Modifying fatigue performance of reactive powder concrete through adding pozzolanic nanofillers. (March 2022)

• Record Type: Journal Article
• Authors: Li, Linwei; Zheng, Qiaofeng; Wang, Xinyue; Han, Baoguo; Ou, Jinping
• Is Part Of: International journal of fatigue. Volume 156(2022)
• Publication Date: 2022-03
• Subjects: Reactive powder concrete -- nano-SiO2 -- nano-SiO2 coated nano-TiO2 -- Compressive fatigue test -- Microstructure characterization; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2021.106681
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Pozzolanic nanofiller is used to improve fatigue performances of concrete. Adding nanofiller significantly improves fatigue life and limit of concrete. Improvement results from modified pore structure and interfacial transition zone. Nanofiller is beneficial for producing more and dense calcium silicate hydrate gel. Fatigue life model based on strain rate at creep-fatigue coupling stage is build up. Abstract: The concrete fatigue performance that determines service life of concrete structure are closely related to its microstructure. Incorporating pozzolanic nanofillers into concrete can yield dense C-S-H gel to increase the logarithmic creep modulus, and modifies the microstructure of concrete to enhance the cracking resistance, which can help to modify the fatigue performance of concrete. This paper investigates the impact of pozzolanic nanofillers on the compressive fatigue performance of reactive powder concrete (RPC), with investigation into the modifying mechanisms. Compressive fatigue test results show that adding nanofillers significantly improve fatigue life and fatigue limit of RPC, whose maximum enhancement is 120.1% and 19.4%, respectively. The addition of nanofillers also leads to the increase in ultimate compressive strain of RPC and the decrease in strain rate at the creep-fatigue coupling stage. The image processing results on morphology at cracking surface of composites demonstrates that incorporating nanofillers approximately reduces the porosity of RPC by half. The scanning electron microscope image indicates the nanofillers are beneficial for producing more and dense calcium silicate hydrate gel. According to the line scanning results of energy dispersive spectroscopy, the average ratio of calcium oxide to silicon dioxide in interfacial transition zone of RPC with pozzolanic nanofillers is obviously lower than that of plain RPC. These are the main underlying mechanisms contributing to the improvement of RPC fatigue performance. In addition, a fatigue equation that reflects the relation between fatigue life and strain rate at creep-fatigue coupling stage is established, making it possible to predict the fatigue life by measuring the strain increase within limited fatigue loading circles.