FREDERICO VASCONCELLOS GUATIMOSIM MECHANICAL BEHAVIOUR AND STRUCTURAL PERFORMANCE OF RECYCLED FOAMED BITUMEN STABILIZED MATERIALS São Paulo 2015 FREDERICO VASCONCELLOS GUATIMOSIM MECHANICAL BEHAVIOUR AND STRUCTURAL PERFORMANCE OF RECYCLED FOAMED BITUMEN STABILIZED MATERIALS Dissertation presented for the degree of Master of Science (Engineering) at the Polytechnic School of the University of São Paulo. São Paulo 2015 FREDERICO VASCONCELLOS GUATIMOSIM MECHANICAL BEHAVIOUR AND STRUCTURAL PERFORMANCE OF RECYCLED FOAMED BITUMEN STABILIZED MATERIALS Dissertation presented for the degree of Master of Science (Engineering) at the Polytechnic School of the University of São Paulo. Research Area: Transportation Engineering Advisor: Prof. Kamilla Vasconcelos, PhD São Paulo 2015 Este exemplar foi revisado e corrigido em relação à versão original, sob responsabilidade única do autor e com a anuência de seu orientador. São Paulo, ______ de ____________________ de __________ Assinatura do autor: ________________________ Assinatura do orientador: ________________________ Catalogação-na-publicação Guatimosim, Frederico Mechanical Behaviour and Structural Performance of Recycled Foamed Bitumen Stabilized Materials / F. Guatimosim -- versão corr. -- São Paulo, 2015. 109 p. Dissertação (Mestrado) - Escola Politécnica da Universidade de São Paulo. Departamento de Engenharia de Transportes. 1.Pavimentação (Reabilitação) 2.Reciclagem 3.Avaliação Laboratorial 4.Avaliação de Campo I.Universidade de São Paulo. Escola Politécnica. Departamento de Engenharia de Transportes II.t. I dedicate this thesis to my grandfather, José Silvério, best human being I’ve ever met, without whom none of this would have been possible... ACKNOWLEDGEMENTS First and foremost, I would like to thank my parents Henrique and Thereza Christina for everything they have done for me. Without their guidance and love I wouldn’t have been able to be achieve all that I have, for my success is a mere result of theirs. I’d like to thank my sister, Mariana, for her kind words and caring. The road has been lighter by your side. For my uncle Rodrigo and my aunt Flavia, for all the support, attention and incentive through all the steps that have brought me here. Your support motivates me and gives me confidence to move forward. I’d like to thank my grandmother, Maria Thereza for always thinking I am two steps ahead, when I am actually one step behind trying to catch up. I would like to thank all the personnel from the Laboratory of Pavement Techology of University of São Paulo for their valuable support in the experimental laboratory tests. I’d like to thank Diomária taking care of all of us students as a mother, Erasmo for helping me with the hard work, Vanderlei for all the patience to help me prepare the tests and the support while performing and Robson and Edson for all the talks and valuable lessons you taught me even when we were just passing time. I would also like to thank ValmirBonfim from Fremix, whose lecture brought me in contact with the BSM theme, and whose support has been vital for this dissertation development. I’d like to thank Wendell Pereira and Cristian Amaro, for all their field support and availability. For my bosses Anselmo and Renato, for helping me throughout and allowing me to spend so many days out of the office without ever complaining. At last, I’d like to thank Dave Collings, Wynand van Niekerk and Professor Kim Jenkins for all their valuable support, kind attention and amazing hospitality. Part of my fondness for this thesis comes from how fondly I remember Africa. RESUMO Em busca de soluções estruturais para restauração de pavimentos rodoviários que que sejam eficientes, mas ao mesmo tempo que sejam econômicas e impactem o mínimo possível na dinâmica de operação da malha rodoviária, tem sido difundida a metodologia de reciclagem a frio de pavimentos com a estabilização com espuma de asfalto. A redução de custos devido a reutilização de material e a menor necessidade de transporte de insumos, além da possibilidade de realização da restauração em um curto espaço de tempo, têm contribuído para a crescente utilização do processo. Este trabalho tem como objetivo avaliar o desempenho e o comportamento mecânico de uma mistura reciclada estabilizada com espuma asfalto, para melhor entender os efeitos do confinamento e do teor de umidade do material, visto que este passa por um processo de cura quando já em serviço. Foi acompanhado um trecho experimental onde o pavimento foi restaurado com a aplicação de uma base reciclada estabilizada com espuma de asfalto. O segmento foi monitorado através do controle tecnológico de execução e de levantamentos deflectométricos com FWD. Verificou-se que as deflexões após quase 24 meses da execução do trecho reduziram consideravelmente. Paralelamente, foram realizados ensaios de resistência à tração por compressão diametral, módulo de resiliência triaxial e de deformação permanente para diferentes procedimentos de cura para verificação do efeito da saída da água nas mudanças de comportamento mecânico do material. Verificou-se ainda o efeito das tensões de confinamento no módulo de resiliência de materiais estabilizados com espuma de asfalto e determinaram-se os parâmetros de cisalhamento do material através de ensaiosTriaxiais Monotônicos. Pode-se concluir que a cura é uma consideração importante tanto com relação a sua duração, quanto com relação ao seu efeito no comportamento do material. Palavras-chave: Reciclagem a frio; Espuma de asfalto; Rigidez; Deformação Permanente; Estado de Tensão ABSTRACT Seeking for pavement rehabilitation solutions that result in efficient and capable structures, that bring economic advantages, and the smallest possible impact to the road network operation, cold recycling with foamed asphalt stabilization has been gaining acceptance and growing steadily. The possibility of economic benefits due to material reuse and the decrease in transportation costs, allied to the reduced time needed to open to traffic, have contributed to the increase in this technique’s use. This study has the objective of evaluating the performance of cold recycled mixes stabilized with foamed asphalt, for a better understanding on the effects of confining stresses, and material moisture content, since it undergoes the curing process when in service. An experimental test section with foamed stabilized recycled material used as the base course was monitored through quality control and quality assurance and FWD tests. It was observed that deflections, after nearly 24 months, have decreased significantly. In laboratory, Indirect Tensile Strength, Triaxial Resilient Modulus, and Permanent Deformation Tests were conducted for samples cured through different procedures, to evaluate the stress dependency and the effect of moisture decrease on the material behaviour. As a complementing test to evaluate the effect of confinement on material mechanical behaviour and to characterize the shear properties in foamed stabilized materials, a Monotonic Triaxial Test was performed. Based on the results obtained, one can conclude that the curing is a critical consideration in terms of timing and its influence on pavement performance. Triaxial tests showed the stress dependency of this bitumen stabilized material, while permanent deformation results indicated some potential for damage in the early stages after construction. Also, foamed bitumen stabilized materials stress dependency indicate that its mechanical behaviour is similar to unbound granular materials. On the field evaluation, FWD data indicated the decrease in deflection with time, resulting in an increase of the layers stiffness. Keywords: Cold Recycling, Foamed Asphalt, Stiffness, Permanent Deformation, Stress Dependency. FIGURES LIST Figure 1 – Optimum water content determination as a function of the expansion rate and half life of the foamed bitumen (Wirtgen, 2012). ................................................. 12 Figure 2 – Curing time and long-term performance of different materials (SANRAL, 2014). ......................................................................................................................... 19 Figure 3 – (a) Specimen with the rubber membrane inside the pressurized chamber; (b) Servo-pneumatic test machine. ............................................................................ 22 Figure 4 – Pavement layer thickness using cold in-situ foamed bitumen recycling (Milton and Earland, 1999). ........................................................................................ 27 Figure 5 – Layer Thickness of in situ and ex situ (plant mix) foamed bitumen recycled material, with 100 mm of asphalt surfacing required for all cases (Nunn and Thom, 2002). ......................................................................................................................... 28 Figure 6 – Criteria for Determining Allowed Capacity from PN (Asphalt Academy, 2009). ......................................................................................................................... 32 Figure 7 – Flow chart of the PN design methodology (adapted from Austroads, 2011) .................................................................................................................................... 33 Figure 8 – Position of analysis for each layer and parameter (SANRAL, 2014) ....... 34 Figure 9 – Location of the Trial Section. .................................................................... 38 Figure 10 – Existing structure in Highway SP-070 prior