Implementation of the Soil Compactor Analyzer Into Test Method TEX-113-E: Technical Report (5-5135-01-1)

Test method Tex-113-E prepares laboratory aggregate base test specimens with an impact hammer compactor. These specimens are used for compaction characteristics and design tests. Although the historical Tex-113-E required a certain amount of compaction energy, no method to validate attainment of that energy existed until Texas Department of Transportation (TxDOT) Project 0-5135 developed the Soil Compactor Analyzer (SCA). The SCA measures the kinetic energy applied by each drop of the impact hammer. In this project, the SCA system was modified to control the compactor, where the SCA starts the machine and then turns off the compactor when the prescribed amount of energy is attained. This project then evaluated how changing the machine operational parameters, such as hammer weight, drop height, and number of blows per lift, impacted test results. In this evaluation, the SCA was used in all cases to control the compactor, so the prescribed amount of total energy was always applied regardless of machine operational parameters. The results showed that while using the current TxDOT-approved SCA to control total energy per lift between 740 and 765 ft-lbf, the number of blows per lift may vary between 45 and 60 with no impact on test results. Finally, this project conducted an interlaboratory study to develop precision statistics of Tex-113-E compaction. This study showed that the SCA enables excellent precision of total compaction energy. Total compaction energy. Total compaction energy should be repeatable and reproducible within about 27 ft-lbf, or approximately 1 percent of the specification value. Compacted dry density should be repeatable within about 2.5 pounds per cubic foot (pcf) and reproducible within about 3.3 pcf.