【国外标准】 Standard Test Method for Measuring Target Modulus Using Light Weight Deflectometer (LWD) on Compacted Proctor Mold Samples

5.1 LWDs are intended to be used as a tool to ensure adequate compaction of unbound materials. Adequate soil compaction of infrastructure projects will provide load capacity, stability of the soil, decrease permeability, and prevent or reduce the settlement of supported pavements and structures. The target modulus or deflections are used to establish QA/QC acceptance criteria for the LWD tests in the field.5.2 This test method covers the determination of target acceptance modulus values of unbound materials based on measuring LWD deflections on laboratory proctor mold samples at varying moisture contents.5.3 This standard test method provides a target modulus calculation that accounts for the constrained conditions (in the compaction mold) of the test sample. The intent is to be able to compare the results from the laboratory samples to those of similar materials in the field at similar stress levels.55.4 The target modulus or deflections may be either correlated directly to pavement or structure performance or used to determine in situ material characteristics of the pavement or structure foundation layers.61.1 This test method describes the procedure to determine the target modulus (or deflection) required for compaction quality control of geomaterials using light weight deflectometer (LWD) drops on a compacted proctor mold in the laboratory.21.2 The same LWD type in terms of brand name, buffer stiffness, and deflection measurement location (on top of the plate or on top of the soil layer) used for the laboratory target modulus testing must be used during the field testing. This is to eliminate differences between measurements from different devices.1.3 This procedure shall be performed in the laboratory on representative soil samples before the field compaction operations.1.4 Gradation, moisture content inconsistency, and surface texture on the mold can affect the material moduli results.1.5 The target surface modulus values can be compared to the field-measured modulus for compaction quality control/quality assurance purposes.1.6 This test method covers the determination of the relationship between moisture content and modulus of unbound granular material using the light weight deflectometer (LWD) on laboratory compaction samples.1.7 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. The values given in parentheses are for information only.1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.