Mechanical and permeability properties of the interface between normal concrete substrate and ultra high performance fiber concrete overlay

Construction and Building Materials, Volume 36, November 2012, Pages 538-548
Bassam A. Tayeh, B.H. Abu Bakar, M.A. Megat Johari, Yen Lei Voo

School of Civil Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang, Malaysia

Engineering Division, Islamic University of Gaza, Gaza, Palestine

Dura Technology Sdn. Bhd., Perak, Malaysia

Abstract

As a rule of thumb, the interfacial bonding between deteriorated concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concreteinterfaces. The objective of this study is to examine experimentally the mechanicalproperties and permeability characteristics of the interface between normalconcrete (NC) substrate which represents old concrete structures and an overlay of ultrahighperformancefiberconcrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear and splitting tensile tests to quantify the influence of the differently roughened substrate surfaces. On the other hand, the permeability characteristics were evaluated by means of the rapid chloride permeability, gas and water permeability tests. The results show that the newly overlay UHPFC achieves high bond strength and bonds efficiently with the NC substrates. The specimens with sand blasted substrate surface give the best interfacial mechanical bonding in comparison to other types of surface preparation. The permeability tests proved that the interfacial bonding is very good and efficient which significantly improve the impermeability of the composites, and this was clearly shown by the SEM micrograph of the interface. Hence, it is envisaged that the use of UHPFC concomitant with appropriate surface preparation of the substrate should be able to provide effective and durable concrete repair.

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