Precast concrete paver blocks are provided with interlocking edge joints so that abutting edges of adjacent paver blocks align when the blocks are installed and are maintained in alignment. At each joint, each block includes a tapered projection and a recess. When edges of two blocks are moved to abut each other, the tapered joint projection on each block enters the joint recess on the other block. The taper on the projections move the blocks to align the block surfaces. The edges of the blocks are angled or relieved below the joints to ensure a tight fit at the top of the paver blocks.

CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable.  
       TECHNICAL FIELD  
       [0003]     The invention relates to precast concrete products and more particularly to a precast concrete paver block.  
       BACKGROUND OF THE INVENTION  
       [0004]     Precast concrete paver blocks are used for many applications, such as patios, driveways, sidewalks and courtyards. In the past, concrete paver blocks have generally been relative small, frequently from about the size of a brick up to about 2 feet square (about 61 cm square). In some applications, thin, decorative pavers are used as overlays on concrete foundations. Large pavers have not been available. One problem with larger paver blocks is to maintain a flat surface where the blocks abut. It is difficult to provide a flat foundation for the blocks and to prevent shifting of the blocks with ground movement, for example, due to frost or heavy rainfall.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     The invention is directed to large precast concrete paver blocks of a type suitable for constructing driveways, sidewalks, patios, courtyards, boat ramps, and the like. Optionally, the exposed surfaces of the blocks are textured and, optionally, colored, to simulate natural stone. The paver blocks are provided with interlocking edge joints so that abutting edges of adjacent paver blocks align when the blocks are installed and are maintained in alignment. At each edge joint, each block includes a tapered projection and a recess. When edges of two blocks are moved to abut each other, each tapered projection on each block enters a recess on the other block. The taper on the projections move the blocks into alignment. Preferably, there are at least two edge joints on each block edge which will abut another block edge. The edges of the blocks are angled or relieved below the joints to ensure a tight fit at the top of the paver blocks.  
         [0006]     Accordingly, it is an object of the invention to provide cast concrete paver blocks with edges which interlock for initially aligning and for maintaining alignment of abutting block edges.  
         [0007]     Other objects and advantages of the invention will become apparent from the following detailed description of the invention and the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a fragmentary perspective view showing an exemplary layout for a driveway, a sidewalk, steps and a patio constructed with cast concrete paver blocks according to the invention;  
         [0009]      FIG. 2  is a top plan view of a rectangular paver block according to the invention;  
         [0010]      FIG. 3  is a top plan view of a corner payer block according to the invention;  
         [0011]      FIG. 4  is a top plan view of a square paver block according to the invention;  
         [0012]      FIG. 5  is a top plan view of a triangular paver block according to the invention;  
         [0013]      FIG. 6  is an enlarged fragmentary cross sectional view showing details of the connection between abutting edges of two paver blocks according to the invention;  
         [0014]      FIG. 7  is a fragmentary side view of abutting edges of two paver blocks which have a slight angle between the blocks; and  
         [0015]      FIG. 8  is a fragmentary cross sectional view showing details of one joint on one of the paver blocks. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring to  FIG. 1 , an exemplary layout  10  is shown for a residential application including a driveway  11 , a sidewalk  12 , steps  13  and a patio  14  made from different types of cast paver blocks. The illustrated layout  10  is formed from four different shaped blocks, consisting of rectangular paver blocks  15 , corner paver blocks  16 , square paver blocks  17  and triangular paver blocks  18 . Although the four illustrated block shapes will work for most applications, it will be appreciated that other block shapes also may be made to meet specific application requirements.  
         [0017]     The blocks  15 - 18  are cast from concrete and, preferably, are reinforced with steel mesh or with rebar rods to provide the strength required for the application. For example, greater reinforcement will be needed for paver blocks used in a driveway  11  which must support the weight of heavy vehicles, than for paver blocks used in a patio portions of a sidewalk  12  which do not cross a driveway. The blocks  15 - 18  are cast to a desired thickness, such as 4 inches (10.2 cm). In order to provide a pleasing appearance, the exposed top surfaces and any exposed edges of the blocks  15 - 18  may be textured, for example, to simulate natural stone. The block surfaces also may be stained or otherwise colored to more closely simulate stone using techniques which are well known in the art or to provide a desired appearance.  
         [0018]     According to the invention, the sides of the blocks which abut the sides of other blocks are provided with one or more joints  19  which engage complimentary joints on the other blocks. The joints  19  are spaced on each block side for engaging the complimentary joint  19  on an abutting block side.  FIG. 2  shows the rectangular block  15  as having two short sides  20  and  21 , each having two joints  19 , and as having two long sides  22  and  23 , each having three joints  19 . The rectangular block  15  may have, for example, a width of 4 feet (122 cm) and a length of 6 feet (183 cm).  
         [0019]      FIG. 3  shows details of the corner block  16 . The block  16  is substantially trapezoidal in shape having a side  24  which is either 4 feet (122 cm) or 6 feet (183 cm) long, two angled sides  25  and  26  which are 4 feet (122 cm) long and, for example, form an angle of 30° to each other, and a side  27  which is shorter than the side  24 . In order to keep the width of the block at 4 feet or the width of the rectangular blocks  15 , ends  28  of the side  24  are slightly angled. By arranging the sides  25  and  26  at an angle of 30°, three corner blocks  16  can be used to form a 90° bend. If the sides  25  and  26  were angled at 45°, two blocks  16  would be used to form a 90° bend. The block  16  is intended to have the sides  25  and  26  abut sides of other blocks  15 - 18 . Thus, the sides  25  and  26  are each provided with two joints  19 . The center portion of the side  24  (without the ends  28 ) may be of the same length as the side  27 , for example, either 4 feet (122 cm) or 6 feet (183 cm). This will allow abutting a block to the center portion of the side  24 .  
         [0020]      FIG. 4  shows the square block  17 , which has-four sides  29 - 32 , each of which is 4 feet (122 cm) long. Each side  29 - 32  has two joints  19 .  
         [0021]      FIG. 5  shows the triangular block  18 , which has two adjacent 4 feet (122 cm) long sides  33  and  34  which form a 90° angle and a long side  35 . Each of the sides  33  and  34  has two joints  19  for engaging joints on the other blocks.  
         [0022]      FIGS. 6-8  show details of a construction for the joints  19 . Each joint  19  extends along an edge  38  of the block parallel to a top surface  39  of the block. Each joint  19  consists of a projecting rib  40  and of a groove  41  sized and shaped to receive a projecting rib  40  from a joint  19  on an abutting block. Preferably, the rib  40  is triangular or wedge shaped in cross section with sides  42  and ends  43  which taper to an apex  44 . Thus, the sides  42  are trapezoidal shaped and the ends  43  are triangular shaped. The groove  41  has complementary tapered sides and ends which are sized to receive the rib  40 . Consequently, when two joints  19  are moved into position where the adjacent sides  38  abut, as shown in  FIG. 6 , the top surfaces  39  of the adjacent blocks are moved into alignment when the rib  40  is moved into the groove  41 . Tapering the ribs  40  in two directions facilitates alignment of the blocks when they are positioned to form a desired layout. In the drawings, the rib  40  and the groove  41  for each joint  19  are shown as being aligned and adjacent each other. It will be appreciated that the rig  40  and the groove  41  may be spaced from each other, so long as they have the same spacing from the top surface  39 .  
         [0023]     A lower portion  45  of the edge  38  on each block may be angled slightly inwardly from the joint  19  to a bottom  46  of the block to form an angle between the lower portion  45  and the bottom  46  greater than 90°. Optionally, a chamfer may be provided between the lower portion  45  and the bottom  46  to eliminate sharp edges which may be subject to impact damage when installing the paver block. The angled lower portion  45  serves two functions. First, it allows a relief area for any dirt or other foundation material which may be trapped between the abutting edges. Second, it allows two adjacent blocks to be slightly angled relative to each other when the ground on which the blocks are placed is not level, while maintaining a tighter fit at the top of the paver block.  
         [0024]     The joints  19  are formed to have the same configuration on each side of the block which will abut a side of another block. Thus, when looking at an elevational view of any block side having a joint  19 , the rib  40  will be on the left side of the joint  19  and the recess  41  will be to the right of the rib  40 . As a consequence, when any two sides are moved into an abutting arrangement, the two joints are complementary and each rib  40  will align with a recess  41 . Alternately, all of the joints  19  can be made with the ribs  40  on the right and the recesses  41  on the left.  
         [0025]     The joints  19  may be omitted from edges of the cast paver blocks which will not abut an adjacent paver block, especially any of these sides which may be visible after the blocks are installed. These edges may be textured with a pattern and colored similar to the exposed top surface of the block.  
         [0026]     It will be appreciated that various modifications and changes may be made to the above described preferred embodiment of a cast concrete paver block without departing from the scope of the following claims. Although a preferred construction for the joints  19  has been described, it will be appreciated that other configurations also may be used to achieve the same results. For example, the ribs  40  can be replaced with round or oval knobs and the recesses  41  can be configured to receive the knobs. Also, the number of joints  19  on each side of the paver blocks may be changed to meet the needs for any particular application.  
         [0027]     The block dimensions provided herein are intended to be exemplary. It will be appreciated that the block dimensions can be modified to meet local building codes and conventional sized in the community in which the blocks are used. However, the invention is particularly useful for paver blocks having a minimum dimension of at least 3 feet (91 cm) for providing larger hard surfaces.