TSB - Polished Concrete Specs

Unfortunately, with existing slabs concrete is not always poured in a suitable way for the concrete to be polished. It is somewhat common to encounter slabs with high and low spots that may not polish to the same luster as the remainder of the floor, and finishers will sometimes push down aggregate in spots where they walk across the slab too soon or when they push down too hard while screeding. This does not mean that existing slabs can not be polished, it just means that it takes a little more work (money) to polish existing slabs and you will end up with a polished concrete floor with extra haracter.

If you have not yet poured your slab, with proper communication you can have a slab poured that will polish beautifully for less money.

Concrete Mix Design

Concrete mixture shall be 3000 PSI or higher.
Any admixtures, plasticizers, slag, fly ash or anything taking the place of Portland-based cement shall be kept to a minimum.
The cement shall be Portland Cement Type I-2, conforming to ASTM C 150.
Maintain concrete temperature below 85 degrees. Keep concrete as cool and moist for as long as possible. In essence, decrease rate of hydration and drying to minimize cracking.
Wet cures are most suitable, but if this cannot be achieved, use a penetrating, dissipating or wax based cure and seal. Do not use a densifier/hardener material due to the grinding of the floor after 6 days.
All mix designs must be approved by the Architect. Send all approved mix designs to us.
The Engineer/Architect shall determine the saw cut patterns, color and layout.
Color loads for integral color should never be smaller than 3 cubic yards.
Use same source for cement, aggregates and pozzolans throughout the job. Monitor and control incoming material consistency. Do not use calcium chloride-based admixtures. Non-chloride admixtures may be used.
Wash out all drums before loading. Keep slumps consistent with a maximum of 4". Minimize driver added water maintaining a .45 water content ratio.
Place concrete to achieve as true and smooth a top surface as possible. Mounds or dips are not acceptable. GC shall control overall flatness and levelness, including on sloping areas to within tolerances permitted by specification - ASTM E1155
- Finish concrete must have a minimum floor flatness rating of at least 40.
- Finish concrete shall have a minimum floor levelness rating of at least 30.
Slab shall be protected from indention and footprints during pour and curing.

Protection of Slab: General Contractor shall protect areas to receive polished concrete finish at all times during construction to prevent oils, dirt, metal and excessive water and other potentially damaging materials from affecting the finished concrete surface. Protection measures listed below shall begin immediately after the slab is poured. (Approximate price to protect slab - $.40-.50 per square foot).

All hydraulic powered equipment shall be diapered to avoid staining the concrete.
All vehicles shall be prohibited on the finish slab area. If necessary to complete their scope of work, drop cloths shall be placed under vehicles at all times.
No pipe cutting machines shall be used on the finish floor slab.
Steel shall not be placed on the finish slab to avoid rusting.
Acids and acidic detergents will not come in contact with the slab.
All painters will use drop cloths on the concrete. If paint gets on the concrete, it must be immediately removed.
All trades will be informed that the slab must be protected at all times.

When should the work be completed? This depends. Edgework is very time consuming and expensive, so sometimes it pays to do the first several grinding steps prior to build out, then complete the process just before fixture and trim installation or substantial completion.

Mock-ups: Samples should be provided on the same slab to receive polish whenever possible. Samples should always be completed using same equipment that will be used for actual job, and edgework should be included in sample. Sample size must be at least 12' x 12' and selected aggregate must be tested to ensure it will accept polish. Approved sample areas may be incorporated into completed work if it remains undisturbed at time of substantial completion.