The potential of waste cooking oil as bio-asphalt for alternative binder – an overview

Enormous quantity of waste products from by-products of frying activity could cause negative impact if not properly managed and disposed. Therefore, recyclability of Waste Cooking Oil (WCO) in binder modification to produce bio-asphalt can be a sustainable ways to minimize waste dumping while at the same time to reduce the usage of natural resources. Bio-asphalt can be described as alternative asphalt binder which differs from conventional asphalt in terms of strength and durability. This review has highlighted the potential of bio-binder to replace with conventional binder by the addition of waste cooking oil in the mixture

Recombination of asphalt with bio-asphalt : binder formulation and asphalt mixes application

The bio-oil from fast pyrolysis is mainly produced using organic waste materials. This is a viscoelastic material, and after a heat treatment it has a viscosity and high/intermediate thermal rheological behavior similar to many types of asphalt used in the paving industry. These two characteristics show that this material could be a good alternative to replace asphalt. In order to improve the performance of bio-oil, it was hypothesized that the addition of crumb rubber would change the rheology of the modified bio-oil, making it rheologically similar to the conventional paving asphalts. Therefore, two sources of ground rubber from used tires (GTR), from different manufacturing processes, were used to modify the bio-oil. Then, two blends were produced by adding 20% (w/w) of this bio-binder to two different asphalts, a PG58-28 and a PG64-22. The binders were aged, and then storage stability tests (separation sensibility) were performed. The rheology of the initial bio-oil, bio-binder, asphalts and resulting binder-blends were assessed by using a Dynamic Shear Rheometer (DSR), namely by performing frequency sweeps at different temperatures. The results were then used to build the master curves of the materials, and to determine their high temperature continuous performance grade. Additionally, the performance related behavior of mixtures produced with this new material was also assessed, in order to evaluate the advantages of its use in pavements. Therefore, two mixes were produced with the binder that showed better performance regarding thermal rheological behavior, aging susceptibility and separation tendency. These new mixes were finally studied using performance related tests that are able to estimate their future behavior in situ in different environmental and traffic conditions, in particular in regard to water susceptibility, fatigue cracking, dynamic modulus, flow number and low temperature fracture resistance. The results from this first set of experiments showed that this material can perform as well or better than conventional asphalts over a large range of temperatures.FEDER -Federación Española de Enfermedades Rara

Rheological behavior and sensitivity of wood-derived bio-oil modified asphalt binders

The demand for bituminous materials is continuously growing; crude oil-based asphalt binders are non-renewable, and are facing rapid depletion. With the increase of petroleum-based asphalt prices, seeking an alternative, renewable material such as bio-asphalt has become a hot research topic. However, shortcomings in this research area have been identified, notably concerning the high-temperature performance of bio-asphalt at present. This research aims to comprehensively apply conventional tests to, and study the rheological behavior of, the high-temperature performances of bio-asphalt binders, i.e., by temperature and frequency sweeps, using a dynamic shear rheometer (DSR). It will also assess the chemical functional groups of specimens prepared by different aging conditions. Fifty penetration grade base asphalt binder (50#), bio-oil modified asphalt binders with 0%, 5%, 10%, and 30% bio-oil contents by mass, and bio-oil modified asphalt binder with combinations of 5% bio-oil-1% SBS, and 10% bio-oil-1% SBS were used in this study. The conventional performance of bio-asphalt binders was tested using penetration, ductility, and softening point, before and after short-term aging conditioning. The temperature sweep and frequency sweep of bio-asphalt under different bio-oil contents were carried out via DSR. Two-logarithmic equations of rutting factor and temperature were established, and the temperature sensitivity of bio-asphalt was analyzed. The master curves of virgin asphalt and bio-asphalt were constructed at 64 °C. The results indicate that the incorporation of bio-oil reduced the anti-rutting performance of asphalt, and the bio-oil content had a significant effect on the mass loss of the bio-asphalt binder. The performance of bio-oil modified asphalt binders using 5% bio-oil, 5% bio-oil-1% SBS, and 10% bio-oil-1% SBS, could meet the requirements of 50# grade asphalt. The temperature sensitivity of bio-asphalt did not show obvious change before and after short-term aging, whereas the temperature sensitivity of bio-asphalt with 5% bio-oil was relatively small. With an increase in temperature, the phase angle increased gradually. In contrast, the storage modulus, loss modulus, and complex modulus decreased progressively. The complex modulus and rutting factor of bio-asphalt with 5% bio-oil steadily increased with the increase in testing frequency. Otherwise, chemical reactions were detected in the 50# base asphalt modified with the bio-oil

Linear viscoelastic properties of high reclaimed asphalt content mixes with biobinders

The use of high Reclaimed Asphalt (RA) content mixtures together with binders produced from renewable resources (biobinders) is one of the current challenges in pavement engineering research. On one hand, RA has been used for decades but there are still some concerns about its performance, especially when high contents are used (>30%). On the other hand, biobinders are relatively new materials which have to be deeply characterised and studied in order to develop good-practices for their use. In this paper, linear viscoelastic properties of biobinders and bio-mixtures manufactured with high-RA content and biobinders are analysed and discussed. High-modulus mixtures with 50% RA were selected for the mix design. Binders and mixtures were tested over a wide range of asphalt service temperatures and frequencies by means of DSR and two-point bending tests respectively. Results show that biobinders have an important effect on mixtures behaviour. However, no direct links between their linear viscoelastic properties were found. Bio-asphalt mixtures still need further development for commercial exploitation; however the take-away fact of this investigation is that it is possible to manufacture asphalt-like mixtures with acceptable viscoelastic properties while being composed only of RA and non-petroleum based binders

Integrating anaerobic digestion and slow pyrolysis improves the product portfolio of a cocoa waste biorefinery

The integration of conversion processes with anaerobic digestion is key to increase value from agricultural waste, like cocoa pod husks, generated in developing countries. The production of one metric ton of cocoa beans generates some 15 metric tonnes of organic waste that is today underutilized. This waste can be converted into added value products by anaerobic digestion, converting part of the cocoa pods to biogas while releasing nutrients, and pyrolysis. Here, we compared different scenarios for anaerobic digestion/slow pyrolysis integration in terms of product portfolio (i.e., biogas, pyrolysis liquids, biochar and pyrolysis gases), energy balance and potential for chemicals production. Slow pyrolysis was performed at 350 degrees C and 500 degrees C on raw cocoa pod husks, as well as on digestates obtained from mono-digestion of cocoa pod husks and co-digestion with cow manure. Anaerobic digestion resulted in 20 to 25 wt% of biogas for mono and co-digestion, respectively. Direct pyrolysis of cocoa pod husks mainly resulted in biochar with a maximum yield of 48 wt%. Anaerobic digestion induced compositional changes in the resulting biochar, pyrolysis liquids and evolved gases after pyrolysis. Pyrolysis of mono-digestatee.g., resulted in a more energy-dense organic phase, rich in valuable phenolics while poorer in light oxygenates that hold a modest value. Our comparison shows that co-digestion/slow pyrolysis at 500 degrees C and mono-digestion/slow pyrolysis at 350 degrees C both present high-potential biorefinery schemes. They can be self-sustaining in terms of energy, while resulting in high quality biochar for nutrient recycling and/or energy recovery, and/or phenolics-rich pyrolysis liquids for further upgrading into biorefinery intermediates

Review on the properties and mechanisms of asphalt modified with bio-oil and biochar

Bio-asphalt has a great application prospect in the replacement of petroleum-based asphalt to pave and maintain asphalt pavement. However, the problems of flow-induced crystallization and phase separation caused by flow-induced crystallization had severely restricted its application. This paper describes the progress of research on preparation, property evaluation and phase separation mechanism of bio-asphalt. The advantages and disadvantages of preparation methods of bio-asphalt are states. The fundamental physical and rheological properties of bio-asphalt are investigated, especially for flow-induced crystallization. There exists obvious flow-induced crystallization because bio-asphalt is rich in waxes that crystallize easily. Owing to the existence of excess biochar, bio-asphalt appears phase separation. A brief review of the effect of bio-oil and biochar on asphalt volatile organic compounds (VOCs) is presented. Research find that bio-oil/biochar are not only replenish the light components of asphalt, but also improve the flow-induced crystallization and phase separation of bio-asphalt. There exists synergistic effect of biochar and bio-oil in asphalt modification. Moreover, biochar can improve the durability of bio-oil modified asphalt, but excessive addition of biochar to bio-oil modified asphalt can cause phase separation. Adding an appropriate amount of bio-oil and biochar to asphalt can improve its high-temperature resistance, low-temperature crack resistance, and system compatibility

Performance evaluation of bio-oil and high rubber content modified asphalt: More effective waste utilization

In this study, the bio-oil was used to reduce the viscosity and preparation temperature of high content of rubber-modified asphalt. The high rubber content modified bio-asphalt (RMBA) was prepared, the rubber and bio-oil contents were 20 %-30 % and 5 %-15 % (mass ratio of neat asphalt), respectively. The viscosity, temperature sweep (TS), frequency sweep (FS), multi-stress creep recovery (MSCR), and bending beam rheometer (BBR) tests were performed to assess the properties of RMBA. The Fourier Transform infrared spectroscopy (FTIR), Fluorescence microscopy (FM), and Scanning electron microscope (SEM) tests were conducted to explore the microscopic morphology of RMBA. Besides, the economic analysis and life cycle assessment (LCA) were assessed. Bio-oil contributed to the viscosity-reduction of the RMBA. When the rubber content was 30 %, the viscosity decreased by 48.16 % with a bio-oil content of 15 %. The temperature and frequency sensitivity of RMBA were lower than neat asphalt. Rubber improved the creep recovery and anti-rutting deformation behavior for bio-asphalt. The absorption peaks appeared at 1010 and 1038 cm−1, which represented the S[dbnd]O function group. The rubber did not absorb enough bio-oil for solubilization. This resulted in the functional group of S[dbnd]O appeared in 30 %+B-10 % and R-30 %+B-15 %. FM and SEM test results indicated that the rubber in RMBA exists in different states: undissolved rubber and dissolved rubber. The high content rubber could be partially dissolved in bio-asphalt and retained its elastic properties. The dissolved rubber particles exhibited a large crosslinked network structure. The raw material cost of RMBA decreased significantly with the rise of rubber and bio-oil contents. The reasonable application of waste rubber is beneficial to the alleviation of black pollution. The efficient application of rubber and bio-oil could contribute to the development of waste utilization and green transportation

Advanced analytical techniques in fatigue and rutting related characterisations of modified bitumen: literature review

Fatigue and rutting are the two major failure distresses in flexible pavement that affect significantly the serviceability of pavement. The properties of bitumen have a direct effect on controlling the fatigue and rutting distresses. Because of the increase in vehicular loading and repetitions, the modification of neat bitumens becomes a widespread practice to improve their mechanical properties. Any improvements obtained from developing modified binders need be reflected by fundamental testing parameters. The empirical testing methods and Superpave grading procedure that were developed mainly for unmodified bitumens have failed in many cases to predict the performance of modified bitumens. Evaluation the influence of such modifiers needs be based on characterising accurately the inherent resistance of binders to fatigue and rutting damage. The most advanced tests and fundamental analysis methods for characterising the fatigue and rutting properties of binders, are discussed and presented in this paper. These include fatigue and ductile fracture evaluation of binders using time sweep and double-edged notched tension (DENT) tests. For bitumen rutting evaluation, the SHRP rutting parameter, Shenoy rutting parameter, ZSV and MSCR are discussed. The dynamic shear rheometer (DSR) has been largely used to characterise fundamentally the viscoelastic properties of bitumens. A detailed description of the main elements associated with the DSR and Dynamic Mechanical Analysis (DMA) are also presented in this paper

Develop Biochar-based Controlled Release Nitrogen Fertilizers

The current efficiency of conventional nitrogenous fertilizers (e.g. urea, ammonium sulfate, etc.) in agricultural practices is low, fluctuating from 30 to 40%. Approximately 60% of nitrogenous fertilizers were wasted due to vaporization into the air, runoff or leaching into water systems. The lost nitrogen (N) resulted in not only high production cost but also serious environmental problems, such as greenhouse gas (N2O) emission in the atmosphere, algal blooms, oxygen depletion, fish kills, and loss of biodiversity in surface water due to eutrophication or pollution. To address these problems, this study aimed to utilize low-cost biochar-based materials to develop a controllable, affordable, and environmentally friendly nitrogen fertilizer. The studies of activated biochar, biochar-based controlled release nitrogenous fertilizer (BCRNF), and asphalt-based controlled release nitrogenous fertilizer (ACRNF) were carried out to achieve the goal. To improve the adsorption ability of biochar, biochar was activated by steam-method. After steam-activation, activated biochar (AB) has attained approximate methylene blue (MB) adsorption with activated carbon (AC). Besides, the film produced in this study by AB and cellulose nanofibrils has formed a stable form, promising to part of BCRNF in the future. To attain a controllable and endurable N-release pattern, polylactic acid (PLA), that, has a strong hydrophobic property, and biochar that possesses, a strong adsorption capability, were chosen as coating material and N carrier respectively to prepare BCRNF In BCRNFs’ N-release in water experiment, BCRNF-P10 continually released N in water in 12 days. In the soil column leaching experiment, for BCRNF-P10 sample, it continually released N for 25 days and only 33.57% of N was leached into water under a rainy simulated environment. These results indicate that the BCRNF has the potential for developing controlled release nitrogen fertilizer in the future. To attain a more durable N-release pattern, another biochar-based nitrogen fertilizer, asphalt-based controlled release nitrogenous fertilizer (ACRNF) was developed. The asphalt used as N carrier in the fabrication of ACRNF was produced from bio-based materials: corn stover and sawdust by pyrolysis and liquefication, respectively. Granular ammonium sulfate was either mixed or coated with asphalt to control N-release. Different ACRNF samples were tested to examine their N-release in water. The results showed that the N-release patterns of ACRNF were significantly different when ammonium sulfate particles were mixed or coated with asphalt under different processing conditions. The Nrelease time of 80% N for the sample ACRNF 230 was more than 20 days. The performance of other ACRNF samples also demonstrated the concept of controllable Nrelease if ammonium sulfate was properly mixing or coating with asphalt. Although further research is needed, the ACRNF has shown very promising potential to improve nitrogen use efficiency in corn production in the controlled release fertilizer market

A Review of Characteristics of Bio-Oils and Their Utilization as Additives of Asphalts

Transforming waste biomass materials into bio-oils in order to partially substitute petroleum asphalt can reduce environmental pollution and fossil energy consumption and has economic benefits. The characteristics of bio-oils and their utilization as additives of asphalts are the focus of this review. First, physicochemical properties of various bio-oils are characterized. Then, conventional, rheological, and chemical properties of bio-oil modified asphalt binders are synthetically reviewed, as well as road performance of bio-oil modified asphalt mixtures. Finally, performance optimization is discussed for bio-asphalt binders and mixtures. This review indicates that bio-oils are highly complex materials that contain various compounds. Moreover, bio-oils are source-depending materials for which its properties vary with different sources. Most bio-oils have a favorable stimulus upon the low temperature performance of asphalt binders and mixtures but exhibit a negative impact on their high-temperature performance. Moreover, a large amount of oxygen element, oxygen-comprising functional groups, and light components in plant-based bio-oils result in higher sensitivity to ageing of bio-oil modified asphalts. In order to increase the performance of bio-asphalts, most research has been limited to adding additive agents to bio-asphalts; therefore, more reasonable optimization methods need to be proposed. Furthermore, upcoming exploration is also needed to identify reasonable evaluation indicators of bio-oils, modification mechanisms of bio-asphalts, and long-term performance tracking in field applications of bio-asphalts during pavement service life