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Aos meus dois grandes amores Fernando eYasmim, por toda a felicidade que me proporcionam. AGRADECIMENTOSA minha querida orientadora Prof. a. Maria Eugenia Gimenez Boscov por todo o esforço e dedicação na árdua tarefa de orientação, sem o qual, não teria sido possível a conclusão deste trabalho. Agradeço, ainda, pela paciência, pelos incansáveis incentivos e por ser, além de orientadora, amiga e companheira. A Prof. a. Elizabeth de Oliveira por toda atenção dispensada, por todo o conhecimento transmitido em forma de sugestões muito elucidativas e por ter cedido o Laboratório de Espectrometria de Emissão e Absorção Atômica do Instituto de Química da USP para a realização das inúmeras análises químicas. Ao Prof. Antenor Braga Paraguassu pelas sugestões recebidas na Qualificação que enriqueceram em muito o trabalho. Ao Geól. Helder de Godoy por orientar a coleta da argila laterítica no Instituto Agronômico de Campinas. Ao Prof. Charles Shackelford, Colorado State University, pelas sugestões feitas quando da sua visita ao Laboratório de Mecânica dos Solos da EPUSP. Ao Joaquim Costa Jr. e ao Antônio Carlos Heitzmann, técnicos do Laboratório de Mecânica dos Solos da EPUSP, por toda a ajuda dispensada para a execução dos ensaios e por toda a dedicação ao laboratório e aos seus usuários. Aos alunos de iniciação científica que colaboraram na execução dos ensaios laboratoriais realizados nesta pesquisa:

The effect of time on soil properties, noticeable in many earthworks, is recognized by geotechnicians. For example, secondary compression and aging pre-consolidation are considered in geotechnical design, and strain rate is standardized in geotechnical laboratory and field tests. Elastic-plastic models, from rigid-perfect plastic to Modified Cam Clay, which do not consider the effects of time, solve most geotechnical problems. However, solutions for prolonged settlements, landslides, debris flow and mudflow could profit from a deeper understanding of rheological models. In fact, rheological concepts, despite not always clearly stated, have been used to address some of these problems, and may also be important for using new materials in geotechnical practice (tailings, sludge, soil-polymer mixtures and other materials with water content higher than the liquid limit). This paper introduces basic concepts of rheology for geotechnicians, specially highlighting viscoelasticity under simple shear stress, which explains with reasonable accuracy well known phenomena dependent on time in soils. The objective is to bring geotechnicians to rheology and show another important tool to access geotechnical problems. On the other hand, a brief explanation of geotechnical tests is presented for rheologists not acquainted with geotechnical engineering. Geotechnical tests procedures are discussed in the light of rheology concepts, terminology is clarified, examples of application of rheology in geotechnics are presented, and determination of soil rheological parameters by traditional geotechnical tests as well as by tests on concrete is commented.

This paper explores the feasibility of employing drinking water treatment sludge (WTS) mixed with soils, lime, or rock powder in geotechnical applications, as well as discusses the sustainability of the approach based on experimental results, aiming at the beneficial reuse of waste and the preservation of natural geomaterials. The selected materials were two soils largely used in earthworks, two WTSs, a high purity calcium hydrated lime, and rock powder from a granitic–gneissic quarry, all occurring in São Paulo State, Brazil. The mixtures were chemically, mineralogically, and geotechnically characterized, and the geotechnical properties permeability, shear strength, and deformability were investigated. Soil-WTS mixtures showed hydraulic conductivity (10−10–10−6 m/s, depending on soil and WTS), effective cohesion (10–30 kPa), friction angle (34°–40°), undrained strength (>50 kPa), and compression index (0.1–0.4) compatible with those of soils usually employed in earthworks. Lime:WTS and rock powder:WTS mixtures achieved 50 kPa undrained strength for WTS contents lower than 24% and 8%, respectively, and could be used as daily and intermediate covers of waste landfills, as well as in other applications with low soliciting stresses. The possibility of WTS being pumped instead of transported by trucks was analyzed in the light of results from rheological tests.

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