Title: Early-Age Shrinkage, Hydration Kinetics, and Workability of Mortars Containing Metakaolin and Limestone Powder

Author(s): Alban Metallari, Mirco Wahab, and Thomas A. Bier

Publication: Symposium Paper

Volume: 362

Issue:

Appears on pages(s): 376-392

Keywords: capillary pore pressure, limestone powder, isothermal calorimetry, metakaolin, plastic shrinkage, supplementary cementitious materials, workability

DOI: 10.14359/51740898

Date: 6/11/2024

Abstract:
The use of supplementary cementitious materials (SCMs) to partially replace Portland cement (PC) as a way of reducing CO₂ emissions has increased considerably during the last decade. Correspondingly, research in traditional and alternative SCMs has been expanded significantly. This study focuses on some early-age aspects of mortars containing metakaolin (MK) and limestone powder (LSP) at five different substitution levels, ranging from 5 to 25 wt.%. Their effect on the early age shrinkage (plastic shrinkage), development of capillary pore pressure, hydration kinetics, and workability of mortars was investigated. It was found that the presence of SCMs significantly influenced the shrinkage behaviour during the early age, due to the development of a negative capillary pore pressure, in combination with other underlying mechanisms as well. SCM-dependent changes in the heat of hydration development investigated through isothermal calorimetry were less pronounced. The workability of the mortars studied varied from low to high due to the amount of water and superplasticizer used. It was further shown to be dependent on the specific type of SCM and the substitution level used.