Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.
Issue link: http://concrete.epubxp.com/i/114208
INNOVATIONS REPORT FINISHER, CIM STUDENT CREWS EXPERIENCE W/C-FRIENDLY TROWELING AID FIRST HAND Breezy and under the deep blue sky typical of the Mojave Desert, the Las Vegas Convention Center Gold Lot proved a fitting environment for CIM students and volunteer finishers to push slab-grade concrete mixes to their limit and gauge Lythic Day1 Troweling Aid performance. Temperatures were in the low-to-mid 60's, but the air was dry. The sun was strong and baked the asphalt pavement, speeding up the concrete's chemical reaction from beneath as well as heating it from above. A light wind often came up in the afternoon. Wind and dry air were robbing moisture that the trowels needed. The object was to experience the failure colloquially known as "losing the slab" on the 'dry' control slab, and then see if the water or Day1 slabs did any better, and by how much. Montana finisher and Day1 demonstration volunteer Curtis Kountz observed that even though the slab had gotten hard underneath, "the top 1/8th inch was really workable. I had plenty of time to work with it." He and peers from across the continent and around the globe took turns powertroweling and hand-finishing edges in the Las Vegas Convention Center Gold Lot demonstration. Over the course of 10 pours, the concrete never behaved exactly the same way twice, a good analog to the unpredictability slab finishers confront daily. MTSU Concrete Industry Management students worked alongside concrete professionals to place fresh slabs for the Day1 Troweling Aid test. 38 | MARCH 2013 An early contender in a new category of slab-finishing products, Day1 Troweling Aid debuted at the 2013 World of Concrete. Performance demonstrated in pre-show research and commercial slab work led developer Lythic Solutions to enlist finishers from across the country and around the world—plus Concrete Industry Management students at Middle Tennessee State University, Murfreesboro—in three days of demonstrations with the agent. Day1 is sprayed on fresh concrete in small quantities and troweled into the surface. It lubricates, making troweling easier, reducing drag, and minimizing blade wear and operator fatigue. Its main ingredient, colloidal silica, reacts with the lime by-product of cement hydration, and turns it into additional cement paste; with more "cream" for the finisher to use, the slab is easier to finish and has a potentially smoother surface. As colloidal silica agent, Day1 seals the surface, slowing evaporation, which extends the cement hydration window and finishing time 15–45 minutes without weakening the slab or adding excess water to the mix. In field trials, finishers used 75 percent less total liquid with Day1 vs. finishing with water. They need less time to close the surface under normal conditions, but can have more time under adverse conditions. The troweling aid's additional cementitious material strengthens the surface. Vancouver, Wash.-based Lythic Solutions, founded in 2008 by veterans of industrial and decorative slabs on grade, formulated Day1 with an eye to helping crews counter the effects of wind, heat, low humidity and sun exposure—variables that can prevent proper finishing or lead to a finished slab's lack of smoothness, unevenness and checking or crazing. Their new product increases workability and imparts water-retention characteristics comparable to liquid membrane-forming curing compounds. Slab finishing demonstrations at this year's World of Concrete were staged in the Las Vegas Convention Center Gold Lot. Concrete supplied by Nevada Ready Mix Corp. was placed by MTSU CIM students, who worked alongside finishing professionals from Carey Concrete and Scott's Concete of Camdenton, Mo. A ready mixed producer and early Day1 WWW.CONCRETEPRODUCTS.COM