Evaluation of Pulps from Natural Fibrous Material for Use as Reinforcement in Cement Product

Abstract

Low-cost natural fibers, available in developing countries, have been studied as replacements for asbestos in fiber cement materials. Laboratory pulps prepared from commercial sisal, by-product sisal, banana strands, and eucalypt kraft residue are compared to Pinus radiata kraft pulp, a reinforcement already widely used in commercial building materials. Fiber aspect ratio, percentage fines, freeness, and coarseness values of the various fiber pulps were measured in an attempt to correlate fiber properties to fiber performance when used as cement composite reinforcement. The effectiveness of mechanical treatments in generating superficial fibrillation of sisal and banana fibers in order to improve the mechanical bonding of these fibers to the matrix was confirmed by scanning electron microscopy. Unrefined Eucalyptus grandis fibers, residues from a kraft pulp mill, were observed to possess irregular shapes and surfaces that could give rise to an acceptable level of mechanical bonding to the matrix. This behavior, coupled with other morphological and physical properties, suggest these short fibers are adequate as reinforcement for cement.

Keywords:

• Microstructure
• Physical properties
• Chemical pulps
• Mechanical pulps
• Recycled materials
• Cement composites

Acknowledgments

The authors would like to thank the Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp) for its financial support of this work (proc. n. 98/0292-0) and Allyson Pereira and Göran Längfors of CSIRO Forestry and Forest Products for their skillful assistance. Thanks also to Dr. Adriana M. Nolasco, Universidade de São Paulo, who kindly provided the banana strands, and the Associação dos Pequenos Produtores do Município de Valente (Bahia, Brazil) and Aracruz Celulose (Espírito Santo, Brazil) for the supply of sisal and eucalypt fibrous by-products respectively.