In earthworks and road construction, coal fly ash is primarily used in a moistened state. The earthworks-related and physical properties of the fly ash play an important role here. By adjusting the optimal Proctor density, the moistened fly ash can be compacted so well that the surfaces are immediately trafficable by trucks. The requirements and general conditions for the use of fly ash in earthworks and road construction are specified in documents published by the FGSV (Research Society for Roads and Transportation) and in a circular decree published by the Ministry for Environment Protection, Agriculture and Consumer Protection (MUNLV) titled "Requirements for the use of mineral substances from industrial processes in earthworks and road construction".