Ca₅O₁₆Si₄Sr₃

Architectural potential

A strontium-substituted calcium silicate fired at 1100 °C, 50 MPa of compression, and a nineteen-per-cent cut in embodied CO₂ against Portland cement — a non-structural binder in the mortar-and-render register rather than the slab-and-panel register. The compression figure closes off load-bearing use and opens up the finishing trades: jointing mortar for low-carbon block-work, render coats on straw-bale and hempcrete walls, repair and patch work on heritage lime-bound masonry, and site-cast decorative elements where the strontium brings a particular whiteness to the mix. Against Portland cement the pouring and trowelling logic stay familiar, and the full supply-chain and safety scores (both 1.0) make this one of the easier binders in this batch to specify at real workshop size — 5 kg ceilings support a full pavilion's jointing work. The HIGH-confidence rating on the compression figure makes the specification legible, so the inevitable question is what the nineteen-per-cent CO₂ reduction is worth against the structural ceiling. The caveat is honest: this is a render and mortar, not a load path, and a project that wants concrete-register performance has to look elsewhere in the calcium-silicate family rather than scaling this one up.

Material character

A clean bright white body, slightly cooler than the iron-tinged calcium-silicate siblings — strontium pulls the whiteness toward a mineral rather than a creamy register, close in tone to a high-grade marble slab. At 3.27 g/cm³ and 85×85×42 mm the slab is firm two-handed, slightly less dense-feeling than the vanadate siblings in the same family. Surface vitrified skin but stopping short of a gloss — the strontium flux does not push the fire as hard as the potassium-heavy exemplars do. Edges cold-cut, the kerf white-dusted and fine. Against a plain calcium-silicate body the ring under tap is brighter and the face holds a subtle pearlescent cast under direct light.