Effects of natural weathering on microstructure and mineral composition of cementitious roofing tiles reinforced with fique fibre G.H.D. Tonoli a,⇑ , S.F. Santos b , H. Savastano Jr. b , S. Delvasto c , R. Mejía de Gutiérrez c , M. del M. Lopez de Murphy d a Structural Engineering Department, Escola de Engenharia de São Carlos, Universidade de São Paulo, Brazil b Food Engineering Department, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Brazil c Composite Materials Group, Escuela de Ingeniería de Materiales, Universidad del Valle, Colombia d Civil and Environmental Engineering Department, The Pennsylvania State University, USA article info Article history: Received 22 January 2010 Received in revised form 13 August 2010 Accepted 15 October 2010 Available online 26 October 2010 Keywords: Air permeability Fibre-cement Durability Cementitious corrugated sheets Vegetable fibres Forchheimer’s equation abstract The objective of the present work was to evaluate the effects of 14 years of weathering exposition on the microstructure and mineral composition of cementitious roofing tiles, still in service, reinforced with fique fibres (Furcrae gender). The results show that tiles under weathering exposition presented higher water absorption and apparent void volume than tiles under laboratory exposition. The continuous hydration of cement and natural carbonation filled the smaller pores but contrarily the large pores remained in the porous fibre to matrix interface in the samples exposed to weathering. On the other hand, their microstructure presented lower air permeability than samples aged in the internal environ- ment of the laboratory. Besides, in the weathering aged tiles takes place a more intensive hydration process as it was identified greater amount of hydrated phases than in the laboratory aged specimens. The present results contribute to understanding the consequences of tropical weathering on the fibre- cement degradation. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Since ancient times, approximately 3500 years ago, brittle building materials, e.g. clay sun baked bricks, were reinforced with vegetable fibres. However, the concept of vegetable fibre reinforce- ment in cement-based materials was developed in 1970s, when vegetable fibres were evaluated as substitutes of manufactured fibres and asbestos fibres [1,2]. Natural vegetable fibres (cellulose pulp, sisal, bamboo, fique, hemp, flax, jute and ramie, for example) are used in regions where these materials are readily available. Motivations for their use include decreased costs and meeting the needs of sustainability and ecology. Composites with vegetable fibres are important for construction of inexpensive buildings in developing regions of the world. On the contrary, the use of synthetic fibres frequently involves higher costs and greater consumption of energy in the processing of fibre rein- forced cementitious composites [3]. According to Swamy [4], the use of composites reinforced with vegetable fibres in flat sheets, roofing tiles and pre-manufactured components can represent sig- nificant contribution to the infrastructure in developing countries. It has been demonstrated that fique fibre, which is a commercially available natural fibre in Colombia, is appropriate for low cost hous- ing applications when incorporated into a matrix based on Portland cement, being suitable for making elements of various shapes using simple production processes [5–7]. Another concern is the durabil- ity of alternative products, as well as their compatibility to the ser- vice life of building components in general [8]. The present study was carried out to evaluate the changes occurring in the microstructure and in the chemical composition of tiles reinforced with lignocellulosic fibres when exposed to 14 years of natural weathering conditions. For comparison, a set of tiles was made and kept under laboratory conditions during the same period prior to testing. 2. Experimental 2.1. Characteristics of the fique fibres Fique fibre or cabuya (Furcrae gender) is a Colombian native vegetable fibre with similar characteristics to sisal. It has been demonstrated that the fique fibre is suitable for cementitious materials in low cost housing applications [5–7] and for fibre rein- forcement of concrete [9]. 0958-9465/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.cemconcomp.2010.10.013 ⇑ Corresponding author. Fax: +55 19 3565 4114. E-mail addresses: gustavotonoli@yahoo.com.br (G.H.D. Tonoli), sfsantos1@ usp.br (S.F. Santos), holmersj@usp.br (H. Savastano Jr.), silviodelvasto@hotmail.com (S. Delvasto), rudeguti@hotmail.com (R. Mejía de Gutiérrez), mmlopez@engr.psu. edu (M. del M. L. de Murphy). Cement & Concrete Composites 33 (2011) 225–232 Contents lists available at ScienceDirect Cement & Concrete Composites journal homepage: www.elsevier.com/locate/cemconcomp