01333212

Component

Due to problems associated with the addition of cellulose fibers to stone matrix asphalt (SMA) mixes, a new binder stabilizer was developed to prevent excessive drainage of the bitumen during hauling and placement of the mix. This stabilizer is an activated fine-grinded raw silica mineral, which is the waste by-product of the mining for the Phosphate Industries. The activation was aimed for obtaining Thixtropic and Shear-Thinning properties for the bitumen, by which the mastic in the mix possesses high viscosity at rest (hauling and after placing) for reducing draindown, and low viscocity at motion (mixing and placing) for maintaining the proper workability. The objectives of this study were: 1) Practical development of a more efficient and user friendly binder-stabilizer for preventing the bitumen draindown in SMA mixes, 2) Identifying some positive added values of the role of the active bitumen-stabilizer in the compacted SMA also under service condition, and 3) Verification of these advantages by comprehensive laboratory study as compared to the cellulose fibers. In preliminary comprehensive laboratory studies it was found that SMA mixes, combined with the new bitumen stabilizer, exhibit low acceptable bitumen draindown values which are comparable to those with the fibers. By systematic mix designs, European and American SMA mixes also show comparable and better mechanical properties related to: resistance to water damage, wear resistance, indirect tensile strength, and rutting resistance. These results were obtained with 0.5% less binder content and 10°C less mixing temperature, as compared to the fibers. In addition to the engineering advantages, an analysis of the environmental benefits was performed. Generally, the comparison of the environmental indicators analyzed clearly demonstrates a quantitative decline in the negative environmental economic cost per ton SMA mix, when using the activated-mineral binder-stabilizer as compared to the cellulose fibers. The present research is continuing to include extensive fatigue, tri-axial shear, and dynamic modulus tests, as well as actual trial controlled field test sections.

01329018

11-1213

English

17p

2011

Transportation Research Board 90th Annual Meeting

DVD

Figures (9) ; References (11) ; Tables (5)

Asphalt mixtures; Binders; Bitumen; Cellulose; Durability; Rutting; Stabilizers; Stone matrix asphalt; Waste products (Materials)

Draindown; Indirect tensile strength

Highways; Materials; Pavements; I31: Bituminous Binders and Materials

Transportation Research Board Annual Meeting 2011 Paper #11-1213

TRIS, TRB

Feb 17 2011 5:43PM