A Highbridge laboratory technician prepares a granite beam for flexural strength testing by carefully measuring and marking load points on the specimen surface.  The beam will be loaded to failure in accordance with ASTM C 880 using specially designed test fixtures.  A lower range calibrated load cell is installed in the testing machine to accommodate the lower flexural breaks.  The higher load conditions for compressive strength tests on the granite are easily measured with the factory installed load cell on the 250,000 lb. capacity machine.

Differential thermal expansion and contraction exacerbated by freeze-thaw cycles has resulted in pervasive weakening of the marble dimension stone shown in the photomicrograph.  Intergranular failure along each calcite grain boundary presents as “sugaring” on exposed surfaces though the crystal bonding failures are found throughout the stone.  This type of failure is unique to marble due to the grain boundary textures and anisotropic coefficient of thermal expansion for calcite.  Different stones would respond to stresses differently at the microstructural level.  These differences are best observed petrographically by a geologist well versed in the mineralogical and textural features of natural stone.

Dimension Stone Testing
Quality assurance for dimension stone typically comprises a battery of physical tests including compressive strength, absorption, flexural strength, and modulus of rupture. Highbridge performs these standard test methods for materials including marble, granite, quartz-based stone, and limestone. However, dimension stone is unique among construction materials in that it is naturally formed with no guarantee of consistency from block to block. The performance and durability of dimension stone is a function of its mineralogical constituents and internal microstructure. These features are readily examined petrographically. In fact, petrography is a tool that was born out of the geological sciences. ASTM has finally approved a standard guide for the petrographic examination of dimension stone (ASTM C 1721). All of our petrographers are degreed geologists with extensive experience in the study of natural stone through petrographic polarized light techniques.
Highbridge also performs a number of other standardized and non-standardized tests for the evaluation of building stone including resonant frequency and dynamic modulus of elasticity determination, freeze-thaw durability programs, and capillary uptake testing.