What used to be a waste by-product of coal-fired boilers at power plants and paper mills has now turned into a viable road preservation product on many state and county roads in Wisconsin.
Fahrner Asphalt Sealers Inc., based in Plover, WI, applied its first boiler slag sealcoating in 1993, and the product has been gaining interest as a viable alternative to conventional aggregate chip sealing ever since. Fahrner specializes in sealcoating, providing customers in the Upper Midwest with services that include coal tar emulsion and chip sealcoating, slurry sealcoating, microsurfacing, rubberized crack and joint sealing, infrared patching, tennis court and running track resurfacing, parking lot and road striping, asphalt milling, cold mix paving, utility cut patching, and street/parking lot sweeping. The company has branch offices in Waunakee and Kaukauna, WI; Gwinn, MI; and Rockford and Springfield, IL.
According to Jerry Fahrner, president of Fahrner Asphalt Sealers, the company generates 40 percent of its revenue through chip seal work, with 35 percent of that work involving the application of boiler slag aggregate. The company employs between 170 and 190 associates during peak construction, with most of its chip seal work concentrated in Wisconsin, Michigan and Iowa. Fahrner maintains a fleet of 150 pieces of equipment (including trucks); with Etnyre chip spreaders, Hypac rollers and Broce sweepers used to support the four road crews in its chip seal operations.
'The slag chip seal portion of our business has really started to grow since 2000,' Fahrner says 'We continue building confidence with the government agencies who have tried the product and we expect to do more business with them, as well as introduce the product to others. When they experience a reduction in windshield claims and see how it also can reduce their winter maintenance costs, they begin to appreciate the value of the product.'
Marketing a solution
Fahrner has been aggressively marketing its boiler slag sealcoating solution for the past 10 years, but it's only been in the past three to four years that this coal by-product has really gained wider acceptance by road agencies the company serves. Tom Johndro, manager of Fahrner's Chip Seal Division, Michael Buss, who's in charge of marketing highway preventive maintenance solutions, and John Fink, who supervises chip seal projects for the company, recently talked about the success of Fahrner's boiler slag chip seal efforts and the education process required to convince prospective customers of its merits.
The three have been actively promoting the solution throughout the 72 counties of Wisconsin, as well as Michigan, Illinois and Iowa.
Boiler slag is a coarse, granular, incombustible by-product that is collected from the bottom of furnaces that burn coal for the generation of steam for the production of electricity. It's produced in wet bottom boilers and consists of uniformly-sized hard, durable, glassy particles. Boiler slag has been used mainly in hot mix wearing surfaces, where it has been found to enhance skid resistance, and to a lesser extent, it's beginning to find its way into asphalt surface treatments as a chip seal application. Boiler slag chips generally range in size from No. 4 to No. 40 sieve, and its permanent black color, which is not affected by the oxidizing effects of sun and weather, enhances its value as an aggregate used in chip seal applications. The black color provides a good contrast to lane striping and it also aids in the melting of snow during the winter because of its heat absorption capabilities.
Smaller chip, less damage
The primary benefit that originally attracted road agencies to the boiler slag chip seal application was a reduction in the number of cracked windshield claims motorists were filing against county highway departments. With the slag crushed at 3/8 in. minus and 80 percent of it smaller than 1/4 in., its lighter weight reduces its airborne damage to traveling motorists.