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

Volume: 355

Issue:

Appears on pages(s): 293-306

Keywords: alternative cementitious materials; CO₂ emissions; hydration; kinetics; optimization; particle size

DOI: 10.14359/51736035

Date: 7/1/2022

Abstract:
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.