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FIELD OF THE INVENTION 
       [0001]    This invention relates to building blocks for temporary structures and more particularly to building blocks which can be rapidly assembled at a location where there is a need fur a temporary structure and afterward, when the need has passed, can as rapidly be dismantled. Once dismantled, the blocks can be shipped at relatively low cost to a new location and reused. 
       BACKGROUND OF THE INVENTION 
       [0002]    When a disaster occurs such as a hurricane or a fire, there are often injuries and loss of life as well as damage and destruction of buildings. Many buildings such as houses, schools and factories must be rebuilt quickly to avoid a prolonged disruption in the lives of the survivors However, in most cases, existing structures are not rebuilt quickly. Rather, there are usually long delays before new structures are constructed and ready for occupancy. 
         [0003]    I have invented building blocks which are suitable for use in temporary structures. The blocks are composed of lightweight material such as polypropylene or other polymeric material so that the blocks can be carried and lifted easily by hand. A crane or other machine for transporting and lifting the blocks into position is not required. 
         [0004]    The blocks interlock to form the shell of a complete structure. Mortar or other bonding material is not required to hold the blocks in place. The blocks can be assembled into a structure quickly and later dismantled for use elsewhere with a minimum of delay and cost. 
         [0005]    The blocks arc hollow to minimize their weight. The hollow interior of the blocks may be filled in the course of construction with a variety of materials. The interior may for example be filled with particles of insulating material or it may be filled with sand. Sand serves to increase the weight of the blocks and to increase the stability of the structure. Afterward, when the blocks are disconnected as the structure is being dismantled, the insulating material or sand can be poured out of the blocks in order to decrease their weight and to make them easier to handle. 
         [0006]    Plugs are provided to close the openings through which the insulating material or sand is introduced into the interior of the blocks and openings are provided in the side walls of the blocks to which straps for drywall may be attached. 
       SUMMARY OF THE INVENTION 
       [0007]    Briefly, the building block of my invention is adapted to interconnect with other like blocks to form a structure. Each building block is defined by a plurality of vertical walls; and top and bottom walls and has a thickness between oppositely facing exterior and interior surfaces of the walls. The interior surfaces define a hollow interior for, receipt and containment of particulate material therein. Each building block further has a first block connector composed of a vertically extending tongue or groove formed in at least one vertical wall. The block connector is adapted to interconnect with another like block connector in another building block disposed beside it and is provided with at least one opening through which particulate material may be selectively introduced and extracted from the hollow interior. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    The building blocks of the invention are described with reference to the accompanying drawings in which: 
           [0009]      FIG. 1  is a perspective view of block for use in the front, rear and side walls of a building; 
           [0010]      FIG. 2  is a perspective view of the block of  FIG. 1  in which an end wall is removed to expose the interior of the block; 
           [0011]      FIGS. 3 and 4  are a plan and a side elevation, respectively, of the building block of  FIGS. 1 and 2 ; 
           [0012]      FIG. 5  is a perspective view of a block for use at the corner of a structure having front, rear and side walls composed of the building blocks illustrated in the previous drawing; 
           [0013]      FIGS. 6 and 7  are a plan and a side elevation, respectively, of the building block of  FIG. 5 ; 
           [0014]      FIG. 8  is a perspective view of a variation of block  5 ; 
           [0015]      FIGS. 9 and 10  are a plan and a side elevation, respectively, of the building block of  FIG. 8 ; 
           [0016]      FIG. 11  is a perspective view of a roof block for use at the roof of a structure having front, rear and side walls composed of the building blocks illustrated in  FIGS. 1-4 ; 
           [0017]      FIGS. 12 and 13  are a plan and a side elevation, respectively, of the roof block of.  FIG. 11 ; 
           [0018]      FIG. 14  is a perspective view of a second variation of a block for use at the corner of a structure; 
           [0019]      FIGS. 15  is a plan view of a variation of the building block of  FIG. 11 ; 
           [0020]      FIG. 15   a  is a plan view of the building Nook of  FIG. 14 ; 
           [0021]      FIG. 16  is a plan view of another variation of the block of  FIG. 14 ; 
           [0022]      FIGS. 17 and 18  are elevations of the blocks of  FIGS. 14 and 16 , respectively; 
           [0023]      FIG. 19  is a perspective view of a block for use as an upper channel of a window frame; 
           [0024]      FIGS. 20 and 21  are an end view and a plan view of the block of  FIG. 19 ; 
           [0025]      FIG. 22  is a perspective view of a block for use as a lower channel of a window frame; 
           [0026]      FIG. 22   a  is an end view of the block of  FIG. 22 ; 
           [0027]      FIG. 23  is a perspective view of a block used as a left channel of a window frame; 
           [0028]      FIG. 23   a  is a view of the bottom wall of the block of  FIG. 23 ; 
           [0029]      FIG. 24  is a perspective view of a block used as a right channel of a window frame; 
           [0030]      FIG. 24   a  is a view of the bottom wall of the block of  FIG. 24 ; and 
           [0031]      FIG. 25  is an elevation of the block of  FIG. 24 . 
       
    
    
       [0032]    Like reference characters refer to like parts throughout the description of the drawings. 
       DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]    With reference to  FIGS. 1-4 , the building block of the invention, generally  10 , has a hollow interior  12  and has a plurality of vertical walls composed of a pair of oppositely facing rectangular front and back side walls  14 ,  16  respectively and oppositely facing rectangular end walls  18   a,b . The block is enclosed by rectangular top and bottom walls  20 ,  22 . respectively . 
         [0034]    Selective vertical walls have first block connectors in the form of either a tongue or a groove which mates with the tongue. End wall  18   b,  for example, has a first block connector in the form of a vertically extending tongue  30  and the other end wall  18   a  has a first block connector in the form of a vertically extending groove  32 . The tongue is adapted to interconnect with a groove in an end of a second identical building block (not illustrated) placed adjacent to end  18   b  of the subject building block and groove  32  is adapted to interconnect with a tongue in an end wall of a third identical building block (not illustrated) placed adjacent to the other end wall of the subject building block 
         [0035]    The top and bottom walls have second block connectors in the form of either a projection of a recess which mates with the projection In  FIGS. 1-4 , a pair of spaced apart rectangular projections  36   a,b  extends upward from the top wall  20  of the building block and a pair of rectangular recesses  38   a,b  extends inward from bottom wall  22 . The projections are received in recesses in the bottom wall of an identical fourth building block (not illustrated) placed on top of the subject building block while the recesses receive projections in an identical building block (not illustrated) immediately below the subject building block. Each projection has an opening  40  in its upper wall for introduction and removal of insulating material, sand or other particulate material in the hollow interior  12  of the building block. The opening may be closed by a cap (not illustrated) to prevent moisture from entering the interior of the block. 
         [0036]    Openings  41  are formed in side wall  14  to facilitate attachment of straps to which dry wall or wooden panels can be attached. 
         [0037]    The thickness of the vertical and the top and bottom walls of the building block should preferably be no more than that necessary to provide sufficient strength to maintain a structure in which the build block is a part intact. Thicker walls will not only add to the cost of construction of the block but also to its overall weight. A heavier block will lack the advantage of a lighter block as a structure is being assembled such as ease of handling and lower cost but will lack the advantage of ease of handling while the structure is being disassembled after it is no longer required. 
         [0038]    As a structure is being constructed the blocks will be filled so that the filling, if it is strong in compression, such as compacted sand, will add strength to the block. If the filling is weak in compression such as insulating chips, it will also be light weight and will not add appreciably to the overall weight of the structure. In such case, the walls of the block need. not be strong enough to support the weight of much more than the weight of block above it. 
         [0039]    With reference to  FIGS. 5-7 , a corner building block, generally  42 , has a vertically extending tongue  44  on one end wall  46   a.  The other end wall  46   b  is flat. A vertically extending groove  50  is formed on one side wall  52   a  while the other oppositely facing side wall  52   b  is flat. Projections and recesses,  56 ,  58  respectively, identical to those in the building block of  FIGS. 1-4  are formed on the top and bottom walls, respectively, of the corner building block. 
         [0040]    The flat walls  46   h  and  52   h  of the corner building block define the exterior faces of the corner of a structure. The tongue and groove  44 ,  50  in the oppositely facing walls  46   a  and  52   a  fit into conforming grove and tongue, respectively, of adjacent non-corner building blocks in the same course as the just-described block  42 . 
         [0041]    The corner building block of  FIGS. 8 ,  9  and  10 , generally  60 , is the same as corner block  42  except that a groove  62  is substituted for tongue  44  of block  42  and a tongue  62  is substituted for groove  50  of block  42 . Corner block  60  is adapted for use at an end of a course of blocks where corner block  42  is at the opposite end. 
         [0042]    With reference to  FIGS. 11 ,  12  and  13 , the roof block, generally  70 , is hollow and bas front and back side. walls  72   a,b , top and bottom walls  76  and  78  and a single end wall  80 . The slope of the top wall  76  is the same as the slope of the roof of building in which the roof block is located. In the drawing, the slope is approximately 45 degrees, which is the angle between the top and bottom walls. 
         [0043]    A pair of rectangular recess  82  is formed in the bottom wall for receipt of the projection of the building block on which the roof block is seated. An opening (not illustrated) is formed in the top wall through which particulate material is introduced into the hollow interior of the block. A hollow  84  is provided on the front wall of the block to which a strap may be attached. 
         [0044]    With reference to  FIGS. 14 ,  15   a  and  17 , the end block, generally  90 , has a hollow interior, front and back side walls  92   a,b , top and bottom walls  96 ,  98  having a projection and recess  100 ,  102 , respectively, for the same purpose as the projections and recesses described above. A vertically extending groove  104  is formed in one end wall while the other end wall  106  as well as the front and back walls of the end block are flat. 
         [0045]    The corner block of  FIG. 15  has a tongue  107  where wall  92   a  of the block of  FIG. 14  is flat, otherwise it is the same as the block of  FIG. 14 . The corner blocks of  FIGS. 16 and 18  have a tongue  112  where the block of  FIG. 14  has a groove  104 . 
         [0046]    With reference to  FIGS. 19-21 , the window block, generally  120 , has a longitudinally extending channel  122  in its bottom wall for receipt of the upper portion of a window frame or sash. A pair of projections  124  in its top wall have openings for introduction of particulate. material. The lower window block illustrated in  FIGS. 22 and 22   a  has a channel  126  for receipt of the lower portion of a window frame. The left and right portions of a window frame are received in channels  130 ,  132  of window blocks  134  and  136  respectively. A groove and a tongue  140 ,  142  are formed on the side of blocks  130 ,  132  respectively for attachment to adjacent building blocks. 
         [0047]    While the building blocks depicted in  FIGS. 22 to 25  lack recesses and projections they all have hollow interiors and have openings (not illustrated) through which particulate material may be selectively introduced and extracted from their interiors 
         [0048]    It will be understood, of course, that modifications can be made in the structure of the building blocks described and illustrated herein without departing from the scope and put view of the invention as defined in the appended claims. For example the side walls of the tongues and grooves may be bevelled for a more secure fit between the two. Likewise the side walls of the projections and recesses may be bevelled for the same reason.

Summary:
The building block interlocks with other like blocks by means of mating tongues and grooves or mating projections and recesses to form a temporary structure such as a garage or a factory. The block is hollow and less an opening through which particulate material may be selectively introduced and extracted from the hollow interior. The block may be composed of light-weight material such as polypropylene or other polymeric material so that the block can be carried and lifted easily by hand when it is empty.