Reducing cement CO₂ footprint is a societal need. This is being achieved mainly by replacing an increasing amount of Portland clinker by supplementary cementitious materials. However, this comes at a price: lower mechanical strengths at early ages due to slow pozzolanic reaction(s). This is being addressed by using accelerator admixtures. In this context, calcium silicate hydrate nucleation seeding seems to have a promising future, as it can accelerate cement and pozzolanic reactions at early ages, optimising their microstructures, without compromising late strength and durability performances. In fact, these features could even be improved. Moreover, other uses are low temperature concreting, precasting, shotconcrete, etc. Here, we focus on reviewing recent reports on calcium silicate hydrate seeding using commercially available admixtures. Current knowledge on the consequences of nucleation seeding on hydration reactions and on early and late mechanical strengths is discussed. It is noted that other features, in addition to the classic alite hydration acceleration, are covered here including the enhanced ettringite precipitation and the very efficient porosity refinement, which take place in the seeded binders. Finally, because the seeded binders seem to be denser, durability properties could also be enhanced although this remains to be properly established.

Belite–ye'elimite–ferrite (BYF) cements are a sustainable alternative to ordinary Portland cement in attempts to reduce carbon dioxide emissions. The aim of this research was to understand the influence of the sulfate source on the hydration of two laboratory-prepared BYF cements. One of the studied clinkers contained β-belite and orthorhombic ye'elimite (non-active) and the other contained α′_H-belite and pseudo-cubic ye'elimite (activated with borax during clinkering). The pastes were mainly characterised through Rietveld quantitative phase analysis of powder patterns, thermal analysis and scanning electron microscopy. The active mortars developed higher compressive strengths than the non-active mortars, regardless of the sulfate source. The highest values of compressive strength for active mortars (w/c = 0·55) were 40 ± 1 MPa (28 d) with anhydrite and 68 ± 1 MPa (120 d) with gypsum.