Applicability of clinker ash as fill material in steel strip-reinforced soil walls

The generation of coal ash by coal-fired thermal power plants has increased in recent years. This study focuses on the use of a type of coal ash, clinker ash, in place of sandy soil as a fill material in soil structures. Clinker ash is an excellent geomaterial to use as backfill for soil structures because it is lightweight and has high shear strength and permeability. In this study, to determine the applicability of clinker ash as a backfill material for steel strip-reinforced soil walls, a series of laboratory pullout tests was conducted on different types of clinker ash to investigate the pullout behaviour of a ribbed strip from a layer of clinker ash and to evaluate the influence of the overburden pressure and the degree of compaction on the maximum pullout resistance. The correlation between the physical properties of clinker ash and the maximum pullout resistance was investigated on the basis of the test results. Additionally, the results of the pullout tests were compared with those of in-situ pullout tests. Furthermore, the usefulness of clinker ash was evaluated by applying the pullout test results to the standard design method for reinforced soil walls and comparing the results with the material constants for commonly used sandy soil. The main conclusions of the study are as follows: (1) The tests performed here confirmed that clinker ash has excellent frictional properties compared with sandy soil. (2) The frictional properties of clinker ash exceed the proposed design values given in the manual describing the reinforced soil wall method. (3) The application of clinker ash in reinforced soil walls is effective from the viewpoint of frictional properties.