Análise de propriedades geotécnicas de misturas de solo com concreto asfáltico fresado e cimento Portland para uso em camada de pavimento rodoviário

Abstract

Due to use, pavements may migrate from optimum to bad condition if not maintained. Milling is one of the technical alternatives used for pavement rehabilitation and consists of thinning deteriorated pavement layers for its recovery. The residue resulting from the asphalt coating layer milling is composed of fragments of it in a aged condition, which can be recycled, resulting in optimization of natural resources and reduction of construction costs. It is also known that soil is a heterogeneous material and may often prove to be unsuitable for a particular use in Engineering, making it necessary to change its properties so that it adapts to technical specifications. Among the ways to promote changes in soil properties there are mechanical stabilization, through compaction and granulometric correction, and chemical stabilization, being Portland cement the most commonly used stabilizing agent. Studies indicate that evaluating the behavior of mixtures of natural soil with milling residue is relevant for pavement design. In this research, asphalt coating milling residue, fine clayed soil and CP V – ARI Portland cement were mixed. Through laboratory tests, physical, mechanical and hydraulic properties of the mixturies were evaluated, in addition to the feasibility of using these mixtures in pavement layers. The granulometry, specific mass, dry and dry surface saturated density, bitumen contente, water absorption and Los Angeles abrasion of the milling residue were evaluated. For soil and mixtures of soil with 20%, 30% and 50% of milling residue, granulometry, Atterberg limits, compaction, California bearing ratio (CBR) and permeability tests were carried out. Mixtures of soil, milling residue at the contents already indicated and 5% of cement were also carried out and granulometry, Atterberg limits, compaction, CBR, unconfined compression strength (UCS), indirect tensile strength (ITS), durability and permeability tests were performed. Then, the feasibility of using the milling residue incorporated to the soil and cement in pavement layers was evaluated. It was found that increasing the milling content up to 50% leads to an improvement in granulometry, reduces plasticity, increases the maximum dry density, reduces the optimum moisture, increases de CBR, reduces the expansion and increases the permeability of the mixes with the soil. The addition of 5% of cement caused strong changes in the granulometry of the mixtures, making them more granular and less plastic. Still, it increased the CBR, reduced the expansion and the permeability. Mixtures with cement presented UCS below the required for soil-cement bases, good ITS and good durability. The mixtures with and without cement did not meet the requirements for use in granulometrically stabilized or cement improved soil base and sub-base layers, nether for soil-cement base, due to the amout of fines and the high plasticity of pure soil. However, it was found that the use of milling residue is promising in improving soil and mixtures properties and as a material to be used in paving.