Concrete is a material made up of cement, stone, sand, and water. Cement is the binder that holds everything together. It goes into the mix as a powder but when combined with water it hardens through a chemical process called hydration. The sand and rock, usually called aggregates, are bound by the hardened cement paste and give strength to the mix. Products like Quikrete® 5000 or PakMix® 5000 are bagged concrete mixes that contain all of the dry ingredients in pre-determined proportions.

These are the sand and rock portion of concrete. In high-strength (5000 PSI) bagged concrete, aggregates include rock material 3/8" in diameter. Since concrete mixes are bagged in different regions around the country, the rock portion of the mix will generally look a little different from one region to another. Aggregates are only visible if you grind your countertop surface.

We use the term "Decorative Aggregates" to describe semi-precious stones used to create surface interest in a ground concrete countertop. Decorative Aggregates are needed only if you intend to grind the surface of your countertop. If so, place the semi-precious stones in the base of your mold (intentionally scattering them throughout) using a bit of spray glue to secure them to the base. Spray glue will keep the stones at the surface of the countertop when you de-mold so that a bit of grinding will expose them (some stones may migrate during vibration so not all placed stones will be exposed even with grinding). Visit Product+Technical FAQs for more on Mold-Making and Grinding.

This occurrence refers to a whitish coating of calcium-carbonate mineral salts that can form on the surface of a concrete countertop piece. If moisture seeps through the concrete, it can bring with it free calcium salts in the concrete, which it deposits on the surface as it evaporates. Efflorescence can occur due to the unpredictable and uncontrollable composition of sand and aggregates in bagged concrete. See "Efflorescence," page 149, in Concrete Countertops.

This refers to a concrete countertop surface that has been ground down and then polished with diamond grinding tools. By cutting into the surface, aggregates (decorative or non-decorative) placed at the base of your mold will be exposed. Grinding creates a terrazzo-like finish.

Pads under 800 grit. Grinding pads cut into the concrete countertop surface and work much like sand paper so that lower number grits remove more material.

Pads 800 grit and higher. They provide luster or sheen to the countertop, by removing a very minimal layer of material.

A technique where mold construction and pouring occur onsite. To even out, the concrete surface requires troweling. There are advantage and disadvantages to this technique when making countertops. Visit Product+Technical FAQs for more discussion.

A technique where mold construction and pouring occur offsite. Even surfaces occur more often with this technique, but it does require moving the final piece to the installation site. There are advantages and disadvantages to this technique, but it is the Cheng-preferred technique for making concrete countertops and is also recommended using our CHENG Pro-Formula product. Visit Product+Technical FAQs for more discussion.

Pounds per square inch.

Quikrete 5000 and PakMix Super 5000 are sacked concrete mixes or "concrete composite products" that are pre-packaged mixes of the individual ingredients that make up concrete (including graded sands, aggregates, and cementitious material or fines). Both these mixes are rated to withstand pressures of up to 5000 pounds per square inch (PSI) when fully cured, resulting in a denser, harder, and more durable surface. Any sacked concrete product rated at 5000 PSI is appropriate for use with our concrete countertop products.

See PakMix 5000.

To determine the surface area of your countertop:
L (Length in feet) x W (Width in feet) = Surface Area

If you are measuring in inches:
L (Length in inches) x W (Width in inches) /144 (inches per s.f.) = Surface Area

Terrazzo is an age-old technique of casting bits of stone into another substance and then grinding the hardened surface away to expose the added material. You can add broken glass to the entire mix as though it were another aggregate, or simply scatter glass into the mold and then pour over it.

Our CHENG Pro-Formula is measured for projects in cubic feet. To determine the cubic feet of your countertop mold:
L (Length in inches) x W (Width in inches) x T (Thickness in inches)/ 1728 = Volume in cu.ft.

Once you determine the cubic feet of your mold, you can then determine the amount of CHENG Pro-Formula (available in 1 or 3 cu.ft. containers) and sacked concrete you'll need to make your countertop.

This refers to a countertop surface that has not been ground, or penetrated to expose any aggregate texture. Visually, an unground surface provides a smooth surface look. The surface can be treated with a matte or polished finish with a diamond buffing and polishing tool. Polishing will not expose the aggregates.