Degradation of Prince Edward Island sandstone road aggregates

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University of New Brunswick


Various forces of nature can cause degradation of base and subgrade materials of a roadway. Prince Edward Island sandstone aggregates are known to be more susceptible to these forces than some of the higher quality aggregates of New Brunswick or Nova Scotia. This report outlines a research program to determine the degrading effect of compaction, cyclic loading and freezing and thawing on P.E.I. sandstone aggregate. The effect of compaction on degradation was monitored in the field on a section of roadway in the summer of 1990. A unique refrigeration chamber was built to allow the simultaneous application of cyclic loads to freezing and thawing samples. Various durability index properties were determined for the coarse aggregate fraction and for cubes of sandstone bedrock. Compaction forces were found to have caused measurable degradation. Laboratory cyclic loading tests did not produce any additional degradation. Freeze-thaw action eventually resulted in aggregate deterioration if saturated conditions were maintained. The use of salt water to saturate aggregate in combination with freezing and thawing, dramatically increased the degree of deterioration.