Which of the following is a common technique to prevent concrete slab curling?

The technique of utilizing rock dust in the base layer is utilized to minimize the potential for concrete slab curling by addressing issues related to slab support and moisture retention. Rock dust can enhance drainage properties and provide a uniform support layer beneath the concrete, which helps to reduce the differential moisture absorption in the slab. This uniformity in support is critical because variations in moisture conditions can lead to uneven curing and shrinkage, ultimately resulting in curling.

By effectively managing drainage and ensuring that the concrete has a stable foundation, the use of rock dust can mitigate the stresses that contribute to the curling of the slab. This technique supports a balanced moisture condition throughout the slab and minimizes the movements associated with drying and environmental changes, which are key factors in curling.

Other strategies, while they have their benefits, do not directly address the foundational support and moisture management in the same way as rock dust. For instance, a thicker slab may provide some benefits in terms of load-bearing capacity, but it does not inherently solve moisture variations. Similarly, moisture-retaining layers and vapor barriers serve specific purposes related to temperature and moisture control at the slab surface, rather than addressing the underlying support structure that directly impacts curling.