Higher Compressive Strength Values Research Articles

Relationship Between Petrographic Characteristics, Engineering Index Properties, and Mechanical Properties of Selected Sandstones

Six different sandstone units were studied to investigate and quantify the relationship between their mechanical properties (compressive strength, tensile strength, Young's modulus, Poisson's ratio), petrographic characteristics, and engineering index properties. Sandstones investigated included the Sharon sandstone, the Juniata sandstone, the Morgantown-Grafton sandstone, and three Berea sandstone units. These sandstones were tested for percent absorption, density, slake durability, total pore volume, uniaxial compressive strength, tensile strength, Young's modulus, and Poisson's ratio. Petrographic characteristics studied included grain size, grain shape, grain sorting, packing density, packing proximity, degree of grain interlocking, and mineral composition. The data were analyzed statistically to determine the quantitative relationships between various properties. Results indicate that compressive strength, tensile strength, and Young's modulus values for the sandstones studied are closely related (r>0.7) to their density, percent absorption, total pore volume, and type of grain-to-grain contacts. Generally, sandstones with higher densities, lower percent absorption, lower total pore volume, and higher percentage of sutured contacts exhibited higher values of compressive strength, tensile strength, and Young's modulus. For Poisson's ratio, however, inverse relationships were observed with compressive strength and Young's modulus. Based on these results, equations were developed for predicting mechanical properties from values of density, percent absorption, total pore volume, and percent sutured contacts.

Modulus of elasticity and strength properties of dental cements

The modulus of elasticity of commercial dental cements was determined by an optical strain gauge method. Values of compressive and tensile strengths also were measured. Of the cements of primary consistency tested, a noneugenol zinc oxide cement had the lowest mechanical properties. A zinc phosphate cement had the highest value of compressive strength and modulus, but a zinc polyacrylate cement had the highest tensile strength. A zinc polyacrylate cement base had the highest tensile strength, but a zinc phosphate cement base had the highest compressive strength and modulus of elasticity. A calcium hydroxide liner had higher mechanical properties than an unmodified ZOE liner.