Browsing by Author "Ershad, Mohamadmahdi (Armin)"

Now showing 1 - 1 of 1
  • Thumbnail Image
    ItemOpen Access
    An Experimental and Numerical Study on Metakaolin-based Geopolymers
    (2021-01-26) Ershad, Mohamadmahdi (Armin); Khoshnazar, Rahil; Moshirpour, Mohammad; Shrive, Nigel Graham
    Portland cement concrete, in its most basic form, is produced by mixing aggregate, Portland cement (PC), and water. High energy consumption and CO2 emissions associated with the production of PC have caused serious environmental issues, and PC production is now responsible for about 5-8% of the global CO2-equivalent greenhouse gas emissions. Extensive research has been conducted to develop new and more sustainable binders that can replace PC paste in concrete without compromising its performance. Geopolymers (GPs) are a class of these alternative binders attracting significant attention in the past few decades. They are produced by mixing an aluminosiliceous powder such as metakaolin (MK) with an alkaline solution. Several parameters such as composition and curing conditions influence the characteristics of GPs, and appropriate selection of material proportions is necessary to achieve the desired performance. This research aims to (i) model the compressive strength of MK-based GPs based on their composition and (ii) suggest new methods for enhancing the compressive strength of MK-based GPs. In the first part of this research, different GPs were prepared with two different grades of MK and various compositions. Machine learning models were then used to classify and predict the compressive strength of GPs using the dataset driven from the experimental plan of this research and the literature. Different models were tested, among which the extreme gradient boosting algorithm was able to classify the GPs with 80% accuracy in three levels of ‘low’, ‘medium’, and ‘high’ strength and predict the strength with R2 = 0.80 given the composition and test age. In the second part, a seeding method was used to improve the compressive strength of GPs. Three different types of zeolite seeds (hydrogen faujasite, sodium faujasite, mordenite) were used. The results showed that all the zeolites could improve the strength of GPs although hydrogen faujasite and mordenite seemed to be more effective than sodium faujasite.