Optimum recycled concrete aggregate and micro-silica content in self-compacting concrete: Rheological, mechanical and microstructural properties

Autor: Mahmood Akbari, Seyed Ali Mahmoudy, Mehdi Zohrabi, Nasrollah Bahrami
Rok vydání: 2020
Předmět:
Zdroj: Journal of Building Engineering. 31:101361
ISSN: 2352-7102
DOI: 10.1016/j.jobe.2020.101361
Popis: The use of additives and their proportioning in concrete to achieve better performance is one of the challenging issues in concrete technology. In this study, the influence of different percentages of recycled fine and coarse aggregates on rheological, mechanical, and microstructural properties of self-compacting concrete (SCC) is investigated. For this purpose, fine and coarse natural aggregates (FNA and CNA) were replaced with fine and coarse recycled concrete aggregates (FRCA and CRCA), respectively, at replacement rates of 25%, 50%, 75% and 100% (by weight). The results showed that in order to meet the rheological requirements of SCC, the quantity of FRCA or CRCA should be limited to 25%. Furthermore, the mechanical properties showed a decreasing trend with FRCA and CRCA content, however, all mixes satisfied the strength requirement of structural concrete (28-day compressive strength of 21 MPa) even at 100% CRCA or FRCA content. In order to enhance the mechanical properties of mixes, 5%, 7.5%, and 10% (by weight) of micro-silica was used as a partial replacement of cement. The results showed that the mix with 25% recycled aggregates and 5% micro-silica presented comparable performance to that of the plain concrete, while using a higher micro-silica content negatively affected the rheological properties. In addition, the effect of recycled aggregate and micro-silica on the microstructure of mixes were examined.
Databáze: OpenAIRE
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