Title:
Designing Alternative Binders Utilizing Synergistic Reactions
Author(s):
Harald Justnes and Tone Anita Østnor
Publication:
Symposium Paper
Volume:
303
Issue:
Appears on pages(s):
191-204
Keywords:
Alternative binders; Accelerators; Calcined clay; calcium carbonate; SCM; Synergy
DOI:
10.14359/51688134
Date:
6/1/2015
Abstract:
Alternative binders are defined as binders without portland cement. Two synergy principles
have been described for making improved binders based on slaked lime and pozzolanic
SCMs. One showing how neutral salts may accelerate by forming strong alkaline solutions
in situ and another showing how calcium carbonate can play a role when alumina
containing SCMs are used by leading to an even higher conversion of liquid water into
solid hydrates, which subsequently leads to lower porosity and higher strength. Examples
are given when the SCMs are calcined kaoline clay contaminated with feldspar and
calcined smectite rich marl, respectively. Mortar strengths exceeding 25 MPa (3626 psi)
when cured at ambient temperature for 28 days were achieved. Predicted phases in the
microstructure, such as calcium monocarboaluminate hydrate, were confirmed by X-ray
diffraction. Other details of the microstructure were studied by capillary suction of water,
thermal analysis and scanning electron microscopy.