Abstract:
A simulated stone or brick column or retaining wall is made up of rows of masonry blocks of generally trapezoidal configuration arranged in end-to-end relation to one another in each row, each block including a recessed portion being aligned with one another in each row and each block having textured wall surfaces simulating the appearance of brick or stone along one or more wall surfaces arranged in different configurations without the necessity of interlocking the blocks together.

Description:
This application claims the benefit of U.S. Provisional Application No. 61/762,685 filed Feb. 8, 2013 for COMPOSITE MOLDED CONCRETE BLOCKS HAVING TEXTURED FRONT SURFACES DEFINING SIMULATED BRICK OR STONE AND MORTAR CLUSTERS AND METHOD OF MAKING SAME and is incorporated by reference herein. 
    
    
     BACKGROUND AND FIELD 
     There is a need for concrete or masonry blocks which can be molded with different textured surfaces and combined to form retaining walls of different sizes and configurations in a simplified, efficient manner. In this regard, it is highly desirable to form each block in a mold which is positioned to provide a textured finished face for each block in a front vertical wall of the mold, and the remainder of the side and end wall surfaces of the mold inclining downwardly and inwardly to result in the formation of downwardly tapered side and rear walls in the resultant block in order to facilitate removal of the block from the mold. In order to further expedite removal of each block, a hinge is provided in opposite sides or along the bottom of each mold together with placement of cavities in the bottom and rear walls of each block in a manner to be described. One or more molds may be placed on a production board, the molds preferably being formed of a rubber or rubber-like material, and the blocks are formed by a wetcast process followed by curing and separation from each mold. In particular, the concrete block is of generally trapezoidal configuration with a front textured surface which takes on the appearance of a brick, stone and mortar cluster, different stone or rock-like textures. Each block is characterized also by having a rear wall and sidewalls joined together into a trapezoidal configuration, and the blocks can be arranged in various configurations, such as, for example, straight, rectangular, circular or serpentine walls without the necessity of inter-locking or otherwise physically joining the blocks together. 
     When used for retaining walls, a typical block is dimensioned to be 16″ wide by 6″ high at the front wall surface  12  and 8″ to 9″ in depth from the front surface  12  to the rear surface  14  depending upon the depth of the texture and the slope at the rear of the block  10  and will weigh in the order of thirty to fifty pounds each, although dimensions and weights may vary without departing from the scope. If necessary, the blocks can be joined by the application of construction adhesive between layers of block to prevent shifting in relation to each other. For taller retaining walls the blocks can also be anchored into the earth fill behind the wall by the use of a geogrid material that will extend between upper and lower layers of blocks. In addition, rods may be placed under each geogrid and within the void on the underside of each block and further anchored by the use of the elongated rods positioned against the geogrid in each void and locked in place by means of friction or pinch points between each rod and void. Both the geogrid and rod for each layer will extend continuously in a lengthwise direction beneath each row of blocks although these may be alternated as well. Also, the rods should be flexible enough to permit shaping of the entire wall into different configurations. 
     In one aspect there is provided a simulated stone or brick masonry retaining wall comprising: a plurality of rows of masonry blocks of generally trapezoidal configuration arranged in end-to-end relation to one another in each row; each of the blocks including a recessed portion extending lengthwise of each row; each of the blocks having textured external wall surfaces simulating the appearance of stone or brick. 
     In another aspect, a method for molding a concrete block comprising the steps of: providing an outer rigid form having upstanding front and rear walls and opposite end walls arranged in a generally rectangular configuration; an elastomeric insert having a generally rectangular cavity defining front and rear wall surfaces and opposite end surfaces removably inserted into the form, at least one of the front, rear and end wall surfaces having a desired texture simulating a brick or stone to a block to be cast in said cavity; providing an upper opening into the cavity and filling the cavity with a wet cast colored concrete; vibrating the mold to densify and level out the concrete in the mold; curing the concrete in the mold over a predetermined time interval to form a hardened block of concrete; and removing the block from the mold. 
     In still another aspect, a mold form for casing a concrete block, the form comprising; an elastomeric mold being open at its upper end and having generally rectangular side walls defining front, rear and opposite end wall surfaces arranged in a rectangular array to define a cavity at its upper end with upright, rear and opposite end wall surfaces, at least one of the surfaces being shaped to define a desired configuration and texture in a block to be cast in the mold, the mold having an upper opening into the cavity; the support frames rigidly supporting the mold when a block is cast in the cavity; the support frames being releasable away from engagement with the mold after the casting has hardened whereby to permit expansion of the upright walls of the mold for removal of the hardened casting therefrom. 
     In a final form, there is provided a masonry block of generally trapezoidal configuration including a recessed portion extending upwardly from a bottom surface of the block and at least one textured external wall surface simulating the appearance of stone or brick. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of one form of concrete block illustrating placement of a geogrid and rod into a void in the undersurface of each block in accordance with one aspect; 
         FIG. 2  is a top plan view of  FIG. 1 ; 
         FIG. 3  is a cross sectional view taken about lines  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a rear view of  FIG. 1 ; 
         FIG. 5  is a perspective view of a retaining wall comprised of a number of composite blocks having different textured frontal surfaces and end surfaces; 
         FIG. 6  is a perspective view of a production board having a plurality of support frames with a mold inserted in one of the support frames; 
         FIG. 7  is a perspective view of a preferred form of mold including a V-shaped slot at each end of the mold adjacent to its front wall; 
         FIG. 8  is a side view of a mold filled with concrete beneath a vacuum tool; 
         FIG. 9  is an exploded view of the mold shown in  FIG. 8  with the cured block being removed with the aid of the vacuum tool; 
         FIG. 10  is a perspective view of a modified form of mold having textured surfaces along the front and end of the interior of the mold; 
         FIG. 11  is a perspective view of the resultant block formed in the mold of  FIG. 10 ; and 
         FIG. 12  is a top plan view of a retaining wall in a serpentine form. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring in detail to the drawings, a composite concrete or masonry block  10  is illustrated in  FIGS. 1-3  and comprises a front textured wall surface  12  and a rear wall surface  14  which is tapered downwardly from a top horizontal surface  16 . Similarly, opposite sidewalls  17  and  18  are generally rectangular or trapezoidal in shape and taper downwardly from the top surface  16 , and along with the front and rear surfaces  12  and  14  terminate in a bottom horizontal surface  20  which is parallel to the top surface  16 . It will be evident by virtue of the downwardly tapered rear surface  14  and sidewall surfaces  17  and  18  which terminate in adjoining relation to the bottom surface  20  that the area or size of the bottom surface is less than the area of the top surface. Nevertheless, by virtue of the perpendicular relationship between the front surface  12  and the bottom surface  20 , the frontal surface is upstanding or vertical when the bottom surface  20  is resting upon a horizontal surface, such as, level ground or on the level top surface of a lower adjoining block of a retaining wall as will be hereinafter described. 
     Preferably, the rear surface  14  is formed with a cavity  22  and the bottom surface is formed with a cavity  24  that extends the length of the bottom surface  20  to reduce the weight of each block and facilitate gripping of the rear surface to remove from the mold and for carrying purposes. 
     For the purpose of illustration but not limitation,  FIGS. 4 and 5  illustrate the utilization of concrete blocks  10  of the present invention in the construction of a retaining wall  30 . Typically, the finished dimension of each block  10  may be on the order of 16″ wide by 6″ high at the front wall surface  12  and 8″ to 9″ in depth from the front surface  12  to the rear surface  14  depending upon the depth of the texture and the slope at the rear of the block  10 . Again, the voids or cavities  22  and  24  in each block on the rear surface  14  and bottom surface  20  serve to reduce the overall weight of each block  10  by reducing the amount of material required without reducing the overall dimensions of each block. Also, the cavity  22  serves as a lifting handle to assist in lifting the retaining wall block from the mold without disturbing the overall dimensions of the block, along with the use of a vacuum to hold the stone while the mold is being removed by hand. The mold may also be removed manually by turning the mold over and allowing the block to be removed by gravity pull. 
     In the retaining wall structure illustrated in  FIG. 5 , like blocks are correspondingly enumerated. Thus, the lower course of blocks  32 ,  10 ,  34 ,  35  and  36  are placed on a level surface either above or below ground level to establish a firm footing for the retaining wall. The next course consisting of blocks  38 ,  36 ,  10 , and  35  may be placed directly on the top surfaces  20  of the first course and an upper course comprises blocks  10 ,  35 ,  36  and  38 . When erected along a straight or curved line the upper front chamfered vertical edges of the adjoining or adjacent blocks are positioned flush with one another with a slight gap between facing sidewalls as a result of the tapered configuration of the sidewalls as described earlier. Blocks can be joined by use of construction adhesives between the layers to prevent movement in relation to one another. Of course, if the retaining wall is curved to any degree or serpentine as shown in  FIG. 12 , the upper edges and adjoining edges will not be completely flush with one another but the chamfered front vertical corners and the wedge shape of the block itself allows for easy configuration of the curved wall. 
     Variations of texture as illustrated in  FIGS. 4 and 5  will be hereinafter discussed in greater detail in connection with the method of manufacture, and the same is true of the composition of the concrete and additives utilized to control the characteristics of the concrete all in accordance with well known practice. Thus any variety of concrete mixture can be used depending upon the desired strength, color and other characteristics to be incorporated into the blocks. 
     Molds and Method of Manufacturing Blocks 
     As illustrated in  FIGS. 6-8 , the concrete blocks are formed by introduction of a concrete mixture consisting of aggregate sand, cement, water, and water-reducing admixtures, with or without iron oxide color. The minimum strength of the concrete is on the order of 4,000 psi. Each mold  50  is preferably of a rubber or rubber-like composition having a central cavity  51  of generally trapezoidal configuration defined by a back wall  52 , opposite sides  53 ,  54  and a front textured wall  55 , the walls  52 - 54  being tapered on both sides to facilitate ease of removal of the hardened concrete from the rubber mold as well as from a production board B. In turn, front wall  55  has an inner face of a stone texture which is duplicated from natural stone. The stone texture is transferred to the mold using a multi-step process combining natural stone, liquid rubber or any liquefied material that will harden to duplicate the texture formed by rubber. A raised portion  58  in the bottom wall of the mold is of elongated triangular configuration and is shaped to form the void or cavity  24  extending from end-to-end in each block; and a raised portion  60  in the rear wall  52  is of elongated generally triangular configuration and results in the cavity  22  in the rear surface of each block. 
     In a preferred method of manufacture, one or more rubber molds  50  are placed on a standard production board B which can be of various sizes depending upon the manner in which concrete is placed in each mold. For each rubber mold  50 , in order to maintain the desired shape, one well known procedure is to utilize a BFS SlabFlex® machine. Any other type of machinery that produces wet cast products may be used as well. Any mold configuration of one or more molds can be mounted on a board B or platform prior to placing concrete in the molds. The molds are positioned so that the textured front wall surface  56  is in a vertical position. Support frames  46  are anchored by screws  48  on the production board B in surrounding relation to the mold during concrete placement. The frames  46  are tight enough to prevent the vertical keyways  62  cut in the mold from opening and allowing concrete to leak through the cuts as hereinafter described in more detail. 
     Preliminary to placement of the concrete in each mold, a form release agent is applied to the interior of the mold to prevent the concrete from sticking to the mold and prevent bugholes from occurring. Preferably, a water-based release agent is used. The inner front wall surface of each mold is surfaced with a different brick or rock orientation. The stone texture may be duplicated from a variety of different styles of natural rock while still maintaining the overall shape of the block. 
     The mold may also have a series of intersecting or crossed ridges or ribs  66  projecting inwardly from a common support surface or mat which is secured to the inner front wall surface of the mold. The ridges are of sufficient rigidity to resist bending when the concrete is poured into the mold so as to form joints or spacing between the individual bricks or rocks very much similar in appearance to bricks or stones and mortar, and the thickness and depth of each ridge may be varied as illustrated. In addition, the wet cast machine allows use of multiple colors of concrete to produce a realistic looking natural stone color. A base color with an accent color can be utilized to provide the naturally variegated look of real stone. 
     Once the molds are placed in the production board, the production board B is then advanced through the filling apparatus for the type of concrete placement equipment that is used to fill the mold with concrete. A preferred approach is to fill the mold in the mold cavity by pouring wetcast concrete into the mold cavity. The SlabFlex® machine permits use of two or more colors of concrete to produce a realistic looking natural stone color, and the entire matrix of the concrete is colored concrete. A base color with an accent color may be used to provide the naturally variegated look of real stone or basic gray concrete without color may be used. The production board B is then run through various vibration cycles to densify and level the concrete in the rubber mold followed by smoothing the top surface by use of a hand cement finishing tool and placing the production board B and molds full of concrete in a suitable curing area during the hardening phase which is normally in the range of 12-20 hours depending upon the type of concrete mixture used and the size of the mold. 
     After curing, each concrete block is removed from the mold and typically is done by hand or using a vacuum demolding device, as shown in  FIGS. 8 and 9 . This is done by removing the mold and concrete block from the frame  46  using the vacuum, followed by using a manual process and removing the remainder of the concrete block. The mold may be peeled off of the textured wall of the mold along the keyways  62  or hinged portions of the mold as shown in  FIGS. 8 and 9 . In this way, the textured wall  56  may be manually peeled away from the textured face to preserve the three-dimensional configuration of the textured wall. In other words, the keyways  62  permit hinging of the rubber mold to facilitate removal of the hardened concrete. The rubber molds incorporate a reinforced mesh fabric or strap  64  embedded within the rubber so as to provide reinforcement to the keyways  62  and to prevent tearing at the bottom of the mold. Reversing the mold and allowing the block to be pulled out using gravity is another form of removal. The mold is then placed back into the frames  46  on the production board B. 
     In the removal process it will be appreciated that the trapezoidal or downwardly tapered configuration of the sidewalls and rear walls greatly facilitate removal of each block along with the formation of voids  22  and  24 , particularly the void or cavity  22  in the rear wall surface. In addition, the tapering of the sidewalls  17  and  18  rearwardly away from the front wall  12  enables much greater latitude in the formation of each wall into linear, curved, square or rectangular shapes. 
       FIGS. 10 and 11  are directed to a modified form of mold  70  which conforms in all respects to the mold  50  and like parts are correspondingly enumerated to the mold illustrated in  FIG. 7 . The major departure is in the formation of a textured surface at one end  54 ′ and the location of keyways  72  at opposite ends of the front wall  52 ′ opposite to the textured surface in the front wall  55 . An additional keyway  74  is formed in the opposite end wall  53 ′ to the textured end surface  54 ′. In this way, upon completion of the casting process curing of the concrete block within the mold, both walls  52 ′ and  53 ′ may be peeled away from the rear wall surface  14 ′ and the end wall opposite to the textured wall surface  54 ′. The block  10 ′ is illustrated in  FIG. 11  and comprises a front textured wall surface  12 ′ and a rear wall surface  14 ′ which is tapered downwardly from top horizontal surface  16 ′. Similarly, opposite sidewall  17 ′ tapers downwardly from the top surface  16 ′, and along with the front, rear sidewall surfaces  12 ′,  14 ′ and  18 ′ terminate in the bottom horizontal surface  20 ′ which is parallel to the top surface  16 ′. The rear surface  14 ′ is formed with a cavity (not shown) and the bottom surface is formed with a cavity that extends a partial length of the bottom surface  20 ′ due to the presence of the sidewall  18 ′. 
     Although preferred and modified forms or embodiments are herein set forth and described, the above and other modifications and changes may be made as well as their intended application for uses other than retaining walls without departing from the spirit and scope.