Adhesion Bonds in Sands at High Pressures

This note summarizes the observed formation of adhesion bonds, during compression tests on clean sand at pressures from 1.0 kg/cm²-140/cm². The soil was a fine sand dredged from the Sacramento River, the same as described elsewhere. Prior to testing the sand had been thoroughly washed between the No. 50 and No. 100 sieves. The individual grains were sound single-minded particles; 50% subangular quartz, 35% subrounded feldspar, and 15% amphibole or pyroxene minerals. A second sand also tested to a limited extent for comparison purposes was the well known Ottawa 20-30 Standard sand with nearly perfectly round quartz grains. All tests were performed on saturated specimens.