Manufacture of eco-friendly cementitious building materials of high performance from Egyptian industrial solid wastes

One of the goals of modern societal development is to achieve environmental sustainability by expanding the number of smart cities with eco-friendly buildings. A research was carried out to investigate the possibility of utilizing Egyptian industrial solid wastes from factories to create sustainable construction materials in order to accomplish this goal. Along with various waste products including cement kiln dust (CKD) and silica fume (SF), which were chemically categorized, the investigation identified metakaolin (MK) and dealuminated kaolin (DK). Various dry mixes were used to determine the hydration characteristics of the binders, including MK-CKD, DKCKD, OPC-DK, DK-CKD-SF, MK-CKD-SF, and OPC-DK-SF. The physico-chemical and mechanical properties of the cement pastes were analyzed using compressive strength (CS), chemically combined water (Wn, %), and free lime (CaO, %) content over time. The hydration products were identified using differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy (SEM) analyses. The findings revealed that DK had a larger surface area (95 m2/g) than MK and displayed greater pozzolanic activity, particularly during early hydration. Moreover, the inclusion of SF provided further densification of the microstructure of the hardened DK-CKD-SF and/or OPC-DK-SF pastes. According to the findings, the OPC-DK pozzolanic cement pastes had a denser structure than the neat OPC paste. Moreover, the inclusion of SF resulted in additional densification of the microstructure of the hardened OPC-DK-SF pastes, which was evident in the observed increase in compressive strength values at all ages of hydration. The use of industrial solid waste as a sustainable building material has the potential to assist Egypt in meeting its goals for sustainable development and climate protection.