Rheological Properties of Recycled Aggregate Concrete Incorporating Supplementary Cementitious Materials

2021 ◽  
Author(s):  
Samer AL Martini ◽  
Ahmad Khartabil ◽  
Narayanan Neithalath
Keyword(s):  
Rheological Properties ◽  
Cementitious Materials ◽  
Recycled Aggregate Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Aggregate Concrete

scholarly journals Combined effects of nano-silica and silica fume on the mechanical behavior of recycled aggregate concrete

2021 ◽  
Vol 10 (1) ◽  
pp. 819-838
Author(s):  
Tang Yunchao ◽  
Chen Zheng ◽  
Feng Wanhui ◽  
Nong Yumei ◽  
Li Cong ◽  
...  
Keyword(s):  
Silica Fume ◽  
Structural Engineering ◽  
Tensile Tests ◽  
Cementitious Materials ◽  
Recycled Aggregate Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Hydration Reaction ◽  
Nano Silica ◽  
Aggregate Concrete

Abstract Recycled aggregate concrete (RAC) is an environmentally friendly material. However, owing to inherent characteristics of the recycled aggregate (RA), it is difficult to promote and apply it in structural engineering. Silica fume (SF) and nano-silica (NS) have different characteristics as additives for RAC. It has been proven that adding SF only enhances the strength of RAC at a later stage, and NS can improve the early strength of RAC owing to its high pozzolanic activity. In this study, to further improve the properties of RAC, two types of additives were combined into RAC, which was named SF-NS-modified RAC (SSRAC). Compression and split tensile tests were conducted to analyze the mechanical properties of SSRAC at different curing ages. The results indicated that the combined addition of NS and SF improved the performance of RAC at early and later curing ages. Scanning electron microscopy and X-ray diffraction analyses were performed to explore the NS and SF mechanism. The results indicated that SF and NS in SSRAC had a good pozzolanic effect and underwent a secondary hydration reaction with calcium hydroxide to increase the production of calcium silicate hydrate, resulting in an increase in the properties of the interface transition zone. Finally, 6% SF and 2 or 3% NS are recommended as supplementary cementitious materials for RAC.

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