Ca₁₂Fe₅O₄₈Si₁₂V₃

Architectural potential

A calcium-iron-vanadate silicate binder sitting in the post-Portland workshop register, with an eighteen-per-cent cut in embodied CO₂ against Portland cement at a familiar 1100 °C fire. The 50 MPa compression ceiling keeps specification within non-reinforced work: mortars, screeds, non-load-bearing slab-work, pavilion infill walls, landscape plinths, prefabricated cladding panels. The very low measured density at 0.37 g/cm³ across a 120×120×188 mm piece reads as a porous, aerated body — closer to an autoclaved aerated concrete than to a dense cement slab — so the natural placements shift toward thermally-insulating infill rather than surface mass: garden-room block, non-structural partition in retrofit housing, lightweight fçade panel behind a rainscreen, interior non-load-bearing wall in timber-framed construction. The Baubotanik-style ground plate and the light-frame landscape wall both suit this register. Against Portland cement the argument is modest but legitimate — a real carbon reduction with no change to workshop practice — and supply-chain reliance is effectively local at a score of 1.0. The caveat is the compressive ceiling: at 50 MPa the piece cannot carry reinforced structural load, and the aerated density makes surface toughness limited. Specification belongs firmly on the insulating-infill side of the concrete conversation.

Material character

The slab reads a muted amber-brown with rust undertones from the vanadium-iron content, closer to a weathered rendered wall than to a fresh cement face. At 0.37 g/cm³ in a 120×120×188 mm piece, the body is startlingly light for its bulk — an aerated, almost softwood register in the hand despite the considerable footprint, distinct from every dense cast sibling in the palette. Surface cold-pressed with fine porosity visible across the face; edges crumble slightly at the cut, closer to autoclaved aerated concrete than to a vitrified body. Fully opaque. Tapped, the body returns a soft, dull note — the characteristic acoustic of a closed-cell aerated silicate.