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Aggregate base stabilization has been widely employed for composite pavement applications with different cementitious admixtures. These mineral inorganic materials are of different types, like commercial chemical admixture (CCA) or supplementary cementitious materials (SCMs). The current study presents a comparative analytical study to evaluate the performance of these admixtures for cementitious stabilized aggregates (CSA). Four admixtures, viz. two CCA (Ac-I and Ac-II), and two SCMs (fly ash and slag) were chosen along with cement to evaluate mechanical strength via Unconfined Compressive Strength (UCS), and Modulus of Rupture (MoR), microstructural properties via Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), scanning electron microscope (SEM), and Thermogravimetric analysis (TGA) for these admixtures, impact on the composite flexible pavement design and costs. Statistical One-way ANOVA test was conducted to determine differences in their strength development at 7 and 28 days. The addition of admixtures showed an increased degree of hydration reaction in the case of CCA and SCMs, and increased strength development in the case of SCMs, while it reduced in case of CCA at 28 days. Composite pavement design for these admixtures revealed a slight benefit of using CCA in terms of reduction of pavement layer thickness, while the minimum thickness of the bituminous layer increased for SCMs by 5 mm. Admixtures were able to resists tensile stresses due to early construction traffic plying after seven days on a short-cured CSA layer in line with cement. Application of SCMs resulted in savings of up to 16% in the cost of the CSA layer, while the cost increased by up to 30% on the application of CCA.

The ascending requirement of railway passengers for fast transit to distant stations has led to the development of high-speed railway networks. Faster and longer trains with heavy axle loads are in operation, inducing stronger ground vibrations in the supporting railway infrastructure. The conventional design of railway track structures are based on the maximum displacements safely allowed in the track under the expected railway loads. However, the vibrations generated in the tracks due to railway operations should also be of concern. This study characterizes the peak particle velocities (PPVs) generated in the component strata of a ballasted railway embankment during high-speed train transit within 160 to 200 km/h. The transient response of each strata is characterized for transit of wheel load in the vibration influence zone, and temporal variation of PPVs have been logged for the transit of wheel load through a distance of 30 m on the railway track. The results from the present study indicate that railway track embankments are subject to strong ground motions during high-speed train transit, which will lead to accelerated degradation of the track structure. Ground vibrations are remnant in the railway embankment, even after passage of train wheels to farther distances. Deployment of vibration mitigation measures are recommended in sensitive locations proximate to railway lines. The particle velocities quantified in this study can be utilized by railway design authorities for estimating ground-borne railway vibrations under multiple train wheel configurations, based on the axle spacing, bogie spacing and the depth of the track under consideration.

Retaining wall with relief shelves is being increasingly adopted to provide an economical and sustainable solution for earth retention purposes. The current study aims to evaluate the effectiveness of relief shelves in mitigating lateral thrust on a rigid, non-yielding retaining wall subjected to static surcharge loading. A comprehensive numerical parametric analysis was performed using the finite difference method to determine the optimal number, width, and position of the relief shelves for a given wall height and uniform static surcharge. The findings demonstrated that the width and position of the relief shelves substantially influence the lateral earth pressure caused by the surcharge on the wall section above the relief shelf and the backfill surface settlement profile. Consequently, the implementation of relief shelves can be considered a viable method for reducing lateral thrust on rigid, non-yielding retaining walls, as long as the parameters are optimized in accordance with the results of this study.