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BACKGROUND OF THE INVENTION 
     The present invention relates to stairway components used in landscaping. Current methods of creating stairs in outdoor settings include the use of landscape timbers, casting of concrete forms in place, or precasting concrete, or by the use of bricks, paving blocks or concrete slabs arranged to serve as stair components. Each of these methods is very labor intensive and is susceptible to large variations in result. One effort to provide prefabricated concrete stair components is disclosed in U. S. Pat. No. 5,479,746. The devices of this patent include an assortment of components which are stacked to create various stairway or platform arrangements. An open-centered elongate block used to receive individual rectangular blocks is offered for sale under the name STAIR STACKER™ by Borgert Products, Inc. and STEP STACKER by Decor Innovative Concrete Systems. This product does not provide any stabilization of the sides of the open block and features a flat face which does not blend with surrounding components of a block retaining wall. Due to the open structure of this prior art stair block, dimensions may vary caused by the lack of predictable spacing between the longer walls during curing of the concrete within the block forms. 
     SUMMARY OF THE INVENTION 
     A stair component block constructed of zero slump concrete is formed with a hollow center section surrounded by orthogonal upright walls. Two opposing walls are interconnected with a narrow vertical web which is provided with two or three vertical slots extending from its top edge toward generally the center of the web. Additional vertical slots are formed in the web at the intersections of the web and the opposing walls interconnected by the web. Each of these slots extends from the top edge of the web part way to the bottom of the web. The web is so slotted such that the top part of the web may be easily removed by striking the sides of the top of the web after the block has been placed. The broken pieces of the web can be left within the central opening of the block during installation. The block is then partly filled with compacted granular material with a covering layer of sand up to a level below the block&#39;s top edges equal to the thickness of paving blocks or bricks to be placed atop the sand layer. Paving blocks or paving bricks may then be placed within the block above the sand in varying arrangements according to the installer&#39;s choice of design. The paving blocks are set such that the tops thereof are generally flush with the tops of the outer walls of the stair block. 
     The outside vertical corners of the blocks are beveled and the outside faces of the vertical walls are formed with vertical grooves formed therein spaced such that seams between adjoining blocks will appear to be part of a continuous wall. The inner and outer corners of the tops of the upright walls are radiused to provide a rounded step surface for the stair user and to blend and match with the corners of the usual paving block to be installed within the opening of the block. The blocks may be formed of dyed concrete in any of many colors as desired. 
     It is an object of the invention to provide a stair component for landscaping applications which is factory produced at low cost and high efficiency. 
     It is a further object to provide an easily installed stairway block which can be used to retain paving blocks in its top section to provide a decorative staircase in landscaping applications. 
     It is a further object to provide a stairway block which is easily handled by the installer. 
     It is also an object of the invention to provide a stair block which is stabilized during installation with a transverse stabilizing web. 
     It is a further object to provide a stairway block which is aesthetically compatible with retaining walls made from blocks. 
     It is also an object of the invention to provide a stairway block which is easy to use and which may be successfully installed on a “do-it-yourself” basis. 
     It is also an object of the invention to provide a landscaping stair block with rounded upper corners. 
     It is further an object of the invention to produce a landscaping stair block which is versatile in arrangement while having an easily removable stabilizing web. 
     These and other objects of the invention will be understood from examination of the accompanying drawings and the detailed description which follows. 
    
    
     DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a front left perspective of the stair block according to the present invention. 
     FIG. 2 is a top plan view of the stair block of FIG.  1 . 
     FIG. 3 is a cross section view taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a perspective view of a stair constructed with the stair block of FIG. 1 with paving blocks installed therewithin shown by dashed lines. 
     FIG. 5 is an exploded perspective view of an embodiment of the mold for making the block of FIGS. 1,  2 ,  3 . 
     FIG. 6 is a cross section of the mold taken along lines  6 — 6  of FIG.  5 . 
     FIG. 7 is a top plan view of the mold of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1,  2 , and  3  of the drawings illustrate the preferred embodiment of the invention composite concrete block  2 . The block is preferably of rectangular shape having opposing end walls  6  and  10  joined to opposing sidewalls  4 ,  8 , and an open top  12 , with sidewalls  4  and  8  being longer than end walls  6  and  10 . In the preferred embodiment, sidewalls  4  and  8  are approximately fifty percent longer than end walls  6  and  10 . Centrally disposed within block  2  are cavities  14  and  16  which extend from top  12  to the bottom  18  of block  2 . Separating cavities  14  and  16  is web  20  which interconnects opposing sidewalls  4  and  8  approximately midway along each. Web  20  is of a thickness substantially less than the thicknesses of front sidewall  4  and rear sidewall  8  and end walls  6  and  10  and is integrally formed with the sidewalls  4 ,  8  and end walls  6 ,  10 . Web  20  is provided with a plurality of spaced apart generally vertical narrow voids  22 ,  24 ,  26  which extend from the top edge  28  of web  20  into the body  30  of web  20 . Preferably void  22  is disposed in web  20  at the intersection of web  20  with sidewall  8  and void  26  is disposed at the intersection of void  20  with sidewall  4  while void  24  is disposed substantially equidistant from voids  22  and  26 . Preferably web  20  is of the same height as sidewalls  4  and  8  and voids  22 ,  24 ,  26  may extend approximately halfway through the body  30  of web  20 ; however, voids  22 ,  24 ,  26  must extend into web  20  at least the height of a paving block, that is approximately 2⅝ inches to 3 inches and preferably 3½ inches. When block  2  is set on a generally level granular base, a user may remove the top segments  32  and  34  of web  20  and may discard the broken pieces thereof into cavities  14  and  16  or otherwise dispose of them. The user then may fill cavities  14  and  16  with granular material in suitable rises to a level below the top  12  of block  2  which allows placement of plural paving blocks on the fill such that the tops of the paving blocks are flush with the top  12  of block  2 . The smaller paving blocks may be installed in various patterns as desired by the user. 
     The exterior vertical surfaces  44  and  48  of sidewalls  4 ,  8  respectively are provided with narrow vertical indentations or V-shaped grooves  52 , preferably visually dividing the outer surfaces  44  and  48  into thirds. The outer surfaces  46  and  50  of end walls  6  and  10  respectively are each similarly provided with at least one vertical indentation or v-shaped groove  52  which is generally equidistant from the ends of the end walls  6 ,  10  to visually divide end walls  6 ,  10  into halves. Each groove  52  is approximately one fourth inch on each side. Each vertical corner  60 ,  61 ,  62 ,  63  of block  2  is provided with a small bevel  64  along its length. The grooves  52  blend visually with the seams created by bevels  64  on horizontally adjacent blocks  2 . 
     Referring to FIG. 3, it can be seen that the upper outside corners  42  of sidewalls  4  and  8  are rounded along a radius suitable for a stair, approximately a one half inch radius. It should also be understood that the lower ends  54 ,  58  of sidewalls  4  and  8  are enlarged slightly and gradually at ramp regions  68  to strengthen the sidewalls  4  and  8  as well as to give a stronger base for resting the block  2  on a pallet during the forming process and to ease the stripping of the block  2  from its mold. Similarly the lower ends  66 ,  70  of end walls  6  and  10  are also graduated inwardly. The enlargements of lower ends of sidewalls  4 ,  8 , and walls  6 ,  10  create ramp regions  68  adjoining the cavities  14 ,  16 . 
     Preferably the length of end walls  6 ,  10  is nominally 15⅝ inches while the length of side walls  4 ,  8  is nominally 23⅞ inches. The height of each of end walls  6 ,  10  and sidewalls  4 ,  8  is nominally seven inches. Each wall  4 ,  6 ,  8 ,  10  may alternatively be six and three fourth inches high or eight inches high. The thickness of end walls  6 ,  19  and side walls  4 ,  8  is nominally one and three fourth inches and each is rounded on a one-half inch radius at its upper corners. Web  20  is nominally one and three sixteenth inches in thickness and extends between sidewalls  4 ,  8 . Voids  22 ,  24 ,  26  are each nominally one-fourth inch wide and extend approximately three and one half inches into web  20 . 
     FIG. 4 depicts a staircase  40  constructed from blocks  2  arranged such that each next higher course of blocks  2  rests with the front sidewalls  4  thereof on the rear sidewalls  8  of the course of blocks  2  below. The rear sidewalls  8  of block  2  rest on grade. Within blocks  2  are installed a plurality of paving blocks  76  in an array which the user finds aesthetically pleasing. The paving blocks  76  are nominally four inches by eight inches in size and approximately two to three inches in height. The paving blocks  76  are placed upon granular material filled in the cavities  14  and  16  of blocks  2  after the top segments  32  and  34  of webs  20  have been removed, typically by blows with a hammer to the vertical faces of top segments  32  and  34 . The cavities  14  and  16  of blocks  2  are filled with sand or other granular materials to a level such that the tops of the paving blocks  54  are generally flush with the top edges  56  of blocks  2 . 
     It can also be seen that grooves  52  of front sidewalls  4  of blocks  2  create a uniform appearance when viewed with seams  74  between adjacent blocks  2  in staircase  40 . 
     FIG. 5,  6 , and  7  illustrate a suitable mold  78  for forming the blocks  2  in a block-making machine. 
     Generally, the process for making this invention includes block molding the composite concrete block by filling a block mold  78  with zero slump concrete mix and casting the block by compressing the mix in the mold through the application of pressure to the exposed mix at the open upper end of the block mold  78 . Dyes, colorants, pigments and other additives may be added to the mix depending upon the physical characteristics which are desired in the resulting block. 
     The fill is then loaded into a hopper which transports the fill to the mold  78  within the block machine. The mold  78  generally comprises at least four sides bordering a central cavity  94 . A core member  86  may be placed in the mold cavity  94  prior to loading the mold  78  with block mix. Generally, the core member  86  may be supported by elongate hangers  88  positioned across opposing first  110  and second  112  sidewalls. The mold  78  may comprise any material which will withstand the pressure to be applied to the block fill by the head as is well known in the art. 
     The walls of the mold box  82  measure the height and width of the resulting blocks. Accordingly, the mold walls must be made of a thickness which will accommodate the processing parameters of block formation given a specific mold composition. 
     A flat pallet  80  which is vertically displaceable in a conventional block machine is initially seated against the bottom of mold box  82 . Mold box  82  comprises a pair of oppositely disposed generally identical mold box side walls  110 ,  112  connected at their ends by end walls  114 ,  116 . Each mold box wall  110 ,  112 ,  114 ,  116  is equal in height. The in-facing surfaces  118  of walls  110 ,  112 ,  114 ,  116  are each provided with vertically disposed elongate triangular ribs  90  which are spaced generally proportionally along walls  110 ,  112 ,  114 , and  116 . Each rib  90  extends from the top to the bottom of walls  110 ,  112 ,  114  and  116 . At the interior corners  120  of mold  80  are gussets  122  which serve to create bevels  64  on the corners  60 ,  61 ,  62 ,  63  of a formed block  2 . Ribs  90  form the grooves  52  in the surfaces  44 ,  46 ,  48  and  50  of block  2 . 
     A surrounding downwardly concave lip  92  slightly overhangs cavity  94  within mold box  82  in order to form a rounded corner on the outside top edges of block  2 . 
     Resting atop mold box  82  is mold top plate  84  which includes a central opening  96  of rectangular shape which coincides with the shape of cavity  94  of mold box  82 . A surrounding low barrier  126  is fixed upon the top of mold top plate  84  at three sides of its periphery. Multiple slots  98  are provided through mold top plate  84  to receive tabs  100  of hangers  88 . 
     Hangers  88  are fixedly mounted to core member  86  such that when core member  86  is lowered into cavity  94  of mold box  82 , core member  86  is suspended from hangers  88  and disposed generally equidistant on its sides from mold box sidewalls  110 ,  112 , and end walls  114 ,  116 . Hangers  88  rest on mold top plate  84  when tabs  100  are received in slots  98  of mold top plate  84 . 
     Core member  86  is sized such that it may seat on pallet  80  when in place in cavity  96 . Core member  86  is provided around its periphery at its upper outer corners  128  with overhanging shelf  102  which forms inside rounded corners on the block  2 . 
     Core member  86  is provided with ramp forms  104  at the lower end thereof which recede at an incline from the generally planar sides  130  of core member  86 . 
     A recess  106  is disposed centrally in core member  86  to permit block mix to enter and form web  20  of block  2 . Bridges  108  extend into recess  106  at the top of core member  86 , each bridge  108  extending downwardly about four inches to form voids  22 ,  24 ,  26  of web  20  of block  2 . Slits  124  in core member  86  are defined by pairs of bridges  108  and provide fill areas for block mix to enter to form the top segments  32 ,  34  of web  20 . 
     In operation, the mold  78  is generally positioned in a block molding machine atop a removable or slidable pallet  80 . The core member  86  is then placed into the mold box  82 . The mold  78  is then loaded with block mix or fill. 
     Zero slump block mix may be introduced from a hopper above mold top plate  84  and enters cavity  94  and slits  124 . The mold  78  is agitated vigorously for a brief period after which a scraper (not shown) is drawn across mold top plate  84  to remove excess fill. A conventional stripper head (not shown) is depressed upon the opening  96  of mold top plate  84  to compress the block mix within the mold  78 . Preferably the head is patterned to avoid the support hangers  88  and core member  86 . Thereafter, the stripper head further depresses as the pallet  80  is lowered from beneath the mold box  82  as the molded block  2  is stripped from the mold  78 . The ramp forms  104  facilitate stripping of the block  2  from the mold  78  and strengthen the sidewalls  4 ,  8  and end walls  6 ,  10  of block  2  as pressure is exerted on the block mix while in the mold. 
     Once the blocks are formed, they may be cured through any means known to those of skill in the art. Curing mechanisms such as simple air curing, autoclaving, steam curing or mist curing, are all useful methods of curing the block of the present invention. A preferable means for curing blocks is by steam. The chamber temperature is slowly increased over two or three hours and then stabilized. The steam is gradually discontinued and the blocks are held at the eventual temperature, generally around 100-130 degrees F. for two to three hours. The heat is then turned off and the blocks are allowed to cool. In all instances, the blocks are generally allowed to sit for at least twenty-four hours before being stacked or stored.

Summary:
A method for molding a block for an outdoor staircase stair includes filling a form with zero slump mix, the form having outer walls and a core member which includes a vertically disposed central recess extending into the core from its lower surface, filling the recess in the core member, agitating the filled form and recess, compressing the top of the mix in the form, passing a compression head through the form to transfer the formed mix to a pallet, and then curing the formed mix in a misting kiln.