Test method of calcium and silica eluted from material of steel slag-dredged soil mixtures for predicting strength development

Abstract

To predict the strength development of steel slag-dredged soil mixture, the test methods to evaluate the elution of silica from dredged soil as well as one of calcium from steel slag are proposed in this research. To determine the calcium eluted from steel slag, the regulatory leaching test method (Notification No.46 from Japan Environment Agency) was modified by using the slag samples without grain size adjustments and subjected to the artificial seawater as solvent under the 30-minute shaking time. Silica elution from dredged soil was determined by the method, which was proposed by Toda et al. (2018) but slightly modified in terms of the stirring period - where approximately 7-minute stirring of the sample in water was applied to effectively obtain the results for a shorter period of testing time. Analysis of these elution test results versus the unconfined compressive strengths on 6 different steel slags and 15 dredged soils concluded that the strength developments can be predicted by the elution values obtained by the proposed methods, which can be utilized as primary assessment of strength development in practice.