Incorporation of high content of Reclaimed Asphalt Pavement (RAP) into fresh asphalt mixtures make them prone to thermal cracking and fatigue failure. Rejuvenators are usually recommended to overcome this problem by restoring the aged asphalt binder properties. This study aims to investigate the feasibility of using Mustard oil as a rejuvenator and to evaluate its effectiveness as a rejuvenator by determining the extent to which it restores the chemical and physical properties of aged asphalt binder extracted from RAP. The effect of Mustard oil on physical, rheological, chemical and thermal properties of aged asphalt binder was studied by employing Rotational Viscometer, Dynamic Shear Rheometer, Bending Beam Rheometer, Fourier Transform Infrared Spectroscopy, Thermogravimetric analysis, Gas-Chromatography-Mass Spectrometry and Rolling bottle equipment. Results indicated that Mustard oil effectively restores the properties of aged asphalt binder and can be used as a suitable rejuvenator. Ten per cent of Mustard oil is recommended as an optimum dose for rejuvenation of aged asphalt binder. This dose is based on restoring the RAP binder to match the properties of neat binder having PG64 and is specific to the stiffness of RAP material being used.

Matric suction is a crucial parameter that affects how unsaturated soils behave in terms of shear strength. Understanding it is essential for solving geotechnical problems like the stability of unsaturated soil slopes, foundations, embankments, and retaining walls. To investigate the shear behavior in unsaturated soil, a double cell triaxial test apparatus is used in the current research to carry out a series of triaxial compression tests under constant water content and constant void ratio conditions. Samples of silty soil, named DL-clay, were prepared with three different degrees of compaction: 80 %, 83 %, and 86 %, and water contents of 20 % (optimum water content) and 25 %. The soil samples were consolidated isotropically under net confining pressures of 300 kPa and 500 kPa before being sheared with constant volume. In another series of tests, water was infiltrated into the sample at 0 kPa deviatoric stress before the start of shearing with constant volume. Some specimens were also sheared with constant confining pressure for comparison purposes. From the test results, it is ascertained that maintaining a constant volume, i.e., constant void ratio during shearing, gives contour-like trajectories that can aid in defining the state boundary surface of unsaturated soil. It was also observed that within the axial strain range of 0–2 %, there was unusual behavior of a temporary sudden dip in the axial stress, which was more perceivable for samples having a high value of initial matric suction.

The presence of soil solids, water, and air complicates understanding unsaturated soil dynamics. A thorough understanding of unsaturated soil behavior is essential for the fruitful design of slopes, embankments, and retaining structures. A series of constant void ratio and constant confining pressure triaxial compression tests were carried out under constant water content conditions (pore air pressure drained and pore water pressure undrained) to study the shear strength and deformation characteristics of a partially saturated silty soil. Test specimens were prepared with a water content of 15%, 20% (Optimum water content), and 25%, with the corresponding degree of saturation of 37, 49, and 62.5%. The degree of compaction of all specimens was kept at 83% while the dry density was 1.29 g/cm3, and the void ratio was around 1.045. All the samples were isotropically consolidated under 500kPa by keeping deviatoric stress at 0kPa. The constant void ratio test results showed that the deviatoric stress reached a peak value followed by a sudden decrease within the axial strain of 0-1.5%. In contrast, the deviatoric stress increased continuously until reaching the critical state without depicting any peak for constant confining pressure tests. However, in both cases, the lower the water content at the time of specimen preparation, the higher the shear resistance.