PORE SIZE DISTRIBUTION AS A FROST SUSCEPTIBILITY CRITERION

Abstract

Two relatively fast methods are described for the determination of pore size distribution. They are the pressure plate suction test and the mercury intrusion test which were used for 36 soil samples. An older method, the capillary rise test was reevaluated. Correlation attempts between field performance and pore size criteria showed that only two criteria were effective. Both of these were based on pore size distributions from the capillary rise test, and showed no advantage over existing criteria. The study led to the conclusion that the existing criteria based on particle size should be used to predict the frost susceptibility of soils. Borderline soils should then be tested by a laboratory frost heave test. A field performance index is described which was determined from the extent of the frost damage to the pavement and the nature of the moisture conditions. Soils were divided into 4 classes (non frost susceptible, slightly frost susceptible, moderately frost susceptible, highly frost susceptible) and the classification procedure is described in a table. The commercially available Barber pressure plate suction test apparatus used in the tests is described, as well as the modified Aminco-Winslow porosimeter used in the mercury intrusion tests. Four pore size distribution curves were plotted for each of the 36 samples. Certain arbitrary parameters were obtained from each of the 4 curves, and correlation between these parameters and field frost performance indices were investigated. Recommendations based on the results of the study are presented.