An unexpectedly high draindown may be obtained during laboratory tests in which components, including a granulated stabilizer, are mixed with a small mixer (or manually). This may be caused by the way the granulated stabilizer was prepared before mixing it with aggregates. As we know from Chapter 4, the granules contain a small amount of binder or wax. This coating makes them less sensitive to moisture and makes dosing easier. However, the coating also requires enough shear force and a high enough temperature to release the fibers during mixing.
To avoid trouble with dispersing the granulated fibers, the container with a weighed-out amount of granulated stabilizer should be put in the oven before mixing and warmed up to a temperature at which the binder or wax in the stabilizer clearly softens. This will make distributing the fibers through the mix easier. In an unheated granulated stabilizer, some granules may remain intact; therefore the stabilizer will not work effectively. The effect will be self-evident—an incorrect (high) result of draindown testing.
Be careful when testing stabilizers with which you are unfamiliar. Learn about appropriate mixing temperatures and mixing details, such as whether the stabilizers should be added to the dry aggregate or to the mixture with binder.
