Effect of lime kiln dust as an alternative binder in the stabilization of construction and demolition materials

Lime kiln dust (LKD) is the by-product powder collected from the downstream process of quick lime production. The LKD powder collected at the kilns of quick lime production plants has a high calcium content that in reality deems it to be suitable for utilization in stabilization activities to replace carbon intensive binders, such as Portland cement. Low calcium class F fly ash (FA) is the by-product of coal fired power stations that in combination, can potentially supplement the lack of silica in LKD. In this study, different combinations of LKD and FA were used as alternative binders to stabilize construction and demolition (C&D) materials. This approach was used to seek a solution to improve the strength and durability of recycled C&D wastes stabilized using an industrial by-product (LKD) and redirect them from current stockpiles accumulating in landfills. This sustainable approach not only reduces the negative environmental impacts associated with landfilling wastes, but also reduces the overall carbon emissions generated by the manufacturing of Portland cement. An extensive laboratory investigation was performed to characterize the stabilized C&D aggregates with combinations of LKD and FA. The stabilization process with LKD and FA was found to improve the load bearing capability of the soil matrix by increasing the contact area between aggregates by the cementitious products. The C&D aggregates stabilized with LKD and FA were found to be a viable solution for infrastructure applications. The combination of C&D + 20% LKD + 10% FA was found to be the optimum in terms of strength and resilient behavior.