fly ash and quick lime are used to improve soft soils. The dispensing formula indoor tests of fly ash and quick lime were done. According to the different proportions of cement (or quick lime) to fly ash
the samples mixed with soft soil of different water contents. Then unconfined compression strengths of the samples at four different ages were tested. The relationship between improved soil strength and content of quick lime as well as ages was analyzed. Compression coefficient and compression modulus of the soil were also discussed. Improving mechanism of fly ash was studied further more. The conclusion of soft soil strength increase and so on were obtained. The aim is to refer to further study and engineering application.