Estudo sobre a validação de uma metodologia de classificação de solos lateríticos com vistas à execução de camadas de pavimentos rodoviários.

Abstract

Tropical soils are formed under many geological and climatic conditions, which grant them a peculiar mechanical behaviour. A new procedure for the classification of lateritic soils was developed based on the mineralogical and physical properties of the soils and on the appropriate conceptions of the tropical humid environment. This procedure will enable the use of greater quantities of lateritic soils in highways pavements. Thus this study aimed to validate the use of the methodology for the classification of lateritic soils developed by Rodrigues et al. (2010) in highway pavement structure building. The methodological procedure included test to determine the soils lateritical properties, classification, resiliency and performance in a mechanistical-empirical analysis with MeDiNa software. The lateritical features of the soil were confirmed through scanning electron microscopy, x-ray diffraction and x-ray fluorescence. The classification began with the granulometric analysis and the division of the soil in fine-grained, coarse-grained and gravel. After that, the materials were selected for the base, subbase and subgrade reinforcement according to the values obtained in adsorption blue methylene, contraction limit, friability, fragmentability, degradability and California Bearing Ratio (CBR) tests. Blue methylene values indicated low activity in samples of sixteen lateritical soils. The limit of contraction stood between 14,59% e 34,08%. Friability and fragmentability tests significantly influenced the compaction process of the samples and the resilient behavior. The CBR value presented high variability, therefore it should not be the sole criterion used to assess soil support capacity. Furthermore, the resilient modulus of the samples reached satisfactory values, some of them higher than 900 MPa. Finally, the mechanistical-empirical analysis of two soils indicated that it was possible to use lateritical fine-grained, coarse-grained soils and gravels in the base layer. The highest traffic supported by the pavement structure adopted in simulation with the MeDiNa software was of N equal to 2,98 x 10 of a standard axis. Therefore, this methodology made possible the use of the studied lateritic soils in pavement structural layers.