Applications
Daravair AE4 may be used whenever the purposeful entrainment of air is required by concrete specifications. It is particularly useful in mass concrete and in high-cement, low-slump paving mixes, which require efficient, effective air-entraining admixtures. Daravair AE4 should be added to concrete mixes or mortar mixes during the mixing process at the same time as the water or the aggregates. It should not be added directly to the cement or mortar.
Air-Entraining Action
Air is incorporated into the concrete by the mechanics of mixing and stabilised into millions of discrete, semi-microscopic bubbles in the presence of a specifically designed air-entraining admixture such as Daravair AE4. These air bubbles act much like flexible ball bearings increasing the workability of the concrete. This permits a reduction in mixing water with no loss of slump. Placeability is improved, and bleeding and segregation are minimised.
Through the purposeful entrainment of air, Daravair AE4 markedly increases the durability of concrete to all exposures - particularly to freezing and thawing. It has also demonstrated a remarkable ability to impart resistance to the action of frost and deicing salts as well as sulphates, sea and alkaline waters.
Addition Rates
The performance of Daravair AE4 is best assessed after preliminary tests on site using the actual mix and the plant under consideration to determine the optimum dosage rates which will give the desired concrete properties.
For foamed concrete-mortar, a 5 - 7% solution of Daravair AE4 is usually added via a foam tube. The quantity of Daravair AE4 added will determine the resultant density of the concretemortar produced.
Hence the volume of aqueous solution added is proportional to the concrete-mortar density required. Conventional mixing equipment can be used to produce foamed, lightweight aggregate concrete.
As a guide to trials, an addition rate of 200mL of Daravair AE4 per 50kg cement should be evaluated.
The air content of air regularly checked, and because of the absorptive nature of most lightweight aggregates, a gravimetric determination is most suitable.