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The use of lightweight concrete allows great flexibility and cost savings when it is used in building construction having a positive impact on the energy consumption of buildings due to its good thermal characteristics. However, it is also known that the differences between the densities of the materials used to produce these concretes make it highly susceptible to the segregation phenomenon. The main objective of the present work is to present a method to quantify this phenomenon using techniques of image analysis. In this work, a lightweight concrete produced was molded in cylindrical molds using different times of internal vibration and causing different degrees of segregation. The samples were cured, vertically saw-cut in two pieces (halves) and the sections were photographed. Subsequently, the halves were saw-cut horizontally in four equal parts and posteriorly their densities were determined experimentally. The densities obtained were used to calculate the segregation index of each sample (experimental method). Furthermore, the photographed sections were processed using image analysis software in order to determine the volumetric proportions of aggregates in each sample (noise reduction, threshold adjustment, binarization and fill holes). The processed images were used to calculate the densities and segregation index of the lightweight concrete produced through image analysis. In addition, using the photographed sections, a vertical density profile was programmed to analyze the distribution of the lightweight concrete components (mortar and aggregate). Finally, the results obtained experimentally and through image analysis were compared. This study demonstrates that the image analysis allows a deeper knowledge of the behavior of segregated concrete.
density, image analysis, lightweight concrete, segregation index, segregation
[1] Hwang, C.L. & Hung, M.F., Durability design and performance of self-consolidating lightweight concrete. Construction and Building Materials, 19(8), pp. 619–626, 2015. https://doi.org/10.1016/j.conbuildmat.2005.01.003
[2] Sari, D. & Pasamehmetoglu, A.G., The effects of gradation and admixture on the pumice lightweight aggregate concrete. Cement and Concrete Research, 35(5), pp. 936– 942, 2015.https://doi.org/10.1016/j.cemconres.2004.04.020
[3] Rossignolo, J.A., Agnesini, M.V. & Morais, J.A., Properties of high-performance LWAC for precast structures with Brazilian lightweight aggregates. Cement and Concrete Composites, 25, pp. 77–82, 2003.https://doi.org/10.1016/s0958-9465(01)00046-4
[4] Rossignolo, J.A., Concreto Leve Estrutural: produção, propriedades, microestrutura e aplicações.São Paulo: PINI, 2009.
[5] Tattersall, G.H. & Baker, P.H., The effect of vibration on the rheological properties of fresh concrete. Magazine of Concrete Research, 40, pp. 79–89, 1988. https://doi.org/10.1680/macr.1988.40.143.79
[6] Banfill, P.F.G., Teixeira, M.A.O.M. & Craik, R.J.M., Rheology and vibration of fresh concrete: predicting the radius of action of poker vibrators from wave propagation. Cement and Concrete Research, 41(9), pp. 932–941, 2011. https://doi.org/10.1016/j.cemconres.2011.04.011
[7] Aïtcin, P.C. & Flatt, R., Science and Technology of Concrete Admixtures, 2016.
[8] Han, J., Wang, K., Wang, X. & Monteiro, P.J.M, 2D image analysis method for evaluating coarse aggregate characteristic and distribution in concrete. Construction and Building Materials, 127, pp. 30–42, 2016. https://doi.org/10.1016/j.conbuildmat.2016.09.120
[9] Navarrete, I. & Lopez, M., Estimating the segregation of concrete based on mixture design and vibratory energy. Construction and Building Materials, 122, pp. 384–390, 2016. https://doi.org/10.1016/j.conbuildmat.2016.06.066
[10] Barbosa, F.S., Farage, M.C.R., Beaucour, A.-L. & Ortola, S., Evaluation of aggregate gradation in lightweight concrete via image processing. Construction and Building Materials, 29, pp. 7–11, 2012.https://doi.org/10.1016/j.conbuildmat.2011.08.081
[11] Yu, Q.L., Spiesz, P. & Brouwers, H.J.H., Ultra-lightweight concrete: conceptual design and performance evaluation. Cement and Concrete Composites, 61, pp. 18–28, 2015. https://doi.org/10.1016/j.cemconcomp.2015.04.012
[12] Larrard, F.D. & Belloc, A., L’influence du granulat sur la resistance a la compression des betons. Bulletin des Laboratoires des Ponts et Chaussées, pp. 41–52, 1999.
[13] Ke, Y., Beaucour, A.L., Ortola, S., Dumontet, H. & Cabrillac, R., Comportement Mécanique des Bétons de Granulats Légers: Étude Expérimentale et Modélisation Rencontres Du Génie Civil Urbain, Costruire. Les Nouveaux Défis, 24, 2006.
[14] Gerritse, A., Design considerations for reinforced lightweight concrete. International Journal of Cement Composites and Lightweight Concrete, 3(1), pp. 57–69, 1981. https://doi.org/10.1016/0262-5075(81)90031-2
[15] American Concrete Institute, 213R-14 Guide for Structural Lightweight-Aggregate Concrete. 2003, Reported by ACI Committee 213.
[16] Ke, Y., Beaucour, A.L., Ortola, S., Dumontet, H. & Cabrillac, R., Influence of volume fraction and characteristics of lightweight aggregates on the mechanical properties of concrete. Construction and Building Materials, 23(8), pp. 2821–2828, 2009. https://doi.org/10.1016/j.conbuildmat.2009.02.038
[17] Ke, Y., Characterization of the mechanical behavior of lightweight aggregate concretes: experiment and modelling. Université de Cergy-Pontoise, 2008.
[18] Barbosa, F.S., Beaucour, A.L., Fanage, M.C.R. & Ortola, S., Image processing applied to the analysis of segregation in lightweight aggregate concretes. Construction and Building Materials, 25, pp. 3375–3381, 2011. https://doi.org/10.1016/j.conbuildmat.2011.03.028
[19] Esmaeilkhanian, B., Khayat, K.H., Yahia, A. & Feys, D., Effects of mix design parameters and rheological properties on dynamic stability of self-consolidating concrete. Cement and Concrete Composites, 54, pp. 21–28, 2014. https://doi.org/10.1016/j.cemconcomp.2014.03.001
[20] Jacek Kwasny, S.M., Sonebi, M., Taylor, S.E. & Bai, Y., Influence of the type of coarse lightweight aggregate on properties of semilightweight self-consolidating concrete. Journal of Materials in Civil Engineering, 24(12), pp. 1474–1483, 2012. https://doi.org/10.1061/(asce)mt.1943-5533.0000527
[21] Navarrete, I., Stratified concrete: understanding its stratification process and modelling its structural behavior. Pontificia Universidad Catolica de Chile: Santiago de Chile, 2015.
[22] Esmaeilkhanian, B., Feys, D., Khayat, K.H. & Yahia, A., New test method to evaluate dynamic stability of self-consolidating concrete. ACI Materials Journal, 111(13), pp. 299–308, 2014.
[23] Baddeley, A. & Vedel Jensen, E.B., Stereology for Statisticians. 2005.
[24] Masad, E., Muhunthan, B., Shashidhar, N. & Harman, T., Internal structure characterization of asphalt concrete using image analysis. Journal of Computing in Civil Engineering, 13(2), pp. 88–95, 1999. https://doi.org/10.1061/(asce)0887-3801(1999)13:2(88)
[25] Scrivener, K.L., Backscattered electron imaging of cementitious microstructures: understanding and quantification. Cement and Concrete Composites, 26, pp. 935–945, 2004. https://doi.org/10.1016/j.cemconcomp.2004.02.029
[26] Fernández-Fanjul, A. & Tenza-Abril, A.J., Méthode FANJUL: Dosage pondéral des bétons légers et lourds. Annales du Bâtiment et des Travaux Publics, 5, pp. 32–50, 2012.
[27] Fernández-Fanjul, A., Tenza-Abril, A.J. & Baeza-Brotons, F., A new methodology for determining particle density and absorption of lightweight, normal-weight and heavy weight aggregates in aqueous medium. Construction and Building Materials, 146, pp. 630–643, 2017. https://doi.org/10.1016/j.conbuildmat.2017.04.052