Hemp-lime is a bio-based material with an embodied energy of around 300 to 800 MJ/m3 [1], compared to 2100 MJ/m3 for reinforced concrete [2] and roughly 3000 MJ/m3 for the main conventional insulating materials [3]. Its limitation lies in its mechanical properties, it is too weak to bear loads. Despite this, a significant body of research has yielded detailed results on various hemp-lime formulations, some of which include additives that enhance the mechanical properties. However, it remains challenging to find comprehensive studies that evaluate the effectiveness of the main additives employed in hemp-lime mixtures [4], such as gypsum, quicklime, pozzolana so that both carbonation and hydraulic setting are shown during the setting; and that compare such behaviour with that of mixes which employ hydraulic lime as the sole binding agent. By adopting a scientific approach grounded in physical and chemical methodologies, this study presents a characterization of four different mixtures, each incorporating two distinct hemp combinations composed of hurds and fibres. The study aims to assess carbonation levels over various periods using phenolphthalein as a pH indicator, as well as the mechanical properties of elasticity and compressive strength through a wide sampling campaign. The mixture exhibiting the best mechanical strength is the one containing hydraulic lime. Moreover, its carbonation is notably more pronounced compared to mixtures based on air lime, depending on the specific additive used. However, when examining the evolution of the modulus of elasticity over time, it is evident that the inclusion of quicklime and pozzolana (mixtures A and A’) achieves strength values comparable with those of hydraulic lime (mixtures D and D’). This improvement is also correlated with the depth of carbonation observed in various areas of the samples. This work suggests that improvements in the mechanical behaviour of hemp-lime could be achieved through specific additives, depending on the desired characteristics. Hemp-lime could evolve into a range of materials with distinct properties, which could be exploited in various construction applications.