The Constructor

Dry Shake Hardener: Types, Applications, and Design Considerations

Dry Shake Hardener types applications and design considerations

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Dry shake hardener is a mixture of cement, aggregate, and admixture which is applied as a dry compound onto the fresh concrete surface to protect floor surface from abrasion and impact effects, provide slip resistance; color; and surface texture, and improve durability.

It is applied on fresh concrete surface by hand or machinery and then power floated and troweled. Dry shake hardener reduces dusting and liquid penetration of concrete surface by declining its permeability.

Based on the type of aggregates used in the dry mixture, the dry-shake hardener is classified into three major groups namely: natural quartz aggregate, synthetic mineral aggregates, and metallic and metallic alloy aggregates. Single type of aggregate or combination of different types can be used to achieve certain concrete surface strength and color.

Types of Dry Shakes

Dry shakes are divided into three basic groups based on the type of aggregate used:

  1. Natural quartz aggregate
  2. Synthetic (non-metallic) mineral aggregates
  3. Metallic and metallic alloy aggregates

Dry shakes can be produced from one type or combination of these aggregates to achieve certain color and performance properties. Several factors such as service condition, durability, aesthetic and cost dictate the decision to choose a type of combination of aggregates for dry shake mixture.

Fig. 1: Dry Shake Hardener

Dry Shake Application Methods

Dry shake is applied onto fresh concrete by hand or machinery. Commonly, hand application is finalized after the initial set and floating of the concrete whereas machine application is conducted immediately after concrete placement, before the concrete sets.

Fig. 2: Dry Shake Application by Machine
Fig. 3: Finishing Process of Dry Shake Hardener

Dry Shake Application Rates

The rate of application of dry shake onto the fresh concrete is based on bulk density of the dry shake and the end use of the floor. Variable rates can be specified in a building to suit the different uses in different places.

The method of application of dry shake also influences its rate of application. For example, minimum application rate of 5 kg/m2 is suitable for machine application in order to prevent the sinking of aggregate into the plastic concrete.

However, application rates of 4 to 5 kg/m2 is suitable for hand application. It is possible to increase the rate of application for hand application based on the site conditions, concrete formula, and the water content in the concrete. It is recommended to apply dry shake in two stages when higher application rates by hand is considered.

Dry Shake Thickness

The thickness of dry shake is at least 19mm.

Design and Construction Considerations

Applications

Advantages

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