Alkali-activated mortar: promising alternative to cement

Alkali-activated mortar: promising alternative to cement

Over de thesis van Marie Vancanneyt

Textile-Reinforced Alkali-Activated Mortar: Material Development and Characterization (2030)

Promotor(en) Prof. dr. ir. Stijn Matthys, Dr. ir. Philip Van den Heede, Faculteit Ingenieurswetenschappen en Architectuur

Picture: rkit via Pixabay
Redactie Marie Vancanneyt; Febe Visart

"Reducing a robust material like concrete in a building, could that be possible?" In some cases, yes. Marie Vancanneyt shows us the advantages and possibilities of alkali-activated mortar, a sustainable alternative with a lot of potential.

A small step to zero, a big step for humanity

As Bill Gates states in his book “how to prevent a climate disaster”, we must reach zero [1]. With this statement, he means that we have to reduce the number of harmful emissions to an amount that we can compensate by nature or by an industrial solution.

One of the big topics he presented was the huge effect of cement production on our planet and the increase in temperature that we must reduce to provide a livable planet for the upcoming generations.

Unfortunately, the most common building material, concrete, consists of cement. By replacing it, where possible, we might prevent catastrophic climate disasters, such as flooding and overheating. Marie Vancanneyt points to the ability of alkali-activated mortar to replace concrete for certain applications, which could be a first step towards zero.

Concrete and cement: big polluters

Concrete and cement are without doubt major fixtures in the construction industry since 1842. Transportation, infrastructure, industry, and cities all rely on these particularly strong and multifunctional materials. More than 10 billion tons of concrete are produced every year. However, because of their environmental impact, these materials should be improved or replaced where possible.

First, they require many raw materials, and their production process emits a lot of CO2 and other harmful gasses. Furthermore, when looking at the lifetime of concrete structures, most have reached their life cycle, causing dangerous and non-environmentally friendly situations. For instance, an uncontrolled failure of a bridge or a building might result in injury or even death.

In addition, the flora and fauna can be affected as well by the release of dust and materials during failure. And finally, in case of transportation, these failures could evoke extra traffic jams, producing even more harmful emissions.

Sustainable alternative

Alkali-activated mortar can provide a solution to these problems. Although it cannot replace all concrete on this planet – only a small number actually – it could prevent failure and reduce the emission of CO2 and other gasses.

In fact, Vancanneyt measured a release reduction of detrimental substances in the air of around 50%, measured in CO2equivalant. If we assume that we replace 1% of the market by alkali-activated mortars, we could reduce the emission of harmful substances up to 0.5%.

This might seem a very small percentage. Nonetheless, you should know that during the lockdowns to prevent the spread of the coronavirus, when almost all economic activities were stalled, the reduction was only 5%. This comparison clearly demonstrates the potential of these alkali-activated mortars.

But what exactly makes them so promising? First, alkali-activated mortars are largely composed of waste materials from other industries, which reduces the need for new raw materials. For example, during her research, Vancanneyt used ‘blast furnace slag’, a waste material of the steel industry.

composition of Alkali-activated mortar
Quite similar composition to conrete but different environmental impact. Picture: Marie Vancanneyt

Second, if we use waste materials of nearby industries, we can lower the transportation distance and thus make the production even more sustainable. Vancanneyt used a waste product of the steel industry because steel is manufactured around Ghent, where she conducted her research.

Third, we can repair constructions in a sustainable way by combining these materials with textile. This method will increase their life cycle duration and consequently diminish the number of pollutions once again.

Finally, the list of composition possibilities is quite extensive. Thereby, we can find the perfect fit for each application to meet our sustainable goals.

SDG’s

If we take a closer look at the sustainable development goals, we see that alkali-activated materials can contribute to four of these: (1) responsible consumption and production; (2) industry, innovation, and infrastructure; (3) sustainable cities and communities; (4) life on land.

The most obvious SDG is definitely ‘responsible consumption and production’. As you know by now, alkali-activated mortar consists of waste materials. By using this instead of concrete and cement we can take a big step towards a circular economy.

resources - processing - manufacturing - distribution - use - end of life

Besides, alkali-activated-mortar allows us not only to build new, sustainable infrastructure, but also to make old, non-sustainable construction more sustainable by combining the new mortar with a textile repair method, called TRAAM. This demands a new industrial process that, in contrast to conventional concrete, releases a lower number of CO2 and other harmful emissions.

Furthermore, it reduces the number of waste and soil pollution, because it makes use of waste materials of other industries. Since a lot of these waste materials are produced in Belgium, their transportation distance is limited.

You might wonder how mortar could contribute to sustainable cities and communities. Well, by using the TRAAM method, we can preserve transportation systems and cultural heritage. Eventually, this increases the safety of all human beings and reduces direct economic losses related to these structures.

Lastly, waste materials of industries are often deposited on land, thus polluting the ground. If we use them for alkali-activated mortar, we can “protect, restore and promote sustainable use of terrestrial ecosystems”, which is what the SDG ‘life on land’ is about.

Endless opportunities

With all this in mind, you could say that Alkali-activated mortar contributes to more sustainable and safe cities on this planet. But will human life still be limited to planet Earth in the future? Due to its composition, we can also create Alkali-activated mortar on the Moon or on Mars, which helps to enable the creation of new civilizations on a different planet and thus to build a new life on “planet B”.

Back to the near future, we need to focus on circular construction, which alkali-activated mortar does by using waste materials. Practicing new things, like using alkali-activated mortars, is hard, as we all have our habits. Nevertheless, the idea that a circular economy has become a necessity is permeating to various levels in society [2]. Just like Vancanneyt, we must think “outside the box”.

And of course, circular economy starts with the design of the building. It is important that recyclable and reusable materials are indeed recycled and reused. Today we still dismantle materials way too often and have no eye for recuperation. A good design can never result in breaking down if recovery is perfectly possible.

Will this process of development be easy? Not at all, but each small step is a step into the right direction. Alkali-activated mortars are a perfect example and can inspire other researchers to opt for new materials. The time is now to put the theory of circular economy and reduction of harmful emissions into practice.

 

[1] Gates, B. (2021). How to avoid a climate disaster: the solutions we have and the breakthroughs we need. Knopf.

[2] Debusseré, E., Steeman, M., & Van Den Bossche, N. (2020). Circulaire gevelsystemen.

Over Marie Vancanneyt

Marie Vancanneyt
23
Melle
Burgerlijk ingenieur: Bouwkunde
MaNaMa: Bedrijfseconomie

Rooskleurig is de toekomst nog niet op het vlak van klimaat, al zijn er wel al roze tinten zichtbaar. Terwijl ik het privilege heb gehad om aan dit project mijn steentje bij te dragen, hebben we heel wat inzichten verworven.

Enerzijds is het duidelijk dat we nog veel werk hebben om onze doelen te behalen en om de uitstoot te verminderen. Anderzijds is er volop onderzoek aan de gang naar alternatieven om de temperatuurstijging, die zo catastrofaal zal zijn, toch zoveel mogelijk in te perken. De grote vraag zit eerder in hoeverre de bevolking die zal toepassen en aanvaarden. Ik geloof erin dat we dit met z'n allen kunnen verwezenlijken.

Op persoonlijk vlak zou ik de komende jaren graag in de consulting gaan. Ik zou mij daarbij graag aansluiten bij een firma die duurzame oplossingen vooropstelt. Op die manier kan ik de industrie en bedrijven in de juiste richting sturen om het klimaat en deze planeet leefbaar te houden.

Met dit onderzoek, niet alleen van mij maar van een heel team, wil ik aantonen dat alternatieven zeker mogelijkheden bieden voor het klimaat. Ze kunnen echt wel een impact hebben, ook al lijkt dit in eerste instantie niet het geval.

Als onderzoeker wil ik uiteraard ons product op de markt zien verschijnen. Hiervoor zal ik helaas nog even geduld moeten uitoefenen, aangezien dit ook afhangt van economische factoren.