Paper Mill Sludge For Stronger Roads
For more durable roads, many countries use the stone mastic asphalt technology developed in Germany. The technology makes use of expensive cellulose fiber to improve the binding of asphalt with the aggregates. The introduction of this technology to Asian countries has encouraged the search for cheaper and better sources of cellulose fiber for asphalt mix.
FPRDI researcher Erlinda L. Mari dried, ground, sieved sludge samples, then mixed them with aggregates and asphalt while heating. The mixture was then compacted after which the properties of the composite were tested.
Dr. Mari found that at 5 to 6 percent asphalt content, asphalt mixtures with 0.03 - 0.05 percent paper mill sludge resulted in asphalt mix specimens with stability, flow and air voids passing the requirements for both medium and heavy traffic road pavement.
“We estimated that good stone mastic asphalt with paper mill sludge as fiber additive could pave a 1-km long, 6-meter wide, 5-cm thick road for only P1.7 million compared to the Department of Public Works and Highways’ at least P5 million budget for constructing and improving a 1 -km stretch of road,” says Dr. Mari.
If successfully commercialized, the technology could help the government save a lot of money and help dispose of the 84,000 metric tons of paper mill sludge which local mills dump into landfills annually.
Dr. Mari recommends that paper mill owners may diversify their operations by converting the sludge into asphalt fiber additive. First, however, a pilot study is necessary to establish the economic viability of the technology, as well as the long-term performance of the asphalt mix in road pavement.
