Sisal fibre and its composites: a review of recent developments

http://www.saetaequina.com/files/1-s2_0-S0950061811006763-main.pdf

A simple review of soil reinforcement by using natural and synthetic fibers

Nearly 40% of mortality in the United States is linked to social and behavioral factors such as smoking, diet and sedentary lifestyle. Autonomous self-regulation of health-related behaviors is thus an important aspect of human behavior to assess. In 1997, the Behavior Change Consortium (BCC) was formed. Within the BCC, seven health behaviors, 18 theoretical models, five intervention settings and 26 mediating variables were studied across diverse populations. One of the measures included across settings and health behaviors was the Treatment Self-Regulation Questionnaire (TSRQ). The purpose of the present study was to examine the validity of the TSRQ across settings and health behaviors (tobacco, diet and exercise). The TSRQ is composed of subscales assessing different forms of motivation: amotivation, external, introjection, identification and integration. Data were obtained from four different sites and a total of 2731 participants completed the TSRQ. Invariance analyses support the validity of the TSRQ acrossallfoursitesandallthreehealthbehaviors. Overall,theinternalconsistencyofeachsubscale was acceptable (most a values >0.73). The present study provides further evidence of the validity of the TSRQ and its usefulness as an assessment tool across various settings and for different health behaviors.

/pdf/validating-the-theoretical-structure-of-the-treatment-self-2uj6sd6snk.pdf

Validating the theoretical structure of the Treatment Self-Regulation Questionnaire (TSRQ) across three different health behaviors

https://upcommons.upc.edu/bitstream/handle/2117/26136/Ardanuy?sequence=5

Cellulosic fiber reinforced cement-based composites: A review of recent research

https://repositorium.sdum.uminho.pt/bitstream/1822/10832/1/Vegetable%20fibres.pdf

Cementitious building materials reinforced with vegetable fibres : a review

Fibre reinforced cement-based composites were prepared using kraft pulps from sisal and banana waste and from Eucalyptus grandis pulp mill residues. The study adapted conventional chemical pulping conditions for the non-wood strands and a slurry vacuum de-watering method for composite preparation followed by air-curing. Plain cement paste and Pinus radiata kraft reinforced cement composites were used as reference materials. Mechanical testing showed that optimum performance of the various waste fibre reinforced composites was obtained at a fibre content of around 12% by mass, with flexural strength values of about 20 MPa and fracture toughness values in the range of 1.0–1.5 kJ m−2. Experimental results showed that, of the waste fibres studied, E. grandis is the preferred reinforcement for low-cost fibre-cement.

Brazilian waste fibres as reinforcement for cement-based composites

This paper examines the microstructure of composite materials containing fibrous wastes (as reinforcement in granulated blast furnace slag or ordinary Portland cement matrices). Both secondary and back-scattered electron imaging and energy dispersive X-ray spectroscopy were used for compositional analysis. Evaluation of both fractured and cut surfaces provided the morphological and bonding information that was related to mechanical performance obtained from flexural tests. Sisal and Eucalyptus grandis pulps showed satisfactory bonding to the cement matrix, with fibre pullout predominating as indicated by high values of energy absorption. In contrast banana pulp reinforced composites exhibited fibre fracture as the main failure mechanism. In all analysed composites, partial fibre debonding and matrix micro-cracking were dominant at the interfaces. However, there was no evidence of a porous transition zone or massive concentration of calcium hydroxide at the interface.

Microstructure and mechanical properties of waste fibre–cement composites

This project evaluated the performance of thin fibre-cement elements produced from alternative raw materials using the Hatschek process, with a view to their use in low-cost housing. Sisal and banana fibres were prepared using mechanical and kraft pulping procedures while residual Eucalyptus grandis pulp was obtained from a commercial pulp mill. Granulated blast furnace slag (BFS) was used as the major component of an alternative hydraulic binder and ordinary Portland cement as a control. Composites were prepared using a slurry vacuum de-watering process, pressing and air-curing. At fibre contents of 8–12% by mass, moduli of rupture (MOR) up to 23 MPa and fracture toughness (FT) values in the range of 0.6–1.7 kJ/m2 were obtained at 28 days. After 12 months of exposure under temperate and tropical conditions, the MOR of the BFS-based composites had decreased to values in the range of 6.6–10.1 MPa. FT values remained stable or even increased with the weathering exposure. The results indicate that the mechanical performance of the composites being studied is currently satisfactory, but further optimisation of formulation and processing parameters should be investigated.

Potential of alternative fibre cements as building materials for developing areas

The performance as reinforcement of fibres obtained from commercial and by-product sisal (Agave sisalana) by thermomechanical pulping and chemi-thermomechanical pulping (CTMP) processes was investigated. Ordinary Portland cement (OPC) and chemically activated blast furnace slag (BFS) were examined as binders. The flexural strengths of OPC- and BFS-based composites incorporating 8% fibre reinforcement by mass were similar at 28 days and ranged from 18 to 22 MPa. Corresponding modulus of elasticity values were in the region of 11 GPa for the OPC-based composites and 7 GPa for the BFS-based composites. Water absorption values at 8% fibre content lay in the range of 21–31% by mass and density values in the region of 1.5 g/cm3. Fracture toughness increased with fibre content, reaching a value of 1.6 kJ/m2 at a content of 12% in the case of by-product sisal CTMP in the BFS matrix. Scanning electron microscopy provided interfacial bonding information that can be related to the mechanical performance of these fibre-reinforced pastes.

Mechanically pulped sisal as reinforcement in cementitious matrices

The use of ground iron blast furnace slag (BFS) as a low-cost alternative to ordinary Portland cement (OPC) binders in fibre-cement products was examined. Both high quality softwood fibres and residual sisal from agricultural waste were chemically pulped and used as reinforcement. Composites based on several different binder formulations consisting of slag chemically activated by mixtures of gypsum and hydrated lime displayed their optimum strength and fracture toughness properties at fibre contents between 8% and 12%, with values in the ranges of 14.7–24.5 MPa and 1.13–2.36 kJ/m2, respectively. Corresponding flexural moduli lay in the range 4.3–7.8 GPa and, at 12% fibre content, the composites possessed water absorption values up to 34% by mass and densities in the region of 1.3 g/cm3. A formulation of BFS activated by 10% gypsum and 2% lime presented a good compromise between strength and energy absorption combined with a reasonable price.

P.G. Warden

Papers

Brazilian waste fibres as reinforcement for cement-based composites

Microstructure and mechanical properties of waste fibre–cement composites

Potential of alternative fibre cements as building materials for developing areas

Mechanically pulped sisal as reinforcement in cementitious matrices

Ground iron blast furnace slag as a matrix for cellulose-cement materials