Journal ArticleDOI
Behavior of calcium aluminate cement (CAC) in the presence of hexavalent chromium
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In this article, the behavior of calcium aluminate cement (CAC) in presence of Cr6+ (0.5, 1.0 and 2.5%) as potassium dichromate (K2Cr2O7) was studied using leaching tests.Abstract:
Chromium forms part of numerous processes and its unsafe disposal increases the risk of pollution of soils and aquatic systems, especially hexavalent chromium. This paper deals with the behavior of calcium aluminate cement (CAC) in presence of Cr6+ (0.5, 1.0 and 2.5%) as potassium dichromate (K2Cr2O7). The efficiency of CAC to immobilize Cr6+ was studied using leaching tests. The hydration temperature, hydration products and compressive strength of CAC in presence of Cr6+ were also investigated. Analysis of the results showed that the presence of Cr6+ strongly reduced the rate of reactions, which was related to inhibition of the consumption of anhydrous phases (calcium aluminate). However, leaching tests showed the high efficiency of CAC regarding Cr6+ immobilization (>90%), better than that presented by Portland cement. CAC also presented both the capacity for hexavalent chromium retention and its reduction.read more
Citations
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Study on the resistance to seawater corrosion of the cementitious systems containing ordinary Portland cement or/and calcium aluminate cement
TL;DR: In this paper, the authors investigated the resistance to seawater corrosion for OPC, CAC, OPC-CAC-gypsum, and OPCSG-FA.
Journal ArticleDOI
Stabilization of lead contaminated soil with traditional and alternative binders.
Silvia Contessi,Loris Calgaro,Maria Chiara Dalconi,Alessandro Bonetto,Maurizio Bellotto,Giorgio Ferrari,Antonio Marcomini,Gilberto Artioli +7 more
TL;DR: The overall results proved that multiple mechanisms are involved in Pb retention and that key parameters regulating the stabilization performance are strongly dependent on the type of applied binder system.
Journal ArticleDOI
Comparative study of stabilization/solidification of dredged sediments with ordinary Portland cement and calcium sulfo-aluminate cement in the framework of valorization in road construction material
TL;DR: In this article, the authors evaluated the efficiency of using a green binder Calcium Sulfo-Aluminate (CSA) cement to solidified Dunkirk sediments.
Journal ArticleDOI
Phase evolution with temperature in chromium-containing refractory castables used for waste melting furnaces and Cr(VI) leachability
TL;DR: In this paper, the formation of various phases of chromium in solid state was studied using XRD and SEM-EDS, and the results showed that the phase of CaCrO 4 formed at 500-700°C while Ca 4 Al 6 CrO 16 formed in the intermediate temperature regime (900-1300°C).
Journal ArticleDOI
Green ceramsite production via calcination of chromium contaminated soil and the toxic Cr(VI) immobilization mechanisms
TL;DR: In this paper, the stability of Cr(VI) immobilization in ceramsite was investigated and the CrVI immobilization mechanism was analyzed through XRF, XPS, XRD, and BSE.
References
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Journal ArticleDOI
Advances in alternative cementitious binders
TL;DR: In this paper, four promising alternative binders available as alternatives to Portland cement are discussed, namely calcium aluminate cement, calcium sulfoaluminate cements, alkali-activated binders, and supersulfated cements.
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High-performance concretes from calcium aluminate cements
TL;DR: In this paper, the authors discuss the use of calcium aluminate cements in hydraulic structures, including resistance to acid attack and particularly to biogenic corrosion and abrasion resistance.
Journal ArticleDOI
Geopolymers for immobilization of Cr6+, Cd2+, and Pb2+
TL;DR: The results of this work tentatively support a previous identification of Pb (3)SiO(5) as a potential candidate phase for hosting Pb(II) within the geopolymer structure, although the data are not entirely conclusive.
Journal ArticleDOI
Alkali-activated cementitious materials: Alternative matrices for the immobilisation of hazardous wastes: Part II. Stabilisation of chromium and lead
Ángel Palomo,Marta Palacios +1 more
TL;DR: In this article, the stabilisation/solidification capacity of a cementing matrix, which has been made using alkali activation of fly ash, in the presence of toxic elements chromium and lead, was compared with that of Portland cement.
Journal ArticleDOI
Influence of lead, zinc, iron (III) and chromium (III) oxides on the setting time and strength development of Portland cement
TL;DR: In this article, a fractional factorial design (24−1) of experiments was carried out to study the influence of metal oxides on cement properties: unconfined compressive strength (UCS), setting time (ST), bulk density (BD) and noncombined water (NCW).
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