Zerocement

zerocement is a term for binders and concretes that contain no Portland cement. It emerged from pressure to reduce the carbon footprint and energy use of the construction sector. zerocement aims to deliver comparable strength and durability with alternative binders.

Two main approaches are used: alkali-activated materials (geopolymers) and lime- or pozzolanic-based systems. Geopolymers use aluminosilicate materials such as fly ash, slag, or metakaolin activated by alkaline solutions to form a solid binder. Lime-pozzolan mixes replace cement with reactive pozzolans and lime, sometimes combined with supplementary cementitious materials, relying on carbonation or slow hydration for strength.

Performance varies by formulation. Geopolymers can reach substantial early and long-term strength under appropriate curing but are sensitive to temperature and moisture. Lime-pozzolan systems typically show slower strength gain and may require longer curing. Durability depends on exposure conditions and mix recipe; some chemistries offer good sulfate and fire resistance, others require protective measures.

Environmental and practical aspects: Zerocement systems usually emit less CO2 than Portland cement and may recycle industrial byproducts. Challenges include variability of precursor materials, lack of universal standards, and limited long-term field data for structural use. Pioneering projects and pilots are expanding experience and informing codes.

Applications and outlook: zerocement is well established for non-structural elements, retrofits, and experimental structures; structural use is growing as standards mature. Ongoing research focuses on mix optimization, curing regimes, and life-cycle performance to enable broader adoption.