Enhanced Resistance to Fire of the Bark-Based Panels Bonded with Clay

The aim of this study was to investigate the flammability of ecologically friendly, 100% natural larch and poplar bark-based panels bonded with clay. The clay acted as a fire retardant, and it improved the fire resistance of the boards by 12–15% for the surface and 27–39% for the edge of the testing specimens. The thermal conductivity was also analyzed. Although the panels had a density ranging from 600 to 900 kg/m3, thermal conductivity for the panel with a density of 600 kg/m3 was excellent, and it was comparable to lightweight insulation panels with much lower densities. Besides that, the advantage of the bark clay boards, as an insulation material, is mostly in an accumulative capacity similar to wood cement boards, and it can significantly improve the climatic stability of indoor spaces that have low ventilation rates. Bark boards with clay, similar to wood cement composites (wood wool cement composites and wood particle cement composites), have low mechanical properties and elasticity. Therefore, there their use is limited to non-structural paneling applications. These ecologically friendly, 100% natural and recyclable composites can be mostly used with respect to their thermal insulation, acoustics and fire resistance properties.

About the Possibility of Recycling Water Treatment Sludge in the Wood–Cement Composites Production

The paper presents the results of a study of the possibility of recycling water treatment sludge in the production of wood-cement composites. Sludge is formed during the treatment of sewage, containing industrial machine oil, with a sorption material, based on thermally modified chestnut tree waste (CTW). It was found that the addition of sludge leads to an increase in the density of the samples. Thus, the samples without the addition of sludge have an average density of 860 kg/m3, samples with the addition of sludge in an amount of 10 mass% - 875 kg/m3, 20 mass% - 879 kg/m3, 30 mass% - 882 kg/m3, 42 mass % - 887 kg/m3. Studies of the change in water absorption of samples, depending on the amount of sludge added, showed that the values slightly decrease for samples containing sludge, what is explained by the presence of oil in the mixture. The compressive strength of the samples with the addition of sludge in the amount of 42 mass% was 3.1 MPa, what corresponds to the regulatory requirements for a wood cement composites.

Alternative vibro-dynamic compression processing of wood-cement composites using Amazonian wood

ABSTRACT Wood-cement composite (WCC) is a potential construction material for tropical regions, due to its physico-mechanical properties and resistance to decay and fungi attack. However it is important to test alternative production methods and wood materials that are easier and cheaper than those traditionally used, in order to create a higher demand for this product. The aim of this work was to evaluate the use of wood from four Amazonian species (Eschweilera coriaceae, Swartzia recurva, Manilkara amazonica and Pouteria guianensis) in the production of wood-cement composites through a vibro-dynamic compression process, an alternative method to the use of a hydraulic press. The inhibition degree caused by the wood to the cement cure, measured by the factor CA, indicated that all species were compatible with Portland cement (CP II-Z). WCC with densities higher than 1,100 kg m-3 (produced with E. coriaceae and S. recurva particles) showed compressive strength values higher than 10 MPa, which fulfills the minimum requirement for lightweitgh reinforced concrete blocks for structural use.

Utilization of wastes from medium density fiberboards production as an aggregate for lightweight cement composite

The possibility of recycling waste from medium density fiberboard (MDF) production into wood-cement composites was evaluated. A large quantity of lignocellulosic wastes is generated worldwide from various sources, including wood and furniture industries, leading to environmental concerns. Medium density fiberboard (MDF) is an engineered wood product, which is made from wood fibers (mainly form coniferous trees) with wax and a resin binder. This paper presents an experimental study which investigated the potential utilization of medium density fiberboard wastes (MDFW) for producing lightweight insulation concrete. The wastes were screened on #8 mm sieve to exlude big irregular elements which could negatively affect compaction and strength properties. All lignocellulosic substrates have detrimental effects on cement setting so different techniques were applied to offset the retarding effect of compounds like sugar and tannin present in the bio-based particles before mixing the wastes with cement. One type of cement CEM I 42,5 R was used in the experiment. Flexural strength, compressive strength in air-dry and wet states, and water absorption of lightweight concrete were tested. Compressive strength ranging from 0,5 to 5.3 MPa was obtained depending on the material used for the initial impregnation of MDFW fibers.

Particle size and lime addiction on properties of wood-cement composites produced by the method of densification by vibro compaction

ABSTRACT: This paper aimed to evaluate the effects of particle size and the use of lime as a pretreatment of Pinus spp wood particles on the production of wood-cement composites by vibro-compaction densification. Specimens for internal bond and static bending were produced with two different particle sizes: G1, particles that pass through a 4mm screen and were retained at 2mm screen, and G2, particles that pass through a 2mm screen and were retained at 0.84mm screen. The use of lime was also tested in two different methods as pretreatment of wood particles: carbonatation of wood particles before being used in the composite mixture; and addition of hydrated lime directly to the composite mixture. Use of larger particles (G1) presented higher values of internal bond and MOR than composites produced with smaller particles (G2). About the pretreatments, the use of hydrated lime resulted in composites with higher density and better internal bond.

Influence of Particle Size and Soak Conditions of the Species Simarouba amara on Cement-Wood Composites

The purpose of this work was to produce a mix design rarely reported in the literature on wood-cement composites, i.e., 1:1:0.5 (cement:wood:water). This design was achieved by using CP IV-32 RS cement and adding 4% of ferric chloride additive plus fibers of the species Simarouba amara (paparaúba) retained on ASTM 7 and ASTM 10 sieves. Before mixing the fibers into the cement paste, they were presoaked for 15 minutes to between 84% to 136% of their mass. In these conditions, all the heat of hydration tests presented low inhibition. Panels measuring 300 x 450 x 25 mm were prepared, and the values of compressive and flexural strength of the composite after 28 days showed no significant differences with respect to soak, but the effect of particle size was significant. These results indicate that more fiber can be added in the mix design of this cement-wood composite without changing its mechanical strength, controlling only the presoak conditions.