In the present work, sustainable use of cement kiln dust (CKD) and feldspar (FS) in the production of
pozzolanic materials with different reactivity and whiteness were investigated. The proposed method
includes thermal treatment of CKD and FS at 1000 C in the presence of sodium hydroxide to convert
crystalline- FS/CKD -structure to amorphous one. Different FS/CKD mixtures were designed at weight
ratios of 50/50, 66.66/33.33, and 80/20 (P-1, P-2, and P-4, respectively) to optimize the whiteness and
amorphous content of the produced pozzolans. A preliminary study revealed that the amorphous content and the whiteness of the prepared pozzolan strongly depend on FS/CKD weight ratio. The optimum
pozzolanic materials with high 89% whiteness and 100% amorphous content were obtained in the case of
P-4. The individual replacement of white Portland cement by 30 wt % of the synthetic pozzolans resulted
in the enhancement of 28-days compressive strength. The use of P-4 pozzolan not only increased the
mechanical properties of white Portland cement, but also enhanced its whiteness. Non-thermally treated
FS/CKD blend (as the counterpart of P-4 pozzolan) showed a lower pozzolanic activity as compared with
thermally treated one. Regardless of the change in the strength activity index (SAI) and the rate of
Ca(OH)2 consumption, all synthetic pozzolans demonstrated a higher pozzolanic activity |
