Abstract: In order to solve the problem of reflective cracks often existed in the pavement structure layer, the construction effect of cement-improved soil pavement bed under the action of ordinary roller and large vibration force roller was compared by taking the construction of an expressway in Longdong region of Gansu Province as an example. Through rolling combined process and compaction parameters, the optimum filling thickness of cement-modified soil under the action of high vibration force roller is obtained. Through the different arrangement of construction period of pavement structure layer on the top surface of pavement bed, the effective way to reduce the reflection crack is studied. The test results show that: Influenced by the hydration reaction of cement-modified soil, with the increase of delay time, its maximum dry density decreases, while its optimum moisture content increases gradually. It is beneficial to improve the compaction degree of cement-improved soil by adopting strong vibration of high-exciting force road roller and increasing the number of compaction times. Due to the development of construction machinery, the compaction thickness can be appropriately increased on the basis of the limit specified in the specification. The reflective cracks of the pavement structural layer are obviously reduced with the increase of the placement time of the formed road bed. The test results can provide reference for the construction of cement improved soil road bed.

Key words: cement-modified soil, road bed construction, large vibration force roller, road bed placement time