Concrete gets a bad rap, but there are times in construction when it’s use is unavoidable. Price & Myers engineers use ground-bearing slabs where there are good soil conditions, to span between any natural soft spots in the ground below and support the floor loads. It’s a more efficient use of concrete than a suspended slab which tends to need a deeper concrete slab with more reinforcement to span between supports. But is there a way to make ground-bearing slabs even more efficient?
The study below demonstrates three different types of ground-bearing slabs.
In diagram 1 we have a typical example of a ground bearing slab – 150mm deep with a single layer of mesh reinforcement on blinding and well compacted hardcore. The number in red indicates the amount of carbon generated per square kilogram of foundation.
In option 1 we omit the reinforcement, reducing the strength of the concrete and adding cement replacement materials to the mix. You can see the amount of carbon is lowered. Lower numbers are good! But can we do better?
In option 2 we reduce the depth of the slab, which reduces the minimum reinforcement required, keeping the lower strength of concrete and the cement replacements in the mix. This method has halved the carbon generated by the slab, while maintaining the integrity of the slab and will be adopted on all suitable P&M jobs in the future!
A few small changes can make a big difference to carbon generation in the built environment. Every bit adds up!
If you’re techy-types like us, we’ve added the calculations for you to check the numbers.