Seven days. Lime-fly ash macadam, also known as lime-fly ash stabilized macadam, is a semi-rigid structure with strength, which is made of inorganic binder lime, fly ash and graded macadam mixed with a certain amount of water, rolled and maintained. Lime-fly ash macadam needs to be combined several times according to different proportions and different water contents, and then heavy compaction tests are carried out respectively. From the generated different strength curves, the maximum dry density and optimum water content corresponding to the unconfined compressive strength of 7 days are comprehensively analyzed and selected, so that the lime-fly ash macadam can be compacted and formed.