STUDY OF THE APPLICATION OF THE CASHEW NUT SHELL LIQUID IN BITUMINOUS PRIMING OF SANDY BASE LAYERS FROM THE STATE OF CEARá,BRAZIL

摘要

One of the concerns about environmental pollution in the asphalt paving is the volatile organic compounds, whose main pollution source is the cutback asphalts frequently applied to the priming of base layers. The use of cutback asphalts has been restricted in some countries in which the environmental legislation is stricter. That reality has awoken the search for alternative materials to substitute the conventional cutback asphalts. Therefore, we conducted this research with the main objective to investigate the use of the cashew nut shell liquid (CNSL), a crop largely cultivated in the State of Ceará, Brazil, as an asphalt diluent. A mixture was produced (AC/CNSL) for priming services based on the addition of 40% of CNSL to 60% of AC 50/60 (petroleum asphalt cement). We studied the interaction among four sandy soils belonging to the A-1 class of TRB (Transport Research Board) and three different binder types (cutback asphalt, asphalt emulsion and AC/CNSL) based on the conduction of priming tests. The soil samples were compacted with five different moisture contents and primed at a rate of 1.0 l/m2 for each of the three binders, producing a total of sixty test specimens. The results obtained indicated the technical viability of using the mixture of CNSL and AC as an alternative solution for bituminous priming, since those products, besides producing a homogeneous mixture without settling down, caused a reasonable penetration in the soil samples compacted.