Ettringite and CSH Portland cement phases for waste ion immobilization: A review

Immobilization of lead in shooting range soils by means of cement, quicklime, and phosphate amendments

“…2a, increasing addition of cement from 5.0% to 10% increased leachate pH, which may result from the inherent alkalinity of cement (Kamon & Nontananandh 1991). Elevated pH would induce solubilization of silica and alumina from the soil clay minerals (Keller 1964), promoting the formation of cementitious hydrates, calcium alumina hydrate (C-A-H) and calcium silicate hydrate (C-S-H) (Gougar et al 1996). XRPD analysis on the treated soils showed that cement induced formation of calcium silicate hydrate (C-S-H) (2θ~29 and 47) and ettringite (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 ·26H 2 O) (2θ~9 and 15.6)…”

“…Ettringite can immobilize heavy metals through isomorphous substitution of the ions in the mineral product (Kamon & Nontananandh 1991). Gougar et al (1996) suggested that Pb can generally replace Ca in the ettringite phase. The C-S-H was often identified as the more prevalent component of the cement-induced stabilization/solidification (S/S) samples (Gougar et al 1996).…”

“…Gougar et al (1996) suggested that Pb can generally replace Ca in the ettringite phase. The C-S-H was often identified as the more prevalent component of the cement-induced stabilization/solidification (S/S) samples (Gougar et al 1996). It was asserted that the C-S-H phases were responsible for the retention of Pb.…”

“…The most commonly-applied pozzolanic materials are portland cement, lime, and/or fly ash (Palomo & Palacios 2003, Dermatas & Meng 2003, Terzano et al 2005. The pozzolanic-based S/S techniques immobilize contaminants by adsorption, incorporation into the pozzolanic products (e.g., calcium alumina hydrate C-A-H or calcium silicate hydrate C-S-H), or via precipitation as metal hydroxides under alkaline pH associated with cement and lime (Gougar et al 1996, Moulin et al 1999. Physical entrapment of heavy metals adsorbed to particle surfaces in a low permeability cementitious matrix is also very likely (Moulin et al 1999, Badreddine et al 2004.…”

Waste dolomite powder as an adsorbent of Cd, Pb(II), and Zn from aqueous solutions

“…That is resolved by addition of such waste to cement production (Nocuń-Wczelik and Małolepszy 1995;Jarosz-Krzemińska et al 2015) or mixing it with concrete (Gougar et al 1996;Batchelor 2006;Giergiczny and Król 2008). Those methods are generally used in the disposal of such types of waste minerals.…”