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

This research focuses on the behavior of the tensile and flexural modulus of polypropylene/hemps strands composites. The intrinsic tensile modulus of the hemp strands was computed using Hirsch model and experimental data of the tensile modulus of the polypropylene composites at the 20–50 wt.% hemp strands content. The modified rule of mixtures was used to evaluate the efficiency factor. Square packing distribution was assumed and the length factor was fixed by Cox–Krenchel’s model. The mean value of the orientation efficiency factor was found to be 0.55. Tensile and flexural modulus were compared concluding that its value was independent of the manner the composite was loaded. Finally the Tsai–Pagano model was applied to predict the behavior of the composite’s tensile modulus.

Analysis of tensile and flexural modulus in hemp strands/polypropylene composites

The structural behaviour of reinforced concrete (RC) elements depends heavily on the bond performance between the concrete and the reinforcing material. Bond behaviour under short-term testing has been extensively analysed for steel reinforcement and many studies have been carried out for fibre reinforced polymer (FRP) reinforcement. However, there has only been limited investigation of the long-term effects of this interaction. Several factors can affect the long-term bond behaviour of these elements, the most important being bond length and the immediate and time-dependent properties of reinforcement and concrete (concrete grade, creep, shrinkage and stiffness). This time-dependent behaviour is likely to cause changes and redistributions in bond stresses not properly considered in the limited existing literature. In this experimental study, the bond performance of GFRP RC under sustained load is investigated through pull-out tests. A total of 12 pull-out specimens were tested for a period of between 90 and 130 days. Two concrete strengths (35 MPa and 50 MPa), two bond lengths (5 and 10 times the diameter of the reinforcing bar) and two reinforcing materials (glass fibre reinforced polymer (GFRP) and steel) were used. Experimental results regarding immediate and time-dependent slip are presented and analysed here. In addition, some specimens were instrumented, with internal strain gauges in the reinforcing bar to provide data on the reinforcement strain, thus allowing the distribution of bond stresses and their evolution during sustained loading to be also presented and analysed.

Experimental study of bond-slip of GFRP bars in concrete under sustained loads

Bond behaviour between recycled aggregate concrete and glass fibre reinforced polymer bars

Experimental study of immediate and time-dependent deflections of GFRP reinforced concrete beams

In this paper, the creep behavior of a structural epoxy adhesive used for strengthening Reinforced Concrete (RC) structures with Carbon Fiber Reinforced Polymer (CFRP) laminates is studied through an experimental program. Long-term tensile creep tests were carried out inside a climate chamber using sustained loading levels, temperature and humidity as the parameters for the study. The specimens were kept loaded inside the climate chamber for 1000 h. Standard Tensile Tests (STT), Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC) tests were carried out to characterize the adhesive used. In general, the results obtained revealed that changing temperature and humidity conditions greatly affect not only instantaneous and creep strain values, but also time to failure, leading to a change in the overall behavior of the adhesive.

Effect of sustained loading and environmental conditions on the creep behavior of an epoxy adhesive for concrete structures strengthened with CFRP laminates

L. Torres

Papers

Analysis of tensile and flexural modulus in hemp strands/polypropylene composites

Experimental study of bond-slip of GFRP bars in concrete under sustained loads

Bond behaviour between recycled aggregate concrete and glass fibre reinforced polymer bars

Experimental study of immediate and time-dependent deflections of GFRP reinforced concrete beams

Effect of sustained loading and environmental conditions on the creep behavior of an epoxy adhesive for concrete structures strengthened with CFRP laminates