Rheological and physical characteristics of bio-derived block co-polymers for adhesive applications

Over the past decade, due to the economic and environmental concerns about the excessive usage of oil and its unstable price, development of renewable resources such as vegetable oils as substitutes for petroleum-based products has received considerable attention. Recently, commercial synthesis of oil-based (e.g. soybean, corn, fish, etc.) polymers has prevailed in several applications including food packaging, biomedical devices, paints, coatings, adhesives, and many other applications. Commercial development of Poly-Styrene Poly-Acrylated Epoxidized Soybean Oil (PS-PAESO) as a bio-polymer is currently in progress through ongoing research at Iowa State University. This thesis focuses on investigating the commercial viability of PS-PAESO block copolymers for adhesive applications, in particular, Pressure Sensitive Adhesives (PSAs). A library of candidate materials has been synthesized based on the recommended formulations by industry experts, and the most important physical, rheological, and adhesion properties of the adhesives have been evaluated and compared to petroleum-based counterparts. The results indicate promising potential of the material to perform as well as the commercially available petrochemical PSAs. However, more comprehensive studies on several factors influencing the behavior of bio-renewable PSAs is recommended before commercialization

Impact of soybean derived chemical additive on the morphology of asphaltenes extracted from virgin asphalt, polymer modified asphalt and recycled asphalt pavement extracted binder through small-angle X-ray scattering by solids and solids in solution

Recent work has shown that epoxidized plant oil materials work well as rejuvenators in recycled asphalt pavement (RAP). At the end of the 2017 construction season, a field trial mix with 30% RAP (total recycled binder content of 30.3%) was produced and placed in Northwest Iowa on US-18, east of Sheldon, Iowa. The rejuvenator (SR) was used at a rate of 0.125% by total mix weight. The mix design for the control section used a PG 58-34H. Due to Iowa DOT specification (recycled binder content greater than 20%) a grade bump was needed for the binder in the SR trial section (PG 52-40H). With 0.125% SR by total mix weight the grade bump was achieved. To better understand the chemistry behind this rheological improvement two chemical characterization methods will be explored (SAXS/USAXS, and IM-MS) on the asphaltene portion of SARA fractions of several binders (PG 52-34, RAP, PG 52-34 w/polymer (PG 58-34H), PG 52-34 w/SR, PG 52-34 w/RAP, RAP w/SR, PG 58-34H + SR, PG 58-34H + RAP, PG 52-34 w/SR + RAP, and PG 58-34H + SR + RAP)

From Laboratory Mixes to Full Scale Test: Rutting Evaluation of Bio-recycled Asphalt Mixes

The present paper describes the rutting behavior of innovative mixes in-corporating 50% of Reclaimed Asphalt (RA) with bio-materials. They were assessed in the laboratory and in a full-scale accelerated experiment. The innovative mixes studied here contain bio-materials especially designed to help recycling by re-activating the aged binder in RA. Four mixes were evaluated: three of them are manufactured with bio-materials, (two bio-rejuvenators and one bio-binder) and one is a control mix, which is a high modulus asphalt mix (EME2). In this study, the rutting resistance of the four mixes was first evaluated in the laboratory with both European and US methods. The full-scale test was then performed in order to evaluate the rutting resistance of the bio-recycled asphalt mixes under heavy traffic (200 000 load cycles loaded at 65 kN) and compare it with the control. A simplified analysis leads to the conclusion that, with the Nantes climate, a daily traffic of 150 heavy vehicles per day applied for 20 years corresponds to approximately 200 000 heavy vehicle loads applied when the surface temperature exceeds 30°C. Therefore, it can be considered that the rutting evaluation made on the carrousel represents almost 20 years of traffic during hot periods. The results obtained on the test track are consistent with the laboratory rutting tests showing good performance of all the mixes. The materials presenting the best performance on the test track also presented the best performance in the laboratory.This is a manuscript of a proceeding published as Juliette Blanc, Emmanuel Chailleux, Pierre Hornych, Chris Williams, Zahra Sotoodeh-Nia, et al. (2022). From laboratory mixes to full scale test: rutting evaluation of bio-recycled asphalt mixes. RILEM International Symposium on Bituminous Materials. ISBM 2020, Dec 2020, Lyon, France. pp.951-957, 10.1007/978-3-030-46455-4_121. hal-04376794. Manuscript is distributed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. © The Author(s), under exclusive license to Springer Nature Switzerland AG 202

Rheological and physical characteristics of bio-derived block co-polymers for adhesive applications

Over the past decade, due to the economic and environmental concerns about the excessive usage of oil and its unstable price, development of renewable resources such as vegetable oils as substitutes for petroleum-based products has received considerable attention. Recently, commercial synthesis of oil-based (e.g. soybean, corn, fish, etc.) polymers has prevailed in several applications including food packaging, biomedical devices, paints, coatings, adhesives, and many other applications. Commercial development of Poly-Styrene Poly-Acrylated Epoxidized Soybean Oil (PS-PAESO) as a bio-polymer is currently in progress through ongoing research at Iowa State University. This thesis focuses on investigating the commercial viability of PS-PAESO block copolymers for adhesive applications, in particular, Pressure Sensitive Adhesives (PSAs). A library of candidate materials has been synthesized based on the recommended formulations by industry experts, and the most important physical, rheological, and adhesion properties of the adhesives have been evaluated and compared to petroleum-based counterparts. The results indicate promising potential of the material to perform as well as the commercially available petrochemical PSAs. However, more comprehensive studies on several factors influencing the behavior of bio-renewable PSAs is recommended before commercialization.</p

Effect of mix scale and rejuvenators on the performance of asphalt binders and asphalt mixtures containing 50% RAP materials- a statistical investigation

Over the past decades, reclaimed asphalt pavement (RAP) materials have been increasingly used in asphalt pavements due to their significant contribution in reducing asphalt production costs and energy consumption. The main drawback associated with using RAP materials is the excessive amount of stiffness which the aged RAP binder introduces to the mixtures, thus reducing the resistance of mixtures to rutting, stripping, fatigue, and thermal cracking. In response to these limitations, researchers have suggested different techniques to avoid such distresses. The most common technique which is widely being practiced recently, is to use rejuvenators in the mix designs. Currently, there are many rejuvenators available in the market with many variations in their origins and description. A successful rejuvenator is one that can be applied to the mix design in low dosages while restoring the chemical and rheological properties of the aged RAP binder as well as improving the performance of mixtures to adequate levels. Several petroleum-based rejuvenators have been used in the asphalt mix designs successfully, and recently, bio-based rejuvenators have attracted the attention of researchers due to the value they add to the sustainability of infrastructures. In this research, two bio-based rejuvenators, one a by-product of the paper industry, and one derived from soybean oil, are introduced to enhance the properties of asphalt mixtures containing 50% RAP materials, and their respective binders. The first bio-rejuvenator is recommended by the manufacturer to be applied directly to the RAP, and then to the mixture, while the second bio-rejuvenator is recommended to be blended with the virgin binder, and then the blend added to the mixture. In the first phase of the study, the alternative binders were produced based on the proportions in the mix design. First, the RAP binders were recovered from the coarse-graded and the fine-graded RAP mixtures in accordance with ASTM standards. A control binder containing 62.4% virgin binder and 37.6% RAP binder was compared with the two rejuvenated binders containing same amount of RAP binder, smaller amount of virgin binder, and a low dosage of the rejuvenators. The initial screening of the binders in terms of their density, viscosity, and performance grade was done according to the AASHTO standards. For the rheological properties evaluation, binders were tested in three aging conditions: unaged, RTFO aged, and RTFO+PAV aged, using a dynamic shear rheometer (DSR) and a bending beam rheometer (BBR). The complex modulus master curves of the binders were constructed based on the two common models: Sigmoidal and Christensen-Anderson- Marasteanu (CAM). The compatibility of the rejuvenators with the RAP and virgin binder was also assessed using a differential scanning calorimetry (DSC) equipment. The results of this phase proved that the rejuvenators can effectively improve the low and intermediate-temperature properties of the control binder, as well as reducing the complex modulus and viscosity, and decreasing the critical high-temperature performance grade. Statistical analysis on the two master curve models indicated no significant differences between the measured and predicted complex modulus data, and no significant differences between the two models at unaged and RTFO-aged conditions. At PAV-aged conditions, a greater R2 value was observed for the Sigmoidal model. Viscosity measurements with the conventional method using a viscometer revealed a decrease in the viscosity of the control binder with the use of rejuvenator. Further study on the complex viscosity of the binders using the DSR equipment indicated statistically significant decrease in the zero shear viscosity (ZSV) values when using the two rejuvenators. From the DSC results the compatibility of the rejuvenators with the binder was validated and possible disaggregation of some of the asphaltenes was observed. In the second phase of the research, because the effectiveness of the rejuvenators was of interest at different mixing locations, asphalt mixtures were mixed in two locations: in the lab, and at the asphalt plant where the large-scale phase of the project was being handled. The plant-produced mixtures where then transported to the laboratory and both the plant-produced mixtures and lab-produced mixtures where compacted in the lab using a gyratory shear compactor (GSC). The specimens were then tested for their dynamic modulus, rutting and stripping resistance, and thermal cracking resistance. For the fatigue resistance, asphalt mixtures were compacted in the shape of slabs using a linear kneading compactor. Testing on the specimens was conducted in accordance with the ASTM/AASHTO standards. The dynamic modulus results indicated lower stiffness of the mixtures at low, intermediate, and high temperatures with the use of rejuvenators. The flow number of the mixtures as a measure of rutting resistance was also decreased with the use of rejuvenators due to the lower stiffness at high temperatures. Using the Hamburg wheel tracking test (HWT), no stripping inflection point (SIP) was identified before 20,000 wheel passes for the control mixture and both the rejuvenated mixtures and it was an indication of excellent stripping resistance in the mixtures and proved that the positive effect of high RAP content was not diminished by using the rejuvenators. The results from DCT testing on the mixtures revealed significant improvement in the fracture energy of the control mixtures after being rejuvenated. Although a significant improvement was observed in the fatigue resistance of the control binder after rejuvenation, however, no significant improvement was detected for the fatigue life of the rejuvenated mixtures, indicating that the existing beam fatigue procedure needs revision to integrate the effect of high RAP contents on the mix performance.</p

Impact of soybean derived chemical additive on the morphology of asphaltenes extracted from virgin asphalt, polymer modified asphalt and recycled asphalt pavement extracted binder through small-angle X-ray scattering by solids and solids in solution

Recent work has shown that epoxidized plant oil materials work well as rejuvenators in recycled asphalt pavement (RAP). At the end of the 2017 construction season, a field trial mix with 30% RAP (total recycled binder content of 30.3%) was produced and placed in Northwest Iowa on US-18, east of Sheldon, Iowa. The rejuvenator (SR) was used at a rate of 0.125% by total mix weight. The mix design for the control section used a PG 58-34H. Due to Iowa DOT specification (recycled binder content greater than 20%) a grade bump was needed for the binder in the SR trial section (PG 52-40H). With 0.125% SR by total mix weight the grade bump was achieved. To better understand the chemistry behind this rheological improvement two chemical characterization methods will be explored (SAXS/USAXS, and IM-MS) on the asphaltene portion of SARA fractions of several binders (PG 52-34, RAP, PG 52-34 w/polymer (PG 58-34H), PG 52-34 w/SR, PG 52-34 w/RAP, RAP w/SR, PG 58-34H + SR, PG 58-34H + RAP, PG 52-34 w/SR + RAP, and PG 58-34H + SR + RAP).</p

Effect of two novel bio-based rejuvenators on the performance of 50% RAP mixes - a statistical study on the complex modulus of asphalt binders and asphalt mixtures

An experimental study was conducted to evaluate the effectiveness of two bio-additives as rejuvenators on the properties of asphalt mixtures containing 50% RAP and their binder constituents containing 37% RAP binder. Before mixing, the rejuvenators were blended with fresh bitumen and the extracted and recovered RAP bitumen, and changes in the rheological properties of the binders were assessed using performance grading (PG) criteria. The results showed that both rejuvenators could improve the low-temperature performance of the aged RAP binder and restore its low-temperature properties. Master curves for the unaged, RTFO-aged, and PAV aged blends were constructed using both the Christensen-Anderson-Marasteanu (CAM) model and the Sigmoidal models. A comparative statistical analysis conducted on the models indicated no significant difference between the measured and predicted complex modulus values at any aging conditions. The pairwise statistical comparison between the two models showed that at unaged conditions, they can perfectly overlap as the p-values were greater than the level of significance. However, for the PAV-aged binders, this behaviour appears to weaken due to the brittle behaviour of the binders. Further statistical analyses revealed no significant differences between the two models at unaged conditions, however, as the binders where subjected to aging, significant differences between the two models began to appear. Mixing was performed in two locations: lab and plant, while compaction was performed only in the lab. After mixing and compaction, mixtures were evaluated for their stiffness characteristics through dynamic modulus testing. Compared to the control mixture, rejuvenated mixtures showed lower dynamic modulus values specially at high temperatures. A statistical comparison between the lab-produced, lab-compacted mixtures and plant-produced, lab compacted mixtures showed that both the rejuvenation and the location of mixing were significant factors in the stiffness measurements