Determining Aggregate Frost Susceptibility with the Tube Suction Test

Hermansson

2003

Self Cite

The occurrence of frost heave in soils and aggregates can be attributed to the redistribution of water in the soil profile. Frost heave testing performed in this study on 71 variably saturated specimens of aggregate base material indicates that although the uptake of new water from outside the soil body is a primary source of moisture in the formation of segregation ice, internal water residing within the soil or aggregate structure can serve as an important supply of water to the freezing front. Frost heave concepts relating to unsaturated soil conditions were reviewed, and a laboratory methodology was employed to study the relationships between the physical properties of the specimens and their frost heave behavior. Degrees of saturation ranging from 45% to 84% were evaluated, and heave–uptake ratios as high as 2.24 were calculated. Ratios less than 1.09 suggest that sufficient porosity exists in the sample matrix to allow the formation of ice without causing frost heave; higher ratios designate samples that are nearly saturated and that undergo substantial upward redistributions of existing water during the initial freezing process, which gives rise to measurable heave even before additional water is imbibed by the sample. The entry of air into freezing soils and aggregates can play an important role in their frost heave behavior.

Section: Test Resultsmentioning

confidence: 94%

Frost Heave and Water Uptake Relations in Variably Saturated Aggregate Base Materials

Hermansson

2003

Self Cite

“…The air temperature in the environmental room and the water temperature in the bath were checked regularly, with the latter being consistently around 5°C for the duration of the testing. Recent frost heave tests of similar materials suggested that the specimens likely developed a constant temperature profile within the first 50 h, with the surface temperature just under the cover cooling to only about −3°C (19). Thus, the temperature gradient in each specimen was about 0.4°C/cm.…”

Section: Methodsmentioning

confidence: 96%

Solute Effects on Long-Duration Frost Heave Behavior of Limestone Aggregate

Zhan

2002

The performance of pavements in cold climates greatly depends on the frost susceptibility of the base and subgrade layers. Frost heave caused by ice lensing within the pavement structure can create distresses in the surface that lead to cracking and poor ride quality. Furthermore, thawing during a warm period can cause a supersaturated condition in the roadbed that dramatically reduces soil strength and increases vulnerability to damage under trafficking. A laboratory study was performed at the Texas Transportation Institute to assess the long-duration frost heave behavior of a limestone aggregate base material. The computer program ICE2, which tracks heat, water, and solute flow during the freezing process, demonstrates the important role of salt content in the ice lensing mechanism. The program successfully models a two-stage frost heave behavior observed in the laboratory and affords an explanation of the frost heave events in a step-by-step fashion. Accurate frost heave modeling must account for changes in solute concentrations during the freezing process.

“…Aggregates having final dielectric values between 10 and 16 are expected to be marginally moisture susceptible. Continuing laboratory tests have confirmed a positive relationship between these moisture-susceptibility classifications and the strength-loss and frost-heave characteristics of granular materials (5,10).…”

Section: Figure 2 Orientational Polarization (8) Figure 3 Typical Tst Arrangementmentioning

confidence: 95%

“…Important factors for determining moisture susceptibility include soil suction, permeability, and the state of bonding of water that accumulates within the aggregate matrix (5).…”

Section: Moisture Susceptibilitymentioning

confidence: 99%

Repeatability and Reliability of the Tube Suction Test

Ellis

Scullion

2001

Self Cite

The tube suction test (TST) was developed in a cooperative effort between the Finnish National Road Administration and the Texas Transportation Institute for assessing the moisture susceptibility of granular base materials. The moisture-susceptibility ranking is based on the mean surface dielectric value of compacted specimens after a 10-day capillary soak in the laboratory. The factors that influence moisture susceptibility are discussed, and the use of dielectric measurements in the TST is explained. The TST protocol is given. The repeatability of the test is then evaluated at three different dielectric values, and statistical techniques are employed to enable estimation of the number of replicate samples required in the TST to achieve specified levels of tolerance and reliability. On the basis of the promising results of the test, the Texas Department of Transportation will begin implementation of the TST statewide during 2001.