Dr Fadhilah Muslim

PhD Graduate
Department of Civil & Environmental Engineering

Imperial College London

Fadhilah Muslim is currently a final year PhD candidate in Civil Engineering at the Imperial College London funded by the Indonesian endowment fund for education (LPDP) and already passed her PhD defence in early August 2018 and has been awarded to the PhD degree. Her research is directed at understanding and improving the long-term performance of the concrete structures that form most of the infrastructure in the world. She was trained as a civil engineer at the University of Indonesia, where she obtained an award as the best-graduated student of her class in 2012 and received an offer to become a lecturer due to her excellent grades. She then completed her MSc in concrete materials at Ecole des Ponts ParisTech, funded by both the French and Indonesian governments. Fadhilah received several prizes and scholarships in recognition of her excellent academic achievements and is involved in many communities and associations due to her outstanding intrapersonal and leadership skills.

Improving the Spacer-concrete Interface for Durable Structures

Reinforcement spacers are important devices in reinforced concrete that are used to support reinforcing steel during concreting in order to achieve the required concrete cover. They are placed at every meter length or less of steel reinforcement and left permanently in the structure. However, available studies on the effect of spacers on the performance of concrete are still limited. This work aims to develop a more fundamental understanding of the influence of spacers on the microstructure and the long-term durability of concrete structures. The work also aims to develop methods to enhance bonding and mechanical interlocking of spacers with concrete. 


Extensive experimental testing was performed. Concrete samples containing a range of commercially available spacers were prepared with different binder types including Portland cement CEM I and CEM I blended with silica fume, fly ash or ground granulated blast furnace slag. Finally, a large number of prefabricated modified cementitious spacers were prepared with a range of mix compositions and surface textures, and then cast into concrete for splitting tensile strength and transport testing. 


Results showed that the inclusion of spacer in reinforced concrete produces a weak, porous and micro-cracked interface. This lowers the resistance of concrete to ingress of aggressive agents causing degradation. Modifying the spacer surface texture has a clear effect on increasing its interlocking with concrete, and this leads to a significant improvement in bond strength of the spacer-concrete interface up to 98%. The implications of the findings from this study on the durability of concrete structures are discussed.