While a high content of reclaimed asphalt in road construction is targeted, recycled bitumen has often undergone chemical and physical damages characterized as ageing. This can be counteracted with additives denoted as rejuvenators and by controlling the heating process during mix production. This study investigated the surface and base layers of three asphalt variants with different levels of reclaimed asphalt and rejuvenator. Asphalt samples were heated either through conventional heat conduction or through dielectrical heating using radio waves. Bitumen analyses included Ring-and-Ball, Needle Penetration, Dynamic Shear Rheometry and Fourier Transform Infrared Spectroscopy while asphalt performance was assessed by Cyclic Indirect Tensile Test. Ageing indicators were derived and correlated quantitatively, revealing high correlation among bitumen analysis results and lower correlation of asphalt analysis results. Some of the test methods explicitly supported the hypothesis that radio wave heating may induce a lower ageing than conventional heating combined with rejuvenation.

Today, the construction sector experiences significant pressure to use green and sustainable materials. In this framework, using biological components derived from agricultural products is the most interesting topic for the stability of asphalt pavement construction materials. Furthermore, the escalation in demand for transportation infrastructure has resulted in a rapid surge in the volume of traffic and premature degradation of asphalt pavements. The primary objective of this study is to assess the efficacy of olive kernel ash (OKA) obtained from olive canning factories in modifying the characteristics of asphalt. The investigation of this function has not been explored in prior research. To this end, a comprehensive analysis of morphological, Thermogravimetric, chemical, and phase separation was conducted, in addition to physical and rheological testing, over three distinct temperature ranges: high, intermediate, and low. The results showed that OKA is thermally stable and has a slow decomposition. Also, using OKA, compared to most biomass employed in bitumen, exhibits a satisfactory amount of phase separation. Despite the enhanced shear strength, the modified samples incorporating OKA do not encounter any operational challenges regarding transportation and pumping. The findings from the rheological experiments indicate that incorporating 20 % OKA in bitumen can increase the shear modulus up to 71 % and recovery percentage up to 20 %. Therefore, it significantly enhances the resistance to permanent deformation under high temperatures. The increase in molecular weight and asphaltene phase creates a resistant binder against high temperatures. Meanwhile, the fatigue life of modified samples containing 20 % OKA decreased to 59 %. However, applying the highest shear stress to the sample containing OKA experiences demonstrates its ability to resist this stress for longer. Also, it was found that regulating the OKA dosage in bitumen can maintain its acceptable resistance level to cracking at low temperatures. This phenomenon is due to the positive effect of OKA on the viscoelastic characteristics of bitumen. Based on our assessments, it has been observed that incorporating OKA up to 20 % in bitumen consistently enhances its performance capabilities at high temperatures. Nevertheless, while using this modified bitumen in cold regions, limiting its utilization to a maximum of 5 % is advisable.

Bitumen has been used in different forms and with various properties in pavement as a binder material. Meanwhile, the properties of soil-rubber mixtures (SRM) have been extensively examined for applications in geotechnical and highway engineering. These applications range from serving as a lightweight fill material, subgrade layers in pavement, and foundation materials for geotechnical seismic isolation (GSI). However, a research gap exists in understanding the effect of the interaction between bitumen and rubber granules on their mechanical properties under a range of confining pressures. In this paper, a series of unconfined compressive strength (UCS) and monotonic triaxial tests were conducted. The results show that a bitumen content as low as 3% of the total mass can significantly increase the shear strength and cohesion of SRM and reduce the deformability. Moreover, the increase in the elastic modulus due to a 3-5% bitumen content is notably less than the reduction obtained from 25% to 45% rubber replacement, which is favourable for GSI applications. The shear strength and elastic modulus in gravel-based mixtures were found to be more sensitive to changes in rubber and bitumen content compared to sandbased mixtures. Conversely, the effect of confining pressure was more pronounced in sandy soil than in gravelly soil.

Earthen houses are practiced as a traditional and low-cost housing in many countries around the globe. These houses were exposed to unacceptable earthquake (EQ) risks despite their environmental benefits. Past earthquakes including the recent past 2017 Tripura EQ has evidenced significant damages mostly in earthen/masonry houses which are built in a non-engineered manner. In this context, the current study aims to investigate the seismic behavior and failure patterns of both unreinforced and using proposed retrofitted rammed earth model houses (with and without openings) built using typical Tripura soils having higher silt content using unidirectional shake table experiments on total 26 physical models. Besides, both seismic strength and structural stability are also examined for retrofitted earthen houses. The study indicates that, proposed novel low-cost natural fiber made textile encasing reinforcement technique has exhibited promising seismic performance of such houses from the view point of structural strength and ductile behavior as compared to traditional cementitious additives and fiber blended stabilized retrofitted houses as well untreated houses. The fundamental lateral period of model unreinforced and reinforced houses found within the range of 0.08 to 0.15 s respectively which indicates increased stiffness of walls due to strengthening may decrease the lateral period maximum up to 46.67%. On the other hand, the maximum increase in seismic strength was observed in order of 4.50 to 6.31 times in the case of bitumen treated bamboo fiber textile based encased houses with L-shaped bamboo splint corner reinforcement whereas traditional cementitious stabilized method has offered maximum 1.13 to 1.83 times increment in lateral strength. Further, the effect of different parametric variations such as area of openings (doors and windows), thickness to height ratio, variation in compaction methodologies on seismic performances of unreinforced rammed earthen houses were also studied in detail. Finally, regression based closed form predictive expressions for seismic strength of rammed earthen houses and without retrofitting are proposed herein. The performed cost analysis study will also help to assess the effectiveness of proposed strengthening techniques.

The influence of bitumen coating on the development of unit shaft resistance along driven steel and precast concrete piles resulting from subsiding surrounding soft soil (gyttja) induced by fill placement at terrain was investigated. All piles were instrumented with conventional discrete-point vibrating wire strain gauges and distributed fibre optic sensors to achieve high-resolution strain measurements. The magnitude of the mobilised unit shaft resistance along uncoated piles was observed to be primarily related to an increase in effective stress resulting from the dissipation of excess pore water pressures. The unit shaft resistance along bitumen-coated piles was found to be primarily related to the rate of relative movement between pile and soil, which highlights the effectiveness of bitumen coating in reducing shaft resistance.

Introduction.The use of bitumen microdispersed emulsion as a resource-saving method for road surface construction is a popular trend in the development of innovative nanostructures. The technological use of petroleum bitumen as a binder for road materials requires a reduction in rheological viscosity. This can be achieved through synergistic developments that involve the use of various additives and modifiers. Methods and materials. The composition of bitumen microheterogeneous emulsions includes: bitumen-containing raw materials (up to 70-80% of mass); water with hardness up to 6 mg-eq/l (from 20 to 30%); emulsifiers (up to 3%) and other components. For large-tonnage production of water- bitumen emulsions, a colloid mill is the most technologically advanced equipment. Results. Water-bitumen emulsions are formed as a result of two competing processes: crushing (dispersion) and coalescence (merging) of microdroplets of the bitumen dispersed phase.The microheterogeneous bitumen phase is distributed in the aqueous dispersion medium in the form of microdroplets ranging in size from 1 to 10 mu m (the main share is made up of bitumen microdroplets with a diameter of 2-4.5 mu m). The synergetic durable microstructure of asphalt concrete road surfaces, which is formed by supplementing interaction in the boundary layers of the bitumen binder with the surface of the mineral component, is determined by the dominant interaction of complementary factors. Discussion. The synergetic approach to extending the service life of asphalt concrete road surfaces by using bitumen microdispersed emulsions holds promise for interpreting their evolution. The road construction industry of the Russian Federation at the beginning of the 21st century is characterized by a large-scale revision of regulatory documents, regulating the requirements for the construction and operation of highways. Conclusion.The optimal solution to the current problems of intensive construction and reconstruction of Russian highways is the improvement of technological characteristics of road surfaces by adding bitumen microdispersed emulsions to the composition. In complementary strengthening of weak soils of the road surface of high-speed highways, the use of water-bitumen microdispersed emulsions is also recommended.