A comprehensive study of weathered basalt for low-volume traffic roads paving

Rio Grande do Sul State presents more than 120,000 km of low-volume traffic roads; most of them unpaved. The Civil Engineering Postgraduate Course of Federal University of Rio Grande do Sul and Roads Department of Rio Grande do Sul have been developing since 1992 a comprehensive study of weathered basalt, a non-conventional material, whose use may reduce paving costs. This study includes laboratory tests of ten weathered basalt deposits and the construction of an equipment for traffic simulation on experimental sections. This paper presents the main results of laboratory study. Characterization and standard rock durability tests results are discussed and an index relating the soaked and dry mineral skeleton strengths is proposed as an acceptance criterion for weathered basalts. Experimental results obtained in test sections where weathered basalts were used as subbase or base layers, are also discussed.