The geotechnical properties of soils are often influenced by chemical compounds and mineral additives. This study investigates the effects of varying calcium chloride (CaCl₂) contents (0% to 6% by weight of dry soil) on the Atterberg limits and classification of Marley soil (MS), stabilized with 8% lime (L), 20% natural pozzolana (NP), and their combination (8%L+20%NP). The research also examines the impact of curing time (1 and 30 days) on the plasticity index (PI) and soil classification, both with and without CaCl₂. In the absence of CaCl₂, the addition of L, alone or combined with NP, significantly reduced the PI of stabilized MS and markedly improved its classification, particularly with the L-NP combination over longer curing periods. In contrast, NP alone caused only a slight decrease in the PI. The inclusion of CaCl₂ further reduced the PI in the MS‒L and MS‒L-NP mixtures. Notably, the transformation in soil classification was more substantial with L and L-NP than with NP alone. A comparative evaluation of the Unified Soil Classification System (USCS) and the British Soil Classification System (BSCS) revealed that the BSCS offered greater precision in classifying stabilized MS, underscoring its suitability for such applications. These findings highlight the significant benefits of incorporating CaCl₂, alone or in combination with L or L-NP, in enhancing the PI and classification of MS. The improvements in both PI and classification are influenced by several factors, including additive type and amount, CaCl₂ content, curing period, and the classification system employed.