We have finally started building something (upwards I mean), which is quite exciting. Work has started on the retaining wall, and we are using a concrete formwork system called Stepoc.
It is a fairly simple system: you dry-lay the blocks, slotting them over the rebars (reinforcing bars made from steel), making sure you get the first course completely straight and level. We are going to go up seven courses, then pump in some concrete, before building a second lift (up to 12 courses). The top will then be shuttered out, creating a wall height of 285cm.
Why are we using Stepoc?
Stepoc are modular formwork blocks, designed to create incredibly strong walls. They have cutouts that slot securely over rebars, and channels at the side which ensure they lock together. Because they are built dry, with no mortar joints, it doesn’t demand the labour of a skilled bricky. It can therefore go up incredibly quickly.
Once the wall is several courses high, concrete is pumped in to the void. This solid concrete wall has incredible thermal mass and also lends itself really well to the important job on our project of holding back the bank.
The alternative would have been a reinforced concrete wall, which involves hiring and erecting the shuttering. That comes at a significant cost. While Stepoc blocks seem expensive, they can be constructed easily and the block itself forms part of the wall, meaning you need less concrete to fill the void (or less than you would need for shuttered walls).
What’s more, we don’t have as many labourers available in this country who are skilled at building shuttered concrete walls. Stepoc has the advantage of being a more accessible way to build this type of wall.
What is a retaining wall?
A retaining wall is built to withstand the lateral pressure of soil. This is usually required where a building sits in a slope or is partially subterranean. Basement levels often require this type of structure to resist both the weight of soil and hydrostatic force of the surrounding earth.
You might also see a retaining wall in a terraced garden to create levels, or at the roadside if the carriageway sits in a hill or ridge.