FROST HEAVE CHARACTERISTICS OF A CLAYEY SILT SUBJECTED TO SMALL TEMPERATURE-GRADIENTS

A frost heave test on a 68.5-cm high soil column composed of a 23.5-cm saturated sand layer adjacent to the cold plate, overlain by about 45 .0-cm of Calgary silty clay instrumented with embedded heave gauges is described. The silty clay frost susceptible soil was reconstituted as a normally consolidated soil and frozen with free access to an extern al water source. The freezing test revealed that consolidation of the unfrozen soil in response to effective stress increase caused by the f reezing-induced suction is an important factor to consider in the anal ysis of frost heave in compressible soils. Surface heave was about one -half of the heave recorded by the embedded heave/thermistor gauges. S egregation potential inferred from surface heave measurements may thus not be representative values for field frost heave predictions. The r esults lend support to the concept of segregation potential even for e xtremely small temperature gradients, at least for temperature gradien ts as small as 4-degrees-C/m.