Rheological Properties of Plastic Modified Bitumen for Sub-Tropical Areas of Ethiopia

Autor: Henok Addissie; Alemayehu Gebissa; Markos Tsegaye
In:

American Journal of Civil Engineering and Architecture, 2018, Vol. 6, No. 6, 223-235

Bandangabe: Vol. 6 No. 6, 2018
Auflage: Vol. 6
DOI: 10.12691/ajcea-6-6-1
Seite: 223 - 235
Jahr: 2018

Einordung:
Institut: Professur Geotechnik und Küstenwasserbau

Abstract:
The principal problems in any asphalt pavement performance are the sensitivity of bitumen towards temperature, loading time and climate in asphalt mixture. In Ethiopia, asphalt binders have been selected based on penetration grade at 25°C for the construction of all road pavements. Daily traffic growth, performance of dense graded asphalt (DGA), maintenance and rehabilitation expenditure demand better, life-long, and high efficient alternative asphalt mastics and mixtures for minimizing pavement distress. The objective of this research is to evaluate the performance of plastic modified bitumen for sub-tropical areas of Ethiopia. The effect of temperature on strain (deformation) were investigated on the rheology of two commonly used bitumens (40/50 and 85/100) in Ethiopia. In addition, the rheological properties of 40/50, 85/100, polyvinyl chloride (PVC) modified 40/50, low density polyethylene (LDPE) modified 40/50, PVC modified 85/100 and LDPE modified 85/100 binders were investigated by penetration grade and SuperPave grading systems. The PVC and LDPE polymers were mixed with the two bitumens from 0-7% and 0-9% (only odd numbers), respectively. The samples were subjected to a series of consistency, rotational viscometer and performance grading tests at different temperatures. Those tests showed that 3% PVC and 5% LDPE modified binders had better penetration, softening point, ductility, viscosity and performance grade results for both 40/50 and 85/100 bitumen grades compared with the other percentages of the two modifiers. Thus, 40/50, 85/100, 40/50+3% PVC, 40/50+5% LDPE, 85/100+3% PVC, 85/100+5% LDPE were subject to additional Superpave rheology test like rolling thin film oven, amplitude sweep, multiple stress creep recovery, and Fourier transform infra-red tests. As observed from the Superpave test results, the PVC and LDPE modified binders had lower % heat loss, higher linear viscoelastic region (LVER), lower unrecoverable creep compliance and higher percent recovery than the unmodified bitumens in both 40/50 and 85/100 grades. In conclusion, the bitumen with penetration grade 40/50 and 85/100 were improved to 30/40 and 60/70 by both selected modifiers respectively. Those neat bitumens were also improved from PG64-Z(40/50) to PG82-Z (by both modifiers), and from PG52-Z (85/100) to PG76-Z(by 3% PVC) and PG82-Z(5% LDPE) by Superpave grading.

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