Effect of stage mixing on rejuvenation level of binder in warm-mix recycled asphalt mixture

Wonbae Kim; Woohyun Kim; Kwang W. Kim

doi:10.22702/jkai.2024.14.1.3

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2024 Vol.14, Issue 1 Preview Page Next Page

Scientific Paper

Effect of stage mixing on rejuvenation level of binder in warm-mix recycled asphalt mixture 단계적 혼합이 중온순환아스팔트혼합물의 바인더 회생에 미치는 영향

12 July 2024. pp. 18-27

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Abstract

In this study, a RAP was used for preparing a warm-mix recycled mix with a bio-warm-mix asphalt rejuvenator (BWR) using the stage mixing (STM) method. A 19 mm virgin aggregate and a virgin PG64-22 asphalt were used for the recycled mix and a normal (control) mix confirming WC-4 mixture gradation. The asphalt binder was recovered from the RAP by Abson method and absolute viscosity (AV) was measured from the recovered binder. Gel-permeation chromatography (GPC) test was used to measure the large molecular size (LMS) of binder from the dissolution of mix particle without binder recovery. Five AV values from AP5 binder and short-term aged (STA) mixes (original, RTFO, PAV, 3-h and 4-h STA at 180°C) and 5 LMS values were measured from the same 5 materials for regression analysis. The regression result showed a very high correlation with R² > 0.98. Therefore, it was possible to estimate AV by LMS, which can be measured from mixture particles without binder recovery. The binder AV of recycled mix was estimated by LMS and the estimated AV (EAV) was used to evaluate rejuvenation level of recycled mix. The EAV of the recycled mix without using BWR (0%) was 9,166p, and was reduced down to 6,886p (24.9% drop) by using STM method. The average EAV in 5 BWR-ratio mixes (0, 2, 3, 4 and 5%) was 23.25% reduced by using STM method. The binder in RAP could be rejuvenated definitely better by STM and the binder EAV in recycled mixes using 3% BWR passed the limit of AV ≤ 5,000p set forced by Korean guide. Therefore, the STM must be used for all recycled mix production, i.e., the RAP, virgin binder and rejuvenator should be blended as the first stage mixing, and then the heated virgin aggregates are added for the next stage mixing.

Keywords

Aging

absolute viscosity

Large molecular size (LMS)

Stage mixing

Warm-mix recycle

Rejuvenator

References

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Information

Publisher :KOREAN ASPHALT INSTITUTE
Publisher(Ko) :한국아스팔트학회
Journal Title :Journal of the Korean Asphalt Institute
Journal Title(Ko) :한국아스팔트학회지
Volume : 14
No :1
Pages :18-27
Received Date : 2024-06-27
Revised Date : 2024-07-05
Accepted Date : 2024-07-07
DOI :https://doi.org/10.22702/jkai.2024.14.1.3

Journal of the Korean Asphalt Institute ISSN:2234-0785(Print) 2635-9553(Online) 한국아스팔트학회지

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