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THE SYNTHETIC AGGREGATE MARKET

Jan, 05 2005

THE SYNTHETIC AGGREGATE MARKET By: David Shulman and Yvonne Smith Synthetic aggregates are recycled materials recombined into a lightweight mineral aggregate substitute. No discussion of synthetics is complete without a quick background on the scope of the underlying natural/mineral aggregate market. Mineral aggregates are composed of sand, gravel, or crushed stone, which is quarried from glaciated areas, riverbeds, and alluvial fans. Over one billion tons of new construction aggregates annually comes from over 5000 U.S. quarries, and only 5% (100 M tons) is recycled concrete (Turley (IL) & USGS). About 70% of all construction aggregates used in infrastructure is for roadbase. The demand for construction aggregates accounts for 73% of all mineral demand, with an annual rise of 1% since 1958 (USGS 1998). Aggregate extraction is complicated by environmental and legal issues, availability, urban expansion, costs, rock geology, and distance from the quarry to site. Mineral aggregate shortages and landfill availability have been hotly debated issues due to increased demand for roads, homes, and office buildings, the aging and replacement of old structures, availability and location of quarries and landfills, and increased transportation, landfill, and energy costs. Synthetics, both standard and light aggregates, are now being recognized as a growth industry and an increasingly viable alternative as a mineral aggregate supplement. The synthetics market alone is a $2+ billion industry in the United States, with estimates that only about 25-30% of currently available recyclable materials are being utilized. The balance is wasted and dumped in landfills. Expanded use of the new technologies could further relieve a portion of the aggregate shortages, increase recycling, and reduce landfill waste. There are about 1200 coal burning power plants in the U.S. producing about 56% of the U.S. electrical power. In 2001, the waste byproducts (also called smokestack emissions) from coal plants alone accounted for 62,000,000 metric tons of fly ash, plus another 17 M metric tons of bottom ash (which equates to about 60 metric tons per plant (40 tons fly ash , 20 tons bottom ash) (Energy Info. Administration / 2002). Seventy (70%) of the non-cementitious ash and bottom ash was dumped into landfills throughout the United States (USGS). The U. S. coal power industry is under increasing pressure to reduce sulfur dioxide emissions further (Clean Air Act 1990), and only 30% of the ash was recycled (Kelly/van Oss). Plastics, polystyrenes, foams, shipping materials, cases, and food containers take 200-400 years to degrade, are derived from oil, and account for about 20% of landfill volume (American Plastics Council). Plastic recycle figures vary by reporting sources between 3-20%. Imagine the positive environmental impact synthetics could have if we only increased production with the use of another 10-20% of recycled materials with new technologies. Consider the size of the untapped market. There are three categories of synthetic aggregates, grouped by production method, the mixture of recycled materials, and the end product form. In general, aggregates should not contain any (or at least minimal amounts) of slick materials (obsidian or glass/adhesion issues), salts, sugars, fats, or heavy metals (leaching). Synthetics have an advantage in they can be produced year round or stockpiled, instead of just during construction seasons, and they carry tax advantages in many states and countries. Synthetic aggregates are 30-70% 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. What are the three groups: their mix, form, and use? Group 1: Waste product that is heated in a blast furnace or rotary kiln to temperatures between 1000 - 1500 degrees Fahrenheit, and then turned into pellets. Waste materials generally used in this process includes sewage sludge, incinerated sewage sludge, pulverized fuel ash, oil sands, slag, and other solid waste materials. High amounts of natural gas & electricity are needed to fuel the kilns and furnaces to eliminate bacteria and produce the pellets. The pellets/extrusions are cooled, sized, crushed, and graded to meet the job specification. Smokestack pollution can be a byproduct. The cost for this group is comparable to production of mineral based expanded shales and clays. Generally these facilities are located at the site of the solid waste plant. The strength ranges from low to medium, except for the slag pellets, which fall in the high range. The synthetics in this group will weigh about the same as standard mineral aggregate. The limitations can be the size of the pellets. In the case of slag aggregate, it cannot be used where the irons may leach from the concrete when water is present, or in esthetic uses where slag would stain or leach from the concrete. Patented technologies include Minergy ™, a subsidiary of Wisconsin Energy Corp, LYTAG, RMC Lytag (UK), LITEX and VITREX of Lafarge Slag (Hamilton, Ontario, Canada), and Pildysh Technologies (oil sand -Calgary, Alberta, Canada). 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 in power plant operations, and the noncementitious fly ash can be utilized in both Group 2 and 3 processes. In Group 2, the pellets/extrusions are cooled, sized, crushed, and graded to meet a job specification. The cost of this production can vary with the supply of ash and energy, and their primary market is roadbase and lightweight concrete in the ASTM 331 or C-90 category. This technology uses less energy than Group 1 blast furnace or kiln processes. The pellet size limits the size of the aggregate. This technology group is sponsored by Universal Aggregates (PA) (one operational plant), and Western Research Institute (WY)/SYNAG (one patent pending/no plant). Group 3: Combines recycled products, such as non-cementitious fly ash, bottom ash, mine tailings, recycled plastics, recycled glass, and other recycled materials. This groups' primary market is every industry where lightweight concrete with high compressive and tensile strength is of primary concern, such as in skyscrapers, bridges, buildings, cultured stone, and roofing materials. It uses both fly ash varieties (noncementitious and cementitious), and bottom ash (the major waste products from the coal plants), and it can be mixed by formula to include plastics or other recyclable materials as listed above. The combined materials are pressed or extruded into a solid block. The solid block is then crushed with a standard rock crusher into a lightweight aggregate. All standard aggregate sizes are available, it can be produced at current coal plants on site, plus the aggregate products meet both ASTM 330 and 331 standards. The Aggregates are high strength, lightweight with weights ranging from 10-50 pounds per cubic foot, and can be used in multiple industries. The ultra-lite concrete weighs 95 pound per cubic foot, with compressive strength of 6000 psi, and a tensile strength of 11% of the compressive strength. The mixtures can be varied to make a wide range of products, wherever high compressive and high tensile strength is requested. Unlike the other two groups, it can be also be mixed as a total replacement of aggregate in concrete, and the concrete can be cut, nailed, and screwed with ordinary tools. This group's primary market would be concrete products such as ultra lightweight concrete for insulated concrete forms, prestress/tilt-up concrete, concrete roof shingles, wall board, block, and pavers, stucco, concrete wall or cultured stone, ultra lightweight 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. This new technology expands the scope for recycled materials, uses both varieties of coal plant ash, increases volume of recycled product use, and is flexible for use in additional industries. It uses the least amount of energy to produce, and has the ability to be 80% (by volume) of the synthetic product. ELITE Aggregates (CO) holds five U.S. patents plus two patents pending (U.S. & World). World Vision: The spectrum of the synthetic aggregate market (using fly and bottom ash and plastics) is considered to be only about 5-10% developed, as well as the tip of a worldwide iceberg. Coal is still the most abundant and cost effective source for the production of energy in most countries. Therefore, the waste byproduct of that industry is also increasing, is underutilized, and most of it dumped. As an example, China alone has 3,000 coal-fire power plants (1/2 government owned), which generate about 75% of their countries' power. In 2003, coal power plants were banned near Beijing and other major cities in 21 provincial capitals in an effort to reduce acid rain and severe air pollution affecting 1/3 of China's landmass, as well as world air quality. Another 137 were being modified with sulfur scrubbing equipment. By adding scrubbers to all coal power plants and using new technologies to make useful products from more bottom and fly ash and plastic waste, all countries could better address air quality, relieve aggregate shortages, and supplement the mineral aggregate market for construction. Not only could most countries develop new economically beneficial industries, they could reuse waste from their coal and heavy plastics manufacturing industries, and be a boon to their construction industry. A countries' economic health is a reflection of the health of their aggregate industry. Worldwide use of synthetic aggregates could spawn new industries, and make current recycling /reuse industries more profitable. Better yet, they could further reduce some substantial environmental challenges, such as increased air, land, and ocean dumping pollution. Summation: All synthetics decrease the negative impact on the environment, with each having benefits in its own niche. Synthetics offer new solutions to very old problems. Their forte is the joining of supply and demand of the aggregate market to the reduction of waste through recycling, via the production of more flexible and profitable products.