Interfacial Bond Quality in Functionally Graded Concretes Incorporating Steel Fibres and Recycled Aggregates

Ricardo Chan*, Isaac Galobardes, Charles K.S. Moy

*Corresponding author for this work

Research output: Chapter in Book or Report/Conference proceedingConference Proceedingpeer-review

1 Citation (Scopus)


A functionally graded material (FGM) is a material presenting gradation in composition and structure, designed to attend to specific functions. FGM produced with concrete, known as functionally graded concrete (FGC), has been studied for several applications by combining layers of distinct types of concrete showing technical benefits. Due to the material discontinuity, an interfacial zone is created between layers, named as layer transition zone (LTZ). As the weakest link between different concrete layers, the bond quality of LTZ may influence the mechanical behaviour of FGC. In this paper, the quality of LTZ in FGC was assessed considering the type of aggregate, content of steel fibres and casting delay between layers. FGC were produced with a top layer of plain cement concrete (PCC) and a bottom layer of conventional fibre reinforced concrete (FRC) or fibre reinforced recycled aggregate concrete (FRRAC). The FGC were assessed for compressive strength and bond strength between layers. The results indicate that the bond quality of LTZ is affected by casting delay and compressive strength of each layer. Moreover, it was noticed that the impact of adding steel fibres was not significant to alter the bond quality in FGC. Overall, adequate bond strengths were obtained in FGCs with casting delays of up to 24 h.

Original languageEnglish
Title of host publicationFibre Reinforced Concrete
Subtitle of host publicationImprovements and Innovations - RILEM-fib International Symposium on FRC BEFIB in 2020
EditorsPedro Serna, Aitor Llano-Torre, José R. Martí-Vargas, Juan Navarro-Gregori
PublisherSpringer Science and Business Media B.V.
Number of pages11
ISBN (Print)9783030584818
Publication statusPublished - 2021
EventRILEM-fib International Symposium on FRC, BEFIB 2020 - Valencia, Spain
Duration: 21 Sept 202023 Sept 2020

Publication series

NameRILEM Bookseries
ISSN (Print)2211-0844
ISSN (Electronic)2211-0852


ConferenceRILEM-fib International Symposium on FRC, BEFIB 2020


  • Bond strength
  • Fibre reinforced concrete (FRC)
  • Fibre reinforced recycled aggregate concrete (FRRAC)
  • Functionally graded concrete

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