<p><p><h2>QC/QA Guidelines</h2>Comprehensive QC/QA guidelines for lightweight fill projects are analogous to those for conventional fill projects. In general, many of the same QC/QA methods and test frequencies should also be used in lightweight fill projects, with some additional considerations for the unusual characteristics of the lightweight material.</p><p>Depending on the lightweight fill material used, there may be increased interest in material testing and verification of properties. For geofoam, material properties are tested by the manufacturer, and certified data sheets are provided to the project engineer. Manufacturing quality assurance and project quality control of geofoam properties are conducted once the geofoam is delivered to the project site. Expanded PolyStyrene (EPS) blocks should be sampled and tested to determine dry density, compressive strength, flexural strength, elastic limit stress, Young's modulus, and dimensional tolerances. Testing should be conducted on initial delivery of blocks and at a subsequent rate of one block per 500 cubic yards of EPS. For cellular concrete, concrete cylinder samples should be taken to verify concrete strength at 2, 7, 14, and 28-day intervals. A minimum of two sets of four cylinders should be taken each day during fill placement with a set of four cylinders taken for each 70 cubic yards of cellular concrete. Granular lightweight materials should be tested to assure they meet gradation requirements, density requirements, and/or appropriate particle size criteria. In addition, fill materials should be free of contaminants, both as particulates trapped in the fill material and as dissolved in leachate passing through the fill.</p><p>Verification of correct fill placement and compaction is a vital part of QC/QA for lightweight fill projects. For many lightweight fill materials, this is only possible through construction observations, which are sometimes verified using test sections. It is recommended that construction be observed continuously to verify placement and lift thickness of fills and to evaluate compaction. Evaluation of compaction for shredded tires, wood fibers, and similar materials can only be done through visual observation or measurements of the resiliency of the fill during compaction. Resiliency refers to the ability of a material to deform elastically during loading, and is typically quantified based on the resilient modulus. Resilient modulus is defined as the applied deviator stress divided by the recoverable strain for rapidly applied loads (e.g., wheel loads on a pavement). In-situ test methods for estimating the resilient modulus include light weight deflectometer and Dynamic Cone Penetrometer (DCP) testing. However, the applicability of these test methods to lightweight fills is not discussed in the literature. For fly ash and slag aggregate, it is possible to use standard density testing to evaluate compaction of the material.</p><p>Inspections, construction observations, daily logs, and record keeping are essential QC/QA activities for all technologies. These activities help to ensure and/or verify that:<br><ul> <li>Good construction practices and the project specifications are followed.</li> <li>Problems can be anticipated before they occur, in some cases.</li> <li>Problems that do arise are caught early, and their cause can oftentimes be identified.</li> <li>All parties are in good communication.</li> <li>The project stays on schedule.</li></ul>Additional technology-specific details for inspections, construction observations, daily logs, and record keeping QC/QA activities are provided in the <em>Individual QC/QA Methods </em>section below.</p></p>