Estudo e classificação de solos lateríticos finos, arenosos e pedregulhosos naturais e melhorados com ligantes hidráulicos para utilização em camadas de pavimentos flexíveis.

Abstract

The soils known as "Lateritic" correspond to approximately 20% of the Earth's surface and can be found in intertropical regions such as South America, Africa, India, and Australia. These soils have specific mechanical behavior due to the varied geological and climatic conditions under which they are formed. The development and improvement of classification procedures for lateritic soils, taking into account their mineralogical, physical, and mechanical properties, as well as appropriate concepts for the humid tropical environment, will allow for their use in highway pavement layers, which are currently underutilized. This study aims to evaluate the potential use of the Universal Classification of Lateritic Soils (CUSL) proposed by Rodrigues et al. (2010), as well as to study the response to resilient and permanent deformation of fine-grained, sandy, and gravelly lateritic soils, both natural and improved with hydraulic binders, when used in road pavement layers subjected to medium and heavy traffic. The experimental program was developed in two phases. The first phase included five steps: I - Characterization and classification of soils based on CUSL, TRB, MCT, and G-MCT; II - Mechanical response to static loading tests; III - Mechanical response to repeated loading tests; IV - Evaluation of resilient behavior and permanent deformation of pure and improved lateritic soils after volumetric shrinkage; and V - Analysis of permanent deformation test results in order to reduce the number of load application cycles in the test. In the second phase, a comparative analysis was conducted on the mechanical behavior of mixtures conventionally used in pavement layers. Additionally, structures were modeled to evaluate the structural and functional performance under simulated traffic conditions using an empirical-mechanistic procedure with the aid of MeDiNa software. The fine-grained, sandy, and gravelly lateritic soils showed good response to resilient and permanent deformation under both natural and chemically stabilized conditions. The influence of volumetric shrinkage due to drying on resilient and permanent deformation values was established in this study. The empirical-mechanistic evaluation demonstrated satisfactory behavior of the materials when applied in base and sub-base layers of flexible pavements under conditions simulating medium to heavy traffic. An excellent correlation was observed between the values obtained in tests with 30,000 and 150,000 load application cycles, significantly reducing the modeling time for permanent deformation. Finally, it was concluded that the classification proposed by Rodrigues et al. (2010), further improved in this study, is technically feasible. Additionally, the good performance of lateritic soils regarding the object of this research was confirmed, further expanding the database for the improvement of classification methodologies and knowledge of their mechanical properties. Despite their widespread availability in Brazil and other countries, lateritic soils are still underutilized in pavement construction.