The hydration of fast setting spray binder versus (aluminum sulfate) accelerated OPC

Autor: Lukas G. Briendl, Florian Mittermayr, Rudolf Röck, Florian R. Steindl, Marlene Sakoparnig, Joachim Juhart, Fatemeh Iranshahi, Isabel Galan
Rok vydání: 2022
Předmět:
Zdroj: Materials and Structures. 55
ISSN: 1871-6873
1359-5997
Popis: Abstract The (early) hydration mechanisms of two different binder systems used for shotcrete were investigated: the so far almost unexplored low sulfate binder (spray binder), used in the field of dry-mix shotcrete; and ordinary Portland cement, accelerated by aluminum sulfate, widely used for wet-mix shotcrete. The basis for the fast setting of the spray binder is the rapid dissolution of C3A and the subsequent formation of flaky CO3-AFm phases. Thereby induced high aluminum concentrations in the pore solution lead to a blockage of alite dissolution during the first hours of hydration. At later stages, higher amounts of portlandite are formed in the dry-mix, compared to the wet-mix system. The lower calcium availability for portlandite formation in the wet-mix system is explained by an enhanced formation of C–A–S–H phases with a higher Ca:Si ratio. Additionally, wet-mix systems show lower porosity and higher compressive strength after 1 d of hydration and beyond. Graphical abstract
Databáze: OpenAIRE
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