Microstructural characterisation of cementitious composite incorporating polymeric fibre: A comprehensive review. (13th June 2022)

• Record Type: Journal Article
• Authors: Tran, Nghia P.; Gunasekara, Chamila; Law, David W.; Houshyar, Shadi; Setunge, Sujeeva
• Is Part Of: Construction & building materials. Volume 335(2022)
• Publication Date: 2022-06-13
• Subjects: Porosity -- ITZ -- Microstructure -- Synthetic fibre -- Fibre-matrix interaction -- Surface treatment -- Elevated temperature; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.127497
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The inclusion of PP, PE, and PVA fibres increases total porosity of cementitious matrices. Hydrophilic fibres tend to reduce the average pore size of cementitious matrices. Pore refinement effect is pronounced with the inclusion of microfibres. Thermal expansion of fibres initiates cracks and releases pressure at elevated temperatures. High melting viscosity of HDPE inhibits vapour transport and show less spalling mitigation. Abstract: Synthetic fibres such as polypropylene (PP), polyvinyl alcohol (PVA), and polyethylene (PE) in both virgin and recycled forms have been widely employed in cementitious composites. Apart from providing bridging action for absorbing stress-induced energy, the addition of polymeric fibres also changes the pore systems in the microstructure of cementitious materials. This paper reviews the microstructure changes of cementitious composite incorporating these three polymeric fibres under both ambient and high-temperature condition. The microstructure of polymeric fibre reinforced concrete is characterised by higher porosity than plain concrete. The use of hydrophilic PVA fibres with microfibres induces pore-refining effects. At elevated temperature PP, PVA and low-density PE (LDPE) exhibit good spalling resistance in concrete due to the formation of microcracks and empty channels left by melted fibre. However, high-density PE (HDPE) fibre is ineffective in mitigating the increased vapour pressure in concrete due to a low coefficient of thermal expansion and high viscosity. Furthermore, to achieve well-balanced interfacial properties, physical/chemical surface modification is necessitated. The introduction of reactive functional groups into the polymer chain of hydrophobic PP and PE fibre significantly enhance fibre-matrix interaction in strengthening interfacial properties with cement paste. Whereas, neutralising hydroxyl functional groups in the PVA polymer chain counteracts extreme delamination or fibrillation of polar PVA fibre when they interact with the cement matrix. With surface modification, the possibility of premature rupture of PVA fibre can be minimised, while improving the transfer of stress-induced energy between the cement matrix and the fibre.