Field Evaluation of the System for Calibration of the Marshall Compaction Hammer

摘要

A system for calibrating the Marshall compaction hammer has recently beendeveloped at the National Institute of Standards and Technology, in collaboration with the American Association of State Highway Transportation Officials (AASHTO), Materials Reference Laboratory (AMRL). The calibration system consists of a spring-mass device with an integral force transducer and a high-speed data acquisition system. The proposed calibration procedure is based on adjusting the number of hammer blows delivered to a specimen, such that a standard compactive effort is supplied during the compaction process, regardless of slight variations in the Marshall hammer. In an earlier laboratory evaluation program, the calibration system and procedure proved to be effective in reducing the variability of Marshall test results. Presented in the report is a summary of a field evaluation program of the calibration system and procedure. In this study, Marshall specimens were prepared in bituminous laboratories using production Marshall hammers: twelve laboratories, or field sites, participated in the study. Sixteen Marshall specimens were prepared at each site.