Improvement of Muddy Soil through the Mixing of By-Product of Industry

Abstract

The purpose of this study is to make clear the possibility of the utilization of muddy soil mixed with incinerated ash or iron/steel slag as an additive. The muddy soil used is dredged soil reclaimed from a river. The strength properties of the dredged soil mixed with various incinerated ashes and so on are tested using the CBR test or cone penetration test. This is in order to be able to use the treated soil as construction material for super embankments and as subgrade material on roads.
As a result, in the case where incinerated ashes are used as an additive, the treated soil mixed with incinerated ash gains high strength due to a reduction in the water content. When fluidized bed combustion coal fly ash is used as an additive, an increase in the strength of the treated soil was observed during aging, and it gives the greatest strength in comparison with other incinerated ashes. Furthermore, in order to gain high strength, it is more effective to decrease the water content of the dredged soil.
In the case where iron/steel slag is used as an additive, the treated soil mixed with slag, with a maximum grain size of 20mm, passes the material standard for grain size distribution of super embankments. The greater the mixing rate of slag, the lower the water content and the higher CBR of the treated soil. The CBR of the treated soil mixed with a lot of fine-grain slag becomes high at a low mixing rate. By contrast, the CBR with a lot of coarse-grain slag becomes high at a high mixing rate.