Title:
Carboaluminates: The Overlooked Key to High Performance, Low-Carbon LC3 Cements
Author(s):
Zunino
Publication:
Web Session
Volume:
ws_F24_Zunino.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
11/3/2024
Abstract:
Limestone calcined clay cements (LC3) represent a ternary blend that combines limestone and calcined kaolinitic clay, effectively replacing 50% or more of the traditional PC. With a 50% replacement level, LC3 achieves strength development comparable to that of conventional PC within 7 days of hydration. The LC3 technology offers the potential to reduce CO2 emissions by 30% to 40% per ton of cement produced compared to PC. During the first 72 hours of hydration, an enhanced precipitation of hemi and monocarboaluminate (AFm phases) is observed in these systems, associated with the high amount of alumina sourced from calcined clay, in contrast to other pozzolanic materials. Carboaluminates precipitate in large pores that remain after clinker hydration, filling space and contributing significantly to strength gain at early age. Approaches to enhance the precipitation of carboaluminate appear then as a key strategy to offset the reduction of early-age performance seen in low-clinker binders.