Alkali-activated materials (AAM)
Alkali-activated materials (AAM) or more specifically Alkali-activated cementitious materials (AACM) might also be referred to as geopolymers, they can be created from a range of different materials, most usually from industrial by-products and are termed precursors. These are added to an alkaline medium or activator to produce a cementitious material that can be used instead of Portland cement in the making of concrete.
It was in 1957, when a scientist from Kyiv, Ukraine (which was then part of USSR), Victor Glukhovsky, put forward a working hypothesis in which he established that there was close relationship between alkalis and cementitious materials. He investigated the production of binders by using low basic or free calcium alumino-silicate source (clay) with alkaline activators, the new binder was referred to as soil–cements or soil silicate concretes. It was his assumptions and investigations that formed the foundation on which new types of cementitious materials could be developed, which were then called alkaline cements and sometime later AACMs.
It was around the 1970's that AAMs were first industrially produced for use as cementitious materials, they had a lower carbon footprint, because the reaction could happen at room temperature and could also contribute to the early ideas around the circular economy because it was possible to use industrial by-products as the raw materials. The term and concept of geopolymer was developed more specifically by Joseph Davidovits, later in 1991, and with ongoing developement in the field, definitions of what a geopolymer is have become gradually more diverse and at times somewhat conflicting.
Alkali-activation is the chemical reaction between a solid aluminosilicate precursor and an alkaline source or activator, importantly it can occur at room temperature to produce a hardened product. The most commonly used alkali sources are sodium or potassium hydroxides and/or silicates, while aluminosilicates may include suitable raw materials and waste products.
The Concrete Society describe alkali activated cements (including geopolymer cements) as:
"The aluminate-containing material - the pozzolan/latent hydraulic binder component of the cement - can be coal fly ash, municipal solid waste incinerator ash (MSWIA), metakaolin, blastfurnace slag, steel slag or other slags, or other alumina-rich materials. The alkali used as the activator tends to be an alkali silicate solution such as sodium silicate (waterglass) but can also be sodium hydroxide solution, or a combination of the two, or other source of alkali (such as lime). Geopolymeric cements are particular examples of ´alkali-activated pozzolanic cements´ or ´alkali-activated latent hydraulic cements´. All alkali-activated cements tend to have lower embodied energy/carbon footprints than Portland cements (up to 80-90% but this is pozzolan dependent). Manufacture on a commercial basis is underway in the UK, Australia, USA and possibly, China. Covered by PAS 8820:2016 Construction materials. Alkali activated cementitious material and concrete. Specification"
[edit] Related articles on Designing Buildings
Featured articles and news
The benefits of writing articles for your organisation
How to create a profile for your organisation and publish for free.
No Falls Week. The importance of safe working at height
What to expect and what is on offer to avoid accidents.
Scottish Government action to reach net-zero targets
Retrofit expert group highlight critical actions needed.
A forward thinking, inclusive global community of members.
From engineered product life-spans, to their extension.
Circular economy in the built environment
A brief description from 2021. Where are we now?
Mental Health Awareness Week with ABS
Architects Benevolent Society programme of activity.
CLC publishes domestic retrofit competency framework
Roadmap of Skills for net zero.
May 13-19: Moving more for our mental health.
Understanding is key to conservation.
Open industry engagement survey seeks responses
Institutions and the importance of engagement.
National Retrofit Hub unveils new guide
Digital Building Logbooks and Retrofit: An Introduction.
Enhancing construction site reporting efficiency
Through digitisation and the digital revolution.
Noise in the built environment
BSRIA guide TG 20/2021.
17,000 people suffer conditions as a result of exposure to excessive noise at work.
Turning down the noise: Auditory health
A pervasive risk with far-reaching consequences.
Getting the most out of heat pumps and heating
How heat pumps work and how they work best.
Electrotechnical excellence, now open for entries.