Strength and Behavior of Materials for Low-Volume Roads as Affected by Moisture and Density

Abstract

The relationships among strength, moisture, and density in pavement subgrades and layerworks are well known, but they have particular significance in low-volume roads. In these roads, the specified density is frequently not achieved (quality assurance testing tends to be reduced), and moisture fluctuations are more severe with greater consequences. Traditional studies of the material strength for these roads in southern Africa are based almost entirely on the California bearing ratio (CBR), a test with inherent problems. The test is routinely carried out to identify whether the materials under consideration have the required soaked strengths (typically CBRs of 80% or 45% for bases of different standards) at the design compaction density. Studies of the CBR at different moisture contents and densities should be carried out to identify the implications of variations in these properties on the behavior of pavement materials. A simple technique to be carried out during conventional laboratory testing was developed. Aspects pertaining to this type of study were evaluated, and the findings were related to low-volume road behavior.