Chloride Diffusion in Concrete Made with Coal Fly Ash Ternary and Ground Granulated Blast-Furnace Slag Portland Cements.

Ternary Portland cement usage with a high amount of cement constituents different from clinker can afford great climate change advantages by lowering the Portland cement clinker content in the final product. This will contribute to cutting greenhouse gas emissions to close to zero by 2050. Such ternary Portland cements can be composed of different amounts of ground granulated blast-furnace slag (GBFS), coal fly ash (CFA), and clinker (K). Cements made with GGBFS, or CFA boast pozzolanic characteristics. Therefore, they would improve both the concrete compressive strength at later ages and durability. The 28- and 90-days mechanical strength test, non-steady state chloride migration test, described in NT BUILD 492, and natural chloride diffusion test (NT BUILD 443) were performed in concrete. Ternary cements made with GBFS and/or CFA presented better chloride diffusion resistance than concrete made with plain Portland cements. Furthermore, the development of compressive strength was delayed. The service life study was developed for concretes made with ternary cements with regard to the chloride penetration case.

Performance of Ground Granulated Blast-Furnace Slag and Coal Fly Ash Ternary Portland Cements Exposed to Natural Carbonation.

Ternary Portland cements are new cementitious materials that contain different amounts of cement replacements. Ternary Portland cements composed of granulated blast-furnace slag (GBFS), coal fly ash (CFA), and clinker (K) can afford some environmental advantages by lowering the Portland cement clinker use. Accordingly, this is an opportunity to reduce carbon dioxide emissions and achieve net-zero carbon emissions by 2050. Furthermore, GBFS and CFA possess pozzolanic properties and enhance the mechanical strength and durability at later ages. Compressive strength and natural carbonation tests were performed in mortar and concrete. Cement-based materials made with GBFS and/or CFA presented a delay in the compressive strength development. In addition, they exhibited lower carbonation resistance than that of mortar and concrete made with plain Portland cements. Concrete reinforcement remains passive in common conditions; however, it could be corroded if the concrete pore solution pH drops due to the carbonation process. Service life estimation was performed for the ternary cements regarding the carbonation process. This information can be useful to material and civil engineers in designing concretes made with these ternary cements.