From the Desk of Weston DeHart
Cast stone is defined as “a refined architectural concrete building unit manufactured to simulate natural cut stone, used in unit masonry applications”. Cast stone is a masonry product, used as an architectural feature, trim, ornament or facing for buildings or other structures. Cast stone can be made from white and/or grey cements, manufactured or natural sands, carefully selected crushed stone or well graded natural gravels and mineral coloring pigments to achieve the desired color and appearance while maintaining durable physical properties which exceed most natural cut building stones. Cast stone is an excellent replacement for natural cut limestone, brownstone, sandstone, bluestone, granite, slate, coral rock, travertine and other natural building stones.
Many of our jobs call for cast stone to simulate cut stone. Connection details and reinforcement will need to be checked by shop drawings. Joint layouts in these shop drawings are very important. We must always require the contractor to field verify if possible. Be sure to double check the dimensions of all structural items and also reference the architectural items. These stones are made off of these dimensions and if any are incorrect it could cause an unnecessary delay.
Color and texture should be inspected in accordance to approved color sample or mock-up panel set up at the job site. In general, the color and texture of the Cast Stone delivered to the job site should be approximately equal to the approved sample when viewed in good typical daylight conditions at 10-foot distance.
Units must be stored and handled with care, as any broken pieces may have to be refabricated. Any chip obvious from a 20' distance should be patched. Most cracks can be patched if the units are reinforced. Chips measuring less than 1/4" in two directions across the face should not be patched and are usually left alone. Stone units with chips larger than 8" square should be replaced, unless the damaged portion can be salvaged and expoxied back to the the unit.
All head joints at coping and joints at column covers, soffits, and in general, all stone sections with projecting profiles, exposed top joints or rigid suspension connections to the supporting structure should be sealant joints. After setting, prime the ends of the stones, insert properly sized backup rod and gun in sealant. Proper sealing of joints will help prevent breaking due to freeze thaw.