PROPERTIES OF GEOPOLYMER CEMENTS

TLDR

Geopolymer cement is an inorganic polycondensation product forming three‑dimensional zeolitic frameworks, and its high‑alkali K‑Poly(sialate‑siloxo) binders are already applied across automotive, aerospace, metallurgy, civil engineering, and plastics industries. MAS‑NMR spectroscopy of 27Al and 29Si combined with a proposed structural model elucidates the geopolymer’s framework. The cement hardens rapidly at room temperature, reaching 20 MPa after 4 h and 70–100 MPa after 28 days, while its low shrinkage, freeze‑thaw, sulfate, and corrosion resistance, along with the absence of alkali‑aggregate reaction, make it suitable for long‑term hazardous waste containment.

Abstract

Geopolymer cement, high-alkali (K-Ca)-Poly(sialate-siloxo) cement, results from an inorganic polycondensation reaction, a so-called geopolymerisation yielding three dimensional zeolitic frameworks. High-tech Geopolymer K-Poly(sialate-siloxo) binders, whether used pure, with fillers or reinforced, are already finding applications in all fields of industry. These applications are to be found in the automobile and aeronautic industries, non-ferrous foundries and metallurgy, civil engineering, plastics industries, etc. Geopolymer cement hardens rapidly at room temperature and provides compressive strengths in the range of 20 MPa, after only 4 hours at 2 0°C, when tested in accordance with the standards applied to hydraulic binder mortars. The final 28-day compression strength is in the range of 70-100 MPa.The behaviour of geopolymeric cements is similar to that of zeolites and feldspathoids; they immobilize hazardous materials within the geopolymeric matrix, and act as a binder to convert semi-solid wastes into adhesive solids. Their unique properties which include high early strength, low shrinkage, freeze-thaw resistance, sulphate resistance and corrosion resistance, make them ideal for long term containment in surface disposal facilities. These high-alkali cements do not generate any Alkali-Aggregate-Reaction. Preliminary study involving 27 Al and 29 Si MASNMR spectroscopy and the proposed structural model, reveal