An effective and reliable method to extract pore solution from concrete and method to quantify the elements from that pore solution.
Dear Shree Raj Paudel,
In Geopolymer concrete, the polymerization process involves a substantially fast chemical reaction under alkaline conditions on silicon-aluminum minerals that results in a three-dimensional polymeric chain and ring structure….” The ultimate structure of the geopolymer depends largely on the ratio of Si to Al (Si:Al), with the materials most often considered for use in transportation infrastructure typically having an Si:Al between 2 and 3.5. This type of geopolymer will take one of the following three basic forms (where “sialate” is an abbreviation for silicon-oxo-aluminate)
Poly (sialate) Si:Al = 1, which has [-Si-O-Al- • O-] as the repeating unit.
Poly (sialate-siloxo) Si:Al = 2, which has [-Si- • O-Al-O-Si-O-] as the repeating unit.
Poly (sialate-disiloxo) Si:Al = 3, which has • [-Si-O-Al-O-Si-O-Si-O-] as the repeating unit.
Although the mechanism of polymerization is yet to be fully understood, a critical feature is that water is present only to facilitate workability and does not become a part of the resulting geopolymer structure. In other words, water is not involved in the chemical reaction and instead is expelled during curing and subsequent drying. This is in contrast to the hydration reactions that occur when Portland cement is mixed with water, which produce the primary hydration products calcium silicate hydrate and calcium hydroxide. This difference has a significant impact on the mechanical and chemical properties of the resulting geopolymer concrete, and also renders it more resistant to heat, water ingress, alkali–aggregate reactivity, and other types of chemical attack.
Also, am attaching some articles, which will be useful further.
Dear Shree Raj Paudel,
In fact, the mechanism of ASR in conventional concrete is not even clear. In geopolymer concrete, it is more complicated. The ASR expansions in geopolymer concrete are affected by many factors, e.g. type of activator, dosage of alkali, type of precursor, type of aggregate, etc. You can find the relevant information in the most recent review article on this topic through the following link:
https://www.researchgate.net/publication/270516596_A_review_on_alkali-aggregate_reactions_in_alkali-activated_mortarsconcretes_made_with_alkali-reactive_aggregates
Best regards,
Zhenguo
Article A review on alkali-aggregate reactions in alkali-activated m...
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