New technologies are paving the way for the comeback of a once-dated decorative concrete application. Exposed aggregate is turning up in prestigious places like the renovation of the Getty Museum in Malibu, Calif., and is adding a touch of glamour to formerly blah driveway, patio, pool deck, and spa areas.

This renewed attention is due to new products and systems that extend the lifespan of these surfaces. The vintage exposed aggregate driveways were thought of as boring and even unsightly, with uneven surfaces and stones that popped out too frequently. Installers told homeowners to expect exposed aggregate concrete to lose its decorative stones over time. But thanks to longer-lasting products, exposed aggregate finishes are seen as a beautiful and durable architectural paving option that includes patterned reveals, multiple stones, and a variety of finishes.

The wide range of stone to choose from—quartz, marble, granite, feldspar, basalt, and obsidian, to name a few—means the design opportunities are endless. Add to this the choice of white or colored cement and specialty seeded materials such as marble, shells, or glass, and clients sometimes have a hard time deciding where to start.

For most contractors, the first step is to connect with a nearby quarry, because specing local stone helps cut down on delivery costs. Chris Fister, owner of Fister Quarry in Batavia, Ill., carries special sands, aggregates, and pigment. “Contractors tell us what they hope to achieve, and we send rock samples to let them develop a mix design,” says Fister.

Materials Mix. Before beginning an exposed aggregate project, it's important to carefully select the types of raw materials for the mix design. If there isn't enough cement paste, for instance, you can get aggregate popouts. If the cement content is too high, it's harder to achieve the desired aggregate exposure.

A Los Angeles exposed aggregate driveway uses stones ½ inch to 2 inches in diameter in a desert brown color. The star pattern achieves textural change by placing the contrasting stones on end. For the popular multiple-stone look, plan to seed the surface. “The key is to get a good matrix surrounding the seeded material,” says Byron A. Klemaske II, executive vice president of T.B. Penick & Sons in San Diego. “Most people put rock into the surface and pound it down. You need to slowly but surely work the matrix up around the rock. Be meticulous, and do not pour too much at a time.”

When it comes to the reveal, designers specify different depths of exposure depending on the installation's purpose and style. Some require low depth reveals to expose sand particle sizes for a slip-resistant surface. Others call for removing enough material to see a 1½-inch aggregate for a visual punch. Because of the range, manufacturers make retarding admixtures for light, medium, or deep exposures. Choose the retarding agent according to the amount of exposure desired.

Personalized Style. Lance Boyer, president of Trademark Concrete Systems in Ventura, Calif., often uses a brick-red Arizona rock to top seed exposed aggregate. Although there are a number of retarding admixtures on the market, his choice is Grace's Topcast, with 13 different profiles to expose concrete. The mix often includes integral color, and Boyer seeds surface aggregates that range from 3/8 to 1 inch in diameter.

“Architects like the sand finish,” says Boyer. “Designers are looking for decorative concrete to look more like natural concrete. For smaller reveals Boyer typically seeds with 3/8-inch to ½-inch stone, saying that it stays in the concrete.

A separate seating area by a water feature uses a concentration of blue and clear glass that mirrors the water coming from the fountain.

To reduce installation headaches, some contractors recommend Lithocrete Architectural Paving, a patented monolithic paving system that employs small-sized surface-seeded materials such as granite, glass, marble, seashells, and other aggregates. Homeowners like the way the crushed materials reflect tiny amounts of light while retaining color integrity. This process is more costly than traditionally exposed aggregate applications, but Lithocrete installers say they are competitive with veneers or real stone.

A natural concrete appearance is something many designers prefer. This Lithocrete installation achieves just that with integral color, surface seeded stones that are ¼ inch and less, and control joints that contribute to the overall geometry. “The Lithocrete specification weeds out less-qualified bidders, and the finishes are 100 percent consistent,” says Neil Hadley, senior associate at Spurlock Poirier, a San Diego landscape architectural firm that specifies Lithocrete when the budget allows.

Designers and homeowners will continue to help make exposed aggregate the comeback kid of the concrete industry, bringing its application inside and outside the home for stamped concrete treatments, concrete countertops, and paving and flooring.

This story originally appeared in RESIDENTIAL CONCRETE magazine.