Why should you apply a dry shake to a slab on grade? The answer is that the surface quality obtained by the usual practices will not be adequate for every purpose. Frequently the top surface is likely to be of lower strength and have the least sound materials in the slab.


Heavy loads on steel wheels can deteriorate a concrete floor slab quickly. Another type of wear is the result of impact. A steel plate dropped on its corner makes a dent or pit in the surface. A hard steel wheel hitting an unprotected edge of a joint may cause a chip, or eventually a broken-down joint shoulder.


Dry shakes are used to improve concrete floor surfaces in several other special ways:

  1. To enhance room illumination in industrial, warehouse, assembly or maintenance facilities.
  2. To mark pedestrian aisles or delineate industrial traffic patterns. One or more colors of dry shakes can be used.
  3. To reduce the noise level of hard-wheeled vehicles.
  4. To provide spark resistance.


Many dry shakes are packaged for sale. Basically, they may be divided into two types: those based on mineral aggregate materials and those incorporating metallic aggregates. Mineral aggregate dry shakes are products that employ materials such as quartz, crystalline granite, trap rock, emery, and other hard materials. Metallic aggregate dry shakes contain graded iron as the aggregate.


Finishers can start applying dry shakes to the surface of a floor slab as soon as the surface is firm enough so that the material doesn't sink and form small pockets of material. If there is any bleed water present it has to be removed before the dry shake is spread. These dry shakes can be distributed with a mechanical spreader manufactured for the purpose. Dry shakes can also be spread by hand or shovel. They should be distributed in a smooth sweeping motion at a low elevation above the concrete.