To achieve carbon neutrality, sustainability as well as long-term durability of AAMs are still under debate. Although these have very useful potentials in various applications. Will we successfully adopt them on a large scale field applications with low emissions?
Hafiz,
You raise two excellent points that are often the Achilles' heels of these materials. The pre-cursor materials (such as bases, etc.) required for activation may not be all that sustainable and the final product may not be all that durable as I have seen final products that could not even survive simple wet/dry cycling tests.....
Dale
solid waste based alkali activated materials can enchance the sustainability, and the durability, that is specific application oriented, can be tailored by properly taking advantage of the wide diversity of precursors, activators and their massive combinatorial spaces
Although alkali-activated and geopolymer binders are an alternative to Portland cement and in most cases superior to Portland cement in terms of their physical and mechanical properties, there are also a number of features that prevent their use under large-scale conditions:
- leaching of alkali onto the concrete surface under wet conditions;
- leaching of alkali into the storage medium occurs during aqueous storage of the samples and this phenomenon leads to loosening of the structure of the concrete based on them, which ultimately reduces the durability of the concrete;
- the high amount of unbound alkali in the concretes remains after some years or even dozens of years and does not change into hard or insoluble compounds in the water;
- high cost of alkaline activators based on sodium and potassium;
- unstable chemical and mineralogical composition of slags and other solid industrial waste used as aluminosilicate component;
- etc.
Although aluminosilicate-based materials are supplied at affordable prices today (these materials are not used in construction applications today, with rare exceptions.), it is a fact that these materials will not be available at these prices due to the increase in demand.
The cost of activators used to activate these materials is also an important problem.
There is a need for very detailed research in terms of the costs that will occur in the case of widespread use of these materials. These studies that I am talking about are very large-scale projects.
The interest in these materials has increased rapidly, we now have information about many of their properties.
CO2 emissions due to cement production are a major problem in reaching the targets set in the Paris climate agreement.
Although there has been an extraordinary interest in these materials in recent years, it should not be forgotten that this technology is still new. When we put all the positive and negative features together, I believe that these materials will be widely used in 20 years.
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