FROST EFFECTS IN LIME AND CEMENT-TREATED SOILS

EXAMINATION WAS CONDUCTED ON THE FROST-RESISTANT QUALITIES OF SELECTED LIME-SOIL AND CEMENT-SOIL MIXTURES. THESE MIXTURES, COMPOSED OF 96 PERCENT BY WEIGHT OF SOIL AND 4 PERCENT LIME OR CEMENT, WERE SUBJECTED TO DELAYS OF 0, 3 AND 72 HOURS AFTER THE ADMIXING OF WATER, BEFORE THEY WERE COMPACTED. THE LIMES USED, ALL HYDRATED, WERE A HIGH CALCIUM LIME, A SEMIHYDRAULIC LIME, & A DOLOMITIC LIME. THE CEMENT WAS AN ORDINARY PORTLAND CEMENT. THE SIX SOILS STUDIED WERE A CLAY, A SILTY LOAM AND FOUR CLAY LOAMS. THE CLAY LOAMS HAD ESSENTIALLY THE SAME GRADATION, BUT DIFFERED WITH REGARD TO PREDOMINANT CLAY MINERAL AND/OR PLASTICITY INDEX. TEST SPECIMENS WERE MOIST CURED FOR 28 DAYS PRIOR TO UNDERGOING FREEZE-THAW TESTING. THE PRINCIPAL PROPERTIES THEN EXAMINED WERE THE RESISTANCE TO FROST HEAVE, THE UNCONFINED COMPRESSIVE STRENGTH AND THE INDEX OF RESISTANCE TO FROST ACTION. IT WAS FOUND THAT WITH CLAYEY SOILS IN WHICH THE PREDOMINANT CLAY MINERAL WAS KAOLINITE THE ADDITION OF A HIGH CALCIUM, DOLOMITIC OR SEMIHYDRAULIC LIME RESULTED IN LESS RESISTANCE TO FROST ACTION THAN DID THE ADDITION OF AN EQUAL AMOUNT OF CEMENT. WHEN THE PRODOMINANT CLAY MINERAL WAS MONTMORILLONITE THE HIGH CALCIUM AND SEMIHYDRAULIC LIMES GAVE GREATER RESISTANCE THAN DID THE ADDITION OF EQUAL AMOUNTS OF EITHER DOLOMITIC LIME OR CEMENT. WITH THE KAOLINITIC SOIL-LIME MIXTURES THE DELAYING OF COMPACTION FOR UP TO 72 HOURS GENERALLY HAD NO DETRIMENTAL EFFECT. WHEN MONTMORILLONITE WAS THE PREDOMINANT CLAY MINERAL ANY DELAY IN COMPACTION HAD A DELETERIOUS EFFECT. IRRESPECTIVE OF THE PREDOMINANT CLAY MINERAL PRESENT IN THE SOIL, DELAYING COMPACTION OF CEMENT-TREATED SOIL MIXTURES RESULTED IN DECREASED RESISTANCE TO FROST ACTION. WHEN THERE IS A DELAY IN COMAPCTION THE QUESTION OF WHICH IS THE MORE EFFECTIVE STABILIZER, LIME OR CEMENT, DEPENDS NOT ONLY ON THE SOIL TYPE, THE LIME TYPE AND THE LENGTH OF THE DELAY PERIOD, BUT, MOST IMPORTANTLY ON THE PREDOMINANT CLAY MINERAL PRESENT IN THE SOIL. /AUTHOR/