A review on the application of bio-oil as an additive for asphalt

Raising the prices of crude petroleum is affected to good performance for the asphalt paving and has encouraged to modify or replace asphalt bitumen. Increasing numbers of commercial vehicles and increase axle load that this trend will continue yearly. Design, construction and maintenance facilitate asphalt roads to provide the high standards of safety and comfortable but certain areas of a road are higher stressed than others. For that reason road paving industry is interested in utilizing alternative and sustainable binder materials for modified asphalt to improve the production, placement and performance of asphalt mixtures. However, sources of materials should be considered economically and environtmentally viable after applied in pavement. According to previous research, that has been developed that non crude petroleum binder derived from the production of bio-oil through fast pyrolysis of biomass. The main source of bio-oil can be contributed from biomass industry or renewable organic industry such as timber waste, oil palm waste, rice husk; coconut trunk fibers, municipal waste and sugar cane waste. Alternatively, the bio-oil can be as substitute material as modification of asphalt. This paper presents a review on the source, characteristic of bio-oil and the effects of bio-oil on the properties of asphalt bitumen

Evaluation on the performance of aged asphalt binder and mixture under various aging methods

Hot mix asphalt (HMA) pavement encounter short and long term aging throughout the service life. Laboratory aging is the method used to simulate field aging process of HMA pavement. This study was undertaken to determine the long term effect of different binder and mixture laboratory aging methods on HMA (binder aging and mixture aging). Three types of HMA mixtures were prepared for this study namely Asphaltic Concrete with 10 mm nominal maximum aggregate size (AC 10), Asphaltic Concrete 14 mm (AC 14) and Asphaltic Concrete 28 mm (AC 28). These specimens were conditioned with nine different methods and durations. Resilient modulus test was carried out at 40°C as an initial indicator of the specimen performance. Permanent deformation of the same specimens was then evaluated by dynamic creep test. Generally, the aged asphalt binder specimens have higher resilient and stiffness modulus compared to aged asphalt mixture specimens. In addition, aged binder specimens have a lower permanent strain which indicates higher resistance to permanent deformation. This study also found that high resilient and stiffness modulus of specimens is attributed by different in heating frequency, temperature, air exposure and binder content of the mixture

Effect of bio-oil from empty fruit bunch on penetration index of asphalt binder

Bio-oil which is derived from pyrolysis palm empty fruit bunch (EFB) is expected to be a potential alternative modifier for asphalt. This study focused on the effect of bio-oil on the penetration index (PI) asphalt. Bio-oil is blended between 2%-10% by weight of virgin asphalt penetration grade 80/100. Physical properties are measured and compared with virgin asphalt by the conventional physical binder test – softening point and penetration. The penetration index (PI) values is calculated to identify the typical values of asphalt type. Based on the findings, it was found that increased bio-oil content can effectively soften the asphalt at the same time maintain the temperature susceptibility. Modification asphalt is still within the grade 80/100 PEN with the addition of 10% maximum of bio oil. The stiffness of modified asphalt need to be further improved by addition polymer for better asphalt binder properties

Effect of styrene-butadiene on rheological properties of asphalt emulsion

One of the main issues with cold mix asphalt (CMA) mixtures is having poor abrasion resistance with low cohesion, longer curing time and low elasticity. SBR is used to improve the rheological properties of the asphalt emulsion. This paper evaluates the effect of using different percentages of SBR in unaged slow-setting emulsion (SS-1K) in CMA. These modified emulsions were blended at various percentages, i.e. 2%, 4%, 6%, 8% and 10% of the weight of asphalt emulsion. The investigation focused on the rheological aspect which correlates the properties of unaged modified asphalt emulsion with its performance. Dynamic Shear Rheometer test (DSR) was used to measure the parameters of complex shear modulus, G* and phase angle, δ of the asphalt samples. Based on the results, it shows that by adding SBR in the asphalt emulsion improve the rutting resistance. From the isochronal curve, the complex modulus, G* of the modified emulsions was found higher than the unmodified emulsion. The modified emulsions show signs of improvement in binder properties in terms of elastic deformation and viscosity reduction. Therefore, it can be concluded that the SBR could improve the performance of the asphalt emulsion used in CMA

Effects of moisture damage sensitivity of asphalt mixtures incorporating treated plastic as additive

The issue of moisture damage due to water intrusion in conventional road pavement is crucial due to increasing traffic load and volume, especially in the dry process. Poor workability occurs between the aggregate and binder interaction, increasing air voids in the asphalt mixture. Consequently, reduce the strength of the asphalt mixture. Hence, the additive material is one possible approach to reduce the issue. The use of treated plastic (Low-density Polyethylene) (TP) has a high potential to improve the interaction of aggregate and binder during the mixing process to against moisture damage. Further investigation on the effect of different ratios of TP content (0, 2.5, 5.0, 0.75, and 1.0% by weight of total aggregate) in asphalt mixture was studied. Mechanical performances on moisture damage of the optimum TP content in asphalt mixture were focused and evaluated with retained stability and tensile strength ratio tests. The finding revealed that 0.75% of TP content increased the resistance of moisture damage in asphalt mixtures compared to the conventional mixture

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population