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Let’s go for the right mix

Why spend so much time perfecting concrete structures, only to bash chunks out of them? By Barney Green

How many sites rattle to the sound of holes being made in recently placed, sound structural concrete?

Why do we do that?

We have teams of designers poring over the big picture and deciding the structural elements and the finishes. They look into loads, vibrations, colours, weights, energy profile, carbon emissions, all manner of calculations and issues that impact the finished building. We then set the spec.

We spend days accurately setting up supports, frames, shutters, forms, lining and levelling. Then, we position reinforcement, shear studs and cover spacers. Finally, we pour a mix designed to achieve a specific structural performance: we build the frame and slabs.

The very next thing we do is get a drilling machine and start bashing holes in it. We have issues with productivity and cost. Drilling takes time. We risk compromising the structure by hitting rebar and reducing cover.

As considerate contractors we have issues with noise and nuisance. We have issues with health and safety and dust.

Planning is the single greatest contributor to good health and safety. It is also the single greatest contributor to better price, performance, productivity.

Planning ahead

So why can’t we plan the holes? This is another example of the fragmentation and the lack of co-ordination within the design and the build process.

When the core is being formed, has the contract for the lift installation been let? When the building edge is being formed, do we know the needs of the cladding fixing? When the floors are being cast, have the service runs been agreed?

The devil is in the detail, and it must surely fall to the manager of information flow to gain early commitment and then cascade these details to maximise this opportunity.

There are prospects for massive savings in cost, programme and material, as well as opportunities for big improvements in project safety.

We can remove HAV, dust, and noise at a stroke. We can confidently build more offsite, and, with accurate setting out, components should simply fit together when they arrive.

It requires early decision making and commitment, detailed planning, close communication and co-ordination. Sounds like a job for a client’s project co-ordinator.

Barney Green is business development manager of Combisafe