Impact of content and length of curauá fibers on mechanical behavior of extruded cementitious composites: Analysis of variance

[EN] The use of composite materials in construction has grown considerably in recent years, such as cementitious matrices and concrete reinforced with fibers. The vegetable fibers have become an alternative due to its abundance, low cost and low energy consumption for its production, and appropriate properties mechanical. Curauá fiber is a plant native from Amazonas harvested manually in commercial farming and it is used in the manufacture of ropes and baskets or as reinforcement in composite with organic matrix of components for cars, buses and trucks. On the other hand, the extrusion process can produce composites with high-density matrix with fibers, low permeability and good interface between fiber and matrix. This process is also compatible with the use of vegetable fibers as raw materials in the production of cost-effective construction elements such as ceiling panels and drywalls. The objective of this research was use the analysis of variance (ANOVA) for evaluating with rigor mathematical the influence of content and length of curauá fibers on the mechanical behavior of the extruded cementitious composites. Composites without fibers and reinforced with 1% and 2% by mass of fibers as well as 6 mm and 10 mm of length these curauá fibers were evaluated. The composites with fibers of 10 mm have showed better mechanical results. Besides, the composites with fibers curauá after 200 accelerated aging cycles were better than one non-aging.The authors acknowledge the financial support provided by Brazilian Agencies: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Grant nº 2013/03823-8 and 2012/51467-3); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Grant nº 3886/2014); and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Grant nº 406429/2015 and 312151/2016-0). The authors thank the Brazilian companies Fibria S.A., Infibra S.A. and Imbralit Ltda. for technical support to the development of this work.Teixeria, R.; Santos, S.; Christoforo, A.; Paya Bernabeu, JJ.; Savastano Jr., H.; Rocco Lhar, F. (2019). Impact of content and length of curauá fibers on mechanical behavior of extruded cementitious composites: Analysis of variance. Cement and Concrete Composites. 102:134-144. https://doi.org/10.1016/j.cemconcomp.2019.04.022S13414410

Alternative Methodology For Calculating The Modulus Of Elasticity Of Wooden Beams Of Structural Dimensions

This study aims to present an alternative calculation methodology based on the Least Squares Method for determining the modulus of elasticity in bending wooden beams of structural dimensions. The equations developed require knowledge of three or five points measured in displacements along the piece, allowing greater reliability on the response variable, using the statistical bending test at three points and non-destructively, resulting from imposition of measures from small displacements L/300 and L/200, the largest being stipulated by the Brazilian norm NBR 7190:1997. The woods tested were Angico, Cumaru, Garapa and Jatoba. Besides obtaining the modulus of elasticity through the alternative methodology proposed, these were also obtained employing the Brazilian norm NBR 7190:1997, adapted to the condition of non-destructive testing (small displacements) and for pieces of structural dimensions. The results of the modulus of elasticity of the four species of wood according to both calculation approaches used proved to be equivalent, implying the good approximation provided by the methodology of calculation adapted from the Brazilian norm.341153160(1997) Standard test method of static tests of lumber in structural sizes, , AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM). ASTM D 198. Annual book of ASTM standards, v. 03.01. West Conshohocken(1996) Standard test methods for mechanical properties of lumber and wood-base structural material, , AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM). ASTM D 4761-96. Annual book of ASTM standards. West Conshohocken(1997) Projeto de estruturas de madeira, , ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS (ABNT). NBR 7190. Rio de JaneiroBurdzik, W.M.G., Nkwera, P.D., Transverse vibration tests for prediction of stiffness and strength properties of full size Eucalyptus grandis (2002) Forest Products Journal, Madison, 52 (6), pp. 63-67Chou, Y., Polansky, A.M., Mason, R.L., Transforming non-normal data to normality in statistical process control (1998) Journal of Quality Technology, Milwaukee, 30, pp. 133-141Christoforo, A.L., Panzera, T.H., Batista, F.B., Borges, P.H., Rocco, F.A.L., Numerical evaluation of the longitudinal modulus of elasticity in structural round timber elements of Eucalyptus genus (2011) Revista Engenharia Agrícola, Jaboticabal, 31, pp. 1007-1014Dong, X.H., Hai, W.L., Comparative study on four different methods for measuring the dynamic modulus of elasticity of Acer mono wood (2011) Advances in Materials Research, New York, 160-162, pp. 384-388(1995), EUROPEAN STANDARD. Estruturas de madeira-Métodos de teste-Determinação das propriedades mecânicas de painéis derivados de madeira. Versão portuguesa. Bruxelas, (EN, 789)Fiorelli, J., Estudo teórico e experimental de vigas de madeira laminada colada reforçadas com fibra de vidro (2005), 108 f. Tese (Doutorado), Ciência e Engenharia de Materiais, Escola de Engenharia de São CarlosLiang, S., Fu, F., Comparative study on three dynamic modulus of elasticity and static modulus of elasticity for Lodgepole pine lumber (2007) Journal of Forestry Research, Colombo, 18, pp. 309-312Miná, A.J.S., Oliveira, F.G.R., Calil, C., Dias, A.A., Sales, A., Avaliação não destrutiva de postes de madeira por meio de ultra-som (2004) Scientia Forestalis, Piracicaba, (65), pp. 188-196Miotto, J.L., Dias, A.A., Produção e avaliação de vigas de madeira laminada colada confeccionadas com lâminas de Eucalipto (2009) Revista Tecnológica, Maringá, 18, pp. 35-45. , Edição EspecialMontgomery, D.C., (2005) Design and analysis of experiments, , Arizona: John Wiley & Sons, 6th edOliveira, F.G.R., Sales, A., Ultrassonic measurements in Brazilian hardwood (2002) Materials Research, São Carlos, 5 (1), pp. 51-55Pigozzo, J.C., Pletz, E., Lahr, F.A.R., Aspectos da classificação mecânica de peças estruturais de madeira (2000), In: VII ENCONTRO BRASILEIRO EM MADEIRAS E EM ESTRUTURAS DE MADEIRA, 7°, São Carlos. AnaisRocco Lahr, F.A., (1983), 216f Sobre a determinação de propriedades de elasticidade da madeira. Tese (Doutorado), Engenharia de Estruturas, Escola de Engenharia de São Carlos, Universidade de São Paulo, São Carlos, 1983Ross, R.J., Brashaw, B.K., Pellerin, R.F., Nondestructive evaluation of wood (1998) Forest Products Journal, Madison, 48 (1), pp. 14-19Sales, A., Candian, M., Cardin, V.S., Evaluation of the mechanical properties of Brazilian lumber (Goupia glabra) by nondestructive techniques (2011) Construction and Building Materials, Guildford, 25 (3), pp. 1450-1454Wang, S.Y., Chen, J.H., Tsai, M.J., Lin, C.J., Yang, T.H., Grading of softwood lumber using non-destructive techniques (2008) Journal of Materials Processing Technology, Amsterdam, 208, pp. 149-15