How to Make a Concrete Countertop: Mix, Cast and Cure

How much water goes into three 80 lb bags of countertop mix? QUIKRETE’s 2018 sheet puts the final amount at 24 to 27 pt, while its 2007 sheet says 21 to 24 pt. The two sheets differ on more than water, so this guide walks the casting sequence and flags every gap.

What Is Countertop Mix Made For?

QUIKRETE Countertop Mix is made for casting concrete countertops, and one 80 lb bag yields about 0.6 cu ft. The 2007 sheet calls it a mix for precast and cast-in-place countertops. Color goes into the mixing water, using QUIKRETE Liquid Cement Color or Stucco and Mortar Color.

This article follows one running example: a 72 x 25 x 1.5 in top. The concrete countertop calculator shows 3 bags for it, which includes 10 percent waste. Everything below treats those 3 bags as the batch.

The sheets also list strength by age. The 2018 sheet gives typical results by ASTM C39: 2,000 psi at 24 hours, 4,000 psi at 7 days and 6,000 psi at 28 days. The 2007 sheet gives 2,500 psi at 3 days, 3,500 psi at 7 days and 5,000 psi at 28 days.

Which Forms and Release Agent Does the Pour Need?

Coat the forms with a light form-release agent and support them so they stay undisturbed after the pour. The 2018 sheet says the forms may need to stay undisturbed for 18 or more hours. The 2007 sheet says 48 to 72 hours.

The sheets state no thickness limit and no weight limit for a finished top. For the weight of your own top, try the concrete weight calculator.

How Much Water and How Long Should You Mix?

Put about 1 gal of fresh water per 80 lb bag in the mixer first, add the bags, and machine-mix at least 3 minutes after the final water (2018 sheet). The mixer can be a barrel or mortar mixer with at least 1 cu ft of capacity per bag mixed at once.

If the mix is too hard to work, add water sparingly until it flows. The final water is 8 to 9 pt per bag, and the recommended slump is 5 to 7 in. The sheet says not to exceed that slump. QUIKRETE Concrete Mix (1101) is a different product, with a typical slump of 2 to 3 in.

1. Mixer size. 3 bags x 1 cu ft = at least 3 cu ft to mix all three at once.
2. Starting water, 2018 sheet. 3 bags x 1 gal = 3 gal.
3. Final water, 2018 sheet. 3 x 8 pt = 24 pt, and 3 x 9 pt = 27 pt. At 8 pt per gallon, that is 3.0 to 3.375 gal.
4. 2007 sheet. About 7 pt per bag goes in first: 3 x 7 = 21 pt, or 2.625 gal. Final water is 7 to 8 pt per bag: 21 to 24 pt, or 2.625 to 3.0 gal.
5. Time limit. Mix no more than can be used in 30 minutes (2018 sheet), or placed in 1 hour (2007 sheet).

The two water ranges overlap only at 8 pt per bag. Check your bag before you pick one.

How Do You Place, Consolidate and Finish the Pour?

Fill the form to full depth at one end and work toward the other, placing the mix quickly and continuously (2018 sheet). Work it around any inclusions that sit in the mold.

• Remove bubbles. Use light rodding to remove bubbles. Vibration may help. The 2007 sheet says to vibrate to remove trapped air.
• Screed and float. Screed with a sawing motion, then float with a darby or bull float.
• Trowel. Trowel finish once the concrete reaches thumbprint hardness.
• Bubbles that remain. Bubbles from trapped air may be grouted after demolding.

The 2018 sheet also says the top may be sanded or polished.

When Can You Pull the Top From the Mold?

The 2018 sheet allows removal at 18 or more hours, while the 2007 sheet says 48 to 72 hours. Start curing as soon as possible and continue until the top leaves the mold.

The 2018 sheet moist-cures by tenting plastic sheeting over the top, without letting the tent touch the fresh concrete, because contact leaves marks. The 2007 sheet says to cure 48 to 72 hours under plastic. As general background, the NRMCA says concrete in a dry environment can lose as much as 50 percent of its potential strength compared with moist-cured concrete.

Take a pour at 4:00 pm. Eighteen hours later is 10:00 am the next day. The 2007 range of 48 to 72 hours ends at 4:00 pm two to three days later. Use extreme caution when removing inserts or knock-outs.

Can You Add Glass, Stone or Color, and What About Sealing?

Yes, within a limit: the 2018 sheet allows not more than 20 lb of glass or colored stone per 80 lb bag. For the 3-bag example, that is 3 x 20 = 60 lb at most.

The 2018 sheet calls for trial pours when you use decorative additions or colors. The 2007 sheet gives no additive limit.

For sealing, the 2018 sheet says kitchen countertops should be sealed with a suitable high-solids acrylic sealer, an epoxy coating or food-safe wax. It cites sanitary use and acid resistance, for example against citric acid and vinegar, and says to follow the sealer maker’s directions. The 2007 sheet names a high-solids acrylic sealer or food-safe wax for kitchens.

Sealer timing and products are outside this article. To estimate how much sealer a top needs, try the concrete sealer calculator.

How Do the 2007 and 2018 Sheets Differ?

They differ on water, time limit, demold time and strength, and the 2018 sheet adds slump, a stone limit and epoxy as a sealing option. The 2018 sheet is the newer one, with a PDF created in 2018; the 2007 PDF title reads “Countertop Mix 3-08-07”.

These are two different documents for two different dates, and this article cannot tell which one your bag follows. Follow the bag.

FAQs About Casting Concrete Countertops

Sources and Further Reading

This article reports what the sheets say; it is not a design for a particular countertop. Steps here follow QUIKRETE’s Countertop Mix data sheets named in Sources and apply to that product. Reviewed for accuracy by Prof. Dr. Khalil Mudassar, PhD. Last updated 2026-10-19.