Pavement inundation disrupts natural drainage, causing its structural damage and potential failure. This study investigates the impact of moisture fluctuations on pavement failure through four distinct approaches. Firstly, the critical strain at the top of the subgrade layer in unsaturated conditions was predicted using non-linear visco-elastic layer analysis. Secondly, structural number (SN) was established to evaluate the pavement strength under unsaturated conditions. Thirdly, the impact of rising groundwater levels on the structural strength of pavement layers was determined using maximum capillary height from soil suction. Finally, characteristic deflection and static moduli of the lateritic subgrade after a rainfall event were determined from field investigations with Benkelman beam deflectometer (BBD). Simulation in KENLAYER showed that the critical compressive vertical strain above subgrade due to different axle loading for bound and unbound granular layers varied with moisture fluctuation. Calculated SN values showed reduced capacity under saturated conditions compared to optimum moisture under the same traffic. BBD test revealed that the static moduli of the subgrade were lower due to increased moisture content, emphasizing the importance of moisture control and effective drainage for the structural integrity of pavements.

The use of geo-synthetics, such as geotextiles, has the potential to enhance the inherent engineering and geotechnical properties of subgrade soils that exhibit poor conditions. The use of geotextiles in pavement construction has many advantages, including enhanced subgrade strength and the ability to construct flexible pavements that are both efficient and cost-effective since it reduces the pavement thickness. In the realm of flexible pavement system development, the significance of subgrade soils and their inherent characteristics, including permeability and strength, is well acknowledged. The study included conducting experiments to investigate the use of geo-polymeric materials like geo-textiles on improving the mechanical properties of the subgrade soils under varying moisture conditions. Geotextiles possess good tensile resistance as it is made up of good polymeric material like polyester, polypropylene and polyethylene. Geotechnical tests including grain size analysis, Atterberg limits, California bearing ratio test, and compaction tests, were conducted. CBR tests and UCS tests were conducted by placing the geotextiles in a singular arrangement at various depths and subjecting them to both soaked and unsoaked conditions to assess the soil's strength. The results demonstrate that the use of geosynthetic reinforcement in the soil effectively enhances the strength of the subgrade across various soil types. The optimal performance of geo-synthetics in relation to their placement inside the CBR mold was found to be at a distance of 1/3 of the mold's height from the top. This placement outperformed the alternative distances of 1/2 and 2/3 of the mold's height.

Recycled concrete aggregates (RCA), derived from demolishing concrete buildings and pavements, have been treated with significant value as a recycled resource. Using RCA instead of virgin aggregates for pavement construction became a feasible approach to conserve construction trash resources since approximately 140 million tons per year were produced in the United States. This research conducted a life cycle cost analysis of stabilized clay subgrade soils in Kansas, USA, combining with RCA from pavements damaged by freeze-thawcycles and theD-cracks process. Class C fly ash and type II Portland cement were stabilizers for subgrade mixture designs. The performance of the mixtures was evaluated through Standard Proctor, unconfined compression strength (UCS), and California Bearing Ratio (CBR) tests. The full-depth flexible pavements incorporating these stabilized subgrades were designed using the AASHTOW are Pavement ME Design (PME) software. Results indicated that a 1:1 mix of Class C fly ash and type II Portland cement was the most effective stabilizer, decreasing the required thickness of the hot-mix asphalt (HMA) layer. The life cycle cost analysis demonstrated that the RCA-stabilized subgrades are economically viable when the chemical stabilizers are used in equal proportions.

This paper reviews works on the dynamic analysis of flexible and rigid pavements under moving vehicles on the basis of continuum-based plane strain models and linear theories. The purpose of this review is to provide information about the existing works on the subject, critically discuss them and make suggestions for further research. The reviewed papers are presented on the basis of the various models for pavement-vehicle systems and the various methods for dynamically analyzing these systems. Flexible pavements are modeled by a homogeneous or layered half-plane with isotropic or anisotropic and linear elastic, viscoelastic or poroelastic material behavior. Rigid pavements are modeled by a beam or plate on a homogeneous or layered half-plane with material properties like the ones for flexible pavements. The vehicles are modeled as concentrated or distributed over a finite area loads moving with constant or time dependent speed. The above pavement-vehicle models are dynamically analyzed by analytical, analytical/numerical or purely numerical methods working in the time or frequency domain. Representative examples are presented to illustrate the models and methods of analysis, demonstrate their merits and assess the effects of the various parameters on pavement response. The paper closes with conclusions and suggestions for further research in the area. The significance of this research effort has to do with the presentation of the existing literature on the subject in a critical and easy to understand way with the aid of representative examples and the identification of new research areas.