Inclined retaining wall

About inclined retaining walls

There are two main inclined retaining wall types. Concrete block and Gabion basket. One uses concrete as its mass and the other stone-filled baskets. Concrete has more mass than stone and therefore needs less volume on large projects. The choice depends on the driver between cost and a long life span.

Gabion baskets can have a guaranteed life span of up to 50 years depending on the specification of the mesh. Concrete block walls can go far beyond this with a high-quality design mix.

The principles of the retaining wall design are exactly the same. The only variable is the mass of the materials being used. We can advise you on specifications and costs when we understand your project a little more, click here to make an initial enquiry.

Concrete interlocking block retaining walls

Concrete interlocking blocks are normally cast off-site at precast yards and delivered to site. The concrete mix is normally C40/C50 and C50/C60 for severe environments and long life. The blocks are modular in design and generally come in two sizes, 600mm wide x 600mm high or 800mm wide and 800mm high.

The selection of the block sizes will depend upon the retaining wall design. Interlocking concrete block walls are faster to build and have a long life span compared to gabion basket.

The blocks are made from high-strength (50N/mm2) concrete, using natural stone and aggregates. This allows the blocks to have high levels of durability.

As each block has its own lifting pin cast into it – you can easily change the way in which they are configured without the need for specialist lifting equipment or grabs.

Block Sizes

600mm blocks: The block is 600mm wide x 600mm high x 1800mm, 1500mm, 1200mm, 900mm or 600mm long. The walls are built to a modular of 600mm. Each standard block builds 1.08m2 of the wall.

600mm blocks are used for wall heights 1.8m, 2.4, and 3.6m, as you can see in the table.

800mm blocks: The block is 800mm wide x 800mm high x 1600mm or 800mm long. Each standard block builds 1.28 m2 of the wall.

800mm blocks are used for wall heights 3.2m, 4.0m, and 4.8m as you can see in the table.

The maximum height of the interlocking block retaining wall is 4.8m. Above this height, the method becomes expensive.

More information for the blocks, drawings, more detail, and ordering form.

Block finishes

The standard finish on the blocks is plain, smooth concrete.

Texture finishes include rock, slate, timber, and many others can be produced using rubber mat forms.

Construction of the wall

Step 1 – Have the wall designed to suit the site conditions, load case and soil type.

Step 2 – Excavate space for the wall to be built and form a safe slope to stop any retained material from falling into the excavation. Excavate the foundation and construct the foundation to the engineer’s design.

Step 3 – Organise the delivery of the blocks together with offloading and lifting equipment. Place the blocks as detailed in the engineer’s design. Once the first layer of blocks are laid, place the perforated drain at the back of the wall and cover it with granular drainage material.

Step 4 – Continue to build the wall and fill behind it with backfill material as specified by the engineer.

Interlocking block design guide

Height	1800	2400	3200	3600	4000	4800
Block Type	600	600	800	600	800	800
Base Width	1000	1000	2000	1800	2000	2800
Base Depth	100-275	100-275	100-350	100-400	100-450	100-600
Base Rebar	A393	A393	A393	A393	A393	A393
Wall Incline	100	100	100	100	100	100
Surcharge	5kn/m2	5kn/m2	5kn/m2	5kn/m2	5kn/m2	5kn/m2
Factor Of Safety	M=1.5	M=1.5	M=1.5	M=1.5	M=1.5	M=1.5
Cost Index	28	35	74	78	100	146
Sketch

The design table below shows examples of the wall heights and block configurations for a number of gravity retaining walls.

This table is for guidance purposes only and may be subject to change following a detailed, site-specific design developed by an approved structural engineer.