Abstract:
Volatile organic compounds are an environmental concern in the asphalt paving industry. A main pollution source is the so-called cutbacks (asphalts with solvents) frequently applied in the priming of base layers. In Brazil, the cutback MC-30 with kerosene is frequently used. However, the use of cutbacks has been restricted in some countries in which environmental legislation is stricter. This has led to the search for alternative materials to substitute for conventional cutbacks. This paper investigates the potential use of a mixture produced from cashew nut shell liquid (CNSL) and asphalt cement (AC) as the prime coat. The purpose is to obtain a less environmentally aggressive bituminous prime coat product. To verify the performance of the prime in sandy soils, 240 specimens were produced and primed with different products: the cutback MC-30, an emulsion MS-1C, and a mixture produced in the laboratory called AC/CNSL (60% AC 50/70 and 40% CNSL). Experimental results have shown that the prime coat is a complex material affected by factors such as the type and the rate of the applied binder, preparation conditions of the base surface, and moisture content in compaction. Results indicated the potential use of the AC/CNSL in compacted sand samples. The product can satisfactorily be used as a cutback, and it attends the parameter of penetration in the base layer.
