Early-age aggregation of alkali-activated slag: from microscopic relaxation to macroscopic elasticity, and the effect of PCE
Abstract
The very early age aggregation of a sustainable cementitious suspension consisting of alkali-activated slag (AAS) particles is studied. Diffusing wave spectroscopy (DWS) is used to monitor the microscopic dynamics of the particles during aggregation and small amplitude oscillatory shear (SAOS) is used to measure the macroscopic rheological response of the pastes. The dissolution of slag and precipitation of C-A-S-H (main hydration products of AAS) are monitored with in situ X-ray powder diffraction. Results show that, immediately after particle dispersion, their dynamics is characterized by two relaxation modes: fast, then slow. As aggregation occurs, the amplitude of the fastest mode decreases and its characteristic time increases, up to a transition towards a slower dynamics where a monomodal relaxation is observed. During this very early particle aggregation, nanometer-size nuclei of C-A-S-H particles develop. The transition to a slower relaxation is associated with an increase of the elastic modulus G ′ (t) of the paste, measured by SAOS. This aggregation mechanism is also obtained when the initial concentration of dissolved species from AAS is varied by aging the paste 1-4 h, and is slowed down by the addition of a superplasticizer (PCE).
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BibTeX
@misc{liberto2026earlyage,
title = {{Early-age aggregation of alkali-activated slag: from microscopic relaxation to macroscopic elasticity, and the effect of PCE}},
author = {Teresa Liberto and Pierre Carmona and Omar Ojeda-Farías and Benedetta Costa and Maria Chiara Dalconi and Agathe Robisson and Pascal Hébraud},
howpublished = {HAL},
year = {2026},
month = aug,
url = {https://hal.science/hal-05731922v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Early-age aggregation of alkali-activated slag: from microscopic relaxation to macroscopic elasticity, and the effect of PCE
AU - Teresa Liberto
AU - Pierre Carmona
AU - Omar Ojeda-Farías
AU - Benedetta Costa
AU - Maria Chiara Dalconi
AU - Agathe Robisson
AU - Pascal Hébraud
PY - 2026
DA - 2026/08/31
PB - HAL
UR - https://hal.science/hal-05731922v1
AB - The very early age aggregation of a sustainable cementitious suspension consisting of alkali-activated slag (AAS) particles is studied. Diffusing wave spectroscopy (DWS) is used to monitor the microscopic dynamics of the particles during aggregation and small amplitude oscillatory shear (SAOS) is used to measure the macroscopic rheological response of the pastes. The dissolution of slag and precipitation of C-A-S-H (main hydration products of AAS) are monitored with in situ X-ray powder diffraction. Results show that, immediately after particle dispersion, their dynamics is characterized by two relaxation modes: fast, then slow. As aggregation occurs, the amplitude of the fastest mode decreases and its characteristic time increases, up to a transition towards a slower dynamics where a monomodal relaxation is observed. During this very early particle aggregation, nanometer-size nuclei of C-A-S-H particles develop. The transition to a slower relaxation is associated with an increase of the elastic modulus G ′ (t) of the paste, measured by SAOS. This aggregation mechanism is also obtained when the initial concentration of dissolved species from AAS is varied by aging the paste 1-4 h, and is slowed down by the addition of a superplasticizer (PCE).
ER -