Gabion Basket v Concrete Blocks to Build Retaining Walls

We are frequently asked what is the cost difference and benefits between the construction of a retaining wall using gabion baskets or concrete blocks. In a nutshell the differences are:

Cost difference – Gabion baskets are more competitive to build

Life span – Concrete blocks have far greater life span

Speed of construction – Concrete blocks can be built 5 x faster on site

Cost Difference

The unit rate for a m3 of gabion basket is built up as:

Basket £23

Stone delivered to site at 1.6 tonne m3 £36

Site plant and labour with an output of 20m3 per day £24

Contractor overhead and profit £15

Total = £98m3

The unit rate for m3 of concrete block is built up as:

Manufacture and delivery of block m3 £156

Site plant and labour with an output of 100m3 per day £6

Contractor overhead and profit £25

Total £187m3

The above costs are approximate as material specifications and location will make a difference to the overall cost.

Life Span

The life span of a C50 concrete block is between 125 to 150 year if not more. The blocks have no reinforcement so they will not crack and degrade from steel corrosion.

The like span of a gabion basket depends on the specification of the wire basket. The normal life span is between 40 and 60 years.

If the retaining wall design life span is more than 60 years it will be more cost effective to use concrete blocks.

Speed of Construction

The site output to build a gabion wall is 20m3 per gang day using a 360 machine and three men.

The site output to build a concrete block gravity retaining wall is 100m3 per day using a tele-handler and two men.

The difference in out put is 5 x faster to build a concrete block retaining wall than a gabion retaining wall. On some projects this can take weeks off a program. If speed is the driver concrete blocks is the answer.