Soil stabilization techniques are being field tested in projects at Kansas City, and in South Dakota, the latter involving work with lignite ashes. (Many other tests have been successfully demonstrated.) In both of these applications, fly ash was used to correct poor soil conditions to permit road construction across the areas including an interstate highway. Results on two other demonstrations are not in yet, involving a de-dusting stabilization of secondary roads program in Iowa and a cold regions evaluation of ash utilization in New Hampshire. Up to this point in time most of the action has been centered in the Eastern coal producing states but with the increased mining activity in Montana, Wyoming, and the Dakotas, we looking forward to applying this technology to the power plant ashes that will result from the use of these low-sulfur fuels. One of the first known large scale case history applications bottom ash in highway construction took place of the use in West Virginia in 1972. Approximately 225,000 tons of power plant ash was utilized in the relocation of a four-mile section of Route 2 south of Moundsville in Marshall County. As Reported by Walter V. Blocker, Sales Engineer for Highway Materials Company, at the March Ash Symposium, "the 21 inch thick roadway incorporated four layers of material with varying blends of PPA as a base material.4/ The application was as follows: (See Table 1) (See Table 11) are The Civil Engineering Department at West Virginia University, which has been extremely active in developing applications and design specifications for power plant ashes, also, played a major role in this project through a study of Portland cement a substantial reduction in costs compared to the use of conventional aggregates. The following construction season, the West Virginia Department of Highways also incorporated the use of PPA in their secondary road improvement program. The mix, appropriately called ASHPHALT was produced by combining bottom ash with emulsified ASHPHALT and applied as a cold mix. The mix formula was designed in the K. E. McConnaughey labs in Lafayette, Indiana, with an assist from Dr. David Anderson of the WVU engineering staff. Result: 79 miles of farm-to-market roads in eight northern counties were surfaced with ASHPHALT. Besides being more economical to mix and place than conventional hot mixes or cement treated bases, ASHPHALT also has some other plus features. It can be pugged, mixed and stockpiled in advance, it can be placed in cold or inclement weather, and it can be blended with other aggregates to meet any desired gradation. Bottom ashes, thus far, have had limited use in wearing course mixes largely because they usually have to be blended with other aggregates to produce a stable surfacing material. Several states now permit the use of these boiler slags in wearing mixtures and such metropolitan centers as Tampa, Cincinnati, and Colombus have effectively utilized "Black Beauty" ash for a skid resistant ingredient in high traffic areas. More research is needed in this area and the National Ash Association is helping fund such a program. The recycling of waste materials into suitable replacement aggregates for conventional highway materials is just in its infancy, but the concept appears quite feasible and ecomonically sound. A follow-up to work initiated by the Transpo '72 project at Dulles Airport near Washington, a project is now being developed to advance this technology to its next step that of actually placing the lime-fly ash sulfate mixtures down on a primary highway for further evaluation. I'm sure you'll be hearing more about this from Chairman Earl Kinter or others in the Federal Highway Administration. - coal mine In fact, I can tell you two coal by-products refuse and fly ash-- have already been successfully put down as a highway base in an experimental project at the U. S. Environmental Protection Agency's Mine Drainage Control Field Site at Morgantown, West Virginia. The material was placed on the driveways and parking area at the station so the sub-surface drainage can be monitered and its potential in road construction can be evaluated. We in the industry are tremendously excited about our role in developing the highways of the future. Ash is Beautiful! Try it and you'll like it! 1 Inch Table I Route 2 Project Design Wearing Coarse (63% BFS, 30% River Sand, 7% Bitumen 5 Inch Asphaltic Concrete (65% MBA, 30% KBA, 5% Asphalt) Substitute Mix-57% BFS, 38% River Sand, 5% Asphalt* Aggregate Base (80-85% MBA, 15-20% AASHO #467 BFS) Cement Treated Base (45% KBA, 42% MBA, 5% Type 1 Portland Cement, 8% Water) 9 Inch 6 Inch 21 Inch Total Thickness Shoulder Application: KBA 18" - W. Va. 18-1 (90% MBA, 10% AASHO #467 BFS) 2" -Open Hearth Slag 1" - Penetration Macadam with #7's and #8's BFS Kammer Wet Bottom Ash, BFS - Blast Furnace Slag, Due to shortage of ash, BFS was substituted by contractor. |