To overcome the problems of segregation between the rubber particles and the asphalt binder in the crumb rubber modified asphalts (CRMAs) different solutions were tested, including the establishment of chemical bonds between the different components of CRMA and the asphalt materials. In this research, a chemical method was employed to treat variously manufactured (ambient and cryogenic grinded) crumb rubbers’ surfaces in order to graft functional groups and improve bitumen-rubber compatibility and reduce segregation. In general, 400 g of crumb rubber was heated to 80±2°C and was continuously stirred with 100.1 ml of hydrogen peroxide and 90.1 ml of FeSO₄ for 30 min. Then the activated crumb rubber was processed into asphalt for 60 min at 177±2°C. Hydrogen peroxide treatment significantly reduced phase separation; it produced even more stable suspension when FeSO₄ catalyst was employed. The surface differences of cryogenic and ambient grinded rubbers resulted differences in the flow properties, especially in shear elasticity.

Hot water activation of crumb rubber has been suggested as a method of improving compatibility between crumb rubber and asphalt binder. This procedure removes light oil fractions present in the crumb rubber particles, thus decreasing segregation occurring between rubber particles and binder. For this research, a PG 64-22 binder was modified with four different crumb rubber sources at concentration of 15% by weight of binder. Binder properties were evaluated for virgin binders, water-activated crumb rubber-modified (CRM) binders, and for non-activated CRM binders. CRM surface morphologies were studied using a scanning electron microscope, molecular size distributions of modified binders were determined using gel permeation chromatography, while storage stability was evaluated by cigar tube testing. Rheological properties of the CRM binder were investigated; improved phase separation properties were observed following water activation, however, these improvements did not result in improved rheological properties of the activated CRM binder.

As a potential approach for enhanced energy generation from anaerobic digestion, iron-based conductive nanoparticles have been proposed to enhance the methane production yield and rate. In this study, the impact of two different types of iron nanoparticles, namely the nano-zero-valent-iron particles (NZVIs) and magnetite (Fe₃O₄) nanoparticles (NPs) was investigated, using batch test under mesophilic conditions (35 °C). Magnetite NPs have been applied in doses of 25, 50 and 80 mg/L, corresponding to 13.1, 26.2 and 41.9 mg magnetite NPs/gTS of substrate, respectively. The results reveal that supplementing anaerobic batches with magnetite NPs at a dose of 25 mg/L induces an insignificant effect on hydrolysis and methane production. However, incubation with 50 and 80 mg/L magnetite NPs have instigated comparable positive impact with hydrolysis percentages reaching approximately 95% compared to 63% attained in control batches, in addition to a 50% enhancement in methane production yield. A biodegradability percentage of 94% was achieved with magnetite NP doses of 50 and 80 mg/L, compared to only 62.7% obtained with control incubation. NZVIs were applied in doses of 20, 40 and 60 mg/L, corresponding to 10.8, 21.5 and 32.2 mg NZVIs/gTS of substrate, respectively. The results have shown that supplementing anaerobic batches with NZVIs revealed insignificant impact, most probably due to the agglomeration of NZVI particles and consequently the reduction in available surface area, making the applied doses insufficient for measurable effect.