<p><p><h2>Summary of Example Specifications</h2></p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> AASHTO Guide Specification for Highway Construction</div><strong>Reference(s):<br></strong><em>AASHTO (2008)</em></p><p>This document is a guide specification for the construction of highways. When specifying compaction, the majority of agencies will employ either this specification or a variation of it. The specification is suited to be a performance approach specification with a performance level of “4,” thus signifying that design related properties are measured during construction to account for QC/QA verification. The applicable sections of this specification to compaction include Division 1 (General Provisions) and Section 203 (Excavation and Embankment) of Division 2 (Earthwork). According to this specification, contractors are required to compact embankment lifts to densities relative to the maximum density as indicated by AASHTO T 191 Method C (Proctor method). The specification also lacks criteria for moisture contents when placing embankment fills. When compacting cohesive soils, an optimum moisture content plus-or-minus a some percentage should be specified. For cohesionless soils, a moisture content range should be specified so as to avoid the effects of bulking when placing fill. </p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> MNDOT DCP Specification</div><strong>Reference(s):<br></strong><em>Siekmeier et al. (1998)</em></p><p>Siekmeier et al. (1998) provides a alternate means of QC/QA verification and acceptance for compaction. Rather than using a field density as an acceptance criterion, a penetration index value, obtained from a dynamic cone penetrometer (DCP), is used as the acceptance criterion. Because of the change in QC/QA verification and acceptance, the specification is oriented more towards a level 2 (Performance-related properties measured at end of construction) performance based specification. With exception to the QC/QA verification and acceptance, this specification is the same as the AASHTO (2008) specification shown above.</p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Rock Fill</div><strong>Reference(s):<br></strong><em>Christopher et al. (2010), Berg et al. (2010)</em></p><p>Rock fill (material with less than 25% passing the ¾ in sieve), does not follow the proctor method for embankment design (i.e., optimum moisture content and maximum dry density are not determined). <br>As regards to the compaction of rock fills, where density testing is not possible, trial fill sections should be constructed with agency supervisory personnel and geotechnical specialist present to determine appropriate watering, in situ modification requirements (e.g., grading), lift thickness, and number of passes to achieve adequate compaction. Compaction can be determined by measuring the settlement of the trial section at a number of points after each pass (e.g., a minimum of 5 points measured at the center of a 1 ft square plate is typically required). Several lifts should be constructed to determine the appropriate number of passes, which will maximize compaction without excessively crushing the rock at the surface. The number of passes to achieve at least 80 percent of the maximum settlement should be required.<br></p></p>