Abstract:
A retaining wall or steeply faced slope is disclosed having a naturally green facade. The wall or slope is made of blocks of compacted earth, each having a face reinforced with wire mesh and covered with vegetation such as native grasses. The blocks may be formed onsite, saving transportation costs and other waste, using native soils. The mesh may extend beyond other faces of each block to provide handles and geogrid anchoring. A press is disclosed to form the blocks by compacting soil mixed with cement, the press including hydraulic rams or screw jacks that create immense pressures and having wedge shaped sides that relieve lateral confining pressure when the block is extracted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of application Ser. No. 12/152,320, filed May 12, 2008, which is incorporated by reference herein. Application Ser. No. 12/152,320 claims the benefit under 35 U.S.C. §119(e) of Provisional Application Ser. No. 60/938,593, filed May 17, 2007 and Provisional Application Ser. No. 60/988,779, filed Nov. 17, 2007, both of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     Soil has been used for construction for many hundreds of years. For instance, walls made of rammed earth and mud at Jiayuguan, China are said to have been built during the Ming Dynasty. Modern rammed earth walls are typically formed by first creating forms outlining the desired shape of a section of the wall. Damp soil that may be mixed with cement or other materials is then poured in to a depth of between 10 cm and 25 cm (4 to 10 inches). A pneumatically powered backfill tamper is then used to compact the soil to about one-half its original height. Further layers of soil are added and the process is repeated until the wall has reached the desired height. 
     Retaining walls for slopes are typically made of masonry, stone, brick, concrete, vinyl, steel or timber. A retaining wall can be made, for example, by pouring concrete into form boards that outline the wall. Also known is to make retaining walls with wide concrete slabs that are stacked on each other to form the wall. Geogrid reinforcement, a metal or plastic mesh that holds rocks or soil in place, can also be used to help secure a slope. 
     SUMMARY 
     In one embodiment, a device is disclosed comprising: a block containing a mixture of soil and a binder that has been compacted into a rigid state; a wire mesh that is integrated into a first face of the block; and a covering of plants on the first face, the plants growing from mulch that is integrated into the first face. 
     In one embodiment, a device is disclosed comprising: a plurality of blocks that are stacked to form a wall, wherein each of the blocks includes: a mixture of soil and cement that has been compacted into a rigid state; a mesh that is integrated into a first face of the block; and a covering of plants on the first face, the plants growing from a mulch that is integrated into the first face; wherein the first faces of the blocks are substantially aligned to provide a revetment. 
     In one embodiment, a method is disclosed comprising: providing a rigid container having a pair of parallel sides and a bottom that abuts the sides; placing a wire mesh in the container adjacent the bottom; placing a layer of mulch in the container adjacent the bottom; mixing a binder into soil to form a soil mixture; placing the soil mixture in the container; compacting the soil mixture into a rigid block; removing the block from the container; stacking the block along with other blocks to form a wall with the mulch exposed; and growing plants in the mulch. 
     This brief summary does not purport to define the invention, which is described in detail below and defined by the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a rigidly compacted soil block with a mesh that is integrated into a face of the block and a covering of plants on the face. 
         FIG. 2  is a cross-sectional view of a wall made of rigid soil blocks such as the block shown in  FIG. 1 , with reinforced faces aligned to form a steep vegetative slope. 
         FIG. 3  is an exploded perspective view of elements used to make the block of  FIG. 1 . 
         FIG. 4  is a perspective view of the elements of  FIG. 3  combined and compacted to form the block of  FIG. 1 . 
         FIG. 5  is a schematic view of a press that can be used to compact binder treated soil to form a rigid earth block such as shown in  FIG. 1 . 
         FIG. 6  is a cross-sectional view of a portion of the press of  FIG. 5 , viewed from a perspective orthogonal to that of  FIG. 5 . 
         FIG. 7  is a cross-sectional view of a device including a rigidly compacted soil block with a step, and an L-shaped retainer that sits on the step and holds soil for plants. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a cross-sectional view of a device  30  including a rigidly compacted soil block  33  with a first mesh  44  that is integrated into a first face  35  of the block. The soil block  33  contains a mixture of soil and a binder, such as cement and/or lime, along with some water, all of which are mixed together prior to compaction. In one embodiment, Portland Class II cement is mixed into the soil at a volume concentration of about ten percent. The mesh  44  in this embodiment is also integrated into a second face  37  and a third face  39  of the block, and extends beyond the second and third faces in portions  42  and  46 , which can be used as handles and for interconnecting the device with similar devices and/or a geogrid reinforcement. A layer of mulch  36  is integrated into the first face  35  and covered by plants  48  growing from the mulch. A second, more finely spaced mesh  34  may also be integrated into the first face  35  to help secure the mulch. The first face  35  is at an oblique angle to the second face  37  and the third face  39 , as it is at a slight angle from perpendicular to those faces. When the device  30  is situated with the faces  37  and  39  approximately horizontal, this slight angle of the first face  35  from vertical provides a steep slope for a wall having a facade that includes that face. 
     Surprisingly, the plants  48  may be grown from seeds that were contained in the mulch  36 , despite the mulch and seeds being subjected to high pressure during compaction of the block  33 . Alternatively, the plants  48  may already be growing from the mulch  36  during compaction, for example as grass turf. In another embodiment, seeds such as grass seeds may be applied to the first face after compaction, for example as grass seeds sprayed on the first face  35  by hydroseeding. 
     In one embodiment, the mesh  44  is made of galvanized wire with ¼-inch (approximately 0.63 cm) grid. The mesh  44  may be prepared by forming two approximately ninety degree bends to fit the mesh inside the press-box, lining the first  35 , second  37  and third  39  faces. The mesh  44  is preferably disposed within about one centimeter of the surface of the first face  35 . The mesh  44  may be held to the compacted soil adjacent the first face  35  by one or more fasteners such as screws and washers  50 . The two sides of the mesh  44  may extend between 10 cm and 1 m above the box edges, for handling and connecting the block to a geogrid reinforcement, following the compaction process. The extensions of the mesh  44  may alternatively be bent to adjoin and reinforce the fourth face  40 . 
     To test the soil block, Atterberg limits, maximum dry density determinations, freeze/thaw and wet/dry analysis, unconfined compression testing and direct shear strength testing was performed on a predominantly clay soil, to assess the impacts of lime, lime/cement, lime/fly ash, and Portland Class II cement admixture to the soil. The moisture content and percentages by volume of the various above listed treatment compounds were varied to define a pattern that would promote optimum strength. A detailed analysis of the results indicated that excess moisture hinders compaction which in turn reduces strength. The introduction of lime improved the strength of clayey soils, however, lime is not expected to have significant effects on the more desirable granular soils. Cement content on the order of 10 percent by volume, with a moisture content near optimum and a high degree of compaction, was found to be the key to promoting strength. These conclusions were applied to prepare a lime and cement treated clayey soil which yielded internal friction angles of 52.5 degrees and cohesion of 4760 lbs/sq-ft (23,238 kg/sq-meter), which indicates that the required strength for the block application is notably exceeded. 
       FIG. 2  shows a cross-sectional view of an engineered landscape  100  including a wall  101  made of stack of rigid soil block devices including device  30 . The landscape includes a roadway section  104  like that which existed prior to the creation of wall  101 , as well as a new section of roadway  106  that could be formed due to the construction of wall  101 . A slope  108  that previously existed beneath roadway  104 , and a bedrock stratum  110  that previously existed beneath slope  108 , are indicated with dashed lines. As the wall  101  construction progresses, the bedrock  100  may be scored with steps  112 . A pier and grade beam foundation  115  for the wall  101  is constructed near the bottom of the steps  112 . The slope and bedrock downhill from the foundation  115  and uphill from roadway section  104  need not be modified. A perforated pipe  117  is placed adjacent to the grade beam within a drain rock  125  envelope. 
     The soil for the blocks in devices  30  can be obtained from the vicinity of engineered landscape  100 , saving labor and transportation costs. A preselected layer of material that is available from the hillside where the landscape is located may be excavated and stockpiled. Granular soils are preferred, however, if clayey soils predominate, lime treatment can be introduced during the initial moisture conditioning phase, or select-materials may be imported. The devices  30  are stacked with their angled faces exposed and aligned, and after each block is placed in the wall, drain rock  125  such as gravel is placed against the fourth face  40  and the area between that drain rock and the step is backfilled with native soil and compacted. A geogrid reinforcement mesh  118  is then placed atop the backfilled area and anchored to the mesh of the lower device  30 , for example with bolts or ties. The geogrid mesh  118  may also extend beyond the face of the wall to be wrapped upwards and attached to the face  35  of the upper device  30 , for example with fasteners  50 , as shown in  FIG. 1 . 
     The angled faces of the devices  30  are substantially aligned and covered with native grasses to provide a steep, aesthetically pleasing revetment. The grasses are not apparent in this figure due to its scale. The roadway section  104  and  106  are constructed atop the geogrid reinforced backfill, and a berm  120  is provided atop the wall  101  to control drainage. 
     Thus, the wall  101  is made of solid, unyielding, soil-block units that form an earth-filled slope with a near vertical configuration, while supporting natural vegetative growth at the surface. The blocks that are created by compressing cement-treated-soil that is reinforced by an exterior mantle of galvanized steel wire mesh. In addition, a secondary, small opening mesh is placed between the primary exterior wire mesh revetment and the mulch to protect the thin layer of mulch that is integrated to the exterior face of the block, from migration/erosion and to promote the growth of natural grasses, at the exposed steep slope surface. 
     The engineered landscape  100  is applicable to slopes that are too steep to receive adequate, in-place compaction efforts on the slope face and be protected from the elements. It is intended to be environmentally friendly, as it eliminates the visual impact that conventional structural retaining walls impose on a landscape. The engineered landscape  100  is significantly different than the well established Geogrid Reinforced Earth-Segmental Block Retaining Wall systems that implement masonry block units, as these are eliminated and replaced by solid-soil-blocks with a reinforced, vegetative revetment. The engineered landscape  100  can be expected to accomplish everlasting stability, provided that the shear strength capacity of the consolidated soil-cement mixture is not exceeded; that provisions are incorporated into the system to protect the integrity of the blocks from moisture infiltration into the solid-soil mass; and resistance to grass fire from the adjacent hillside areas. 
       FIG. 3  is an exploded perspective view of elements used to make the device  30 , which are shown generally in the order they are used, from bottom to top. Initially, a press box  200  is provided that can withstand the pressure that is used to compact the soil mixture and form the soil blocks. The press box  200  is perforated with holes  202  that allow moisture to escape from the soil mixture during compaction, relieving hydrostatic pressure. A wedge shaped insert  205 , which may be made of wood, metal, plastic or other suitable material, is placed in a bottom of the press box  200 , to produce a desired face batter angle. The first wire mesh  44 , which is bent to fit into the press box  200 , is then placed atop the insert  205 . The second, mulch confining mesh  34  is subsequently placed on the bottom face atop the primary wire mesh  44 . The layer of mulch  36  that may contain seeds or, turf is then placed in the press box  200 , followed by the soil mixture which will become soil block  33 . To make the soil mixture, in one embodiment a volume of moisture conditioned soil that is needed for the creation of a single block is introduced in a soil mixing apparatus and the desired volume of Portland Class II cement is then added. 
     Following the thorough mixing of the soil and cement, the moisture conditioned soil-cement mixture can then be placed in the press-box, on top of the mulch, and the surface of the mixture may be hand leveled. A press plate  208  is then placed atop the soil mixture  33 , so that the combined elements look generally as shown in  FIG. 4 . Pressure  210  of tens of thousands of pounds per square foot (at least 100,000 kg/sq-meter) is then applied to the press plate  208  to compact the soil mixture. Close monitoring of the consolidation process of the soil mixture can serve to establish the required time of active pressure delivery. Upon completion of a specific time interval of pressure application, the top of the press is pushed off to the side and the block is extracted. The extraction may be achieved by pulling up on the two wire mesh segments  42  and  46  that act as handles, or from the handles  325  of the galvanized sheet metal  323  shown on  FIG. 6 , that project from the sides of the box, for placement on the outer face of the fill slope. The procedure is continuously repeated to progress upwards with the slope construction. 
       FIG. 5  is a schematic view of a press  300  that can be, used to compact treated soil to form a rigid earth block  33 . The particular press  300  that has, been used to test the invention can apply pressure of up to 40,000 lbs/sq-ft (195,280 kg/sq-meter). A pair of arms  303  can rotate about axes  305  as shown by arrows  301  to be positioned lap (vertically) to apply the compression load from a pair of hydraulic rams or screw jacks  308 , or rotated down to the sides of press box  202 , to allow for the extraction of the compressed block and subsequently replenish the press box with new cement treated soil. The hydraulic rams  308  are constrained by arms  303  to push down on press plate  208  during compaction. Blocks may be provided to extend the distance over which rams  308  can compact the soil mixture. Also shown in this schematic diagram is the wedge shaped insert  205 , mulch layer  36 , and a bottom plate  313  that can be used to push the compacted soil out of the press box. Four hydraulic rams  310  are provided on the four, lower corners of press box  202  to be used to apply an upward force on bottom plate  313 . 
       FIG. 6  is a cross-sectional view of a portion of the press  300 , viewed from a perspective orthogonal to that of  FIG. 5 . An interior of the press box  200  is partially lined with a sheet or band of galvanized metal  323  that has two approximately ninety degree bends, extends beyond press box  200  to provide handles  325  that can be used to extract the compressed block  303  from the press box. A pair of interior side plates  327  are tapered to laterally recede as the plates are pushed upward by the lower hydraulic rams. The press box  200  may also be tapered in regions that adjoin the side plates or, alternatively. An additional tapered but inverted pair of side plates can be provided that adjoin the side plates  327 . When hydraulic jacks  310  press upward on bottom plate  313 , which in turn pushes upward the side plates  327 , the lateral displacement created by the interior movement of the side plates facilitates the extraction of the compressed block. 
     A gas powered, portable masonry saw can be used to cut the blocks for corner/bends, to conform to the wall alignment and at various intervals where the block layer is interrupted by the need to vary the wall height. 
       FIG. 7  is a cross-sectional view of a device  130  including a rigidly compacted soil block  133  with a first mesh  144  that is similar to that described above, but is in the example shown in  FIG. 7  bent to from a bench or step  134  in an outward facing portion  135  of the block. To form this bench or step  134  a spacing block (instead of the wedge shaped insert  205  of prior embodiments) can be placed in the press and the mesh bent around the spacing block before the soil mixture is added and compacted. The bench or step  134  may be disposed at about one-half the height H of the block  133 . In one example, the spacing block and the resultant bench or step  134  can be about four inches by nine inches, for a soil block having a height H of about eighteen inches, although variations in these ratios as well as in the absolute dimensions of the blocks of up to about fifty percent may be possible. A notch  137  may be formed in the soil block  133 , the notch used to fit a L-shaped retainer  155 , described below. The notch  137  may be made by having a protrusion on the spacing block, and the mesh  134  may be bent around the protrusion, which may for example measure one inch by one inch by the length of the block. The notch  137  may be considered an inward extension of the bench or step  134 . 
     The soil block  133  contains a mixture of soil and a binder, such as cement and/or lime, along with some water, all of which are mixed together prior to compaction. In one embodiment, Portland Class II cement is mixed into the soil at a volume concentration of about ten percent. The mesh  144  in this embodiment is also integrated into a second face  137  and a third face  139  of the block, and extends beyond the second and third faces in portions  142  and  146 , which can be used as handles and for interconnecting the device with similar devices and/or a geogrid reinforcement. 
     A first generally L-shaped concrete retainer  155  has been separately formed and then placed on the bench or step  134 , the retainer then filled with a growing medium  136  such as mulch or topsoil for growing plants  148 . Although the weight of the growing medium  136  can hold the retainer  155  to the outward facing portion  135 , the bottom of the L-shaped retainer  155  can be fitted into the notch  137 , while screws, pins or other fasteners  138  can also be attached to the retainer  155  to hold it to the soil block  133 . The L-shaped retainer  155  can be made of material other than concrete, such as a metal or plastic mesh for the side and/or bottom that can retain its L-shape, and the angle between the bottom and side of the retainer can be between about 90° and about 120° to provide expanded surface area for the plants  148 . The retainer  155  should have a depth of at least about six inches for adequate root growth. 
     A second retainer  156  is placed atop a second device  170  that is much like device  130 . Devices  130  and  170 , and if desired additional such devices, can be stacked to form a retaining wall, including additional features such as described above for such a wall. The plant roots of the second retainer may grow into a compacted soil block  177  that is part of the second device, for the case in which the second retainer  156  has a bottom that is penetrable by plant roots. The retaining wall may have a level to slightly positive slope on the surfaces where plants grow, and a negative slope in the areas defined by the faces of the L-shaped retainers. 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.