The results of a study of the use of electric furnace slag as pavement aggregates are presented. Slag is generated as waste during steel production in industrial plants that use electric arc furnaces. Tests for the following were carried out to determine the characteristics of the aggregate: grain size distribution, soundness, Los Angeles abrasion, compaction, California bearing ratio, resilient modulus, and expansion. To use the slag as a granular layer, its grain size distribution had to be corrected. This procedure increased the bearing capacity and workability of the material. Evaluation of the expansion potential showed that the slag must be stocked in the open air for at least 4 months before it can be used in pavement construction. After correction of the gradation, the slag presented a resilient modulus that exceeded those of traditional granular materials; its use resulted in thinner and cheaper pavements. The results of the study led to the conclusion that the use of electric arc furnace slag as pavement material is possible and that it provides remarkably good technical quality and economic advantages.
It is of a great importance to know binders' viscosity in order to perform handling, mixing, application processes and asphalt mixes compaction in highway surfacing. This paper presents the results of viscosity measurement in asphalt-rubber binders prepared in laboratory. The binders were prepared varying the rubber content, rubber particle size, duration and temperature of mixture, all following a statistical design plan. The statistical analysis and artificial neural networks were used to create mathematical models for prediction of the binders viscosity. The comparison between experimental data and simulated results with the generated models showed best performance of the neural networks analysis in contrast to the statistic models. The results indicated that the rubber content and duration of mixture have major influence on the observed viscosity for the considered interval of parameters variation
O presente artigo apresenta o estudo do comportamento de quatro solos com origens geológicas diferentes, quanto à sua resistência e deformação resiliente, comumente empregados em subleitos rodoviários no estado do Rio Grande do Sul. A metodologia aplicada consistiu em ensaios de caracterização física e mecânica, obtenção da curva característica dos solos, além de simulações numéricas assistidas por dois programas computacionais: AEMC e AASHTOWare Pavement ME Design. Os resultados indicaram que os limites descritos em norma para utilização dos solos como material de subleito foram satisfeitos. Verificou-se que uma variação de ± 2% no teor de umidade provocou considerável alteração na resistência desses materiais, evidenciando a influência da sucção na resistência ao cisalhamento dos solos. As análises mecanicistas permitiram constatar a limitação do método de dimensionamento do DNIT, principalmente no que tange à ruptura por fadiga, além de destacar a importância do módulo de resiliência no comportamento da estrutura como um todo.
The influence of suction on the resilient modulus of a shale residual lateritic soil was analyzed. Laboratory tests were carried out to obtain the moisture content-suction relationship and determine the resilient moduli of specimens submitted to drying, wetting, or wetting-after-drying paths. A supplementary study on the effects of compaction method on soil resilient modulus was carried out. Soil suction was measured in situ, with jet-fill tensiometers installed along test sections built in a pavement testing facility. Test sections were loaded by a traffic simulator, and periodically deflections were measured for modulus backcalculation. Laboratory and in situ results confirmed the consensus that suction remarkably affects soil elastic deformability. Wetting-after-drying paths proved to be an extremely severe condition that may lower resilient modulus up to four times. Static compaction led to resilient moduli higher than those of specimens compacted dynamically or by kneading. In situ results matched reasonably well with laboratory moduli of specimens compacted by kneading and tested at optimum moisture content. In general, the importance of drainage design and maintenance was clearly confirmed. In well-drained pavements, subgrade soils will not be saturated for long periods. Suction will control stress state and soil deformability and guarantee that the pavement will carry the designed traffic before failure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.