Ruggedness Evaluation of the Tube Suction Test

Abstract

The tube suction test (TST) was developed for assessing the moisture/frost susceptibility of granular base materials. The susceptibility ranking is based on the mean surface dielectric value of compacted specimens after a 10-day capillary soak in the laboratory. During the process of implementing the TST statewide, Texas Department of Transportation personnel raised concerns about the reproducibility of the test procedure, leading to the ruggedness testing performed in this research. Seven factors were investigated, including air temperature, mixing and soaking water salinity, dielectric probe seating force, number of days of drying before the start of capillary soaking, aggregate fines content, water bath height, and specimen compaction energy. Sixteen specimens of each of the two aggregates, a limestone and a caliche, included in this study were treated with specific combinations of the different levels of these factors according to the Plackett-Burman experimental design. Statistical hypothesis tests performed on the data indicate that air temperature, drying time, fines content, water bath height, and compaction energy are significant for the caliche, while only air temperature is statistically significant for the limestone. Small variations in mixing and soaking water salinity and dielectric probe seating force do not apparently exert significant influence on final dielectric values in the TST. Based on the results of the research, recommendations are given for improving the interlaboratory reproducibility of the TST.