Coefficients of friction between calcareous sands and some building materials, and their significance

Friction tests of a coralline and an oolitic sand and a foraminiferal sand-silt against smooth and rough steel and concrete surfaces were run in a modified soils direct shear machine. Friction test results for these calcareous materials did not differ markedly from the results for a quartz sand. These results indicate that there is nothing inherently different in the capability of these calcareous materials to develop frictional forces on typical building material surfaces - when compared to quartz-predominant sands - except that some calcareous materials experience large volume decreases during shear. These large volume decreases would impair the development of high effective normal stresses against the building material surface, resulting in low friction forces on piles, some anchors, and penetrometers in calcareous materials. This latter hypothesis is stated, but not directly addressed in this reported work.