Hybrid bio-composites reinforced with sisal-glass fibres and Portland cement particles: A statistical approach

Abstract

The hybrid configuration of bio-reinforced composites has established a new extended boundary for the development of pro-ecological technologies due to light weight, moderate specific strength, low cost, environmental benefits, and potential applications of natural components. This work investigates the physical and mechanical properties of hybrid composites made of sisal/glass fibres and Portland cement inclusions. A full factorial design was generated to identify the effects of the stacking sequence and cement particles on the flexural strength, flexural stiffness, apparent density, apparent porosity and water absorption of the composites. The significant contributions of these main factors and their interactions were determined via Design of Experiments (DoE) and Analysis of Variance (ANOVA). The fracture features and damage mechanisms of hybrid composite were also reported. The inclusion of cement microparticles led to an increased apparent porosity, as well as enhanced water absorption, flexural stiffness and flexural strength of the hybrid composites. The mechanical properties were strongly dependent on the fibre stacking sequence, which accounts for approximately 98% of the effects observed. Moreover, the stacking sequence affected the damage mechanism of the bio-composites. Finally, the replacement of glass fibres by unidirectional sisal reinforcements may potentially improve the specific properties in structural applications with an environmental sustainable footprint.

Evaluation of the stiffening mechanism based on micro-sized particle inclusions in laminated composites

“…The hybrid composites only reach an elastic modulus higher than the reference condition when fabricated with 7.5wt% of silica placed in the lower or upper layers of the laminate. This finding indicates that the interlocking effect, achieved by the particles in the interlaminar region, plays an important role in the stiffening and strengthening of hybrid composites, as reported in the literature [1][2][3][4][7][8][9]16,18,[22][23] . It is well known that the bending load combines tensile (bottom beam side), compressive (upper beam side) and shear loadings 1 .…”

“…This phenomenon is controversial in the literature, especially when micro-sized particles are considered. An increase in flexural stiffness and a reduction in strength and toughness are commonly reported 1,3,15,17,27,28 . In general, the mechanisms of improvement are attributed to the stiffening of the matrix phase and the shear interlocking effect.…”

“…This paper focuses on hybrid composites that combine synthetic fibres and micro-sized ceramic particles. The motivation of using micro rather than nanoparticles is the ability to spread easily over large surface areas with a constant concentration [1][2][3] . According to the literature, the incorporation of microparticles into fibrereinforced polymers (FRPs) can bring benefits to mechanical, tribological and thermal performances [4][5][6] .…”

“…The incorporation of rigid particles in the matrix phase makes it stiffer, affecting the stiffness of the composites 1,[7][8][9] . The amount of particles is extremely important to achieve a positive effect, since a large amount can reduce the contact with the surface and hinder the adhesion condition between the layers 3,8 . The presence of particles in the interlaminar region of the laminate also provides increased friction under shear loads, leading to improved bending behaviour [16][17][18] .…”

Investigations on sustainable honeycomb sandwich panels containing eucalyptus sawdust, Piassava and cement particles

“…Melo et al [19], Torres et al [20] and Ribeiro Filho et al [21], leading to an increase in mechanical properties. Melo et al [19] reported that the cement particles increased flexural strength and flexural modulus of glass fibre reinforced composites.…”