Experimental study on the use of compound alkaline materials to solidify lake sediments

The disposal of lake sediment is a major problem in dredging and lakeside construction projects. Due to its poor mechanical properties and contamination, sediment is difficult to use directly in resource appli¬cations. Previous research has found that alkali-acti¬vated reactions can improve the mechanical properties of silicon- and aluminum–rich solid waste. In this study, the basic physical and mechanical properties of dried sediment from a lake in Wuhan, China, were analyzed. Orthogonal tests, compressive strength measurements, and X-ray diffraction spectrum and scanning electron microscope analyses were used to investigate the solidification effects of three types of alkaline materials used alone or in combination with the lake sediment: straw ash, calcium lime, and sodium silicate. In the single-doped samples, calcium lime had the best curing effect, with a maximum seven-day compressive strength of 1.31 MPa (190 psi). When the compound-doped samples were cured to seven days, the maximum compressive strength was 7.18 MPa (1040 psi). Furthermore, with the compound-doped materials, sediment solidification was aided by suitably alkaline conditions and large quantities of active sili¬con-calcium components. As a result, the microstruc¬tures of the cured compound-doped samples were more compact and their overall mechanical properties were greatly improved.