The global population continues to grow, ensuing the expansion of urban building construction and the depletion of natural aggregates, which damage the ecosystem. Meanwhile, concrete is one of the most used materials in the civil construction sector, as well as an enormous quantities are produced yearly and poorly regulated due to their harmful environmental impact and significant disposal costs. In addition, the abundance of marl soils in Morocco's Fez-Meknes region, complications with infrastructure and construction projects are eventually anticipated due to the soil's vulnerability to changes in moisture content swelling, shrinking, and mechanical characteristics, associated with, high water absorption, and low bearing capacity. This paper emphasizes the suitability of reusing concrete waste (CW) originated from one of multiple concrete plants in the Fez-Meknes region as recycled concrete aggregates (RCAs) in marl soil’s improvement. In this investigation, different mixtures incorporating 15%, 30%, 45%, and 60% of RCAs were examined. The laboratory tests were conducted to classify the soil through the different additions and determine its strength and deformation parameters. Results indicate that higher additions of RCA led to sustainable soil improvement, as evidenced by a decrease in plasticity and an improvement in grain size distribution and compaction quality. The compaction quality improved up to 45% of RCA’s addition with an increase in dry density as well as bearing capacity, coupled with a decrease in plasticity values, which indicates the insensitivity to water and the effectiveness of the treatment. This treatment remains an ideal solution to stabilize these types of soil for economic, ecological and technical reasons.