What is the standard for assessing compaction when dealing with cohesive materials in pavement reconstruction?

The standard used for assessing compaction when dealing with cohesive materials in pavement reconstruction is ASTM D1557. This standard is widely recognized for determining the optimum moisture content and maximum dry density of soils using a modified Proctor test, which is particularly applicable to cohesive materials like clay and silt.

ASTM D1557 is critical because it specifies the proper method to achieve maximum compaction, which is essential in ensuring the stability and durability of the pavement structure. Cohesive materials can behave differently under varying moisture conditions, and this standard helps engineers find the correct balance to achieve the desired density.

The other standards mentioned have different focuses or applications. For instance, ASTM D2726 is used for determining the bulk specific gravity of compacted asphalt mixtures, while ASTM D4253 and ASTM D4254 concern the relative density of soils and the specific gravity of soil particles, respectively. Therefore, the focus of ASTM D1557 aligns specifically with the needs of assessing compaction in soils used for pavement reconstruction.