Hot weather is here! And that means it is time to start thinking about keeping your concrete from setting up before you’re ready. Sugar has been a popular choice for concrete retardation, but using this material can be risky and may cost you more money in the long run.
Concrete and Hot Weather
Concrete sets up through a process known as hydration. Hydration is the chemical reaction between water and cement, which produces calcium silicate hydrate. The calcium silicate creates the hard crystals that bond the cement together and create the structure of crystals. The heat generated by the chemical reaction causes the crystals to form. The formation of these crystals can increase with external heat, which is why concrete tends to set up faster during hot weather.
Sugar and Concrete
The solution is to add a chemical substance that will temporarily slow the formation of the crystals. For many years, sugar has been used for this task, and is popular because it is a very affordable, readily available material. Unfortunately, if you don’t properly dose the sugar, you can delay the setting time indefinitely.
You see, water and sugar both have polar molecules that are attracted to one another when mixed. This allows the water to pull apart the sugar until it “dissolves” and the individual sugar molecules are floating around in the water. When added to the concrete mix, the sugar molecules prevent the hydration reaction from producing the calcium silicate crystals. As you increase the amount of sugar in the mix, fewer cement molecules can produce calcium silicate crystals. This is why sugar will eventually prevent concrete from setting up altogether.
Delay Set Admixtures and Concrete
Unlike sugar, which dissolves in the water and reacts with the cement molecules to prevent the development of calcium silicate, our Standard Delay & Mini Delay Set forms a film around the cement molecules to temporarily stop the reaction between the cement and the water. The film gradually wears down as the materials rub together, allowing the hydration process to continue. Standard Delay Set and Mini Delay Set have been approved for use by several DOT across the country and are ASTM C-494 Type D certified. So you won’t have to worry about your load being rejected from municipal projects.
If you would like to learn more about Fritz-Pak’s delay set admixtures, check out our videos on YouTube. Don’t forget to follow our social media channels for more information about how our products can improve your concrete.