Clay product-faced precast concrete panels combine the pleasing visual appearance of traditional masonry products with the strength, versatility and economy of precast concrete. Clay products that can be cast integrally with precast concrete panels include brick, ceramic tile and terra cotta.
The clay product can cover the entire exposed panel surface or only a portion, serving as an accent band or contrasting section. Marble, glass and ceramic mosaics also can be cast integrally (which is preferred) or applied to the hardened concrete.
The combination of precast concrete and clay products has several advantages over site laid-up masonry. By using precast concrete panelized construction, the need for on-site scaffolding is eliminated, which can be a significant cost savings over masonry construction.
Structural design, fabrication, handling and erection aspects of clay product-faced precast concrete units are addressed similarly to those for other precast concrete wall panels, except that special consideration must be given to the clay-product material and its bond to the concrete.
The physical properties of the clay products must be compatible with the properties of the concrete backup. The most significant property is the coefficient of thermal expansion, which causes volume change. It is best to select material with similar coefficients of expansion.
Reinforcement of the precast concrete backup should follow recommendations for precast concrete wall panels relative to design, cover and placement. Because of the difference in material properties between the facing and concrete, clay product-faced concrete panels are more susceptible to bowing than non-faced concrete units. However, panel manufacturers have developed design and production procedures to minimize bowing.
Natural stone has been widely used in building construction due to its strength, durability aesthetic effect, availability and inherent low-maintenance costs. Stone veneers for precast concrete facings are usually thinner than those used for conventionally set stone, with the maximum size generally determined by the stone strength.
As with clay product-faced panels, veneered panels are more susceptible to bowing than all-concrete units. The flat surfaces of cut stone will reveal any bowing more prominently than all-precast concrete panels. Again with these products, precasters have created procedures that minimize bowing.
Cast stone is manufactured to simulate natural cut stone. It is used in masonry work mostly as ornamentation and architectural trim for stone bands, sills, lintels, copings, balustrades and door and window trimming. It replaces natural cut stone or terra cotta in these applications.
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