Day One Article
BETTER CONCRETE BEGINS WITH DAY1
When placing a concrete slab, you want everything to be perfect. But of course, it never is. Wind, heat, low humidity, even strong sunshine can dry out the surface, or cause it to set prematurely, before you can finish it properly. “Losing the slab” is every concrete contractor’s nightmare, because fixing it can eat up all the profits of a job.
There is a new product that can save a concrete finisher from this unpleasant outcome. DAY1 Finishing Aid, from Lythic Solutions, truly represents a new category of product. It is not a film-forming or membrane-forming compound, but it helps keeps moisture in the slab. It is not a chemical set-retarder, but it helps keep the surface workable longer and brings up more cream for a smooth, easy finish.
Best of all, it eliminates the need to add excess water (“blessing the slab”) during finishing. Added water weakens concrete. It raises the water/cement (w/c) ratio, and a low w/c ratio is one of the key factors in concrete strength. When water is added to the surface, it weakens the surface and makes it more porous. The surface is more vulnerable to wear, and liquids can get into it more easily, including staining liquids. Blessing the slab is especially bad for colored concrete, since it can cause color shifts and matching problems. DAY1, on the other hand, gives you the workability you need without raising the w/c ratio, so it doesn’t damage the long-term performance of the surface, and it doesn’t affect color.
DAY1 is sprayed on the slab as soon as the concrete is screeded off, and then bull-floated into the surface. It contains colloidal silica, a densifier that reacts with the lime (calcium hydroxide) in the cement, and turns it into useful cement paste. This increases the amount of cement paste, and improves its quality, making it easier to close the holes quickly without adding excess water. DAY1 slows down evaporation through the surface, too, protecting the concrete from moisture loss.
When the slab has set enough to start troweling, DAY1 is applied again, and troweled into the surface. It lubricates troweling. You can hear the power-trowel speed up the moment it’s sprayed on. It raises the cream and eliminates the need for “blessing the slab” with excess water. For the finisher, it means a buttery surface to work with.
It also means that sun, heat, wind, and low humidity will not dry out the surface as quickly. It stays workable longer, about 15-45 minutes longer.
This effect was tested at World of Concrete 2013 in side-by side “torture-tests.” Fresh slabs were poured over hot asphalt three times a day, in the bright sun and dry air of Las Vegas. They were hot mixes, designed to set up fast. Under these extreme conditions, they often set completely in less than 45 minutes. There were three slabs in each pour: one finished with water, one finished with DAY1, and one finished “dry.” Professional finishers from all over the world volunteered to run the trowels and test the performance of the finishing aid.
Workability was timed. On the best set of slabs, the “dry” slab lasted 115 minutes, the water-added slab 135 minutes, and the DAY1 slab 160 minutes. That extra 45 minutes is 39% more finishing time.
On the most extreme pour, the dry slab was gone in 20 minutes, the water-added slab in 22 minutes, but the DAY1 slab was workable for 35 minutes, an increase of 122%!
Similarly positive results have been seen on commercial jobsites. Robert Kimball, foreman for Poppoff Inc. in eastern Washington state, described using DAY1 on a 7000 sf pour in hot, dry weather. “We were trying to pour it all out before the whole crew fell back to begin finishing.” Their method was to place the fresh concrete, apply DAY1, and move on with the pour. “When we were ready to trowel, the bottom was crazy hard, but the surface had a nice cream on it. It was probably 90 degrees outside, and after feeling how hard that concrete was underneath, I would normally think the surface would be right there with it. It was probably about 4 hours after we poured, but the surface was waiting for us. It pretty much saved me.”
Mike Seegmiller, a ready-mix producer in the Salt Lake City area, has seen several projects where contractors were saved from losing the slab by using DAY1. The most extreme example occurred at his own yard. They had a load of “hot mud” – concrete that had been returned from a job, and was hours old. They decided to try and include it in a section of the yard they were re-paving, alongside other sections of fresh concrete. “It was a terribly windy day, and hot, a day you wouldn’t pour concrete under normal conditions. With DAY1, it finished better. It made the finishing of it easier.”
Joel Funk a contractor in Saskatchewan, Canada tried it on a pour in early summer, when the humidity can get down around 20%. “It gives a better finish to the floor. It seemed to have a – I hesitate to say a shine, but a slight sheen. Water would tend to puddle, like on a sheet of wax paper. It didn’t let the water through really fast. I pointed that out to customers; if you spill something you have more than 3 seconds to clean it up.”
Because it extends workability and speeds finishing, it can literally save labor and time. Some contractors have described it as “like having an extra finisher on the job,” and others say it’s a bit like having finishing “insurance.”
Contractors have also reported using it to solve a variety of special problems. Poppoff used it in a food processing facility that was specified to receive one pound of shake-on hardener for every square foot of floor. “We couldn’t get the hardener worked in. Trying to work a bunch of powder into concrete, it dries out the surface.” They added DAY1, and the cream rose. They were able to work in all the hardener they needed.
There have also been recent trials applying it to roller-compacted concrete (RCC), a product that is notorious for its rough, pockmarked surface. Applying DAY1 from the roller tank, they got a very smooth surface and eliminated the problem of tiger-striping. Someone described the result as “taking the ugly out of RCC.”
One question that often arises concerning DAY1 is the fact that it is a water-based treatment, so it is adding water to the surface. Normally, that would be expected to raise the w/c ratio, which, as mentioned earlier, is bad for the concrete. In fact, DAY1 lowers the w/c ratio.
DAY1 adds much less liquid to concrete than blessing the slab with water. The typical finisher using DAY1 adds only about 20% of the total liquid he would add if using water.
More important, the liquid and the silica in DAY1 react with calcium hydroxide, making additional useful cement paste. This reaction actually uses up more water than is added with DAY1. It bind excess water that’s in the concrete for workability but is not actually needed to react the cement, reducing bleed water. Thereby, it lowers the w/c ratio at the surface, making the surface harder and more durable.
DAY1 is available through the Solomon Colors/Brickform network. It ships as a concentrate to save shipping costs and lower the environmental impacts of transportation. It is available in 1-gallon and 5-gallon packages, which are diluted 4:1 with water to make 5 gallons and 25 gallons, respectively. It is applied at a rate of 1000sf/gal.
For example, 1 gallon of concentrate makes 5 gallons of ready-to-use mixture (RTU), which covers about 5000 sf.
Another interesting effect of DAY1 has been observed on some jobsites: the DAY1 smile. It appears on the faces of finishers the first time they try edging or hand-troweling with DAY1. It was first documented at World of Concrete, and has since been observed in many locations where DAY1 is in use.