Bio-based fibres for use in cement composite materials

Abstract

The invasive Agave plant has been rapidly spreading in the Maltese islands, displacing native species and potentially harming local structures and biodiversity. Extensive removal efforts have been undertaken, but the disposal of these alien species through incineration poses a significant environmental challenge. To mitigate this issue, it is crucial to utilize this by-product in an innovative and sustainable way that contribute to a more circular and sustainable economy. This study investigates the potential use of Agave Sisalana fibres in self-compacting concrete (SCC) and their impact on its fresh properties, early age characteristics and hardened properties of concrete. The influence of different fibre lengths, specifically 15mm, 25mm and 35mm, with various fibre volume percentages of 0.25%, 0.50% and 1%, were considered. To evaluate the performance of the concrete specimens, experimental tests were conducted to assess the compressive, flexural, tensile and shrinkage behaviour. The findings obtained from the testing of the fresh properties indicated that the introduction of fibres in the concrete mix reduced its self-compacting characteristics. This reduction was primarily observed in the passing ability of the mix, with instance of clogging resulting in loss of performance. However, despite this expected decrease in performance, the SCC still maintained certain flow characteristics. For the early age characteristics, both concrete and mortar were subjected to controlled environmental conditions. The concrete specimens were placed in an environmental chamber, while the mortar panels were exposed to directed wind from high-velocity fans. The results indicated that the addition of Agave fibres contributed to a decrease in plastic shrinkage cracks widths and delayed crack development. Additionally, the restrained concrete ring test also demonstrated higher strains exerted on the steel ring with an increase in fibre percentage. Regarding the mechanical properties, the addition of fibres resulted in a decrease in density, ultrasonic pulse velocity and compressive strength of the concrete. However, it also led to an increase in the flexural peak load and tensile splitting strength.