L9 Heavy Duty Retaining Wall Block (RWB)

Planning

Measure the length and height of the proposed wall and multiply these two numbers to calculate the square meter surface area.

For the open block layout and/or using a slider, multiply the number of square meters by 7 for the L7, or 9 for the L9, alternatively when laying the blocks direct next to each other, by 12 for the L7 by 15 for the L9, to obtain the number of blocks required either for the L7 or L9 GreenLock RWB  (excluding possible cutting and/or wastage).

A rule of thumb is, where the wall is less than 1,2m and built to a batter of 75° (from horizontal) and where soil and drainage conditions are good and well compacted, there should be no need for an engineer. Where however, the height of the wall exceeds 1,2m, or if problem soils (clay) or a high water table exists, or where a structure is to be erected on top of the retained fill close to the wall, or even load bearing walls, then the services of an engineer or competent person are required. In such cases, the local authorities should insist on a design and stability certificate from the engineer.

Typical Installation

Measure the wall layout & mark the course using string and stakes. In the closed layout the L7 and the L9 block is self aligning. Dig a trench 400mm deep, 700mm wide for single skin walls and create either a compacted gravel or a concrete base 300mm deep. (Gravel foundations are usually sufficient for walls under one (1) meter in height) It is imperative that the foundation is level in all directions. For additional wall strength the foundation top surface may have a max. of 5 degree angle slanting towards the embankment.

Place first row of blocks onto the foundation, whichever layout is chosen, ensuring that the blocks are spaced with the correct spacing for the open layout and without slider and that for the closed layout the interlocking ends of the blocks mesh as closely as possible. The blocks must be placed level in all direction on the foundation. If the foundation surface is sligthly angled towards the embankment, then the blocks should follow that angle. For additional wall strength the first block row should be imbedded in a mortar bed and the blocks and cavities filled with a weak concrete mix.

Place a flexible perforated drainage pipe, 75 – 110mm in diameter, behind the first blockrow above ground level and wrap this in filter fabric. Ensure that 19mm gravel is wrapped in filter fabric around the drainage pipe. The gravel layer should be at least 400mm wide and 220mm deep.

Please note that for proper drainage the drainage pipe assembly must be placed slightly higher than the ground surface area of the front of the retaining wall. Drainage outlet pipes, connected to the main drainage pipe, should be installed intermittent and in accordance to the length of the wall, allowing any accumulating seepage water behind the wall to escape freely.

“OFF SET”

The L7 and the L9 are automatically spaced correctly if the slider is used and/or if the vertically placed front face groves are used, if the open face layout is used. For more information please read the detailed information under the PRODUCTS heading.

For the L7 and the L9 retainer block it is important that the OFF SET dimension is always in accordance with the chosen layout used and that with each block row laid that the same dimension is maintained. If one follows this advise the finished wall will look stunning, aesthetically pleasing and important for the eye, with evenly fluted joints. If one does not follow this rule, the wall will not be weaker but it will visually look untidy and create a “dizzy” look.

Important Note

The joints between the blocks, whether laid with or without a gap or with or without a slider,

each block row will automatically form an evenly distributed fluted pattern over the whole length and height of the finished wall. To achieve different wall angles, refer to the L9 and L7 PRODUCT specification and write up to select the reqired wall angle. Because of the front lip on the block and on the lip on the slider, both the the L7 and the L9 have three adjustable wall angles to choose from.

Please read the detailed information provided under the PRODUCTS column for the L7 and the L9 retainer blocks. Remember to fill all blocks and cavities with top soil before the next block row is placed if these are to be planted, and to compact the backfill as much as possible and the fill in the blocks only slightly. Behind the RWB wall there should be a layer of minimum 300mm wide of compacted drainage material, such as free draining sand. Compact the backfill of not more than every second block row laid. 

For the L7 and L9 RWB it is not necessary to install geofabric on compacted backfill to wedge between the blocks. The L7 and the L9 has unique additional wall anchor possibilities by using horizontally placed reinforcing Y-bars in the grooves inbedded on the top surfaces of the blocks.  For detailed and additional information please read the information under PRODUCTS information for the L7 and the L9 retainer blocks.