Patent Publication Number: US-10322525-B1

Title: Universal mold for fabricating revetment blocks

Description:
RELATED APPLICATIONS 
     This new non-provisional patent application is a divisional patent application of pending U.S. non-provisional application Ser. No. 14/934,359 filed Nov. 6, 2015, which claims the benefit of provisional application 62/123,095, filed Nov. 6, 2014. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates in general to apparatus for fabricating revetment blocks for controlling erosion, and more particularly to universal molds that are adapted for making different types of revetment blocks. 
     BACKGROUND OF THE INVENTION 
     Erosion control blocks protect the underlying ground against erosion of the soil and maintain the terrain in a desired condition. Interlocking erosion control blocks are well adapted for protecting the ground, as such type of blocks are constructed with interlocking arms that extend from one or more sides of a block, and interlocking sockets formed in other sides of the block. When interlocked together, neighbor blocks cannot be laterally moved from each other, thereby allowing high water flows thereover without compromising the integrity of a mat of blocks. 
     An interlocking revetment block generally has at least four sides with at least one interlocking arm or an interlocking socket on each side. Often, the corners of the revetment block are formed at an angle so that overall the block has an octagonal shape. Such a revetment block is disclosed in U.S. Pat. No. 5,556,228 by Smith. As can be appreciated, if a mat of such type of revetment blocks were installed, then the perimeter or border would have exposed interlocking arms and unfilled interlocking sockets. The irregular edge of the mat with unused arms or sockets allows the border blocks to more easily break or allow cracks to form through the block. 
     Interlocking revetment blocks are also formed with one or more vertical holes formed therein, from the top surface to the bottom surface. The vertical holes allow vegetation to grow therein and help anchor the block to the ground. A revetment block that has five vegetation holes therein is disclosed in U.S. Pat. No. 8,123,435, also by Smith. 
     Revetment blocks are often installed in watershed areas where soil erosion is to be prevented. The watershed areas are in many instances located in areas controlled by local or federal governments, and the primary concern is the long term protection of such areas from the erosion of soil due to frequent high-volume flows of rainwater, and the like. Generally, the aesthetics of such an area is not a concern, as the prevention of erosion is the primary goal to be achieved. 
     Generally, large areas of revetment blocks are installed using a single type or style of block. The use of two different types of blocks is usually not an alternative that is available because two different types of blocks must be maintained either in inventory, or must be fabricated for the project. For example, if an area to be protected from erosion requires the borders to be linear and without unused interlocking arms or sockets, then different shaped blocks must be employed. The fabrication of different style interlocking blocks necessitates the use of different shape molds at the fabrication plant. Revetment blocks are typically fabricated with heavy duty steel molds that are repeatedly used, thus making such molds expensive. Moreover, if a different style revetment block is to be fabricated, this requires that the entire female mold and male press head be removed and replaced with a different mold and press head adapted for fabricating the different shape block. This results in more costly revetment block products. 
     From the foregoing, it can be seen that a need exists for a mat of interlocking revetment blocks where the perimeter thereof is linear and devoid of interlocking arms or sockets. Another need exists for a mat of interlocking revetment blocks that has a linear perimeter so that it easily abuts against a linear border of concrete, such as a paved road, sidewalk, etc. Yet another need exists for a mat of interlocking revetment blocks that has a linear border, so that such mat can be used as a roadway and the perimeter is less likely to deteriorate and more likely to remain intact, even with heavy equipment traffic running over the edges of the mat. A further need exists for an economical method of fabricating different style revetment blocks using a universal mold where various components can be fastened or removed from the male and female mold parts, without changing out the entire mold. 
     SUMMARY OF THE INVENTION 
     In accordance with the principles and concepts of the invention, disclosed are different style revetment blocks that can be installed and interlocked so that there is a linear border around at least a portion of the area covered by such blocks. In a preferred embodiment, in which the perimeter of the area to be covered is linear, the revetment blocks include border blocks with a linear side, corner blocks with two linear sides, and interior blocks that interlock with each other as well as with the border and corner blocks. 
     A feature of the invention is that a mat of the revetment blocks can be installed in abutment with a concrete curb or other linear edge, so that there is no unused interlocking arms or sockets on the desired borders of the perimeter of the area to be covered. With this arrangement, there is less chance that the border blocks will break or crack when subjected to heavy loads. Otherwise, the unused arms or sockets that are not interlocked with other blocks could crack or break and degrade the integrity of the mat. 
     An additional feature of the invention is that the revetment blocks are constructed with positive interlocking arms and sockets so that the blocks cannot be separated from each other by substantial lateral movement. The positive interlocking aspect allows the blocks to be individually removed only by upward lifting of a block. A mat of such revetment blocks can thus withstand substantial hydraulic forces of water flowing thereover without compromising the stability of the mat of blocks. 
     A universal mold can be employed to efficiently and economically fabricate the different types of revetment blocks required to construct a mat of blocks having a linear border. The mold includes a female mold body and a male press head, each with arm and socket components that can be attached or removed to reconfigure the mold to fabricate the different types of revetment blocks. The mold body and press head can be easily modified with the arm and socket components so that the entire mold parts do not have to be replaced, thereby allowing multiple types of revetment blocks to be fabricated by a single reconfigurable mold, without having to have entirely different molds, which would be expensive. 
     According to an embodiment of the invention, disclosed are revetment blocks for making a mat having a linear border. An interior block has two engaging arms and two engaging sockets, the arms for engaging with respective sockets of two neighbor revetment blocks, and the sockets for engaging with respective arms of two other neighbor blocks. A border block has three engaging members for interlocking with respective members of three neighbor revetment blocks. The border block has a linear edge forming a portion of the border of the mat. A corner border block has two engaging members for engaging with the respective members of two border blocks. The corner block has two linear sides. 
     According to another embodiment of the invention, disclosed is universal mold for fabricating revetment blocks. The mold includes a mold body having formed therein a hollowed out part defining at least a part of an outline of a revetment block to be fabricated. The outline has at least one depression for forming an arm of the revetment block to be fabricated, and the outline has at least one planar side defining an entire flat side of the revetment block to be fabricated. The universal mold also includes a removable arm member adapted for being fixed in the depression of the mold body. The removable arm member has a planar side defining a part of a flat side of the revetment block to be fabricated. When the removable arm member is removed from the depression, the depression forms an arm of the revetment block to be fabricated. A removable socket member has a planar side attachable against a planar side of the mold body. When the removable socket member is attached to the planar side of the mold body, a socket is formed in the revetment block to be fabricated. 
     According to yet another embodiment, disclosed is universal mold for fabricating revetment blocks. The universal mold includes a mold body having formed therein a hollowed out part defining at least a part of an outline of a revetment block to be fabricated. The outline has two outwardly-directed depressions for forming respective arms of the revetment block to be fabricated. The outline also has two planar sides, where one of the planar sides of the outline defines an entire flat side of the revetment block to be fabricated. Two removable arm members are included, where each is adapted for being fixed in a respective outwardly-directed depression of the mold body. Each removable arm member has a planar side defining a part of a flat side of the revetment block to be fabricated, whereby when each removable arm member is removed from a respective outwardly-directed depression, the resulting depression forms an arm of the revetment block to be fabricated. Two removable socket members are included, where each has a planar side attachable against a planar side of the mold body. When a removable socket member is attached to a respective planar side of the mold body, a socket is formed in the revetment block to be fabricated. 
     With regard to a further embodiment of the invention, disclosed is a method of adapting a mold to fabricate different revetment blocks. The method includes using a mold body having a hollowed out part; using one or more outwardly extending depressions within the hollowed out part of the mold body to form a respective arm of the revetment block to be fabricated, and filling in the one or more outwardly extending depressions to form respective flat sides of the revetment block to be fabricated. The method further includes attaching one or more socket members to respective planar sides of the hollowed out part of the mold body to form a respective socket of the revetment block to be fabricated, and removing the one or more socket members from the respective planar sides of the hollowed out part to form respective flat sides of the revetment block to be fabricated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages will become apparent from the following and more particular description of the preferred and other embodiments of the invention, as illustrated in the accompanying drawings in which like reference numbers generally refer to the same parts, functions or elements throughout the views, and in which: 
         FIG. 1  is a mat of twelve interlocking revetment blocks having a linear border all around the perimeter of the mat; 
         FIG. 2  is an exploded view of various components of a block plant fabrication unit; 
         FIG. 3  is an isometric view of a universal mold box adapted for fabricating different shape revetment blocks; 
         FIG. 4  is an isometric view of a universal press head for use with the universal mold box of  FIG. 3 ; 
         FIG. 5  is a top view of a mat of revetment blocks having interior revetment blocks and opposing edge revetment blocks having respective linear edges; 
         FIG. 6  is a cross-sectional view of the mat of revetment blocks taken along line  6 - 6  of  FIG. 5 ; and 
         FIG. 7  is an isometric view of an edge revetment block having an interlocking part and an anchor part. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a small twelve-block mat  13  of interlocking revetment blocks. The mat  13  includes a number of different shape blocks in order to achieve a linear perimeter, shown by broken line  15 . Although the perimeter  15  is generally linear, it has small indentions  14  where the diagonal corner of neighbor blocks meet. Accordingly, as used herein the term linear generally means that there are two or more blocks interlocked together with no arms or sockets on the selected edges or borders of such interlocked blocks, and the borders can be curved based on the articulation ability of the blocks. The mat  13  also includes diagonal angled corners  16 . However, the mat  13  does not include any arms or sockets along the perimeter, as each border block is constructed with one or two linear sides that do not have either an arm or a socket. This prevents the breakage of the border blocks when heavy loads are carried on the unused arms and sockets of the border blocks. For example, the first corner block  1  is a border block and is constructed with a first side  18  and a second side  20  orthogonal thereto, and neither side has an arm or a socket. Rather, such sides are linear. Opposite linear side  18  of the first corner block  1  is an interlocking socket  22 , and opposite linear side  20  of the first corner block  1  is an interlocking arm  24 . The border of the area to be covered may extend all around the perimeter, but the border may also encompass only one side, two or three sides of the perimeter. 
     The top edge of border block  2  is constructed with a single linear side  26  that is collinear with the linear side  18  of the first corner block  1 . Opposite the linear side  26  of border block  2  is an interlocking socket  28 . The border block  2  has a side with a socket  30  that interlocks with the arm  24  of the first corner block  1 . Opposite the socket  30  of border block  2  is an interlocking arm  32 . 
     The second corner block  3  is also a border block and is constructed differently from first corner block  1  and border block  2 . The second corner block  3  is constructed with a first linear side  34 , and a second linear side  36  that is orthogonal to the first linear side  34 . The second corner block  3  is constructed with an interlocking socket  38  opposite linear side  36 , and an interlocking socket  40  opposite linear side  34 . The socket  38  interlocks with arm  32  of the neighbor border block  2 . 
     The side border block  4  is constructed with a single linear side  42  and an interlocking arm  44  opposite the linear side  42 . An interlocking arm  46  is constructed on a side of side border block  4 , where the arm  46  interlocks with a socket  22  of the first corner block  1 . Side border block  4  is constructed with an interlocking socket  48  opposite the interlocking arm  46 . 
     A interior block  5  is one of many interior blocks of a typical mat, and includes an arm or a socket on each side thereof. In particular, interior block  5  includes an interlocking socket  50  that interlocks with the arm  44  of the side border block  4 . Interior block  5  includes an interlocking arm  52  formed on a side that is opposite the interlocking socket  50 . An interlocking arm  54  is formed on interior block  5  and interlocks with the socket  28  of border block  2 . An interlocking socket  56  is formed in block  5  opposite interlocking arm  54 . The interior block  5  is constructed differently from border blocks  1 - 4 . Except for the arrangement of vegetation holes formed in interior block  5 , the interlocking arms and sockets of interior block  5  are constructed very similar to the revetment block disclosed in U.S. Pat. No. 5,556,228. 
     Side border block  6  is constructed with a linear side  58  that is collinear with the linear side  36  of the second corner block  3 . The side border block  6  is constructed with an interlocking socket  60  opposite the linear side  58 , where the interlocking socket  60  interlocks with the interlocking arm  52  of interior block  5 . An interlocking arm  62  is formed on side border block  6  and is interlocked with the socket  40  of the second corner block  3 . An interlocking socket  64  is formed in side border block  6  opposite the interlocking arm  62 . 
     Side border block  7  is constructed in an identical manner to side border block  4 , with a linear side  66  and an interlocking arm  68  extending from a side opposite the linear side  66 . The linear side  66  of side border block  7  is collinear with the linear side  42  of side border block  4 . The side border block  7  has an interlocking arm  70  that interlocks with the interlocking socket  48  of the side border block  4 . An interlocking socket  72  is formed opposite the interlocking arm  70 . 
     Interior block  8  is constructed identical to the interior lock  5 . Interior block  8  has an interlocking socket  74  that interlocks with the interlocking arm  68  of side border block  7 . An interlocking arm  76  is formed opposite the interlocking socket  74 . An interlocking arm  78  of interior block  8  interlocks with interlocking socket  56  of interior block  5 , and an interlocking socket  80  is formed in interior block  8  opposite interlocking arm  78 . 
     Side border block  9  is constructed in an identical manner as side border block  6 . Side border block  9  includes a linear side  80  that is collinear with the linear side  58  of side border block  6 . Side border block  9  is constructed with an interlocking socket  82  that is opposite the linear side  80 , and interlocking socket  82  interlocks with interlocking arm  76  of interior block  8 . An interlocking arm  84  is interlocked with the interlocking socket  64  of side border block  6 . An interlocking socket  86  is formed in side of border block  9  opposite the interlocking arm  84 . 
     The third corner block  10  is a border block and is constructed with a first linear side  88  and a second linear side  90  orthogonal thereto, where neither side has an arm or a socket. Linear side  88  is collinear with side  66  of side border block  7 . Opposite linear side  88  of corner block  10  is an interlocking arm  94 , and opposite linear side  90  of corner block  10  is an interlocking arm  92  that is interlocked with the socket  72  of side border block  7 . 
     The bottom border block  11  is constructed with a linear side  96  that is collinear with the linear side  90  of the third corner block  10 . The bottom border block  11  includes an interlocking arm  100  opposite the interlocking socket  98 , and includes an interlocking arm  102  opposite the linear side  96 . The interlocking socket  98  interlocks with interlocking arm  94  of the third corner block  10 . 
     Lastly, in the twelve-block mat  13 , there is a fourth corner block  12  that is a border block and is constructed with a first linear side  104  that is orthogonal to a second linear side  106 . The linear side  104  is collinear with the linear side  96  of bottom border block  11 . Similarly, the linear side  106  of the fourth corner block  12  is collinear with the linear side  80  of side border block  9 . An interlocking socket  108  is formed in the fourth corner block  12  opposite the linear side  106 , and an interlocking arm  110  is formed in the fourth corner block  12  opposite the linear side  104 . The interlocking socket  108  interlocks with the interlocking arm  100  of the bottom border block  11 . The interlocking arm  110  of the fourth corner block  12  interlocks with interlocking socket  86  of side border block  9 . 
     While the mat  13  includes only twelve interlocking blocks, in practice many more interlocking blocks would be employed to cover a large ground area. A larger mat of interlocking blocks, where the mat has a linear border or perimeter, can be installed by adding additional blocks  4  or  7  in the first column to make the mat as long as desired. The additional side border blocks  4  or  7  would be added in the first column at line  112 . In order to make the mat  13  longer, additional interior blocks  5  or  8  would be added in the second column at line  112 . The additional interior blocks  5  or  8  would have interlocking sockets that interlock with the respective interlocking arms of the added side border blocks  4  or  7 . Lastly, in order to lengthen the mat  13 , additional side boarder blocks  6  or  9  would be added at line  112  in the third column of the mat  13 . The added side border blocks  6  or  9  would have interlocking sockets that interlock with the respective interlocking arms of the added interior blocks  5  or  8 . 
     Of course, when making a mat of interlocking revetment blocks longer than the mat  13 , one would start at the bottom or top of the mat and install as many blocks as necessary until the other end of the mat is reached. The mat  13  can be made wider than the three-block wide mat  13  by adding additional top border blocks  2  at line  114 , between corner border blocks  1  and  3 . Similarly, the mat  13  can be made wider by adding additional interior blocks  5  between side border blocks  4  and  6 , at line  114 . The same can take place by adding additional interior blocks  8  between side border blocks  7  and  9  at line  114 . A wider mat  13  is achieved by adding additional bottom border blocks  11  between the third and fourth corner blocks  10  and  12 , at line  114 . 
     Although the interlocking blocks of the mat  13  can be constructed in different sizes, a preferred embodiment of each of the interlocking blocks has a length/width dimension of 15 inches by 15 inches. The interlocking blocks can be 4.5 inches thick and fabricated with 4,000 psi concrete. A mat of interlocking blocks for making a roadway ten foot wide would be installed with eight blocks across. A roadway fifteen feet wide would be installed with twelve blocks across. A mat  13  of revetment blocks can be installed in abutment with a roadway concrete curb or strip  27  or  29 , or other linear edge, so that there is no unused interlocking arms or sockets on the desired borders of the perimeter of the area to be covered. 
     As noted above, each interlocking block of a mat  13  is constructed with vegetation holes therein. In a preferred embodiment, each block is formed with five vegetation holes, in the location of the five dots of a gambling dice. The vegetation holes, one shown as numeral  113  in the first corner block  1 , are formed in the manner described in U.S. Pat. No. 8,123,435, the disclosure of which is incorporated herein by reference. In general, the vegetation holes are formed as a vertical cone shape, with the larger opening in the bottom of the block. The larger opening in the vegetation holes placed in the bottom of each interlocking block allows the blocks to be better anchored to the ground when the holes are filled with soil, small stones, vegetation, etc. Thus, the interlocking blocks should not be turned upside down and installed. 
     If those skilled in the art prefer to make the vegetation holes as cylinders with the same size opening in the top and bottom of the blocks, then the blocks can be installed right side up or upside down. If this is desired, then the first corner block  1  can be turned upside down, reoriented and installed in the position of the fourth corner block  12 . Similarly, the top border block  2  can be turned upside down, reoriented and installed in the position of side border blocks  6  and  9 . Lastly, the side border block  4  can be turned upside down, reoriented and installed in the position of bottom border block  11 . 
     In the linear-border mat  13  of  FIG. 1 , there are nine different types of interlocking blocks. In the conventional construction of such blocks, in a dry cast block plant process, there would be required nine different molds for making each type of block. This is expensive, as molds constructed of steel for making revetment blocks, are expensive. The cost of a typical mold for block plant fabrication of revetment blocks can range upwardly of $35 k-$40 k. 
       FIG. 2  illustrates in rudimentary form the equipment for mass producing revetment blocks using dry cast molds and block plant techniques. The resulting revetment block fabricated is shown as interior block  5  in its completed form after the casting process. According to this technique, a mold box  120  is used, which has a depression with an outer perimeter in the shape of the block to be formed therein, except for the vegetation holes. It can be seen that this mold box  120  is for making the interior block  5  of  FIG. 1 . The depth of the depression  122  in the mold box  120  is about twice the actual thickness of the interior block  5 . The mold box  120  has hollow outwardly-directed depressions  124  and  126  to form the respective interlocking arms  52  and  54  of the interior block  5 . Two inwardly-directed arms  128  and  130  in other sidewalls of the depression  122  of the mold box  120  form the two corresponding sockets  50  and  56  in the interior block  5 . The mold box  120  is constructed of solid steel and can be used many times to make revetment blocks without replacement or repair due to wear. A small draft angle is formed in the sidewalls of the depression  122  of the mold box  120  to allow the interior revetment block  5  to remain on a metal pallet  140  when the mold box  120  is lifted. 
     The block plant equipment further includes a reciprocating unit  130  which includes a plunger  132  and a thick square plate  134  (shown in broken lines) attached to the bottom thereof. The plate  134  can be about the size as the top of the mold box  120 . A press head  136  is attached to the bottom of the plate  134 . The press head  136  is shaped in the outline of the interior block to be formed, and fits down into the top portion of the hollowed out part  122  of mold box  120 . As can be appreciated, when making a different shaped revetment block, a different mold box  120  and a corresponding different press head  136  are required. As noted above, the molding apparatus for a different mold box and press head can range upwardly to $35,000 to $40,000. 
     A further component  150  of the mold box  120  is a set of solid core cans  152  that form the vegetation holes in the interior revetment block  5 . This apparatus  150  is shown to the side of the mold box  120 , but in practice is welded to the bottom of the mold box  120 . The interior block  5  is formed with five vegetation holes, and thus the array of vegetation holes  150  also includes five solid core cans  152 . The bottom of each solid core can  152  is attached to a support rod  154  (shown in broken line), and the ends of the support rods  154  are welded to the bottom of the mold box  120 . While not shown, the press head  136  is constructed with five cylindrical voids in the bottom thereof to receive therein the core cans  152 . 
     A further component of the block plant system is a movable pallet  140  that underlies the mold box  120 . The pallet  140  is a thick steel plate that is laterally moved under the mold box  120  to temporarily form the bottom of the mold box  120 . After the interior block  5  is cast in the mold box  120 , the mold box  120  is lifted and the molded interior block  5  remains on the pallet  140 . The pallet  140  is situated on a conveyor-like apparatus so that it can be moved away from the mold box  120  and downline to allow the interior revetment block  5  to be cured. At the same time, another pallet is moved under the mold box  120 , whereupon the mold box  120  is lowered onto the empty pallet  140  and the block casting process is repeated. 
     In practice, the mold box  120  resting on the pallet  140  is filled with concrete of the desired psi, and with a predetermined amount. In the dry cast technique, the concrete partially filling the mold box  120  has only about 7% water and thus is not runny. Then, the press head  136  is pushed down into the mold box  120  to compress the concrete mix filling the bottom portion of the mold box  120 . Additionally, the press head  136  is vibrated to remove all air pockets to assure the integrity and strength of the resulting interior block  5 . When the plate  134  above the press head  136  contacts the top of the mold box  120 , this is sensed by a sensor (not shown), whereupon the plunger  132  is moved upwardly, bringing with it the plate  134  and the press head  136  attached thereto. Also lifted by means not shown is the mold box  120  so that it is lifted from the pallet  140 . The mold box  120  is lifted and separated from the molded interior block  5  which remains on the pallet  140 . As noted above, the pallet  140  with the newly-molded interior block  5  resting thereon is moved downline. The procedure is repeated to fabricate another block of the same shape, by lowering the mold box  120  onto a subsequent pallet, partially filling the mold box  120  with fresh concrete, and repeating the process described above. 
     As illustrated above, there are a number of different revetment blocks needed to provide a linear border around the mat  13  of revetment blocks. A corresponding number of different molds would be required in order to fabricate nine different shaped revetment blocks for the mat  13 . This would be prohibitively expensive. In accordance with a feature of the invention, a single mold with replaceable arm/socket members can be utilized to thereby make a universal mold adapted for making different-shaped blocks by attaching or removing the arm/socket members to the body of the mold. 
     With regard to  FIG. 3 , there is disclosed a universal mold  160  and the associated components. In particular, the universal mold  160  includes a body  162  having a hollowed out part  164  formed in the basic shape of the perimeter of the block to be formed, including the four angled corners, one shown as numeral  169 . The body  162  of the universal mold  160  includes the two outwardly-directed depressions  166  and  168  that would form the corresponding arms  52  and  54  of the interior block  5 . As will be described in detail below, the outwardly-directed depressions  166  and  168  can be filled in with respective filler plugs to effectively make the universal mold  160  function to eliminate one or the other of the interlocking arms  52  or  54 . Rather than forming the inwardly-directed arms that would otherwise form the sockets  50  and  56  in the interior revetment block  5 , the two sides of the depression  164  formed in the mold body  162  are made planar. The planar sides  170  and  172  correspond to the respective planar sides of the border blocks of the mat  13 . 
     The body  162  of the universal mold  160  is constructed to make any of the four sides (excluding the angled corners) planar and without any arm or socket. This is accomplished by making the socket sides  170  and  172  of the mold body  162  planar, as described above. When it is desired to form a socket in either of the two sides  170  and  172 , then a socket member  174  is bolted in the position where a socket should be formed in the revetment block. The socket member  174  is shown removed and above the mold body  162  for purposes of clarity. The socket member  174  is formed of steel and has two threaded holes  176  therein. Bolts  178  pass through respective holes  180  formed in the body  162  of the universal mold  160  and are fastened into the threaded holes  176  of the socket member  174 . This removably fastens the socket member  174  to the inside surface  170  of the mold body  162 . With this arrangement, this side  170  of the mold body  162  can be modified to be either a planar side when the socket member  174  is removed, or a socket when the socket member  174  is bolted to the mold body side  170 . The socket member  182  is shown bolted in position to the mold body side  172 . In like manner, when the socket member  182  is removed, the side  172  of the mold body depression  164  is planar. 
     The mold body  162  includes an outwardly-extending depression  166  that otherwise forms an arm  52  of the revetment block to be formed. An arm member  184  has a shape substantially like that of the outwardly-extending depression  166 , but has a planar side  186 . When the arm member  184  is inserted into the depression  166 , it fills the depression  166  and provides an inside planar side  186  that is coplanar with the sidewall of the depression  164  of the mold body  162 . The other outwardly-extending depression  168  of the mold body  162  is shown with an arm member  188  inserted therein, and the planar side  190  of the arm member  188  is coplanar with the respective side of the mold body  162 . The arm member  184  is fastened within the outwardly-extending depression  166  using bolts  192  inserted through respective holes in the mold body  162  and threaded into threaded holes (not shown) in the arm member  184 . 
     As can be seen, the mold body  162  is formed so that two sides  170  and  172  are normally planar and can be made into corresponding sockets by bolting respective socket members  174  and  182  thereto. Conversely, the other two sides of the mold body  162  are formed so that such sides are constructed with normally outwardly-extending depressions  166  and  168  for forming corresponding arms of the revetment block, but have arm members  184  and  188  inserted therein to make the respective mold body sides planar. 
     The press head  200  shown in  FIG. 4  (without the overlying plate  134 ) can also be constructed so as to be universal in making the different shapes of revetment blocks. The press head  200  can function in conjunction with the universal mold  160 . The press head  200  includes a body  202  that is the same general shape of the block to be made so that it presses down on the wet concrete in the mold body  162  to compress the wet concrete of the block. The press head body  202  can thus be constructed in the same shape as the hollowed out part  164  formed in the mold box  162 , having two sockets  204  and  206 , and two planar sides  208  and  210 . Socket members  212  and  214  are insertable into the respective sockets  204  and  206  and bolted thereto by bolts  216 . Corresponding arm members  218  and  220  are boltable to the planar sides  208  and  210 . The insertable socket members  212  and  214  as well as the arm members  218  and  220  are used to modify the outline shape of the press head body  202  for correspondence to the manner in which the mold box  162  is modified. In other words, when there is no arm member  184  inserted into the outwardly-directed depression  166  of the mold body  162 , then there would be an arm member  218  bolted to the corresponding position in the press head body  202 . Thus, when the outwardly-extending depression  166  in the mold body  162  is vacant and filled with concrete, the corresponding arm member  218  attached to the press head body  202  would come down and compress the concrete that partially fills the outwardly-extending depression  166  in the mold body  162  and form an arm. The same would be true with the use or nonuse of the arm member  220  attachable to the press head body  202  in the position corresponding to the removable arm member  188  of the mold body  162 . 
     A socket member  212  shaped much like socket member  174  can be fastened to the press head body  202  in the location corresponding to mold body side  170 . The socket member  174  is slightly larger than the arm member  184  of the mold body  162  to make a block that allows a desired degree of articulation between mating arms and sockets of neighboring revetment blocks. If the socket member  174  is bolted to the side  170  of the mold body  162 , then the similar-shaped socket member  212  would not be bolted into the socket  204  of the corresponding side of the press head body  202 . On the other hand, if the socket member  174  was not bolted to the side  170  of the mold body  162  to form a planar surface, then the socket member  212  would be bolted into the corresponding socket  204  of the press head body  202 . The same would be the case when the socket member  214  is used or not used on the side of the press head body  202  corresponding to the side of the mold body  172  to which the socket member  182  is shown attached. With this socket member arrangement, when a planar side  170  of the mold body  162  has no socket member attached thereto, the press head body  202  does, whereby the wet concrete adjacent the planar side  170  of the mold body  162  will be compacted appropriately. 
     When fabricating the interior blocks  5  and  8  of  FIG. 1 , the molding apparatus would be modified according to the following. Since the interior block  5  has two arms and two sockets, then the arm members  184  and  188  would be removed from the corresponding outwardly-extending depressions  166  and  168  of the mold box  162 , and both arm members  218  and  220  would be bolted to the respective planar sides  208  and  210  of the press head  202 . The two arm members  218  and  220  of the press head  200  would thus come down into the mold box body  162  and into the corresponding sockets  166  and  168  to compress the concrete arm members  52  and  54  of the block  5 . Outwardly-extending arms  52  and  54  would thus be formed on the interior block  5 . When forming the two sockets  50  and  60  of the interior block  5 , the two socket members  174  and  182  would be bolted to the respective planar sides  170  and  172  of the mold body  162 . The press head  202  would be configured so that both arm members  212  and  214  would be removed from the respective sockets  204  and  206 . The sockets  50  and  60  of the interior block  5  would thus be formed. 
     In forming, for example, the border block  9  which has an arm  84 , two sockets  82  and  86  and a linear side  80 , the universal mold  160  would be configured as follows. The arm member  188  would not be bolted into the depression  168  of the mold body  162  so that the arm  84  of the border block  9  would be formed. The arm member  220  would be bolted to the press head body  202  to compress the concrete in the socket  168  of the mold body  162 . The arm member  184  would be bolted in the outwardly-extending depression  166  of the mold body  162  and the arm member  218  of the press head body  202  would be removed so that a corresponding arm would not be formed in the border block  9 . The linear side  80  of the border block  9  would thus be formed instead of an arm. Since the border block  9  has two sockets  82  and  86 , both socket members  174  and  182  would be bolted to the respective sides  170  and  172  of the mold body  162 , thereby causing two sockets  82  and  86  to be formed in the border block  9 . The press head body  202  would be modified so that the arm members  212  and  214  would be removed to receive therein the respective arm members  174  and  182  of the mold body  162 . The border block  9  would thus be formed by the universal mold  160 . 
     From the foregoing, a universal mold  160  is disclosed so that it can be used to fabricate different shape interlocking revetment blocks using the same general mold body, by attaching or removing various socket or arm members therefrom. The foregoing has been described in connection with a preferred embodiment in which interlocking revetment blocks are constructed and installed in a mat. Those skilled in the art may apply the teachings disclosed herein to construct revetment blocks and other types of blocks with arms and sockets that interengage, but do not positively interlock to prevent lateral separation. 
       FIGS. 5-7  illustrate another embodiment of a mat  230  of revetment blocks, where the blocks are installed within a border of spaced-apart toe blocks  234  and  238 . The interior revetment blocks, one shown as  232 , are constructed with two interlocking arms and two interlocking sockets, much like the interior blocks  5  described above. The interlocking interior revetment blocks  232  provide an excellent roadway adjacent to an area where water can occasionally flow and provide the possibility of erosion. According this embodiment, the mat  230  of interior blocks  232  has a first border constructed of toe blocks  234 , each of which has an interlocking socket  236  formed therein. A second and oppositely-located border is constructed of toe blocks  238 , each of which has an interlocking arm  240 . 
     The respective sockets  236  the first border of toe blocks  234  interlock with the corresponding arms of the interior blocks  232 . The linear outer side  237  of the toe blocks  234  forms a straight or linear edge to the road. In like manner, the socket of each interior block  232  forming the opposite side of the road, interlocks with a corresponding arm  240  of a neighbor toe block  238 . Each toe block  234  is constructed with one socket  236  and three linear sides, one of which is the outer side  237  of the toe block  234 . Each toe block  238  is similarly constructed with one arm  240  and three linear sides, one of which is the outer side  239  of the toe block  238 . With this arrangement of toe blocks  234  and  238 , each side of the mat  230  of interior blocks  232  is constrained within the lateral area between the respective rows of toe blocks. 
     The details of the construction of the toe block  234  is illustrated in  FIGS. 6 and 7 . The purpose of the toe blocks  234  and  238  is to anchor the sides of the mat  230  in the ground and prevent the erosion of soil by water attempting to flow under either side of the mat  230 . The toe block  234  is constructed with two parts. A top interlocking part  242  of the toe block  234  has the interlocking socket  236  and is substantially the same size and thickness as the neighbor interior block  232 . In practice, the socket  236  of the toe block  234  is somewhat larger than the arm of the interior block  232  to allow a desired degree of articulation between the neighbor blocks. An anchor part  244  of the toe block  234  has a length substantially the same as the interlocking part  242 , but is narrower in width. The length is measured into the drawing, and the width is measured sideways in the drawing of  FIG. 6 , and the depth of the anchor part  244  is measured up and down in the drawing of  FIG. 6 . For clarity, these dimensions are set forth in  FIG. 7  also. The anchor part  244  of the toe block  234  is buried in the ground, and preferably in a trench formed along the side of the road to be paved with the mat  230 . The depth of the anchor part  244  of the toe block  234  can be about 13.5 inches to thereby substantially reduce the possibility of water eroding under the mat  230  and compromising the integrity and stability thereof. The other toe block  238  is constructed in a substantially similar manner, except with an interlocking arm  240 , rather than an interlocking socket  236 . 
     The row of toe blocks  234  remain adjacent each other due to the interlocking connection between the neighbor interior blocks  132 . However, those skilled in the art may find it advantageous in some applications to provide the capability for each toe block  234  in the row to interlock with each other using respective sockets and arms. The same could be with the other row of toe blocks  238 . Also, each toe block  234  and  238  is constructed with interior beveled corners, but this is not a necessity to the proper function of the toe blocks  234  and  238 . The beveled corners of the toe blocks  234  and  238  provide an opening at the corner intersection between blocks to facilitate the growth of vegetation and anchoring of the blocks and the mat  230  to the underlying ground. 
     With reference to  FIG. 7 , there is illustrated the interlocking part  242  of the toe block  234 , as well as the anchor part  244 . In practice, the toe block  234  is constructed in two parts by block plant techniques, using respective molds. Three different molds can be utilized, one for molding the interlocking socket part  242  of the toe block  234 , a second mold for making the interlocking arm part  240  of the other toe block  238 , and a third mold for making the anchor part  244  of both toe blocks  234  and  238 . As noted above, the interior revetment blocks are about 15 inches by 15 inches and 4.5 inches thick (depth). The interlocking part  242  of the toe block  234  is made compatible with the interior blocks  232  by constructing the interlocking part  242  about fifteen inches wide, about twelve inches long and about 4.5 inches thick (depth). The anchor part  244  of the toe block  234  is constructed about 4.5 inches wide, about twelve inches long and about 13.5 inches in depth. Those skilled in the art may find that the interior blocks  232  and the toe blocks  234  and  238  can be constructed with other dimensions. 
     When fabricating the toe blocks  234  and  238  using a mold and block plant techniques, it is expected that such block can be made more efficiently in two parts  242  and  244  and then fixing the two parts together before being installed in an interlocking manner with the interior blocks  232 . As such, the interlocking part  242  is first made using the first mold, and then the anchor part  244  is made using a different mold. Then, the interlocking part  242  is attached to the anchor part  244  by a layer of mortar therebetween. When the mortar has cured, the interlocking part  242  is thus fixed to the anchor part  244 . The other toe block  238  is fabricated in a similar manner. Of course, when a certain mold is fixed to the block plant equipment, many corresponding toe block parts would be molded before changing the mold to make the other toe block parts. 
     When constructing a road, such as a conventional ten foot wide road, using a mat of interlocking blocks, the following steps can be carried out. Two six-inch wide trenches can be formed in each boundary path of the road, where the outer edges of the two trenches are ten feet apart. A first lateral row of interior blocks  232  are then installed in an interlocking manner between the two trenches, and the anchor parts  244  of the toe blocks  234  and  238  are then lowered into the respective trenches and at the same time interlocked with the respective neighbor interior blocks  232 . The space between the anchor parts of toe blocks  234  and  238  and the inside of the trenches can be backfilled with dirt. The space between the outside surface of the anchor parts  244  and the outer edge of the trenches can be backfilled with dirt at that time, or at any later time when the road is completed. Subsequent lateral rows of interior blocks  232  and toe blocks  234  and  238  are thus installed, with the second row of interior blocks interlocked with the neighbor interior blocks. With this technique, a road is provided for carrying the load of vehicles thereon, the edges are linear and aesthetically pleasing, and the edges of the road are protected from erosion thereunder by flowing water during flooding or otherwise. 
     While the preferred and other embodiments of the invention have been disclosed with reference to specific revetment blocks, and associated mold constructions, it is to be understood that many changes in detail may be made as a matter of engineering choices without departing from the spirit and scope of the invention, as defined by the appended claims.