Polished Concrete Floors vs. High SCM Slabs

Max Driscoll

VP, Sustainability

AECOM, Construction Management

LEEDuser Basic Member

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August 20, 2024

On a large sports project, we worked with the structural engineer to spec low carbon / high SCM concrete mixes. Much of the floor area will be sealed and polished concrete, and a concrete sub is pushing back on the SCMs saying they should not be above 20% (with a preference for 0%) for the polish to finish properly, per the manufacturer. Anyone else encounter this issue? Also, are there sealers and polish you all have found work better with higher SCM slabs (40%)?

Thanks,

Max

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Melanie Goerke

Manager, Sustainability

Page

LEEDuser Premium Member

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Tue, 08/20/2024 - 14:30

Max, We have found this issue to be true, and typically pursue higher SCM replacement in other mix designs on the project. Out here on the east coast, a large industrial client of ours did several test pours/polish areas and found that higher percentages of fly ash/slag can affect the clarity of the final polish. When the mix designs have higher SCM's, the set time can vary less uniformly than a more pure portland cement mix, and if polished too early, might result in cloudiness or a "smeared" appearance. We don't do polished/exposed floors over 15% because of this reason and instead find those reductions elsewhere in our mixes.