title: Solidification/stabilization of toxic metals in calcium aluminate cement matrices.
abstract: The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60 °C/100% RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.
authors.affiliation: Inorganic Materials & Environment (MIMED), School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Navarro-Blasco
authors.forename: A
authors.initials: A
authors.lastname: Duran
authors.forename: R
authors.initials: R
authors.lastname: Sirera
authors.forename: J M
authors.initials: JM
authors.lastname: Fernández
authors.forename: J I
authors.initials: JI
authors.lastname: Alvarez
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D019245:Compressive Strength; D003252:Construction Materials; D003300:Copper / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013997:Time Factors; D018505:Waste Management; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; C035219:calcium aluminate; D007854:Lead; D003300:Copper; D015032:Zinc
keywords: Cement; Leaching; Metal; Sorption; Strength