CoatingsPro Magazine

JAN 2019

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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COATINGSPRO JANUARY 2019 53 Science Behind It Cement Technology Powers Logo By Matt Sambol, Manager of Flooring and Polymer Systems at CTS Cement Manufacturing Corporation T he University of Cincinnati logo proved to be a challenge for Hardig Industrial, but they found the winning formula. e crew was tasked with finding an overlay material to make a 30-year-old slab look new. In addition to that, it needed to be integrally colored and polished to a high shine to bring the University of Cincinnati logo to life. It would also be expected to remain durable in a high traffic environment for years to come. Hardig Industrial chose CTS Cement Manufacturing Corporation's Rapid Set TRU PC, a hydraulic cement-based self-leveling topping that could be placed at ½-inch (1.3 cm) thick and ground and polished to simulate the appearance of polished concrete. e backbone of Rapid Set TRU PC is Rapid Set calcium sulfoaluminate (CSA) cement: a high-performance, hydraulic cement that provides structural strength in one hour with reduced shrinkage, low permeability, and superior resistance to sulfate attack. How does it work? Hydration and Crystallization In Rapid Set CSA cement, the CSA hydrates quickly by chemically reacting with calcium sulfate and water to form ettringite. Ettringite is a strong, needle-like crystal that gives Rapid Set products high-early strength properties and allows TRU PC to exceed 5,000 psi (34.5 MPa) in 24 hours without additional chemical accelerators. e high early strength and surface hardness supplied by ettringite are critical when polishing to a high gloss the following day after placement. In addition to the high-early strength, Hardig Industrial needed to ensure the floor product would maintain this high strength in the long term. Rapid Set CSA cement also contains dicalcium silicate (Ca₂S), which reacts to form calcium silicate hydrate (C-S-H). is compound, also found in portland cement, reacts more slowly than the CSA and continues to react for a longer period, which helps provide the matrix with long-term strength and durability. ose characteristics were ideal for the University of Cincinnati arena floor. Water Woes Water is essential to hydrate cement, but too much water can traditionally create challenges as well. In traditional cement systems, the water required to get the necessary flow or workability during installation is more than what is neces- sary to hydrate the cement. e excess water is called water of convenience. But what happens to that excess water? As the material sits in place, the heavier particles settle and displace the mix water. e water then forms capillaries as it rises to the surface. W hen the water reaches the surface, it is called bleed water. e bleed water eventually evapo- rates and the capillaries in the hardened material become microscopic voids that decrease the density and strength of the floor. Any water of convenience that is still trapped after the material has hardened will slowly evaporate over time, leading to drying shrinkage cracks. With Rapid Set CSA cement, the ettringite forms quickly, preventing the settling, and it consumes more water in the hydration process, which eliminates bleed water and greatly reduces long-term drying shrinkage. Instead, TRU PC forms a dense, strong matrix that allowed Hardig Industrial to grind and polish within 24 hours. Winning Formula For the University of Cincinnati arena floor, Hardig Industrial was able to deliver a durable floor that could be integrally colored and polished to make the university logo shine. Rapid Set CSA cement's chemistry provided the backbone that allowed them to polish the following day after placement. It provided a dense matrix to allow a high gloss on the finished floor, and it will remain durable in the high traffic environment for years to come. CP

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