Influência das propriedades morfológicas e dos métodos de seleção granulométrica nas propriedades mecânicas de misturas asfálticas.

Abstract

The aggregates are responsible for resisting about 80% of the pavement stresses, making their adequate selection an important factor for the production of resistant asphalt mixtures. The granulometric selection methods aplication allows to identify an asphalt mixture capable of resisting the pavement stresses, as well as the possibility of using differentes aggregates. The objective of this research was to evaluate the influence of the lateritic aggregates morphological characteristics and the granulometric selection methods on the asphalt mixtures resistance. In order to evaluate the characteristics of the aggregates, were perfomed granulometry lab tests, specific mass and absorption, shape index, sand equivalent, elongated and flat particles, fractured particles, angularity, durability, adhesiveness and abrasion. These samples were also submitted to the AIMS2 (Aggregate Image Measurement System - 2) to better evaluate the angularity, texture and shape characteristics. Three granulometric selection methods: the DNIT (National Department of Transport Infrastructure), the Bailey, the French were used to select mixture to be evaluated. The DASR (Dominant Aggregates Siza Range) evaluation method was used to predict the behavior of the mixtures against permanent deformations. The elaborated mixtures had their resistance evaluated by means of the properties (sliding, Marshall stability, modified Lottman, tensile strength, weld, resilience modulus, controlled voltage fatigue, dynamic modulus and flow number). The results indicated the importance of considering the aggregates characterization methodologies to obtain more reliable measures and with less operator influence; in the same way that it revealed the importance of adequate granulometric selection. The analyzes allowed to conclude that the mixture using laterite aggregate selected by the French method was the one that presented better overall performance, while the DNIT method allowed to obtain better responses among the mixtures using granite aggregates. The evaluation of the mixtures revealed that the lateritic aggregate can be used instead of conventional granite to produce mixtures with resistance to the requirements of current standards.