Development and Characterization of a Portlandite Limestone Calcined Clay Cement Binder

The global clinker cement industry is responsible for about 5% of the global CO2 emission, a major greenhouse gas, and the by-production of cement kiln dust (CKD). Every 1000 ... kg of clinker produced yields about 850 and 150 kg of CO2 and CKD, respectively. The principal investigator has recently developed a new CKD derivative, cement dust-derived portlandite (CDP), as a potential ingredient in blended cement binder systems. The primary mineralogical components of CDP are portlandite [Ca(OH)2] and CaCO3. The principal investigator’s recent publications have shown CDP to outperform raw CKD in a number of technical indicators. Developed about a decade ago, the Limestone Calcined Clay Cement (LC3) binder cuts the cement manufacture-related CO2 emission by about 30% through the substitution of clinker by a mixture of limestone (mineralogically, calcium carbonate) and calcined clay. Since limestone needs to be mined to produce LC3, a waste-originated alternative to limestone would contribute significantly to sustainability in the built environment in (at least) three ways: (i) conservation of natural resources, (ii) utilization of industrial wastes, and (iii) reduction of embodied carbon and energy related to the mining of limestone. The proposed study intends to explore the development of a new variant of LC3 binder using CDP as a limestone alternative in line with the foregoing exposition. Since CDP contains a significant amount of portlandite and the nature of its calcium carbonate constituent may be different from that of the limestone, the proposed LC3 variant is expected to exhibit different properties than the conventional binders. Therefore, the proposed study would include an extensive investigation into the mineralogy of the binder and its key engineering properties. The outcome of the project is expected to generate useful information for further development in this area, contribute to the ongoing global decarbonization of the cement industry, and contribute to the attainment of the KSA’s 2060 net-zero emission target.