Recently, there has been a rapid growth in research and innovation in the natural fibre composite (NFC) area. Interest is warranted due to the advantages of these materials compared to others, such as synthetic fibre composites, including low environmental impact and low cost and support their potential across a wide range of applications. Much effort has gone into increasing their mechanical performance to extend the capabilities and applications of this group of materials. This review aims to provide an overview of the factors that affect the mechanical performance of NFCs and details achievements made with them.

A review of recent developments in natural fibre composites and their mechanical performance

Construction and demolition waste generation and properties of recycled aggregate concrete: A global perspective

Plant fibres, perceived as environmentally sustainable substitutes to E-glass, are increasingly being employed as reinforcements in polymer matrix composites. However, despite the promising technical properties of cellulose-based fibres and the historic use of plant fibre reinforced plastics (PFRPs) in load-bearing components, the industrial uptake of PFRPs in structural applications has been limited. Through an up-to-date critical review of the literature, this manuscript presents an overview on key aspects that need consideration when developing PFRPs for structural applications, including the selection of (I) the fibre type, fibre extraction process and fibre surface modification technique, (II) fibre volume fraction, (III) reinforcement geometry and interfacial properties, (IV) reinforcement packing arrangement and orientation and (V) matrix type and composite manufacturing technique. A comprehensive materials selection chart (Ashby plot) is also produced to facilitate the design of a PFRP component, based on the (absolute and specific) tensile properties.

Developing plant fibre composites for structural applications by optimising composite parameters: a critical review

A critical review and assessment for usage of recycled aggregate as sustainable construction material

Properties and applications of FRP in strengthening RC structures: A review

A total of ten simply supported beams reinforced with different amounts of GFRP and steel bars were subjected to two consecutive test phases in order to evaluate their short and long-term cracking behaviour. The beams were initially tested up to service load and subjected to two additional load cycles. Subsequently, the specimens were subjected to two different levels of sustained load for 250 days. The effect of cyclic load during short-term tests resulted in an increase in crack width up to 25% more than the initial value. The sustained load led to an increase in crack width up to 2.9 times larger than that measured under the corresponding short-term load. A similar cracking behaviour was observed when reinforcing solutions with similar stiffness (GFRP or steel bars) were used. Existing models to estimate crack spacing and crack width for FRP and steel reinforced concrete elements, including ACI 440.1R-06, Eurocode 2 and Model Code 2010 are discussed and their performance is assessed against the experimental results. Model Code 2010 was found to yield more accurate predictions of the cracking behaviour of the test specimens under both short-term and long-term loading.

Short and long-term cracking behaviour of GFRP reinforced concrete beams

Effect of material properties on long-term deflections of GFRP reinforced concrete beams

Experimental study and code predictions of fibre reinforced polymer reinforced concrete (FRP RC) tensile members

The differences in mechanical and bond properties of FRP bars when compared to those of traditional steel reinforcement for reinforced concrete (RC) structures may affect the cracking and deformability behaviour of FRP RC members. To analyse this cracking behaviour, the reinforcement strain profile along a reinforcing bar has been experimentally recorded by using a specially manufactured reinforced concrete element in tension, in which the FRP reinforcement was internally strain gauged. Furthermore, a general procedure derived from a cracking analysis based on slip and bond stresses has been used to study the deformability of FRP reinforced concrete elements under tension. The tension stiffening effect is included via the experimental nonlinear bond–slip law obtained from pull-out test of an experimental programme previously published. The comparison between numerical predictions of the reinforcement strain profile along the reinforcing bar during a tensile test and experimental data confirms that the bond-based model adequately reproduces the redistribution of stresses after crack formation. To further prove the model reliability, numerical predictions of the load–mean strain relationship are compared to previously reported experimental data on FRP RC tensile elements and predictions furnished by the models usually adopted for the analysis of FRP reinforced concrete structures.

L. Torres

Papers

Short and long-term cracking behaviour of GFRP reinforced concrete beams

Effect of material properties on long-term deflections of GFRP reinforced concrete beams

Experimental study and code predictions of fibre reinforced polymer reinforced concrete (FRP RC) tensile members

Analysis of cracking behaviour and tension stiffening in FRP reinforced concrete tensile elements

Bond response of NSM CFRP strips in concrete under sustained loading and different temperature and humidity conditions