Karla Salvagni Heineck

Fundamental Parameters for the Stiffness and Strength Control of Artificially Cemented Sand

The treatment of soils with cement is an attractive technique when the project requires improvement of the local soil for the construction of subgrades for rail tracks, as a support layer for shallow foundations and to prevent sand liquefaction. As reported by Consoli et al. in 2007, a unique dosage methodology has been established based on rational criteria where the voids/cement ratio plays a fundamental role in the assessment of the target unconfined compressive strength. The present study broadened the research carried out by Consoli et al. in 2007 through quantifying quantifies the influence of voids/cement ratio on the initial shear modulus ( G0 ) and Mohr-Coulomb effective strength parameters ( c′ , ϕ′ ) of an artificially cemented sand. A number of unconfined compression and triaxial compression tests with bender elements measurements were carried out. It was shown that the void/cement ratio defined as the ratio between the volume of voids of the compacted mixture and the volume of cement is an ap...

High-Pressure Isotropic Compression Tests on Fiber-Reinforced Cemented Sand

High-pressure isotropic compression tests were carried out on reconstituted sand samples that were reinforced with cement, randomly distributed fibers, or both, making comparisons with the unreinforced sand and conducting tests from a variety of initial specific volumes. The results indicated changes in the isotropic compression behavior of the sand due to the inclusion of fibers and/or cement. Cementitious bonds are sufficiently strong relative to the particles to allow the cemented samples to reach states outside the normal compression line NCL of the uncemented soil, but the effectiveness of cemented fiber-reinforced specimens is even larger due to the control of crack propagation in the cemented sand after the inclusion of fibers. Distinct NCLs were observed for the sand, fiber-reinforced sand, cemented sand, and fiber-reinforced cemented sand. Both fiber breakage and fiber extension were observed in fibers measured after testing indicating that fibers individually have worked under tension, even though in the macroscopic scale, isotropic compressive stresses were applied. Fiber reinforcement was found to reduce the particle breakage of both the uncemented and cemented sands.

Análises do comportamento físico de um solo contaminado por borra oleosa ácida e encapsulado com cimento Portland

The objective of this study is applying the encapsulation technique in soil contaminated with increasing amounts of acidic oily sludge industrial residues, using Portland cement CP-V ARI as the encapsulating agent. The application of the encapsulation technique consisted in the accomplishment of post-treatment studies, analyzing the contaminated soil physically through unconfined compressive strength and durability tests. The results showed that an increasing amount of acidic oily sludge in the encapsulated soil ends up lowering the unconfined compressive strength as well as increasing the mass loss.

Engineering Properties of Fibrous Paper Mill Sludge from Southern Brazil

The paper recycling process generates a sludge characterized by a high content of cellulose fiber. To understand the behavior of this fibrous material, this article presents an interpretation of the geotechnical behavior of a waste sludge from a paper recycling plant situated in southern Brazil using data from laboratory tests. Engineering properties of compacted paper mill sludges are similar to those of most fibrous organic soils: low hydraulic conductivity upon compression and high compressibility. The waste studied has a water content of approximately 250%, organic content of 48%, mineral charges, and water. The one-dimensional compressibility parameters are indicative of high compressibility. For the determination of the strength parameters of the material, undrained triaxial tests were carried out. An incredibly high effective friction angle (ϕ′=53°) was found, probably because of the fibrous nature of the paper sludge. In addition, hydraulic conductivity tests were performed on a flexible wall perm...

Treatment of contaminated soil: Encapsulation analysis of heavy metals

Este artigo tem como objetivo aplicar a tecnica de encapsulamento, conhecida tambem como solidificacao/estabilizacao, em um solo contaminado em laboratorio com crescentes quantidades do residuo industrial borra oleosa acida, utilizando como agente encapsulante o cimento Portland CP_V ARI. A metodologia consistiu na realizacao de ensaios de lixiviacao em coluna, sendo que, previamente foram realizados ensaios de caracterizacao geotecnica para o solo em estudo. Os resultados evidenciam a capacidade do equipamento de lixiviacao em coluna em possibilitar a analise da efetividade do encapsulamento. A partir do calculo da taxa de reducao dos metais pesados pode-se confirmar que a adicao de cimento Portland mostrou-se eficaz na reducao dos parâmetros analisados. Os metais pesados Al, Cd, Mg e Zi apresentaram bons indices de reducao, todos acima de 90%. Palavras-chave: encapsulamento, metais pesados, solo contaminado.