What is a tamper used for in concrete work?

A tamper is primarily used in concrete work to consolidate the concrete and push the coarse aggregate below the surface. When concrete is poured, it often contains air voids and improperly distributed aggregates. By using a tamper, workers can compact the concrete effectively, ensuring that it achieves the necessary density and strength. This process not only helps in reducing air pockets but also leads to better bonding of the aggregates within the concrete mix, resulting in a more durable and solid final product.

The use of a tamper also contributes to a more uniform surface finish by ensuring that the more aggressive coarse aggregates are embedded adequately below the surface layer. This technique is crucial in preparing the slab for any further finishing work that may be required, such as surface treatments or decorative elements.

In contrast, the other options focus on different aspects of concrete work. Smoothing the surface is typically achieved with tools like float pans or trowels. Controlling expansion involves the use of expansion joints rather than tamping. Creating decorative patterns is done with tools specifically designed for texturing or stamping surfaces, rather than a tamper. Thus, the role of the tamper is distinctly centered on consolidation and proper placement of the concrete mix.