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Abstract

The immense majority of the infrastructures nowadays are mainly constructed of concrete and steel. However, the strengthening and maintaining of concrete infrastructures have been of particular interest to researchers, especially in regards of temperature issues and the viability to be used in constructing of the nuclear power stations. The composite materials (fiber reinforced polymers and textile reinforcment fibers) have been introduced for the strengthening of concrete structures in recent decades. In this study FRP as composite and the newly-developed fibre-reinforced cementitious matrices (FRCM) were considered. FRCM composites have become popular in the construction and building industry as a flexible replacement strengthening system for the old and classic composite materials (FRP). The former composite became an alternative for the FRP composites in the rehabilitation of historical and damaged masonry and concrete structures due to the use of inorganic mortar in the application instead of epoxy (used by FRP). Fabric grids and cementitious matrices are the components forming the mesh acting as matrix and binder in FRCM and TRM textile systems.

In this thesis, experimental and analytical results studied from the previously established researchs and then compared to the current research outcomes. The investigation is to evaluate the improvement obtained thorough the use of fibre reinforced cementitious matrix (FRCM) as the strengthening materials for concrete beams at different temperatures. FRP composite is not effective (when its used as strengthening material) at temperatures above glass transition (Tg) level (75 C), (Eligh 2011). FRCM strengthening system is studied at normal and elevated temperatures, for that purpose a numerous of small and large-scale beams were casted and then tested under four-point bending method.

Several groups of concrete beams were casting, in the initial portion the casting were consists un-reinforced concrete beams to be strengthened externally with FRCM system. The samples were strengthen with different plies (carbon and steel net), to be examined for the material properties investigation and compare them to un-strengthened specimens, respectively.

For the structural investigation, further tests were carried out on large Reinforced Concrete (RC) beams to be strengthened with FRCM system (carbon and steel net) on the Tension (flexure) side, and then to compare with the control beams.

Although abundant reports are available in the literature regarding FRCM use as a strengthening system in concrete structures but temperature studies are almost totally neglected. This research is to study FRCM system concerning ambient and elevated temperatures which adds important contribution in engineering research. This study consists of investigation of various parameters that are affecting the newly developed systems (elevated temperature, different materials used, steel net and carbon, and material properties i.e thickness and reinforcement application).

A simple computer-based (2D) program, FEAPpv (finite element model), was introduced for simulating the nonlinear finite element analysis of the small beams to support the results at normal temperature. Furthermore another complex three-dimensional software, was utilized to validate the experimental results at normal and elevated temperatures which is ABAQUS (Version 6.14).

This thesis also included a detailed study on the failure types and causes of the bonding of the cementitious mortar to the fibre slippage within the fabric and matrix. Failure modes observed were mainly due to de-bonding at the interface of the cementitious mortar and concrete (i.e FRCM steel net) as well as fibre rupture and fibre pull-out of the matrix mesh (I.e FRCM-carbon).

The viability of this thesis substantiates the engineering research on the effectiveness of FRCM strengthening system on concrete infrastructures at various temperatures. It will contribute to better understanding the system and can be used as a guide to enhance the present knowledge in engineering production. Further study can enrich the topic on the use of FRCM materials on different infrastructures, temperatures and durations.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > Q Science (General) T Technology > TA Engineering (General). Civil engineering (General) T Technology > TG Bridge engineering T Technology > TH Building construction
Departments:	School of Science & Technology > Engineering > Civil Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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