City Research Online

Abstract

Concrete is extensively used in the construction of infrastructures, however formation and development of cracks undermines the integrity of the structure. Thus, both improving the mechanical properties of this construction material as well as structural health monitoring of structures are essential tasks to be tackled.

The research covered in this thesis is concerned with mechanical properties of carbon nanofiber reinforced concrete and the effect of this type of concrete on structural performance of the composite steel-concrete sandwich (SC) system. The use of nanofibers such as Carbon Nanofiber (CNF) within cementitious materials is found to be effective in enhancing the mechanical properties of the cementitious material as well as enhancing the sensing ability of the cementitious composites. Despite the abundant experimental work on nanofiber reinforced cementitious composites by researchers, their use within concrete has not been fully addressed. Therefore, the significance of this research is to assess mechanical properties of nanoreinforced concrete along with its sensing capability.

The steel-concrete sandwich system consists of thick concrete core with exterior steel faceplates acting as reinforcement. The steel faceplates are anchored to the concrete core with shear connectors. This study presents the structural performance of the SC element with fiber reinforced concrete (FRC) core using both single fiber and hybrid fiber (i.e. consisting of two types of fibers) in the core. For this study carbon nanofiber and steel fiber, which is conventionally used in practice, are used for the FRC. Static tests were conducted on eight SC beams with different concrete types. In addition to studying the structural performance of the SC element with fiber reinforced concrete, the self-sensing capability of beams with CNF reinforced concrete core were assessed. Furthermore, finite element analysis was conducted to evaluate the effect of some design parameters on the behaviour of SC element.

The outcome of this thesis enhances the current knowledge on the use of nanofibers in civil engineering industry as nano reinforcement and nanofilaments within cementitious materials, typically concrete and it will contribute to the understanding of the effect of CNF on concrete mechanical properties. This research laid the groundwork for additional in-depth study on using carbon nanofiber reinforced concrete within structural members and determination of their effect as nanofilaments on the self-sensing capability of the structural element.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	Doctoral Theses School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses

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