Blended cements with kaolinitic calcined clays: Study of the immobilization of Cr(VI).

MÓNICA ADRIANA TREZZA; ALEJANDRA TIRONI; EDGARDO FABIÁN IRASSAR; ALBERTO NESTOR SCIAN

RILEM Bookseries

Springer Science + Business Media

Lugar: Nueva York; Año: 2015 vol. 10 p. 203 - 209

2211-0844

Numerous investigations on the immobilization of chromium incement-based systems were carried out in the recent years. The aim of thisstudy is to analyze the influence of the crystallinity of kaolinite used tomake calcined kaolinitic clay when are used in pastes for immobilization ofCr(VI). In previous study, it was found that the reactivity of kaoliniticcalcined clays used as partial replacement of Portland cement largely dependson the crystallinity of kaolinite in the raw clay. Calcined clays obtained fromraw materials containing kaolinite with disordered structure presents a veryhigh pozzolanic activity allowing high-percentage replacement (30%) in blendedcements. In this study, pastes of blended cement with 15% and 30% by mass of twokaolinitic calcined clays (order and disorder structure of kaolinite) wereelaborated using a solution of 5000 ppm of K2Cr2O7 and a solution-to-cementing material ratio of 0.50. Theimmobilization efficiency was measurement by lixiviation test and themodifications in the hydrated phases was studied by X-ray diffraction andSEM/EDS analysis.Theresults shown that kaolinitic calcined clay from ordered kaolinite was moreefficient than disordered kaolinite to retention of Cr(VI), reaching valueshigher than that of PC-paste.