The behaviour of mussel shell particulate as fine aggregate for mass concrete has been analysed. The shells were washed and mechanically crushed to obtain a particle size similar to that of the natural aggregate (fine) to be replaced, which was dried at 140 C. The Faury-Joisel method was used to design the H-35(95)-20-6 structural mass concrete sample, with 0%, 10%, 30% and 60% replacements of fine aggregate by mussel shell particulates, performing compressive strength and thermal conductivity analyses at 7 and 28 days. The results indicate that in order to maintain the compressive strength of H-35(95)-20-6 structural mass concrete, the replacement percentage should not exceed 40%. On the other hand, as the mussel shell particulates in the concrete increase, the thermal conductivity decreases, turning into a material with a tendency to increase thermal insulation, which would help to improve the new demands on energy saving and efficiency in households, if used as coating. Hence, it can be concluded that it is feasible to replace fine aggregate with mussel shell particulate matter, which would be useful in increasing the recycling of this residue and in reducing its natural exploitation.