TEA-21, which is expected to provide at least $198 billion for highway and transit construction over a six-year period, will strengthen demand for aggregates. Imagine receiving-in addition to normal product sales-a purchase order for a new project on a nearby interstate requiring 400,000 tons of minus-1-in. Yen #4-mesh and minus-31/48-in. Yen #8-mesh premium products for the pavement, structures and pipe embedment. Is it time to celebrate or to wait until determining what to do with the estimated 60,000 tons of extra fines that will be produced along with premium products?

The International Center for Aggregates Research and the aggregates industry have identified excess fines as one of the greatest challenges and opportunities facing aggregate producers today. For each ton of crushed stone premium product produced, the industry produces about 15% fines.

According to the U.S. Geological Survey and estimates by Rock Products, the U.S. production of crushed stone in 1996 was 2.53 billion short tons, growing to 2.74 billion short tons by 1998. This will generate millions of tons of fines. It doesn't matter too much what type of crusher used, there will be 10% to 15% fines to sell, waste or find new markets for.

To waste it creates a cost to handle and haul. To market it usually requires additional capital investment for processing, such as drying, screening, air separating, pulverizing, classifying and sometimes packaging.

If there is a roofing company nearby producing asphalt shingles, there could be a market for as much as 100,000 tpy of minus-200-mesh mineral filler and an additional 15,000 tpy of fine-graded material for shingle backing. Both of these materials sell for higher prices than construction aggregates, if you don't mind calling them ground calcium carbonate (in the case of limestone fines) or mineral filler.

Another possibility could be a large poultry raiser or processor that may use 20,000 tpy of poultry grit. Table 1 lists other opportunities to consider as markets for limestone fines.

These fillers and fine-graded products sell for two to three times the price of construction aggregates, provided the color, chemistry and sizing are right.