FA 1.1 Binders with low emission and reduced resource consumption
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Objective:
To establish the basis to deveping all round environmentally friendly binder systems.
| Project manager and | |
| disciplinary responsible: | Harald Justnes |
| PhD: | Klaartje De Weerdt and Kien Hoang |
| International advisor: | Professor Fred Glasser, University of Aberdeen, UK |
The project co-operated with the Industrial-Academic Network Nanocem, fib committee 8.12 "Constitutive laws for concretes with supplementary cementitious materials" and the RILEM Technical Cimmittee 238-SCM
The research was dominated by a chemical approach, and included the following activities
- Accelerators for blended cements
- Synergy between calcium carbonate and aluminates in blended cements
- Calcined marl as supplementary cementing material
- Synthetic MeSH particles as accelerator
- Gypsum free Portland cement
Main topics
Sustainable binders and hardening accelerator
The easiest way of making concrete more sustainable is to either replace clinker in cement, or cement in concrete, with supplementary cementing materials, e.g. fly ash, that have a smaller "carbon footprint" than clinker or cement, respectively. A combination of 30% fly ash/5% limestone has proven to give higher strength than 35% fly ash only, meaning that limestone has higher efficiency factor than fly ash in terms of strength. A 35% calcined marl replacement showed much higher strength than any of the other replacements. Also, replacement with calcined marl up to 50% show really lowered intrusion of chlorides. Using fly ash blended with higher replacement level of OPC is limited by the low rate of reaction at early age of fly ash, leading to low early compressive strength. Therefore, a hardening accelerator was developed and patented. A combination of small dosages of a sodium thiocyanate, diethanolamine and glycerol ("three component admixture") appeared to be effective in enhancing the early strength of OPCFA.