Partnership for Advancing Technologies in Housing: An Integrated Program to Examine the Moisture-related Performance of Fiber-cement Composites

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PATH: An Integrated Program to Examine the Moisture-related Performance of Fiber-cement CompositesThe effect of wet/dry cycling on fiber-cement composites and the resulting mechanisms of damage have not been the subject of an extensive systematic examination. This lack of fundamental knowledge limits our ability to accurately predict service lives of fiber-cement materials and our ability to select materials for fiber-cement composites which are expected to exhibit good performance in exposures where moisture fluctuations are expected. A comprehensive research plan is necessary to fully understand the implications of fiber swelling/shrinking on the fiber-cement composite system - the changes that occur in the fiber, surrounding brittle matrix, and the performance of the composite as a whole. The objective of the integrated research project, to be undertaken by a research team composed of concrete technologists from Civil Engineering and paper physicists from Paper Science and Technology, is to link changes that occur on a microstructural level as a result of cyclical moisture changes to the changes in macroscale mechanical properties of the fiber-cement composite. The goals of the proposed research are (1) to assess the effects of repeated wetting and drying (rain and heat) cycles on dimensional changes of wood fibers, physical bonding at the fiber/cement paste interface, and bond strength between the fiber and matrix and (2) to assess if improved bonding can be produced through tailoring the fiber processing for this application. The proposal includes preparation of special aligned fiber cement-composites that will offer improved opportunities for both qualitative and quantitative microstructural analysis.