In the ternary cementitious systems, limestone, along with calcined clay, shows good mechanical and durability performance at a lower clinker factor as compared to Portland Cement (PC) concrete. The amount of cement-grade limestone in mine reserves is decreasing as the demand for cement rises. This makes it important to explore the potential of low-grade limestone rejected by cement industries during clinker production. This work focuses on the use of rejected limestone with magnesium, clay, and silica impurities present in excess, along with calcined clay/ fly ash, in ternary cementitious systems. The experimental work includes cement substitutions of 30 wt% and 45 wt% with calcined clay and limestone in 2:1 and 1:1 proportions, respectively. The long-term mechanical properties and durability parameters of concrete will be assessed, such as resistance to chloride ingress, water sorptivity, and gas permeability. The preliminary results at 28 days using limestone with a high magnesium content (dolomite) indicate that the 30% ternary blended concrete has better compressive strength and durability as compared to Portland Cement concrete, and the 45% ternary mix has very good durability performance. However, these results are from trial experiments for early ages only, and long-term performance evaluation using one high-grade limestone and three low-grade limestone will be assessed in this work. Therefore, the long-term performance evaluation of binary and ternary blended low-grade limestone concrete will help to decide the application of different types of low-grade limestone in concrete.