COLD-ROOM STUDIES OF FROST ACTION IN SOILS, A PROGRESS REPORT

THIS PAPER IS A PROGRESS REPORT OF COLD-ROOM STUDIES OF FROST ACTION IN SOILS PERFORMED BETWEEN FEBRUARY 1950 AND OCTOBER 1952 BY THE FROST EFFECTS LABORATORY, NEW ENGLAND DIVISION, CORPS OF ENGINEERS. THEY ARE PART OF A COMPREHENSIVE FIELD AND LABORATORY INVESTIGATIONAL PROGRAM FOR THE IMPROVEMENT OF ENGINEERING DESIGN, CONSTRUCTION, AND EVALUATION CRITERIA FOR PAVEMENTS AND OTHER STRUCTURES CONSTRUCTED ON SOILS SUBJECT TO SEASONAL FREEZING AND THAWING. COLD-ROOM TESTS ARE BEING PERFORMED TO DETERMINE THE EFFECTS OF INDIVIDUAL FACTORS CONSIDERED TO INFLUENCE ICE SEGREGATION IN SOILS. TESTS HAVE BEEN CONDUCTED ON A LARGE NUMBER OF NATURAL SOILS OBTAINED FROM SEVERAL LOCATIONS AND ON SPECIMENS PREPARED BY BLENDING SOIL FRACTIONS IN PROPORTIONS TO GIVE DESIRED INVESTIGATIONAL GRADATIONS. DATA FROM PHASES OF THE INVESTIGATION WHICH ARE SUBSTANTIALLY COMPLETE INDICATE THAT (1) THE INTENSITY OF ICE SEGREGATION IN SOILS IS DEPENDENT NOT ONLY ON THE PERCENTAGE OF GRAINS FINER THAN 0.02 MM., BUT ALSO ON THE GRAIN-SIZE DISTRIBUTION OR PHYSICAL-CHEMICAL PROPERTIES OF THESE FINES, (2) FINE SOIL FRACTIONS WITH A HIGH PERCENTAGE OF FINE CLAY SIZES APPEAR TO BE MORE EFFECTIVE THAN SILT SIZES IN PRODUCING ICE SEGREGATION IN SOILS OF NEAR BORDERLINE FROST SUSCEPTIBILITY, (3) IN WELL-GRADED FROST SUSCEPTIBLE GRAVELLY SOILS, THE INTENSITY OF ICE SEGREGATION INCREASES MODERATELY WITH INITIAL DENSITY UP TO APPROXIMATELY 95 PERCENT OF MODIFIED AASHO DENSITY, ABOVE WHICH THERE IS A DECREASE IN ICE SEGREGATION WITH INCREASE IN DENSITY, (4) IN INORGANIC SILT SOILS, THE INTENSITY OF ICE SEGREGATION INCREASES WITH INITIAL DENSITY FOR THE FULL RANGE OF DENSITIES ATTAINABLE IN THE LABORATORY SPECIMENS, (5) THE INTENSITY OF ICE SEGREGATION IN SOILS IS DECREASED APPRECIABLY BY AN INCREASE IN OVERBURDEN PRESSURE, ALL OTHER FACTORS SUCH AS RATE OF FROST PENETRATION BEING EQUAL. (6) THE INTENSITY OF ICE SEGREGATION IN A FROST SUSCEPTIBLE SOIL VARIES DIRECTLY WITH THE INITIAL DEGREE OF SATURATION, WHERE WATER IS AVAILABLE ONLY BY WITHDRAWAL OF A PORTION OF THAT EXISTING IN THE VOIDS OF THE SOIL UNDERLYING THE SURFACE OF FREEZING, (7) THE RATE OF HEAVE OF THE SURFACE IS GENERALLY INDEPENDENT OF RATE OF FREEZING WITHIN THE RANGE OF 1/4 TO 1-3/4 IN. PER DAY, BUT THE HEAVE PER UNIT DEPTH OF FROZEN MATERIAL IS INVERSELY PROPORTIONAL TO THE RATE OF PENETRATION OF THE FREEZING TEMPERATURE, (8) NEGLECTING EFFECT OF SALINITY OF PORE WATER, VIRTUALLY ALL WATER PRESENT IN CLEAN SANDS AND INORGANIC SILT SOILS FREEZES AT 32 F. WHILE IN LEAN CLAY SOILS THE FREEZING TEMPERATURE OF THE SOIL MOISTURE IS NOT CONSTANT BUT DECREASES BELOW 32 F. WITH A DECREASE IN WATER CONTENT, (9) THE PERCENTAGE HEAVES OF SPECIMENS WITH FINE SOIL FRACTION (MINUS 200 MESH) COMPOSED OF THE THREE COMMON CLAY MINERAL GROUPS DECREASED IN THE ORDER OF KAOLINITE, ILLITE, AND MONTMORILLONITE, (10) SOILS MAY BE MADE LESS SUSCEPTIBLE TO FROST BY MEANS OF TRACE (LESS THAN 1 PERCENT OF DRY WEIGHT OF SOIL) CHEMICALS WHICH EITHER DISPERSE, AGGREGATE, OR WATERPROOF THE SOIL GRAINS. /AUTHOR/