Next to water, concrete is used more than any material in the world. It is poured, formed, molded, colored, and textured into every conceivable use. Thought to be a product of the modern world, the ancient Egyptians used a primitive concrete in their pyramids and the Romans built the Coliseum with it. Today, it is taken for granted; however, without concrete, our world would be considerably different.
Precast concrete tile is just one of its many forms. Tiles are manufactured by three different processes: wetcast, ram pressed, and extruded. They can be produced in many varieties of shapes, sizes, textures, and colors. There is no limit to the textures, whether man-made or duplicating a creation of nature.
Still, concrete tile has its proponents and its detractors. Some overlook the simple fact that hundreds of thousands of square feet have been installed properly around the world for centuries without any unusual problems. The key words are “properly installed.”Concrete tile's history
In Southern California during the 1920s and 30s, precast concrete tiles were used extensively. In the 1940s, 50s, and 60s, marble chips were added to make popular precast terrazzo tiles. After the 1970s, the many small manufacturers throughout Southern California did not communicate for the betterment of the industry. Thus, there were no specific concrete tile specifications or standards for either the tiles or their installation.
When problems arose, they were usually judged by the specifications or standards of other products, such as ceramic tile or natural stone. Although some specifications were applicable, most were not. With no specific benchmarks, the end products and their installation varied so much, they often fell short of the end user's expectations, damaging the industry's reputation.
Then, in the late 1990s, a group of concrete tile manufacturers formed the Concrete Tile Manufacturer's Association (CTMA), based in Buena Park, Calif. The CTMA had four initial goals:
- Establish a set of ridid standards.
- Severely test the complete tile assembly (tiles installed on a concrete substrate) to closely duplicate what happens in the real world after installation.
- Once these standards are established, publish a specification, Handbook for Concrete Tiles, containing standards for the individual tiles and the entire tile assembly, including instructions on how to properly install concrete tiles for tile and masonry installers.
- Promote concrete tiles to the construction industry through a quality assurance (Q-Tile)+ program and promotional activities. To address these goals, CTMA had Smith-Emery Laboratories perform a series of severe tests on the individual tiles and most important, on the complete tile assembly. They reasoned that a thin ½-inch-thick, 12-x12-inch concrete tile was never designed or intended to be a stand-alone product. Rather, it is a component of the tile assembly. This explains why testing the entire assembly was very important.
The CTMA compiled the results in a 12-page Handbook for Concrete Tiles. Part One, Material Used in Concrete Tiles, and Part Two, Performance Specifications, Product Performance, achieved CTMA's first goal. Under Product Performance, 10 different test procedures are listed. One of the most important, determining whether moisture will cause excessive movement in concrete tiles, adhered to the extreme moisture test according to ASTM C-157 (CTMA Modified), measuring Length Change (+/-).
Next, to test the tile assemblies, the CTMA wanted to duplicate what happens after the concrete tiles have been installed in exterior applications, and determine how they perform in their final environment as part of the tile assembly.
To accomplish this, Smith Emery and the CTMA developed two very severe test procedures to accelerate a test of time and determine how the entire tile assembly would perform over an extended period when exposed to extreme moisture. Over time, the installation process for concrete tiles is just as important as the individual tiles and the raw material used.
Of the six tests that created the ultimate specifications in the Handbook for Concrete Tiles under The Tile Assembly Performance, two specifically focused on accelerating the test of time. For these tests, a licensed tile contractor bonded 48 12-x12-x½-inch concrete tiles, half with thin-set and the balance mortar-set, to 14-x14-x3½-inch-thick concrete slabs. Twenty-four units had a minimum of 80% coverage and 24 were back buttered to obtain 95% coverage. See the two new tests, Nos. Three and Four.
The CTMA cannot say all concrete tiles have been tested to meet these high standards of excellence, although many do. However, we can assure that to meet these standards, Smith Emery randomly selects and tests all tiles manufactured by CTMA members. To reassure the end-users that CTMA members produce consistent quality products, the association developed an A-Tile quality assurance program.
You can obtain a free copy of Handbook for Concrete Tiles from CTMA's Web site. As for our fourth goal, we will develop more newsletters, technical bulletins, literature, and architectural portfolios on precast concrete tiles and their proper installation.
— Budd Newcomb is chairman of the Concrete Tile Manufacturers Association and is editor of CTMA publications. For more information, visit the CTMA atwww.concretetile.org, or you can telephone 800-970-2862.