Portland-based Limestone Calcined Clay Cements, LC3, are receiving considerable attention because the CO2 footprint can be reduced up to 40 %. Here, we report a related family: Belite-rich-LC3. These blends are expected to have very good durability performances. Selected properties for two members are reported including calorimetric data and mechanical strength developments. The phase evolutions are studied by Rietveld analysis backed by the thermal behaviour. Their microstructures are studied by mercury intrusion porosimetry. The hydration rates of these blends have been boosted by C-S-H seeding which led to an increase of mechanical strengths. At 28 days, seeded mortars with cement replacement degrees of 30 and 45 wt% displayed 74 and 61 MPa of compressive strengths, respectively. Moreover, overall porosities and pore entry threshold values decreased in the admixture-containing binders.
