Partial Replacement of Reclaimed Asphalt Pavement, (RAP) and Extracted Binder in HMA Using Marshal Method
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Date
2022-01
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Addis Ababa University
Abstract
The shortage of road construction materials and supplies along with the increase in processing
and hauling cost has encouraged the use of Reclaimed Asphalt Pavement (RAP) materials in hot
mix asphalt (HMA). The use of RAP is becoming a common practice around the world and
involved a regular improvement in various countries. RAP has only limited application in
Ethiopia.
The aim of this study is to evaluate the effect of RAP in HMA in the form of Solid aggregate
weight and extracted binder using Marshall Method based on laboratory experiment by applying
Direct and Extracted RAP methods. The binder was extracted by using Trichloroethylene to
separate the bitumen and the aggregate. Marshall Mix design is used for the analysis based on
0%, 15%, 25%, 35% and 45% of RAP by weight of the mix. Nine mixes were tested; four RAP
materials without extraction, four extracted aggregate with RAP binder and recovered RAP
binder one Control/Virgin Mixes. Each mix has been tested on four different percentages of RAP
15%, 25%, 35% and 45%.
The Marshal Test result in both methods indicates that when the RAP percentage increases the
Air voids, Stability, VMA and VFA increase accordingly. On the other hand, the Bulk Density,
Dust to binder Ratio and flow decrease. Based on laboratory results as well as Marshal Criteria
properties and performance, it has been recommended it is possible to reuse the RAP up to 45%
with improved performance as compared to control /virgin mix In addition by using both
methods it was justified that all RAP mixtures results found to be adequate and meets the
minimum requirements as per MS-2 Criteria.
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Keywords
Reclaimed Asphalt Pavement, (RAP), Extracted binder, Marshal Method, HMA