Volumen II - SAM

Congreso SAM/CONAMET 2009 Buenos Aires, 19 al 23 de Octubre de 2009
INFLUENCE OF WOOD TREATMENTS FOR REMOVAL OF SETTING INHIBITORS
ON MECHANICAL PROPERTIES OF WOOD-CEMENT COMPOSITES
V. Marzocchi (1) , A. Quiroga (2) , A. Marcipar (2) and I. Rintoul (3)
(1) Instituto de Tecnología Celulósica – Facultad de Ingeniería Química
Universidad Nacional del Litoral
Santiago del Estero 2654 (S3000AOJ) Santa Fe, Argentina.
(2) Centro de Investigación y Desarrollo para la Construcción y la Vivienda – Facultad Regional Santa Fe
Universidad Tecnológica Nacional
Lavaise 610 (S3004EWB) Santa Fe, Argentina.
(3) Instituto de Desarrollo Tecnológico para la Industria Química
Centro Científico Tecnológico Conicet Santa Fe
Ruta Nac.168 Km 472 Paraje “El Pozo” (S3000GLN) Santa Fe, Argentina.
E-mail (autor de contacto): irintoul@santafe-conicet.gov.ar
ABSTRACT
Wood-cement composites are promising materials for structural and isolation purposes. High dimensional
stability, toughness, economic factors, resistance to environmental degradation are features that can be
exploited in many applications for housing components. The main inconvenient affecting its manufacture is
the incompatibility between wood and cement, caused by setting inhibitory substances naturally present in
woods. Wood treatments are then required for the correct curing of cement on wood surfaces. However, they
can affect the final mechanical properties of the resulting materials. The knowledge of wood-cement based
composites is rather limited for local raw materials, impairing the production of this composite at national
industrial scale. This work evaluates the influence of three wood treatments (water conventional extraction,
degradation by alkaline hydrolysis and retention of inhibitory substances) on mechanical properties of wood
strands and of final wood-cement boards. Populus X Euroamericana CV provided from residues of local
wood industry and commercially available Portland were selected as case materials. Tensile properties of
individual wood strands and compression properties of wood wool-cement boards were studied for
evaluation of the mechanical behaviour. The alkaline hydrolysis was found as the most effective treatment
for the suppression of inhibitory effects, followed by retention and extraction methods.
Keywords: wood-cement boards, building material, composite, wood compatibility, setting.
1. INTRODUCTION
Since more than 100 years, wood-cement boards (WCB) have been widely used for various housing
components in Europe and United States [1]. In Argentina, conventional building materials such as ceramic
brick have been always preferred for housing construction industry. Therefore, the knowledge of woodcement
based composites is rather limited for local raw materials. Nowadays, housing deficiency has grown
over the last years and the need to develop alternative materials for rapid construction methods has become
an important factor for social development. This is especially important at the Argentinean Litoral area,
where regional materials are now investigated for emergency situations [2-6].
One of the most important advantages of WCB is the short time required for assembly housing components.
Apart from the very high durability, dimensional stability and fire resistance, other desirable aspects are
based on the good acoustic and thermal insulation properties [7], resistance to biological degradation and low
production costs.
However, the main inconvenient affecting the WCB manufacture is the well-known incompatibility between
wood and cement caused by setting inhibitory substances present in woods such as hemicelluloses and
sugars. This problem has been subject of many studies, especially for European woods, nevertheless there is
a lack of knowledge concerning local species. It is known that the presence of inhibitory substances
promotes the formation of impermeable membranes around non-hydrated cement grains, impairing the water
access into them. Consequently, this undesirable phenomenon causes a reduction of the material cohesion.
Different methods can be applied to solve inhibition problems, most of them based on extraction, alkaline
hydrolysis and sugars retention [8-10]. Although these treatments effectively improve the performance of
cement setting on wood surfaces, each one acts in a very different way. Aqueous extraction removes
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