Production of waste bio-fiber cement-based composites reinforced with nano-SiO 2 particles as a substitute for asbestos cement composites R. Hosseinpourpia a,b,⇑ , A. Varshoee c , M. Soltani c , P. Hosseini d , H. Ziaei Tabari e a Young Researchers Club, Islamic Azad University, Chalous Branch, Chalous, Iran b Department of Wood Biology and Wood Products, Georg-August University, Goettingen, Germany c Department of Wood and Paper Science and Technology, Islamic Azad University, Chalous Branch, Chalous, Iran d Department of Civil Engineering, Sharif University of Technology, Tehran, Iran e Department of Wood and Paper Science and Technology, Islamic Azad University, Science and Research Branch, Tehran, Iran article info Article history: Received 25 November 2010 Received in revised form 26 December 2011 Accepted 27 December 2011 Available online 21 January 2012 Keywords: Asbestos fiber Waste bio-fiber Green cement-based composites Silica nano-particles abstract The environmental impact of asbestos fibers on human health and their consequent safety-related prob- lems indicate that there is a significant need to replace this material in all asbestos-containing products. Many different types of fibers have been introduced to replace asbestos fibers. In this study, the performance of silica nano-particles combined with waste paper pulp fibers (sulfite fibers) has been investigated. Different mechanical (compressive and flexural strengths and bending performance), durability (water absorption), physical (bulk density and flowability), and microstructural (scanning electron microscopy) tests were conducted to examine the properties of manufactured green composites. The results reveal that the mechanical properties of cement-based composites containing a ternary system of ‘‘natural waste fiber–silica nano-particle cement’’ have been enhanced. Adding silica nano-particles allows the development of green cement-based composites and movement toward sustainable development in the concrete industry. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Asbestos had numerous applications in many different countries during previous decades due to its reinforcement, thermal and elec- trical insulation, and heat resistance properties. Moreover, it had been widely used in the textiles industry because of its high flexibil- ity and strength. It had also been used in packaging, joints and seals. In the early 20th century, thin sheets of a combination of Portland cement and asbestos fibers were produced, and many remarkably durable and flexible asbestos products, such as asbestos cement particles, asbestos yarn cord and fabric, asbestos joint and mill- board, and water and sewage pipes were introduced [1]. Asbestos is a collective term given to a group of minerals whose crystals occur in fibrous forms and includes two types, serpentine and amphiboles [2]. In a general consensus among scientific communi- ties, different types of asbestos were classified as carcinogens, and it was declared that these fibers can cause lung cancer if they are inhaled. Chrysotile asbestos, which is a type of serpentine asbestos, was introduced as a carcinogenic factor for the human body. Inhal- ing the chrysotile asbestos odor damages lung tissue [3]. Previous studies on workers showed that chrysotile in several sections of a factory broadly contributed to terrible diseases. In addition, air movements were shown to promote the movement of asbestos fibers through different parts of a factory [4]. This event proved that inhaling the air containing asbestos particles leads to extreme respiratory problems. This disease was referred to as asbestosis [2]. Given the hazards of asbestos, researchers introduced appropri- ate replacements for these fibers. Although a material with similar effectiveness and an acceptable price, such as asbestos, has not been found, cellulose fibers have been introduced as an alternative for some applications of asbestos. In addition to cellulose, resis- tant-to-alkali fiber glass performs acceptably to improve the strength and other qualities of cement products [5]. However, among various types of existing cellulose fibers, paper pulp fibers produced by a sulfite process are crucial. They are used commer- cially as sheets with different thicknesses, which are applicable for manufacturing tissues, print papers, and hygienic products [6]. In contrast with the environmental compatibility of cellulose fibers, their reinforcing capability is lower than that generated by applying carcinogen asbestos fibers in a cement-based matrix. 0950-0618/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2011.12.102 ⇑ Corresponding author at: Department of Wood Biology and Wood Products, Georg-August University, Goettingen, Germany. E-mail address: rhossei@gwdg.de (R. Hosseinpourpia). Construction and Building Materials 31 (2012) 105–111 Contents lists available at SciVerse ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat