An MgO-based binder was developed in our previous study that could store atmospheric carbon dioxide while stabilizing contaminated sediments/soils. The purpose of this study was to test the feasibility of enhancing the mineral carbonation performances of the MgO-based binder ability by utilizing conditions that could accelerate the carbonation of the treated sediment. The treated sediment was investigated with respect to the changes in mechanical properties, hydration and carbonation characteristics by use of the MgO-based binder containing magnesia and supplementary cementitious materials (SCMs). To determine the degree of carbonation and to observe the changes in compressive strength, expansion, carbonation depth, pH, and microstructure, the MgO-based binder-treated sediment was cured under a non-CO2 condition, an ambient condition, and an accelerated carbonation condition. The strength of the treated sediment that was cured under the ambient condition was slightly higher than that achieved under non-CO2 conditions. Under accelerated carbonation conditions (50% and 100% of CO2), cracks were observed, and the strength was significantly low (0.13-0.28 MPa). Microstructural analyses identified that the main cause of expansion under accelerated carbonation conditions could be the formation of the products such as hydromagnesite Mg6Al2(CO3)(OH)16?4H2O, nesquehonite (MgCO3?3H2O) and lansfordite (MgCO3?5H2O). The decrease in pH under accelerated carbonation conditions should have resulted in limited generation of C-S-H and led to low strength. Under the 100% CO2 condition, the amount of CO2 that the treated sediment sequestrated for 28 days was 99.4 kg-CO2/ton-treated sediment.

Performance of the MgO-based binder for treating sediments in the accelerated carbonation condition

248th National Meeting (2014)

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