Ca₈La₂OSi₆

Architectural potential

A calcium-silicate binder in the post-Portland workshop register, close in chemistry to the atlas's flagship Portland-substitute but distinct in two ways: the lanthanum content drives a cleaner white-grey colour and the strength register sits at 50 MPa rather than 500. That lower compression puts this firmly in the screed, mortar and thin-panel role rather than in the slab-and-block role. The nineteen-per-cent CO₂ cut against Portland is modest but real and comes with the full workshop infrastructure of a familiar binder: pour like concrete, form like concrete, cure like concrete, fire once at 1100 °C. Natural placements are floor-topping screeds in gallery and retail retrofit, non-reinforced pavilion-wall infills, thin cladding panels on prefab façades, repair mortars in masonry restoration, and garden-wall blocks where the clean white-grey reads as part of the project surface. The lanthanum gives the body a slightly brighter, colder tone than a pure calcium-silicate, which changes the architectural conversation — this is a pigmented binder by chemistry rather than by additive. The 1 kg batch scaling to 5 kg gives it real workshop viability for panel-scale work. The caveat is cost: €24.23 per 1 kg batch is nearly six times the cost of the manganese-silicate variant, and the lanthanum pushes supply-chain logistics past the ordinary cement-replacement workshop.

Material character

The slab reads a clean white-grey with a faint cool undertone from the lanthanum content — whiter than the manganese-silicate sibling, cooler than a Portland grey, closer in first reading to a high-grade plaster or a fine lime render. At 2.95 g/cm³ and 85×85×47 mm the tile lifts with a steady two-hand grip at the full kilo weight, handling closer to a fired porcelain than to a stone. Surface finishes vitrified-matte from the 1100 °C fire, with a fine even grain that holds light softly; edges cold-cut, kerf-whitened. The colour runs uniformly through the slab so cut edges read the same white-grey as the face.