Concrete Walls in Kent

Four types cover most enquiries, each with very different requirements. A retaining wall is decided by how much ground and water sits behind it; a basement or below-ground wall does the same job while also keeping water out of an occupied space; a foundation or ground-beam wall carries structure; and an agricultural push wall or silage clamp wall takes impact from machinery and chemical attack from what is stored against it. Naming which of the four you are pouring is the first thing that changes the order.

Retaining walls are engineered, not estimated

A retaining wall fails by overturning, by sliding, or by the ground behind it failing, and all three are matters of design rather than construction. Height, surcharge from anything standing behind the wall, drainage behind the wall, and the reinforcement in it are set by a structural engineer.

That design gives you the concrete designation, which will be a reinforced concrete class rather than a general-purpose mix. We supply what it names. Where a wall is retaining any meaningful height of ground and no design exists, the missing item is the engineer, not the concrete.

Below-ground walls and water

Waterproofing of below-ground structures in the UK is covered by BS 8102, which sets out the forms of protection available. One of them, described as Type B, is structural integral protection: the concrete itself is the barrier rather than a membrane applied to it.

Where that is the approach, the concrete is specified accordingly and the workmanship carries the performance. Joints between pours become the critical detail, since water finds a construction joint long before it finds sound concrete. If your design calls for water-resisting concrete, say so at enquiry stage, because it is a specification and not a finishing option.

Agricultural walls and what they are exposed to

Push walls and clamp walls take repeated impact from loader buckets, so they are heavily reinforced and generously proportioned.

Silage introduces a second problem. Silage effluent is acidic and attacks ordinary concrete, so clamp walls need a mix that accounts for that exposure. Construction and containment of silage stores in England are also governed by the Silage, Slurry and Agricultural Fuel Oil Regulations, which set requirements for how effluent is contained. Check the current requirements with the Environment Agency before building, because they govern the design your concrete goes into.

Formwork, lifts and cold joints

Wall formwork sees the same pressure question as a column, and the same reference, CIRIA Report 108, governs it. The rate of pour is part of the design.

Pour a wall in continuous horizontal layers, each one placed and compacted into the one below before that layer stiffens. Where a pour stops for long enough for the previous layer to set, the result is a cold joint, which is a line of weakness and a path for water. Planned construction joints are made deliberately, in the right places, with the right preparation. Unplanned ones happen when the concrete supply cannot keep up with the placing.

That is why the delivery pattern matters on a wall pour and why it is worth agreeing with the supplier rather than assuming.

Working out wall volume

Length times height times thickness, in metres. A wall 10 metres long, 2 metres high and 250mm thick is 10 x 2 x 0.25, so 5 cubic metres.

Add the base. Most retaining walls sit on a footing or toe that is wider than the wall itself, and it is frequently a larger volume than the stem above it. Deduct nothing for reinforcement, and allow for whatever remains in a pump line at the end.

Getting a wall pour scheduled

Send the wall type, its dimensions, the designation from the design, whether it is below ground, and the placing method. Your quotation, delivery and payment are agreed directly with the approved supplier appointed to your pour.

Wall pours are the ones where continuity of supply matters most, so tell us the placing rate you need as well as the total volume. An approved supplier would rather plan the sequence than send everything at once.