Pour-in-Place Method
Q1: Can CHENG Pro-Formula Concrete Countertop Mix be used for pour-in-place countertop projects?
Yes, CHENG Pro-Formula Concrete Countertop Mix is not only ideal for precast projects but also for casting pour-in-place projects. And, with a working time of 30-45 minutes, Pro-Formula Concrete Countertop Mix is also ideal for large or small projects.
For a troweled finish, just mix the CHENG Pro-Formula with sacked concrete, according to instructions, place in your mold, and trowel the surface to achieve your desired finish.
If you are planning to grind the surface and expose aggregate, simply screed the surface to ensure the top is flat and free of dips or high spots and allow to cure 4-7 days before grinding or polishing.
Q2: Can CHENG NeoMix Original Products be used for pour-in-place countertop projects?
Yes, however, the working time of CHENG NeoMix Original Products is shorter than might be required to successfully pour a large project. If you are pouring a large project which will require more than 30 minutes to place the concrete, we recommend customizing your mix. With CHENG NeoMix Original Products, you can increase the working time to 45 minutes by reducing the powdered portion of our NeoMix Original Admixture by half.
You cannot however eliminate the admixture completely as it contains key ingredients necessary to strengthen your concrete countertop mix (you want to keep and use all the micro-reinforcement fibers that come in the admixture). If you reduce the admixture, please remember to allow for a longer curing time (2-3 additional days) prior to de-molding and grinding/polishing.
Another important note is that most pour-in-place concrete countertops will not display integral decorative aggregates as most people leave the troweled finish untouched. If you are planning on grinding, you can try to sprinkle decorative aggregates on the surface of the concrete countertop during troweling for a more unique finish.
For more information about the pour-in-place technique, refer to Appendix B, "Pouring a Countertop in Place", in Concrete Countertops.
Q3: Why do you focus more on the precast concrete countertop method vs. the pour-in-place method?
CHENG Concrete and Cheng Design (both founded by Fu-Tung Cheng) do not specialize in pour-in-place countertops because we prefer the benefits of precast, or cast-in-mold, countertops and projects. Our clients value the sculpted drainboards and details we incorporate into their concrete pieces. However, we realize that certain applications, or projects, call for the pour-in-place technique and is used by some professionals or DIYs.
Q4: Can I pour-in-place for a hand-troweled finish?
Yes, a hand-troweled treatment is the most popular finish given to pour-in-place concrete countertops. While we prefer pouring our concrete countertops into a mold for better control of the surface finish and integration of sculptural elements, many people appreciate the more rustic look and feel achieved by hand-troweling. Hand-troweling concrete is an art unto itself and requires a lot of experience to master.
For more information on hand-troweling, refer to Appendix 3, "Pouring A Countertop In Place," in Concrete Countertops.
Q5: What is the best way to achieve a smooth finish on a poured-in-place countertop?
Screed the countertop piece with absolute precision, and have an expert trowel the surface. Timing and feel are critical in getting a flat, smooth finish. If you're planning on lightly grinding and polishing the concrete after it has sufficiently cured, you'll want the flattest surface possible to avoid extra grinding work.
Ultimately, however, a troweled finish will never be as even, smooth, and glossy as a pre-cast countertop. For more information about pouring a countertop in place, refer to Appendix B, "Pouring a Countertop in Place," in Concrete Countertops.
