A way of using fly ash and water to make a road base material is disclosed. Class C fly ash, which sets up very quickly, is mixed with a hydrating liquid and compacted prior to initial set. To facilitate mixing, transportation and placement of the wet mixture, a set sequestering additive may be added to the water before mixing the water and the fly ash. Also disclosed is a mixing device designed to be attached to the underside of a tanker trailer of the type used to transport dry fly ash. The mixer introduces water to the inside and outside areas of a falling tubular stream of fly ash.
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