Journal of Civil Engineering Beyond Limits (CEBEL)

Kenan Mert ÖKSÜZ İlker USTABAŞ Doğukan Diren

The effective use of concrete in underwater engineering applications requires optimization, especially in terms of washout resistance, workability and mechanical strength. This study analyzed the compressive strength development of underwater concrete in marine and freshwater environments to determine the effect of environmental factors on concrete strength. In this context, the same underwater concrete was poured on the Black Sea coast and in the İyidere Stream and underwater concretes on the shore exposed to air. Core samples were extracted from concretes cured in seawater, river water, outdoor air, and laboratory environments at 7 and 28 days. Their compressive strengths were then measured and compared. As a result of this study, it was determined that the compressive strength of underwater concretes exposed to Black Sea water and river water was higher than that of concretes cured in air. Despite the wave motion in the Black Sea and the river flow, the underwater concretes exhibited similar strength development, comparable to concretes cured in laboratory conditions.

https://doi.org/10.36937/cebel.2025.1994

Saad Issa Sarsam

Asphalt concrete pavement is usually subjected to heavy vehicular loading and environmental impact. The tensile strength of the pavement could be improved by reinforcement to withstand such loading impacts. This work presents a laboratory investigation to evaluate the change in the viscoelastic behavior, stiffness and deformation characteristics of reinforced Asphalt concrete pavement. Two types of nonwoven continuous fiber geotextile with two different thicknesses (Geofalt and Typer) have been implemented. Asphalt concrete mixtures were designed as per Marshall test requirements and prepared as per the requirements for binder course of SCRB with 19 mm nominal maximum size of aggregates. Circular asphalt concrete specimens of 152.4 mm diameter and 38.1 mm thickness have been constructed using optimum asphalt content, and static compaction to a target density. The specimens were coupled, and the geotextile reinforcements were introduced in between, then tested in a model box of (50 x50 x70) cm filled with loose sand layer of 40 cm thickness representing the poor subgrade condition. A total of 12 circular specimens have been constructed and tested in duplicate. The load – deformation data was plotted and analyzed for the deformation and stiffness characteristics. It was noticed that at failure, the load sustaining capacity of geotextile reinforced mixture at the end of the viscoelastic stage increased by 116 % as compared with the case of control mixture. It is higher than that of the control mixture by (29, and 35.4) % for Geofalt and Typer reinforced asphalt concrete mixtures respectively. However, the stiffness of asphalt concrete mixtures at failure had increased after implementation of geotextile reinforcement by (25, and 31.2) % for Geofalt and Typer reinforced mixtures respectively. It was concluded that implementation of the nonwoven continuous fiber geotextile is beneficial in enhancing the sustainability of asphalt concrete.

https://doi.org/10.36937/cebel.2025.11002

Saad Issa Sarsam

Grid reinforced overlays are considered for flexible pavement rehabilitation to ensure that the pavement condition can be maintained, with extended service life. This work evaluates the influence of two types of plastic biaxial geogrid reinforcement (AR-G and AR-1) on viscoelastic behavior of asphalt concrete in terms of stiffness, deformation, and load bearing ability. Asphalt concrete mixture for surface course layer was prepared. Circular asphalt concrete specimens of 152 mm diameter and 38 mm thickness have been constructed with optimum asphalt content, and static compaction to a target density. The overlay mixture was compacted over those circular specimens, and the Grid reinforcements were introduced in between, then, tested in a model box of 50 x50 x70 cm filled with loose sand layer of 40 cm thickness representing the existing subgrade. It was found that at failure, the load bearing capacity increased by (56.25 and 55.62) % for grid reinforced mixture with (AR-1 and AR-G) respectively as compared with the control mixture. Smaller aperture size and lower thickness of geogrid had furnished higher load bearing capacity for AR-1 geogrid as compared with that of AR-G geogrid. The stiffness of the grid reinforced asphalt concrete is higher than that of the control mixture by (56.2, and 62.5) % for AR-G and AR-1 geogrids respectively. It was concluded that implementation of the geogrids is beneficial in enhancing the sustainability of asphalt concrete. The obtained mathematical models of viscoelastic and viscoplastic failure stages can be used to predict the improvement in the properties of reinforced asphalt concrete.

https://doi.org/10.36937/cebel.2025.11005