USE OF THE SOIL-TAR MIXTURES IN FOREST ROADS

Abstract

The purpose of this study was to analyze the engineering behavior of the soil-tar mixtures considering their application in forest road. The laboratory-testing program encompassed characterization and California bearing ratio (CBR) tests performed on soils and soil-tar mixtures. Three representative soil samples from the Viçosa, Minas Gerais State, Brazil, and tar contents of 0,25; 0,5; 1; 2; 4 and 6% in terms of dry soil mass were considered throughout the study. All the samples were compacted at the Standard AASHTO compaction effort. Data support that: (i) addition of tar contributed to improve the mechanical engineering response of the tested soils, for some treatments, in comparison with the plain soils; (ii) curing time influences the mechanical response of the soil-tar mixtures; (iii) although it was observed mechanical improvement of the soil-tar mixtures comparing to the plain soils, it was not reached the Brazilian National Road Engineering Office (DNER) minimal stability requirements for sub-base layers of flexible pavements.