Sustainable Subgrade Stabilization with Calcium Lignosulfonate: A Dual Assessment of Economic Costs and Carbon Footprint in Road Pavements

This study evaluates the economic and carbon footprint impact of using calcium lignosulfonate (CLS) in stabilizing highway subgrade on road pavement. Specifically, the effect of stabilized soil strength on layer thickness, costs, and carbon emissions during the initial construction phase was investigated. Two different soil types (clayey and sandy) were used with varying CLS concentrations. Furthermore, the performance of CLS was evaluated using sodium hydroxide-based alkaline activation (AAS). Standard proctor, unconfined compressive strength (UCS), and California bearing ratio tests were applied to the prepared samples. The experimental results showed that CLS significantly increased the CBR and UCS values of the soil samples. Additionally, it was calculated that the initial construction costs of flexible and rigid road pavements designed on stabilized clayey soil decreased by 14.34% and 25.24%, respectively, while on sandy soils, the decreases were 8.10% and 14.95%, respectively. Meanwhile, it has been determined that CO2 emissions were reduced by up to 10.76% in flexible pavement designs and by up to 17.88% in rigid pavement designs. Consequently, these findings show that the use of CLS in soil stabilization enables both a reduction in the layer thickness of road pavement designs and a reduction in environmental impacts.