Compaction of soil-grits mixtures for use in forestry road : influence of time between mixture and compaction on mechanical strength

Vários fatores influenciam a execução e a "performance" de camadas de pavimentos rodoviários constituídas de solos estabilizados quimicamente, com destaque para a homogeneização da mistura e o período de tempo decorrido entre a mistura e a compactação, bem como para a escolha do equipamento de compactação. Aborda-se, no presente artigo, a influência do tempo decorrido entre a mistura e a compactação (TMC) nos parâmetros de compactação e na resistência mecânica de misturas de dois solos típicos da Zona da Mata Norte de Minas Gerais, com o resíduo da indústria de celulose denominado "grits", com vistas à sua aplicação em estradas florestais. Analisa-se, também, a influência de diferentes lotes desse resíduo na resistência mecânica das misturas. Trabalhou-se com os resultados de ensaios de índice de suporte Califórnia (ISC ou CBR) realizados em corpos-de-prova de misturas moldados na energia de compactação do ensaio Proctor Intermediário. Os resultados permitem concluir que o tempo decorrido entre mistura e compactação influencia significativamente a resistência mecânica das misturas analisadas, recomendando-se, para fins práticos, que estudos dessa natureza devam ser feitos em bases regionais de ocorrência de solos. Observou-se, também, influência significativa do lote na resistência mecânica das misturas. _______________________________________________________________________________ ABSTRACTMany factors affect the construction and performance of chemically stabilized highway pavement soil layers, especially mixture homogenization, time between mixture and compaction, and selection of compaction equipment. Regarding forest road application, this paper addresses the influence of time between mixture and compaction (TMC) on compaction optimum parameters and on mechanical strength of mixtures of two typical soils from the region ‘Zona da Mata Norte’, State of Minas Gerais, and grits, a waste from the cellulose industry, as well as the influence of grits sampling on the mechanical strength of soil 2-grits mixtures. California bearing ratio (CBR) data from laboratory specimens compacted at the Intermediate Proctor compaction effort were used throughout the study. The laboratory testing data supported that time between mixture and compaction significantly affected the mechanical strength of the tested soil mixtures. Regarding soil samples and from a practical point of view, it is recommended that such studies should be always performed on regional basis. It was observed significant influence of grits sampling on the mechanical strength of soil 2-grits mixtures

Development, Fabrication and Verification of the LSU in Situ Testing Calibration Chamber (LSU/CALCHAS).

This dissertation introduces the Louisiana State University Calibration Chamber System (LSU/CALCHAS) for calibrating electronic cone penetrometers and other in situ testing equipment. It permits the simulation of the K\sb{\rm o} consolidation and the four (4) traditional boundary conditions commonly referred in the literature. The calibration chamber system encompasses a 304 stainless steel cylindrical calibration chamber which can house a soil sample.55 m (20 21/32 in.) in diameter and.79 m (31 1/16 in.) in height. A fully computerized control panel, a data acquisition and reduction system, a large dimension automatic tamper for preparing compacted soil samples, and accessories comprise the complete system. Compacted soil samples can presently be prepared in the LSU/CALCHAS, but capability for testing pluviated sand and preconsolidated clay samples are also available. In addition, the dissertation includes a preliminary test program to calibrate in the LSU/CALCHAS the 1.27 cm\sp2 Fugro-McClelland miniature electronic cone penetrometer (MQSC). This cone is expected to be used in engineering design and construction control of transportation facilities in the State of Louisiana, U.S.A. The laboratory verification phase of the research involved the compaction of a mixture of 80% of fine sand and 20% of kaolinite by weight, K\sb{\rm o} consolidation of the soil sample at 210 kPa (30 psi), and penetration of the sample via the MQSC at the penetration rate of 2 cm/sec. under boundary conditions 1 and 3. A sister field study is presented in order to examine the scale effect topic when comparing sounding data obtained with the standard 10 cm\sp2(reference) Fugro electronic friction cone penetrometer versus the MQSC and the 15 cm\sp2 Fugro electronic friction cone penetrometer. Five (5) representative sites in the State of Louisiana were selected for the field testing program, encompassing the range of sandy, silty and clayey soils. Compacted embankments and natural grade soils were investigated. Sounding 10 m deep were performed in two (2) highway embankments and three (3) natural ground sites. The statistical evaluation of the field testing program data and the corrective measures recommend for their proper cross-correlation are presented

Efeito da cinza de casca de arroz na plasticidade e compactação de uma mistura solo-cal

O artigo direciona-se à avaliação do uso potencial de cinza de casca de arroz (CCA) como pozolana, atuandojuntamente com cal no processo de estabilização química de um solo residual da região de Ilha Solteira, estadode São Paulo, Brasil.Trabalhou-se com o teor de cal de 8% e com os teores de cinza de 5% e 10% em relação ao peso de solo seco.Na análise do comportamento de engenharia do solo e das misturas solo-cal e solo-cal-CCA, foram consideradosparâmetros geotécnicos de caracterização (distribuição granulométrica, limite de liquidez (LL) e limitede plasticidade (LP)), parâmetros ótimos de compactação obtidos na energia do ensaio Proctor normal (umidadeótima (wot) e massa específica aparente seca máxima (ï²dmax)), bem como foi realizada a classificaçãodos materiais segundo a Metodologia MCT.Os resultados obtidos levaram à conclusão de que a adição da CCA foi responsável por: (i) aumentos nosparâmetros LL, LP e wot, bem como redução nos parâmetros IP e ï²dmax do solo e de sua mistura com cal; (ii)segundo a Metodologia MCT, o solo e suas misturas foram classificados como solos arenosos lateríticos(LA')

Use of industrial grits in forest road pavements : influence of curing times on the mechanical strength and swelling of compacted soil-grits mixtures

Analisou-se a influência do teor de estabilizante, da energia de compactação e do período de cura na resistência mecânica e expansão de dois solos da Zona da Mata Norte de Minas Gerais. As amostras de solos residuais de gnaisse coletadas na cidade de Viçosa, MG, Brasil, respectivamente, de texturas argilo-arenosiltosa e areno-argilo-siltosa, foram denominadas solos 1 e 2. Empregou-se como estabilizante químico o resíduo “grits” fornecido pela empresa de Celulose Nipo Brasileira (CENIBRA); os teores, em massa, de 4, 8, 12, 16, 20, 24 e 28% desse resíduo foram utilizados nas misturas solo-“grits”. Corpos-de-prova das misturas solo- “grits” foram compactados nos teores ótimos de umidade relativos às energias de compactação dos ensaios Proctor intermediário e modificado e curados por 0, 7, 28 e 90 dias. Avaliou-se a resistência mecânica dos solos e misturas através dos seguintes parâmetros: (a) índice de suporte Califórnia (ISC ou CBR), resistência à compressão não confinada (RCNC) e resistência à tração em compressão diametral (Rt). Os resultados permitiram concluir que todos os parâmetros considerados na análise influenciaram, significativamente, a resistência mecânica das misturas solo-“grits”, sendo o comportamento das misturas solo 1-“grits” influenciado, também, pelo teor de sódio presente na constituição química do “grits”. ____________________________________________________________________________________ ABSTRACTThis paper addresses the influence of stabilizer content, compaction effort and curing time on the mechanical strength and swelling of two soils from the “Zona da Mata Norte” region, State of Minas Gerais, Brazil. Two residual gneiss soils from the municipality of Viçosa, Brazil, silt-sand-clay and silt-claysandy soils named soils 1 and 2, respectively, were used in this study. Industrial grits provided by Celulose Nipo Brasileira - CENIBRA was used as stabilizer, with contents ranging from 4 to 28 % regarding soil dry mass. Specimens of soil-grits mixtures were compacted at the Intermediate Proctor compaction effort and curing times of 0, 7, 28 and 90 days. Mechanical strength was evaluated as follows: California bearing ratio (CBR), unconfined compression strength (UCS) and indirect tensile strength (ITS). Data from the laboratorytesting program supported that all parameters affected mixture mechanical strength significantly, and the mechanical behavior of soil 1-grits mixtures were also influenced by sodium content of grits

Rheology and mechanical aspects of a self-compacting soil-cement in the fresh state

The article presents a study of design parameters for the fresh self-compacting soil-cement so that it can beframed under the action of its own weight in the production of prefabricated elements.In the experimental work, it was used a residual soil of the region of Porto, Portugal, Portland cement, waterand an additive of steric and electrostatic actuation as superplasticizer.The proportion of materials were related to soil dry weight with cement contents ranging from 20, 25, and30%, water from 41, 44 and 47%, and superplasticizer from 0.66, 0.84 and 0.93%.The tests performed on fresh state fit into assessment protocols used for self-compacting mortars and concretes,and refer to the spreading test using a mini cone and the flow test with the aid of a funnel. In the hardenedstate, it was performed the unconfined compression test.The results indicated that the fresh self-compacting soil-cement falls technologically into the behavior observedin concretes and mortars, distinguishing the expressive influence of water and superplasticizer as fluidityagents, and soil and cement as viscosity controlling agents. Amounts of these constituents were definedin order to better optimize the conditions of fluidity and mobility of the mixtures, which may have as primaryparameter of dosage the water/cement ratio, with regard to mechanical strength, and the specimens apparentdensity. The properties of fluidity and mobility are preferably correlated with the water/(cement+soil) ratio

Utilização do resíduo sólido industrial (lama-de-cal) em pavimentos de estradas florestais

O objetivo do presente estudo foi avaliar os efeitos do resíduo sólido industrial (lama-de-cal) nas propriedades geotécnicas de amostras de solo da região de Alagoinhas, BA, Brasil. Das sete amostras coletadas, apenas duas foram selecionadas, por apresentar maior potencial geotécnico. Utilizaram-se ensaios de caracterização, CBR e permeabilidade, cujos resultados indicaram que a amostra de solo denominada good gravel quando estabilizada com lama-de-cal, na dosagem de 20 e 25%, foi a mais promissora. ____________________________________________________________________________________ ABSTRACTThe objective of the present study was to evaluate the effects of industrial solid waste (whitewash mud) on geotechnical properties considering the following engineering parameters: California Bearing Ratio (CBR), Atterberg limits and Permeability test. Seven soil samples derived from Alagoinhas, Bahia - Brazil, were classified by the Transportation Research Board (TRB) system. Two were selected as having a great geotecnical potential classified as A-3 (0) and A-2-4 (0), whitewash mud contents 10%, 15%, 20% and 25% dry weight and medium compaction effort were studied in the laboratory testing program. The results indicated the soil denominated good gravel as being the most promising one, when stabilized with whitewash mud, reaching the best results with the dosage of 20 and 25% of whitewash mud

Optical Properties And Antiangiogenic Activity Of A Chalcone Derivate

Chalcones and their derivatives exhibit numerous pharmacological activities such as antibacterial, antifungal, cytotoxic, antinociceptive and anti-inflammatory. Recently, they have been assessed aiming for novel application in nonlinear optics and in the treatment of immune diseases and cancers. In this study, we investigate the optical properties of synthetic chalcona 1E,4E-1-(4-chlorophenyl)-5-(2,6,6-trimethylcyclohexen-1-yl)penta-1,4-dien-3-one (CAB7β) and its antiangiogenic potential using the chorioallantoic membrane (CAM) with the S180 sarcoma cell line. Experimental and theoretical results show intense absorption in the UVA-UVC region, which is associated with a π → π* transition with intramolecular charge transfer from the trimethyl-cyclohexen-1-yl ring to the chlorophenyl ring. Quantum chemical calculations of the first hyperpolarizability, accounting for both solvent and frequency dispersion effects, are in very good concordance with hyper-Rayleigh scattering measurements. In addition, two-photon absorption allowed band centered at 650 nm was observed. Concerning antiangiogenic activity, CAB7β causes a significant reduction in the total number, junctions, length and caliber of blood vessels stimulated by S180 cells reducing the presence of blood vessels, inflammatory cells and others elements related to angiogenic process. It is found that CAB7β is a versatile compound and a promising candidate for linear and nonlinear optical applications, in therapy against sarcoma and phototherapy