This research studied the influence of individual heavy metal on the hydration reactions of major cement clinker phases in order to investigate the performance of cement based stabilization/solidification (S/S) system. Tricalcium silicate (C3S) and tricalcium aluminate (C3A) had been mixed with individual heavy metal hydroxide including Zn(OH)2, Pb(OH)2and Cu(OH)2, respectively. The influences of these heavy metal hydroxides on the hydration of C3S and C3A have been characterized by X-ray diffraction (XRD) and differential scanning calorimetry-thermogravimetry (DSC-TG). A mixture of Zn(OH)2, Pb(OH)2and Cu(OH)2was blended with Portland cement (PC) and evaluated through compressive strength and dynamic leach test. XRD and DSC-TG data show that all the heavy metal hydroxides (Zn(OH)2, Pb(OH)2and Cu(OH)2) have detrimental effects on the hydration of C3A, but only Zn(OH)2does to the C3S at early curing ages which can completely inhibit the hydration of C3S due to the formation of CaO(Zn(OH)2)·2H2O. Cu6Al2O8CO3·12H2O, Pb2Al4O4(CO3)4·7H2O and Zn6Al2O8CO3·12H2O are formed in all the samples containing C3A in the presence of metal hydroxides. After adding CaSO4into C3A, the detrimental effect of heavy metals increases due to the coating effect of both calcium aluminate sulphates and heavy metal aluminate carbonates. The influence of heavy metal hydroxide on the hydration of C3S and C3A can be used to predict the S/S performance of Portland cement.
- Cement clinker
- Heavy metal
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal
- Health, Toxicology and Mutagenesis