Title:
Formulation of Hybrid Cements based on Construction Demolition Waste
Author(s):
Vlastimil Bilek, Lukas Prochazka, Filip Khestl, Katerina Matyskova
Publication:
Symposium Paper
Volume:
370
Issue:
Appears on pages(s):
199-208
Keywords:
alkali-activated materials, hybrid cement; fly ash; recycled masonry; slag
DOI:
10.14359/51751779
Date:
6/1/2026
Abstract:
Hybrid cements contain a small amount of Portland cement; the rest of the binder is made up of pozzolanic or latent hydraulic admixtures. Another component is an alkaline activator. These binders, therefore, combine the advantages of alkaline activation and Portland cement. In this work, a combination of Portland cement, ground granulated blast furnace slag (GBFS), siliceous fly ash (FA), and ground recycled masonry (GRM) is chosen. The GRM mainly contains ground bricks - i.e., heat-treated clay with potential pozzolanic properties and usually about 7-8% CaCO3 from the original mortar. Sodium water glass modified with potassium hydroxide is used as an activator. Potassium ions improve the workability of the mixture and limit the efflorescence of the hardened mixture. The dose of cement was optimized, as well as the dose of the activator. Furthermore, mixtures with different GBFS or FA and GMR ratios were tested. With an optimal composition and a water-to-binder ratio of 0.50, it is possible to achieve compressive strengths between 15 and 20 MPa at the age of 28 days, with the expectation of further improvement.
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