Shaped concrete blocks are provided each having generally parallel top and bottom surfaces, a shaped front face (adapted to be exposed as the wall element), side walls and a rear wall. The one surface of each block is provided with shallow parallel grooves, while the other surface of each block is provided with rows of projecting knobs respectively positioned correspondingly with the grooves. In this manner, successive blocks may be stacked on top of one another with the knobs engaging the grooves.

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.

A cast concrete block for use in a vertical retaining wall. The block has a generally vertical front face which is visible when the block is stacked in a retaining wall. A pocket is formed in the block to project from a portion of the visible face of the block. The pocket has an upwardly directed opening which is exposed for receiving soil and plants when the block is located in a vertical retaining wall. The opening may extend through the block to a rear of the block.

A construction unit adapted for constructing a retaining wall to keep a bank of earth from sliding or water from flooding, includes a plurality of U-shaped concrete panels having at least one drain, at least two I-shaped concrete panels each of which is connected to the rear end of one of the U-shaped panels, and at least one concrete shelf plate both ends of which are received by shelf receiving recesses formed in the inner surfaces of the U-shaped panels and the I-shaped panels. The U-shaped panels are vertically piled and further include a vertical engagement means to engage with the plurality of said vertically piled U-shaped panels, and connection members to connect to the I-shaped panels. This vertical engagement means includes an upper hole formed in the top surface of a lower panel of the vertically piled U-shaped panels and a lower hole formed in the bottom surface of an upper panel of the vertically piled U-shaped panels, and a steel bar installed in the upper and lower holes. Concrete is filled into each of the cavity defined between the horizontally adjacent panels, and crushed stones are packed into the inner space defined by said U-shaped panels and two I-shape panels.

Retaining walls are formed from one or more tiers of concrete blocks. Top projections on all except the uppermost tier of blocks are received in recesses in the bottom of blocks in an adjacent upper tier. The top of the retaining wall may be finished with blocks which have a surface portion recessed below an upper edge of the face of the block for extending top soil or other material up to the block face. Alternately, the top blocks may form a drainage ditch which extends along at least a portion of the top of the retaining wall. Blocks used in tiers below the uppermost tier may have troughs suitable for filling with soil and plants. The exposed faces of the blocks are textured and, optionally, may be colored to simulate the appearance of stone or rocks.