Effect of Biochar from Oat Hulls on the Physical Properties of Asphalt Binder

Evaluation of Rheological Properties of Asphalt Binder Modified with Biochar from Oat Hulls

In this study, the effect of biochar from oat hulls (BO) on the rheological properties of a PG 64-22 asphalt binder was evaluated using a full factorial design, which included the following factors: pyrolysis temperature (PT) (300 °C and 500 °C), BO particle size (<20 µm and <75 µm), and the amount of BO (2.5%, 5%, and 7.5%). First, the morphological and physicochemical properties of BO were analyzed by comparing it with graphite powder (CFG) and commercial activated carbon (CAC). The physicochemical properties of the modified asphalt binder were then evaluated using confocal laser microscopy, scanning electron microscopy (SEM-EDX), and Fourier-transform infrared spectroscopy (FTIR). Its storage stability was also evaluated. Subsequently, the rutting parameter G*/sin(δ) and the Fraass breaking point were analyzed to select asphalt binders that extended their viscoelastic range. The asphalt binders selected were those with 2.5%, 5%, and 7.5% BO, produced at a PT of 300 °C with a particle size <20 µm (BO300S). Next, the rheological properties of the selected samples were evaluated by testing for rotational viscosity, rutting parameter G*/sin(δ), multiple stress creep recovery (MSCR), fatigue parameter G*·sin(δ), and creep stiffness by bending beam rheometry (BBR). The rheological aging index according to rutting parameter G*/sin(δ) (RAI) was also evaluated. These tests were conducted in different states of the asphalt binder: original, short-term aged, and long-term aged. According to the results, the application of BO300S significantly increased the resistance of the asphalt binder to rutting and rotational viscosity, proportional to the amount added to the asphalt binder. Moreover, low modifier percentages improved fatigue resistance, outperforming CFG and CAC. In addition, it performs well at low service temperatures, registering better resistance than the control asphalt binders.

Exploring Oat Husks as Aggregates in Limestone-Based Composites: Effects of Surface Treatments and Binder Selection on Mechanical Performance

The viability of incorporating agricultural by-products, such as oat husks, not yet explored in limestone-based composites, as more sustainable alternatives for use as novel aggregates may be improved through the adoption of well-known valorisation strategies applied to other plant-based resources. In this context, this work innovates by assessing how treatments on oat husk surfaces and the choice of limestone-based binders impact the mechanical performance of composites. The strategy adopted to achieve these objectives, in addition to carrying out the physical and geometric characterisation of the husks, consists of treating the husks' surface using washing cycles in water, cement/pozzolan binder, and linseed oil. Furthermore, matrices combining cement, calcium hydroxide Ca(OH)2, and microsilica (SiO2) were used. In conclusion, even though the effects of different binder combinations are inconsistent, coating oat husks-especially with linseed oil-works well in delaying particle degradation and improving mechanical strength compared to untreated particles. Furthermore, when aggregates are substituted with the longer and lamellar particles of oat husk, the impact of the water/cement ratio on mechanical performance and composite workability significantly decreases.

Possible Options for Utilization of EU Biomass Waste: Pyrolysis Char, Calorific Value and Ash Content

The application of biomass as a co-feed in coal power plants and in standalone biomass power plants, as well as in char production for soil remediation, is a currently important issue. This paper reports on the investigation of biochar formation from agricultural waste crops that are used for soil upgrading, but which do not meet the standards of EU crops, as well as largescale food processing waste. These were compared to test results from basket willow, which is commonly used for energy generation. Food industry waste is often produced in cities on a large scale and is generally easier to process due to lack of other stream components. The key parameters, namely, the content of volatiles, energy content of the formed biochar and the composition of the ash, were determined for a number of herbaceous materials locally available in the European Union. All of them can be used as a cheap source of biochar. A novel procedure of capturing volatiles and hence minimizing the PAH content in the biochar, as well as enabling the recovery of energy from the volatiles is presented. Knowledge of the composition and form of elements in ash is very important for designing ash management systems if co-combustion is implemented. The aim of this study was to determine if the types of biomass are better suited for biochar production or energy generation.