title: Stabilization of ZnCl2-containing wastes using calcium sulfoaluminate cement: cement hydration, strength development and volume stability.
abstract: The potential of calcium sulfoaluminate (CSA) cement was investigated to solidify and stabilize wastes containing large amounts of soluble zinc chloride (a strong inhibitor of Portland cement hydration). Hydration of pastes and mortars prepared with a 0.5 mol/L ZnCl(2) mixing solution was characterized over one year as a function of the gypsum content of the binder and the thermal history of the material. Blending the CSA clinker with 20% gypsum enabled its rapid hydration, with only very small delay compared with a reference prepared with pure water. It also improved the compressive strength of the hardened material and significantly reduced its expansion under wet curing. Moreover, the hydrates assemblage was less affected by a thermal treatment at early age simulating the temperature rise and fall occurring in a large-volume drum of cemented waste. Fully hydrated materials contained ettringite, amorphous aluminum hydroxide, strätlingite, together with AFm phases (Kuzel's salt associated with monosulfoaluminate or Friedel's salt depending on the gypsum content of the binder), and possibly C-(A)-S-H. Zinc was readily insolubilized and could not be detected in the pore solution extracted from cement pastes.
authors: Commissariat à l'Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze Cedex, France.
authors: Stéphane
authors: S
authors: Berger
authors: Céline
authors: C
authors: Cau Dit Coumes
authors: Patrick
authors: P
authors: Le Bescop
authors: Denis
authors: D
authors: Damidot
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003252:Construction Materials; D008855:Microscopy, Electron, Scanning; D011850:Radioactive Waste; D013457:Sulfur Compounds / Q000737:chemistry*; D014867:Water; D014961:X-Ray Diffraction; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D002712:Chlorides; D011850:Radioactive Waste; D013457:Sulfur Compounds; D017967:Zinc Compounds; C529583:calcium sulfoaluminate; D014867:Water; C016837:zinc chloride