The initial weight and volume relationships play a crucial role in determining the strength of cement-stabilized soils. Since 2007, the porosity/binder ratio has been widely utilized as a control index for stabilized soil mixtures. However, this approach does not take into account the water content used during the stabilization process, which can affect the strength of the final product. To address this issue, this paper introduces the porosity-water and binder relationship as a new index to predict the strength of artificially cemented soils. The strengths of different stabilized soils were compared based on the new index and the comprehensive results were analyzed to demonstrate the efficacy of the new index. The findings indicate that the new index is an appropriate design parameter for soil–lime, soil–cement, and geopolymerized soil mixtures; moreover, the water content was identified to have no effect on the splitting tensile strength to compressive strength ratio. The results of this study provide valuable insights on the optimization of stabilized soils and development of improved soil stabilization processes.