Aging mechanisms in cellulose fiber reinforced cement composites |
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| Affiliation: | 1. Faculty of Forestry, University of Toronto, Toronto, Ontario, Canada, M5S 3B3;2. Institute of Wood Research, School of Forestry and Wood Products, Michigan Technological University, Houghton, MI 49931-1295, USA;1. Pennsylvania State University, 3127 Research Dr., State College, PA 16801, USA;2. Pennsylvania State University, 109 Agricultural Engineering, University Park, PA 16802, USA;3. Pennsylvania State University, 231M Sackett Building, University Park, PA 16802, USA;1. China Building Materials Academy, Beijing, 100024, China;2. Jiahua Special Cement Co., Ltd, Leshan, 614000, China;3. School of New Energy and Materials, Southwest Petroleum University, Chengdu, 610500, China;4. Engineering Technology Research Institute, PetroChina Southwest Oil & Gas Field Company, Guanghan, Sichuan, 618300, China;1. Department of Forest Science, Universidade Federal de Lavras, C.P. 3037, 37200-000 Lavras, MG, Brazil;2. Department of Bio-Systems Engineering, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo (USP), Avenida Duque de Caxias Norte, 225, Pirassununga, SP 13635-900, Brazil;3. Eduardo Torroja, Institute for Construction Science (CSIC), C/Serrano Galvache, 4, 28033 Madrid, Spain;4. Department of Construction Engineering, Escola Politécnica, Universidade de São Paulo, 05508-900 São Paulo, SP, Brazil;1. Department of Forest Science, Universidade Federal de Lavras (UFL), C.P. 3037, 37200-000 Lavras, MG, Brazil;2. Department of Biosystems Engineering, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo (USP), Avenida Duque de Caxias Norte, 225, Pirassununga, SP 13635-900, Brazil;3. Infibra S.A., Rodovia Anhanguera km 186, Leme, SP 13612-200, Brazil;4. Department of Construction Engineering, Escola Politécnica, Universidade de São Paulo, São Paulo, SP 05508-900, Brazil |
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| Abstract: | This paper examines the effects of laboratory scale accelerated aging exposures on the changes in physical and mechanical properties of commercially produced cellulose fiber reinforced cement composites. Two different accelerated aging methods were used to simulate the possible aging mechanisms for which the material may experience under service conditions, both methods being compared to material naturally weathered for 5 yr in roofing. The first aging method consisted of different cycles of water immersion, carbonation, and heating exposures whereas in the second method, cycles of water immersion, heating and freeze-thaw exposures were used. The porosity, water absorption, permeability of nitrogen and compressive shear strength of the composites were examined before and after aging exposures. The surface morphologies of the composites fractured in compression shear tests were examined using scanning electron microscope. Experimental results showed that the compressive shear strength of the accelerated aged composites were related to the microstructures within the composites. Both natural weathering and accelerated aging in CO2 environment reduced the porosity, water absorption, and nitrogen permeability in the cement matrix, and enhanced the durability of the cellulose fiber-cement composites. The aging test based on artificial carbonation was more effective in simulating natural aging performance of the composites, while the freeze-thaw cycling method failed to induce significant aging effects on the composites even after 21 cycles. |
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