Bond strength between corroded steel and recycled aggregate concrete incorporating nano silica. (20th March 2020)

• Record Type: Journal Article
• Authors: Alhawat, Musab; Ashour, Ashraf
• Is Part Of: Construction & building materials. Volume 237(2020)
• Publication Date: 2020-03-20
• Subjects: Bond strength -- Recycled aggregate concrete -- Nano silica -- Corrosion rate -- Pull-out test; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.117441
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: NS slightly improved the bond strength for un-corroded specimens. The effect of NS was more pronounced with increasing RCA content and corrosion period. NS was appreciably sufficient to recover the decrease in RCA concrete performance. NS significantly improved bond resistance after exposure to corrosive conditions. Abstract: Limited information related to the application of nano silica in recycled aggregate concretes has been available in the literature. However, investigations on the effect of nano silica on the bond performance of reinforcement embedment length in recycled aggregate concrete have not been conducted yet. Therefore, the present study aimed at investigating the bond strength for recycled aggregate concretes incorporating nano silica under different levels of corrosive environments. The experimental work consisted of testing 180 pull-out specimens prepared from different mixtures. The main parameters studied were the amount of recycled aggregate (i.e. 0%, 25%, 50% and 100%), nano silica (1.5% and 3%), embedment length (5 and 13Ø) as well as reinforcement diameter (12 and 20 mm). Different levels of corrosion were electrochemically induced by applying impressed voltage technique for 2, 5, 10 and 15 days. Finally, the experimental results were compared with the existing models. Experimental results showed that the bond performance between un-corroded steel and RCA concrete slightly reduced, while a significant degradation was observed after being exposed to corrosive conditions, in comparison to normal concrete. On the other hand, the use of a small quantity of NS (1.5%) showed between 8 and 21% bond enhancement with both normal and RCA concretes under normal conditions. However, much better influence was observed with the increase of corrosion periods, reflecting the improvement in corrosion resistance. NS particles showed a more effective role with RCA concretes rather than conventional concretes in terms of enhancing bond and corrosion resistance. Therefore, it was superbly effective in recovering the poor performance in bond for RCA concretes. By doubling the content of NS (3%), the bond resistance slightly enhanced for non-corroded samples, while its influence becomes more pronounced with increasing RCA content as well as exposure time to corrosion.