Paper Mill Sludge as Fiber Additive for Asphalt Road Pavement


Erlinda L. Mari*, Ma. Salome R. Moran, and Cesar O. Austria

Forest Products Research and Development Institute
Department of Science and Technology
College, Laguna

*Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.


sludgepics for webpage



This study evaluated the properties of stone mastic asphalt mixtures made with paper mill sludge from four paper mills, as well as wastepaper, as fiber additive. Marshall specimens were prepared with asphalt content of 4.5, 5.0, 5.5, 6.0 and 6.5% and sludge or fiber contents of 0.2, 0.3, 0.4 and 0.5 percent. Properties tested were bulk specific gravity, stability, flow, air voids, voids in mineral aggregates and voids filled with asphalt. Effects of asphalt and fiber contents on flow and stability were analyzed statistically. Asphalt contents between 5 and 6 percent and sludge or fiber contents between 0.3 and 0.5% from any of the four paper mills resulted in Marshall specimens with properties generally passing the Department of Public Works and Highways specifications for both medium and heavy traffic road pavement.



A good road is paved or covered with a structure to supplement the natural strength of the soil foundation. The pavement may either be rigid (portland cement concrete) or flexible (hot-mix asphalt) [HMA]. HMA pavements suffer damage in the form of cracks that result in high maintenance cost. These cracks are caused by any or the combination of several factors, namely: asphalt, mix, traffic, environment, pavement structure, construction, geology, and pavement design (Soupe 2001). For all types of cracks, the quality of the asphalt and the mixture used is of prime importance.

In the early 60s, Germany began developing stone mastic asphalt (SMA) for the reduction of wear caused by studded tires. SMA is a dense, gap-graded bituminous mixture with high contents of stone, filler and bitumen, modified with a suitable binder carrier such as cellulose fiber (Richardson 1999).

The cellulose fiber additive used in SMA is said to prevent drainage of asphalt binder and thus improve binding with aggregates. Such additive has been introduced in the Philippines and pilot-tested. After some years of observation, the Department of Public Works and Highways (DPWH) has released a technical report (Faustino & Valencia 2003) specifying the material and construction requirements of SMA containing fiber.





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