Title: Multi-Objective Design of LC3: Sustainability and Strength
Author(s): Oğulcan Canbek, Francesca Lolli, Christopher M. Childs, Newell R. Washburn, Kimberly E. Kurtis
Publication: Symposium Paper
Appears on pages(s): 293-306
Keywords: alternative cementitious materials; CO2 emissions; hydration; kinetics; optimization; particle size
The global warming potential (GWP) of limestone calcined clay cements (LC3) is mainly affected by the production of Portland cement (PC) and calcined clay, and by the transportation of the raw materials. However, the relative contributions of varying proportions and particle sizes of constituent materials to LC3 sustainability have not been studied extensively, particularly in the context of their influence on other properties like strength development. In this research, a quantitative multi-objective design tool that can predict the LC3’s GWP and compressive strength development was developed. The model was supported by experimental results from 18 LC3 compositions with varying proportions of PC:MK:LS and limestone (LS) particle sizes, and a “cradle-to-gate” life cycle assessment (LCA) to quantify the GWP. Key findings include: (1) the nucleation effect by fine (D50 = 3 μm) limestone is pronounced and increases early (3-D) strength but only if limestone proportion is higher than that of metakaolin (MK), and (2) MK:LS affects both the 3-D strength and the GWP, while PC content is the main determinant for long-term strength gain. The multi-objective optimization results suggest that strength and sustainability improvements for LC3 can be realized by optimizing the limestone particle sizes and the PC:MK:LS.