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Acceptance levels of surface disfigurement - tolerance to defects of coated wood
2015 - IRG/WP 15-20564
Service life planning (PSL) has become an important issue in performance based building and substantial progress has been made in recent years. The role of predicting the aesthetical service life of wooden building components has been underestimated for quite long time but is recently attracting more and more notice. It is influenced by numerous factors such as discoloration, fading, flaking, cracking, and in extreme deformation due to interior rot. However, still the acceptance of such superficial disfigurement is subjected to the subjective sensation of consumers and end-users. This study aimed on evaluating different ‘technically defined’ limit states of weathered coated wood surfaces with respect to the acceptance of users. Therefore different groups of users were addressed in the frame of a survey as well as two different commodity groups were looked at separately, i.e. wooden window joinery and claddings. A remarkably high percentage of respondents ranked color and gloss related deficiencies as high as technical defects of the coating and recommended maintenance measures even when the coating was still fully intact. Technical characteristics such as the formation of cracks and flaking need to be considered separately from optical and aesthetical parameters for the definition of acceptance levels of coating disfigurements and defects. Limit states need to get defined specifically for different building components since acceptance varied significantly as shown exemplarily in this study between windows and cladding boards. For service life planning the overruling role of the subjective sensation of the user necessitates careful consideration.
C Brischke, P Kaudewitz


CCA-treated Wood Disposed in Landfills and Life-cycle Trade-Offs With Waste-to-Energy and MSW Landfill Disposal
2005 - IRG/WP 05-50231
CCA-treated wood as a solid waste is managed in various ways throughout the world. Although some wood is combusted for the production of energy in the U.S., more often than not, CCA-treated wood is disposed in landfills. In other countries, wood, often including CCA-treated wood, is combusted for the production of energy. This paper is presented in two parts. Part I evaluates the impact of CCA-treated wood in three landfill settings: a wood monofill, a C&D debris landfill and a municipal sold waste (MSW) landfill. Part II utilizes the data found in the first part, along with data found in the literature to examine the trade-offs between landfilling and waste-to-energy (WTE) combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). The disposal of CCA-treated wood affected all three landfill disposal scenarios increasing concentrations of arsenic and chromium especially. Although the acid-forming phase of the MSW landfill aggressively leached metals, the methanogenic phase was not as aggressive and the impact to the leachate from the CCA-treated wood was less than for C&D debris landfills. Additionally, the decreased impact is a result of the CCA-treated wood comprising a smaller portion of the MSW waste stream by mass. For this reason, and because MSW landfills are lined, MSW landfills were concluded to represent a preferred disposal option over unlined C&D debris landfills. If leachate is collected, leachate treatment in both situations may become more difficult and expensive if concentrations exhibited in this research are observed. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with U.S. EPA regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash, the MSW landfill scenario releases a greater amount of arsenic from leachate on an annual basis, but it is more dilute. The ash disposal scenario releases less arsenic from leachate on an annual basis, but concentrates it. The ash disposal releases more chromium on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase disposal costs.
J Jambeck, K Weitz, T G Townsend, H M Solo-Gabriele