1. Friction between sand and concrete;Hayasi,1987
2. Characteristics of particle displacement of sand subjected to shear;Murayama;Proc. of JSCE,1981
3. Japanese Standards Association: JIS A 1108, Method of Test for Compressive Strength of Concrete.
4. Skin friction between various soils and construction materials;Potyondy;Géotechnique,1961
5. A new roundness scale for sedimentary particles;Powers;Journal of Sedimentary Petrology,1953