Question: What are some important steps to remember in setting up a mixing station?
Answer: A properly set up mixing station is an important part of a successful topping installation. Not only should the mixing station be outfitted with all the equipment and supplies you’ll need to mix materials properly, it should also provide efficient access to the point of placement so you can deliver materials in a timely fashion. Consider the following:
Protect surrounding surfaces
Short of grinding or acid etching, it’s nearly impossible to remove any spillage that occurs during mixing. So your first task is to protect the surface you are mixing on, especially if you’re working indoors. Cover the entire area with a drop cloth, building paper, plastic, or similar protective covering. Also lay out a paper or plastic covering over the path running from the mixing station to the drop-off point. This will protect the path from any material that gets on the bottom of your shoes and on the wheels of the concrete buggy or wheelbarrow you’re using to cart materials. And don’t neglect to protect the floor you’re resurfacing if you need to carry or cart materials across it. The last thing you want to do is contaminate the surface you worked so hard to profile, repair, and prime.
Horizontal surfaces aren’t your only concern. Mixing can create splatter that gets onto nearby walls and other vertical surfaces, especially if you’re working in a confined space. Take the time to mask off these surfaces with plastic or paper sheeting.
Don’t set up too close to the work area
While easy access is important when locating your mixing station, don’t set up too close to the slab being resurfaced.
If you’re mixing cement-based products, some of the fine dry material could go airborne before it’s thoroughly blended with the liquid component and end up settling on the concrete surface, where it will act as a bond breaker. In fact, whenever you’re mixing outdoors, be alert to anything downwind of the mixing station. We learned that lesson on one job, when some of the material we were mixing went airborne and landed on a very expensive car. Fortunately, the car owner accepted our sincere apologies, and a car wash on us.
Address noise and odors
Is your resurfacing project in an occupied building or within shouting distance of a home or business? If so, be sensitive to the ears and noses of the people around you by minimizing the use of loud mixing equipment and products that emit odorous fumes, such as solvent-based materials. Proper ventilation is imperative when you’re mixing materials in occupied indoor spaces or near food preparation facilities, such as a restaurant.
Provide backup sources for power and water
You can’t mix most topping materials without having power and water on hand, so it’s essential to ensure an uninterrupted supply. Even on jobs where electrical outlets and working plumbing are readily available, you can’t rely on these sources alone, as I’ve learned first-hand. We were making excellent progress on a large mall construction project when a backhoe hit the water main and shut off our source of water. Luckily, we had the foresight to fill four 55-gallon drums with water, which allowed us to continue our mixing operations. On another job, lightning struck the building we were working in and knocked out the power supply as we were trying to mix and place a skim coat. This time, our backup generator (with a full tank of gas) saved us. Also, be sure to check out the location and capacity of your power supply. On some jobs, you may need 220-volt three-phase power to operate certain equipment, like a pump. Also have extension cords in case you need to plug into a distant outlet.
Bob Harris, founder of the Decorative Concrete Institute, Temple, Ga., and senior decorative concrete consultant for Structural Services Inc., has more than 25 years of experience in the construction industry. He conducts seminars in architectural and decorative concrete worldwide, is involved with numerous associations, and is a popular speaker at World of Concrete and other events. The information in this article is based on Bob Harris’ Guide to Concrete Overlays & Toppings, which now comes with a DVD that provides step-by-step instructions for rejuvenating floors and exterior finishes. Visit www.decorativeconcreteinstitute.com.