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In this work, we investigate, on a laboratory scale, the influence of the leaching conditions on the release of various chemical elements from a cementitious material obtained by solidification of PbO, Ni2O3 and Cr2O3 with blended cement (CEMII-B32.5, according to European Standards). The pH effects on the pollutants release and the composition of the initial pore solution (target elements: chloride, sulfate, sodium, potassium, calcium, lead, chromium and nickel) were assessed through an experimental procedure consisting of two equilibrium leaching tests [the acid neutralization capacity (ANC) and the pore water (PW) tests] and the maximum mobile fraction (MMF) text. Samples of the same material were submitted in parallel to dynamic leaching tests in order to assess the influence of the boundary conditions (instantaneous liquid/solid (L/S) ratio, solution renewal) on the leaching kinetics of the target elements. The comparison criteria were the leachate saturation state, the released cumulative quantities and the leaching flux. Generally, leachate quantities obtained by the ANC, PW and MMF tests were important. However, the lowest released amount was observed for the monolith leaching test, and leachate saturation slowed down the dynamic release. Finally, experimental results highlighted another important parameter: the influence of the liquid/solid contact type on leaching kinetics.

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A total of six washed French and Algerian kaolins were studied. Kaolinite, halloysite, muscovite, feldspars, anatase, rutile, gibbsite, goethite, and todorokite were present. The thermal behavior of the samples was studied and the transformation heats were determined and quantified by differential thermal analysis. Calcined samples from 900°C to 1400°C are studied by X‐ray diffraction, the results show that the crystallite sizes of mullite rises as the temperature rises. The calcined samples showed an inverse correlation of L* and the crystallite sizes of mullite due to the incorporation of chromophore elements (Fe3+, Ti4+, and Mn2+) in its structure. Muscovite and rutile phases decreased lightness and increased chromaticity. The reduction state of Fe3+/Fe2+ and Mn4+/Mn2+ at 1400°C enhanced lightness leading to the diminution of the b* parameter. The CIELAB color parameters were significantly affected with mineralogy and chemical compositions of the samples. Lightness of the natural kaolins is decreased (L* < 59) when organic matters beside manganese and iron oxides are present. L* was not affected when only iron (Fe2+) is present in the kaolin; however, the chromaticity is increased (b* > 22). Whiteness and tint indices (W10, Tw,10) revealed that only one kaolin could be considered white (limits of CIE Colorimetry, 1986), though upon calcination, this number is enhanced to two. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 499–505, 2014