Concrete block and paver manufacturers have an opportunity to capitalize on new technology with synthetic aggregate technology. The synthetic aggregate market is a $2 billion industry in the United States, with estimates that only about 25% to 30% of currently available recyclable materials are being utilized.
There are about 820 coal burning power plants in the nation, producing 56% of U.S. electrical power. In 2001, the waste byproducts (also called smokestack emissions) from coal plants alone accounted for 62 million metric tons of fly ash, plus another 17 million metric tons of bottom ash.
Seventy percent of the non-cementitious ash and bottom ash was dumped into landfills in the United States. The U.S. coal power industry is under increasing pressure to reduce sulfur dioxide emissions further, and only 30% of the ash was recycled.
There are three categories of synthetic aggregates, grouped by production method, the mixture of recycled materials, and the end-product form. Synthetic aggregates can be produced year-round or stockpiled, to plan for construction season. They may be 30% to 70% lighter than mineral aggregate. While some synthetics can be used as roadbed underlay, they are not generally used as a substitute for natural mineral aggregate in many industries.
Group 1: Waste product is heated in a blast furnace or rotary kiln to between 1000 and 4500° F and then turned into pellets. Waste materials used in this process includes sewage sludge, incinerated sewage sludge, pulverized fuel ash, oil sands, and slag.
Group 2: Combines only non-cementitious fly ash with a binder, and then presses or extrudes the synthetic aggregate into pellets. Fly ash is a smokestack waste/byproduct after the burning of coal. The non-cementitious fly ash can be utilized in both Group 2 and 3 processes.
Group 3: Combines recycled products, such as non-cementitious fly ash, bottom ash, recycled plastics, recycled glass, and other recycled materials. This group's primary market includes every industry where lightweight concrete with high compressive and tensile strength is of primary concern. This group can be made from recycled materials, such as a mixture of plastic, fly ash, or bottom ash (a waste product of coal fire electricity plants), and both fly ash (cementitious) and bottom ash.
A patented product by ELITE Aggregates is high-strength, lightweight aggregate. Weights range from 10 to 65 pounds per cubic foot. The ultralite concrete using ELITE Aggregate as a total aggregate replacement weighs 95 pounds per cubic foot, with compressive strength of 9000 psi, and a tensile strength of 11% compressive strength.
The mixtures can be varied to make a wide range of products, wherever high compressive and high tensile strength is required. Unlike the other two groups, it also can be mixed as a total replacement of aggregate in concrete. The concrete can be cut, nailed, and screwed with ordinary tools.
The primary market would be concrete products such as ultralightweight concrete (for insulating concrete forms, prestressed or tilt-up concrete, concrete roof shingles, wall-board, block, pavers, stucco, concrete wall or cultured stone, ultralightweight concrete dry mix (bags), well cementing and grouting, culvert pipe, concrete underground vessels, pan floors/decking, geo-technical fill, landscape fill (rock), architectural cultured stone, and horticulture applications.
Most coal generating power plants east of the Rocky Mountains are located in large cities, the same areas as concrete block and paver producers and lightweight aggregate customers. The cost to produce ELITE Aggregates is significantly less than producing expanded shell or clay.
The second part of the green story is the use of recycled material in new products. Like in the 1970s, the use of recycled products is increasing. And just like in the past, producers and manufacturers are capitalizing on opportunities that use recycled material in their products.
In some cases, city, state and federal governments may also give tax incentives to those producers who uses recycled material in their products. The public is looking for products that use recycled material in the manufacturing process.