Aging effects on the structure and properties of recycled wastepaper fiber cement composites: Fid-Bau Portal

Aging effects on the structure and properties of recycled wastepaper fiber cement composites

Soroushian, P. / Shah, Z. / Won, J. -P.

Abstract Dry-processed wastepaper (magazine) fibers possess desirable mechanical characteristics as reinforcing fibers in cement-based matrices; up to 50% of virgin wood fibers have been replaced with wastepaper fibers in cement composites without any significant change in short-term performance characteristics. The large volumes of fibrous cement board used in building construction promise to provide wastepaper with a large-volume and high-value application. In this study, the effects of weathering on the performance of recycled wastepaper fiber-cement composites were investigated through accelerated aging tests simulating natural aging conditions. Microstructural studies were conducted in order to establish the mechanisms of aging in the composite material. These mechanisms provided the basis for the selection of certain refinements in the matrix composition, which were successfully evaluated for the control of weathering effects on the composite material structure and properties. The effects of aging and moisture on composites were best controlled by measures which reduced the calcium hydroxide content of hydration products and improved the watertightness and the structure of interface zones; these refinements were made using relatively high levels of cement replacement with silica fume or through full substitution of Portland cement with a special cement.