General Contractor Practice Exam

What chemical is commonly used to create high-heat concrete?

1. Accelerator

2. Retarder

3. Plasticizer

4. Superplasticizer

The correct answer is: Retarder

The commonly used chemical for creating high-heat concrete is an accelerator. Accelerators are additives that speed up the hydration process of the concrete, allowing it to cure more quickly and achieve higher early strength. This is particularly beneficial in high-heat concrete applications, as the increased hydration rate can help manage temperature rise during the curing process, which is crucial in preventing thermal cracking. While retarders, another type of additive, are used to slow down the curing process for various reasons such as allowing more workable time in hot weather or large pours, they are not designed to enhance heat development as accelerators do. Similarly, plasticizers and superplasticizers primarily function to improve the workability of concrete without adding heat; they reduce the water content needed for a certain workability without compromising strength. Thus, for high-heat applications, the use of an accelerator is the appropriate choice.