Fernando Caldeira Jorge

Characterizing the setting of cement when mixed with cork, blue gum, or maritime pine, grown in Portugal I: temperature profiles and compatibility indices

Data are presented on the effects that cork, blue gum, or maritime pine, all grown in Portugal, have on cement setting. These materials were mixed with cement either without any treatment or after being extracted previously with a range of solvents (ranging from nonpolar to very polar). Other experiments were carried out in which extractives or calcium chloride were added to the cement paste. All lignocellulosic substrates have detrimental effects on cement setting, which is mostly seen by a delay in attaining the maximum temperature in the process. However, the addition of calcium chloride was able to overcome this disadvantage. Extraction of the substrates with some polar extraction agents before addition to the cement paste only slightly improved compatibility, and the addition of water-based extractives to a cement paste affects the setting much less than the lignocellulosic material by itself. Several thermal compatibility indices, including a new index proposed in this article, were calculated from data taken from temperature profiles, and conclusions are presented on the performance of the setting systems, as compared with a neat cement paste. In addition, comments are expressed on the level of accuracy offered by the indices applied in this study, and how such accuracy can be checked or improved by matching them to the physical properties of the wood-cement composites.

Characterizing the setting of cement when mixed with cork, blue gum, or maritime pine, grown in Portugal II: X-ray diffraction and differential thermal analyzes

It is already known by the scientific and industrial communities that lignocellulosic substrates are, to a certain extent, inhibitors of the hydration reaction of cement. The extent to which and how they influence such reactions is still a matter of debate. Several techniques, such as calorimetry, i.e., the measurement of the heat evolved or obtaining temperature profiles during the hydration, the determination of extractive contents of lignocellulosic substrates and their relation with the characteristics of the hydration curves, or even testing of the mechanical properties of the wood-cement composites, have been used in previous research. This study complements past research using two techniques that have been used in the analysis of cement hydration but are not usually applied to lignocellulose-cement mixes, namely X-ray diffraction (XRD) and differential thermal analysis (DTA). The raw materials for this study were three lignocellulosic materials of Portuguese origin: cork (the bark of Quercus suber L.), blue gum (Eucalyptus globulus Labill.), and maritime pine (Pinus pinaster Ait); and Portland cement. The two techniques allowed tracking of the evolution of the main cement constituents during hydration. It was found that all the lignocellulosic substrates had detrimental effects on cement hydration. The blue gum exhibited the fastest hydration kinetics in the initial stage of reaction, but was then overtaken by cork, which at the end gave the highest hydration conversion amongst the three lignocellulosic substrates. Although pine caused the slowest initial hydration kinetics, with the passage of time its effect approached that of blue gum. At the end of the hydration period, specimens containing either species had similar quantities of hydration reaction products. The DTA and XRD results were consistent and are in good agreement with the temperature profiles and compatibility indexes reported in a previous work.

Reducing Negative Environmental Impacts from the Manufacturing and Utilization of Lignocellulosics-Derived Materials: An Overview on Research in 2007–2009

A review on research has been made regarding recent developments aiming at reducing the negative environmental impact (because sometimes it might be positive) derived from industrial manufacturing processes of lignocellulosic-derived products, from their utilization, and also from their disposal at the end of their life. The most common journals of the wood science and environmental fields have been screened and relevant papers on this topic are referred and commented. This paper covers mainly lignocellulosic-based products taken as materials. That is saying, materials of common use and that were made incorporating mostly raw materials from forest or agriculture plants. Examples of such products are particleboard, waferboard, MDF, OSB, plywood and lignocellulosic-plastic composites. Excluded from this review are utilizations of biomass for heat/energy production or its processing for chemicals (e.g., ethanol). Important issues for this paper are: lignocellulosic wastes and sub-products recycling, Wood preservation environmental issues, VOC – Volatile Organic Compounds emissions, adhesion of wood and LCA – Life-Cycle Assessment of forest products.

Comparison of quantification methods for the condensed tannin content of extracts of Pinus pinaster bark

Bark from Pinus Pinaster is an interesting source of polyphenolic natural compounds, that can be used successfully as total or partial replacement of conventional phenolic resins. These compounds, among other applications, are used as adhesives in the wood agglomerate industry. In this kind of application some problems remain to be solved in order to obtain a Pine extract of commercial value. It is necessary to optimise the extraction procedure and select a suitable method for the quantification of the tannin content of the bark. In order to study these problems, the tannin extraction from the Pine bark was tested with an alkaline solution (NaOH), and with a fractionation procedure based on a sequence of an organic (ethanol) and aqueous extraction. The phenolic content of each extract or fraction was evaluated by the FolinCiocalteu colorimetric assay for total phenols and two procedures using the Stiasny reaction: the gravimetric Stiasny method and the indirect colorimetric procedure that uses the Folin-Ciocalteu reagent to evaluate the total phenols present in the extract solution before and after it condenses with formaldehyde. The yield value when the alkaline extraction is used is substantially higher than the values obtained with organic or aqueous solutions. However, the selectivity of the process is low. In fact, it was found that the alkaline extract Formaldehyde Condensable Phenolic Material (FCPM) content represents 95-96 % of the total phenols content of the extract but this fraction is only ≈ 40 % of the total mass of extract. So, the alkaline extract is relatively poor in phenolic material, exhibiting a large variety of non-phenolic extractives. On the other end, ethanol provides a very rich phenolic extract, in which 96 % of total phenols are condensable with formaldehyde, but exhibits a relatively low extraction yield. The aqueous extract presents the lowest extraction yield with low content either in phenolic material as in FCPM, but, as most of the phenolics had already been extracted by the previous organic extraction, especially the low molecular weight fractions, this result was predictable.

Recent Advances on Lignocellulosic-Based Composites for Performance and Environmentally-Compatibility Improvement

To write this article, more than 300 articles were overviewed, that covered what has been published in the most important journals of the research area of Wood Science and Technology, from 2002 to 2006. From those, 115 are referred in this article. This review presents the latest results from research on wood composites, and more broadly, on lignocellulosic-based composites, aimed, obviously, at improving performance in service, but with a special emphasis on research progresses that have bringing about environmental benefits, too. Topics covered include chemical modification, nonwood fiber resources, thermoplastic-based composites, composites from waste or recycled lignocellulosics, improvement of biodeterioration resistance, adhesives based on renewable chemical resources, low- or near-zero-emission formaldehyde-based adhesives, reduction of volatile organic compounds emissions, structural applications, inorganic binders, LCA – Life-Cycle Assessment, heat treatment, binderless composites.