Five Factors in Controlling Concrete Set Time

Controlling set time is vital to achieve the perfect concrete pour in Central Indiana

Here are Shelby Materials’ five key factors to help finish contractors control the set time.

1. Slump

The best retarder for concrete is water. Low slump concrete requires large crews and vibrating placing equipment. It is nearly impossible to place flat concrete efficiently with dry concrete. Water is needed so we must add cementicious. Better concrete is needed if you need time to place the concrete

2. Mineral Pozzolins

There is a limit to the amount of cement in a mix. Additional cement reduces working time. The concrete sets faster. Fly ash costs about the same as cement but it slows everything down so crews have time to place and finish concrete

3. Admixtures

The easiest way to adjust the speed of concrete is with admixtures. We have accelerators and retarders. The correct dosage is easy for the batch men loading the truck. We use admixtures us a final adjustment for our customers but only as needed.

4.  Sand Heaters and Chillers

Many of our plants have the ability to adjust the temperature of the concrete at delivery. We talk with the contractor about the conditions and agree on what we should try. It is a team problem and only the contractor knows the details and capacity of his crew.

5. Mix Design

Often we are requested to deliver concrete that can be opened to traffic in 18 hours. To meet these demands we must adjust the mix and discuss the details with the crew. In very cold conditions like industrial freezer floors, the temperature never gets above zero. To perform as a team we must agree on the details, and limits.

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