contain errors)
y 1943- F. w. SC HAEFFER 2,323,848
PAVEMENT Filed Feb. 13, 1941 Patented July 6, 1943 UNITED STATES PATENT FFlCE PAVEMENT Frederick William Schaefler, Chicago, Ill. Application February 13, 1941, Serial No. 378,697
The present invention relates to pavements and particularly is directed toward a novel constructlon of concrete pavements. The principal object of the present invention is to provide concrete slabs of such a character that expansion thereof cannot cause the paving to buckle or "blow up." A further object is to provide a concrete pavement wherein cracks are less likely to occur than in the pavements now in use. Another object is to provide a plurality of concrete slabs in a pavement in such a fashion that the cracks which must occur between the slabs due to thermal expansion and contraction of the slabs will not affect to any degree the riding characteristics of the roads surface.
With these and other objects in view I have provided a concrete pavement made up of a D111- rality of sections or slabs. Two sizes and shapes of slabs are used in my herein disclosed preferred embodiment. One slab, for convenience hereinafter called the large slab, may be, for example, forty feet long and twenty feet'wide. These .slabs are constructed with V-shaped or pointed ends,. the inclined sides thereof extending, for example, to the apex from the quarter point of the slab. In a slab or the given dimensions, therefore, the inclined sides are at an angle of 45 with the centerline of the pavement.
The second slab, for convenience hereinafter called the small slab, is half as wide as the large slab and, for example may be about three-fourths its length. Each end of the small slab is inclined to cooperate with and substantially abut a side of the V-shaped end of the large slab. Two
small slabs are placed side by side with their shorter sides in abutting relationship, whereby their inclined ends cooperate to define a V-shaped notch which receives a V-shaped end of a large slab. In this way, the large slabs are spaced by two side by side small slabs.
In a pavement construction of the character described, the thrust due to expansion of the concrete slabs will not result in buckling or cracking of the slabs, but rather it will be dissipated in lateral movement of the small slabs. A reason for constructing these second slabs somewhat shorter than the large slabs is to insure that the small slabs readily can be displacedin the case of a larger slab, friction between the slab and the subgrade might prevent this movement with the result that the pavement would buckle and crack.
Expansion does result in separating to an extent the small slabs. However, this longitudinal crack is in the center of the road or of the two lanes and is therefore relatively unobjectionable insofar as the riding characteristics of the road are concerned. It may be desirable to provide a fabricated joint construction between the small slabs in order to prevent moisture from entering the roadbed through the joint. It is present practice to provide a longitudinal joint of this character in concrete pavements. In the pavement here contemplated. only about one-fifth as much of this longitudinal Joint construction is required as in the case of the conventional continuous centerline joint.
Inasmuch as the joints between the large and small slabs are inclined at an angle with respect to the centerline of the road, both front wheels and both rear wheels of a car do not strike the joints at the same time. The result is easier and smoother riding and less impact damage to the pavement.
For a better understanding of the present invention, reference may be had to the accompanying drawing in which:
Fig. 1 is a plan view of a length of pavemen embodying the present invention;
Fig. 2 is a plan view of a length of pavement after expansion has occurred;
Fig. 3 is a sectional view on the line 3-3 of Fig. 2; and,
Fig. 4 i a plan view of a. four-lane pavement embodying my invention.
Referring now to the drawing, the pavement co prises a succession of large concrete slabs 5 spaced by pairs of side by side small slabs 6. The slabs 6 are one half as wide as slabs 5 and are somewhat shorter in length. The slabs 5 are provided with pointed or V-shaped ends as shown at 1, which ends present sides 8. The intermediate small slabs 6 have inclined ends 9 which are adapted substantially to abut the end sides 8 of the large slab as shown by joints III. In the case of a two lane pavement, as illustrated in Figs. 1 and 2, joint ll between two side by side small slabs is on the centerline of the pavement.
Referring now to Fig. 2, the slabs have expanded so as to result in a slight lateral displacement of the slabs 6. Because of the size of slab 5 and the friction between the slab and the subgrade, slab 5 is not displaced, and all the thrust due to expansion in both the slab 5 and the slabs 6 is dissipated in the lateral movement of slabs 6.
Any conventional expansion joint may be used at the joints Ill. The character of the joint used depends, of course, on the amount of expansion expected as well as on the concrete used, the character of the subgrade and the amount of trams: anticipated. In certain cases the joints between the slabs may be filled with ordinary bituminous material such as asphalt.
Fig. 4 shows my invention applied to a wider pavement, in this case a four-lane pavement. This embodiment includes slabs 5a and Ba which are imilar to slabs 5 and 6, respectively, described above. A slab I! placed in the center of the pavement has the configuration of two small slabs joined along their long sides. Any desired joints may be used between adjacent slabs. Generally it is desirable to provide an expansion joint bet een the sides of adjacent slabs 50, as well as between the sides of the adjacent small slabs Ba and I5. It will be noted that the joints between the sides of adjacent small slabs 6a and II are on a line which bisects the angle defined by a V-shaped end of a slab is similar to the Joints between slabs 8 described above. Therefore, longitudinal expansion of the large slabs (having V-shaped ends) results in lateral displacement of the small slabs 6a.
The concrete slabs may or may not be reeniorced, the matter of reenforcement not being a question within the purview oi! the present invention.
From the above description, it will be seen that I have provided a pavement construction wherein expansion of the composite slabs may not result in a buckle or blow up. As the excessive strains which result in buckles are not here present, cracks in the slabs are not as likely to occur as in pavements subject to buckling. Also, the joints between the slabs are disposed at an angle with the line of trafilc whereby the vehicles may pass smoothly over the cracks to the greater comfort of the passengers and to less impact on the pavement. Having thus described my invention, what I claim as'new and desire to secure by Letters Patent is:
1. A pavement construction of the character described comprising slabs of paving material having V-shaped ends extending substantially from the quarter point'oi' said slabs, said slabs being spaced by a pair of side by side shorter slabs which are half as wide as said first named slabs, each shorter slab having ends inclined in opposite directions whereby adjacent ends cooperate to define a V-shaped opening which receives a V-shaped end of said first named slab.
2. A pavement construction of the character described including rows of side by side slabs, said slabs having V-shaped ends, said rows being spaced by side by side shorter slabs, said shorter slabs' having inclined ends, the adjacent sides of which cooperate with and substantially abut the ends of said first named slabs, the Joints between the longitudinal sides of adjacent shorter slabs being on a line which bisects the angle defined by a V-shaped end of a first named slab.
3. A pavement construotion of the character described comprising slabs of paving material having V-shaped ends extending substantially from the quarter point of said slabs, said slabs being spaced by a pair of side by side shorter to define a V-shaped opening which receives a V-shaped end of said first named slab.
FREDERICK WILLIAM SCI-IAEFFER.