Color is in. And since color is also a personal decorating choice, producers who see color as an opportunity to increase concrete's market share want to expand on hue selection.
In the early 1990s producers' greatest concern was the paver's ability to retain its originally designed color. However, if the concrete paver industry wanted to establish a dramatic growth in market share against asphalt, brick, and plain gray concrete, producers needed to offer a product that would retain its designed hue for at least 3 and preferably 5 years after installation.
Charles Gamarekian, CEO of Cambridge Pavingstones in Lyndhurst, N.J., and others adopted a European blockmaking technique called face topping to satisfy the demand for vibrant colors. According to industry experts, practically all colored pavers produced in Germany are face-topped. At the same time, less than 10% of colored pavers produced in North America are face-topped.
In face topping, a thin crust of highly pigmented mix is placed on top of a lightly tinted base product. Since the topping layer is only about 2 to 3 centimeters thick, producers can use expensive white cement along with a high dosage rate to create deep and intense colors. In many cases the same quantity of coloring applied to the small cross-section as in typical colored paver production yields a significantly brighter and more vibrant color for about the same production costs.
But what Gamarekian likes best is that face-topping creates a surface that is more resistant to wear and fading than that of a typical paver. "A top-mix surface contains more pigment particles, so the color is not only brighter, but it lasts longer," says Gamarekian.
Gamarekian, one of the strongest advocates of face topping, started Cambridge Pavingstones and now markets a trademarked face-topped paver. His company has grown threefold since it began operation.
Cambridge sells both standard colored and face-topped pavers but markets the face-topped paver as a sort of premium unit. Several years after placement, colors are still strong, and the pavements look good.
The face-topping process, well established in Europe, calls for the paver producer to place two layers of concrete in a mold, with the upper layer filled with more color pigment than the lower portion. Since the producer casts the mixes while both are in their plastic (yet near-zero-slump) state, the two batches cure together and harden into one unit.
Many producers who operate older block machines avoid face topping for economic reasons. In an industry known for tight operating margins, spending capital on a process that produces practically custom projects doesn't offer a chance to make a lot of money.
The process increases cycle times, and combined with increased capital costs, producers must pass on these additional operational costs to buyers.
Gamarekian anticipates the paver industry will recognize the economic challenge of the new technology in a market that seems to be willing to pay for the quality.