Among emerging, alternative Supplementary Cementitious Materials, calcined clays are a promising route to partially substitute clinker.Previous research has shown that up to half of the clinker can be replaced by a combination of calcined high-grade kaolinitic clay and limestone.Excellent mechanical properties were obtained and a refined porosity was observed due to the synergetic reaction between the calcined clay and limestone.However, the use of high-grade clays is expensive and thus unsuitable for massive clinker substitution.On the contrary, the idea of using lower-grade kaolinitic clays becomes very appealing since they are inexpensive and not used by other industries.The objective of this paper is therefore to investigate the use of low-grade calcined clays in combination with limestone as clinker substitute.