Abstract: In order to study the influence of different conditions on the compressive strength of fly ash-cement mixed soils, the unconfined compressive strength as well as electronic microscope scanning tests on mixed soil samples with different mixing ratios curing ages and curing environments were carried out. The test results show that the mixing ratio, curing age and environment all have the obvious influence on the compressive strength of the mixed soil samples. Under the same curing age and environment, the higher cement content in soils, the higher the compressive strength of the mixed soils. Under the same mixing ratio and curing environment, the compressive strength of the soil sample increases with the growth of curing age. Under the same mixing ratio and curing age, humidity has a decisive influence on the compressive strength of the tested samples, the lower the humidity, the higher the compressive strength of the soils samples, the higher the humidity, the lower the compressive strength, which is mainly related to the moisture content of soil samples.

Key words: fly ash-cement mixed soils, unconfined compressive strength, mixing ratio, curing age, humidity