Abstract: After the construction of the Pinglu Canal, the operation of the ship lock induces saltwater intrusion into the Qingnian Reservoir, threatening the drinking water supply of Qinzhou City. Despite its significance, studies on the dynamics of low?salinity and non?tidal saltwater intrusion in large artificial canal?reservoir systems remain limited. This study therefore establishes a three?dimensional hydrodynamic and salinity transport numerical model validated against field measurements and laboratory experiments, with discrepancies of less than 0.05 m for water levels and 4% for salinity transport, to systematically investigate the spatiotemporal evolution of saltwater intrusion in the Qingnian Reservoir.This work provides novel insights by quantifying the relationship between upstream inflow and intrusion distance, and by deriving specific operational criteria for drinking-water safety based on stratification analysis.The results show that saltwater intrusion displays a distinct salt?wedge pattern, with the bottom saline layer intruding up to 7.54?km. The maximum intrusion distance is positively correlated with the salinity boundary at the upstream approach channel and negatively correlated with upstream inflow. Specifically, a 411% increase in runoff (from 21.8 to 111.3 m³/s) reduces the intrusion distance by 70% (5.36 km), indicating that higher upstream discharge effectively suppresses the upstream advance of saltwater.Density?driven vertical salinity stratification develops, with the stratification coefficient increasing along the intrusion path. Specifically, safety?margin analysis confirms that under upstream salinity?boundary conditions of 1‰ to 3‰, the use of surface water intakes can reliably maintain output salinity within permissible limits. The research results provide a theoretical basis and technical support for the water resource safety of large?scale estuarine canal projects. Keywords: Pinglu Canal; Saltwater intrusion; Salinity stratification; Numerical simulation.

As a foundation solution for offshore wind turbines, suction bucket foundations offer significant advantages in resisting high-intensity horizontal loads induced by wind and waves. This paper systematically reviews the research progress on the horizontal bearing behavior of monopod and tripod suction bucket foundations. It summarizes the methods for determining the ultimate horizontal bearing capacity, the variation pattern of the rotational center position, the failure modes, and influencing factors for monopod foundations. The applications and limitations of analytical methods, including the limit equilibrium method, limit analysis method, and subgrade reaction methods are critically discussed. Subsequently, the current research status on the pile group effect of tripod suction bucket foundations, the variation patterns of bearing capacity with spacing and load direction, as well as layout optimization, has been reviewed. Conclusively, the paper identifies existing research gaps, such as the influence of drainage conditions in silty clay, the lack of robust theoretical calculation models for the bearing capacity of tripod foundations, and insufficient research on the bearing mechanisms of non-standard tripod configurations. Recommendations for future research directions are provided.

Electric Arc Furnace Slag (EAFS), an eco-friendly waste obtained from steel making, serves as the main binder, reduce environmental harm and advance sustainability. The purpose of this research is to provide the findings from the factory in Misurata City, Libya, using EAFS. The percentages of EAFS that can be used to replace ordinary Portland cement (OPC) in the production of chemical mortar are 0%, 5%, 10%, 15%, 30%, 60%, 80%, and 100%. With a (R=Na2SiO3/NaOH) of 0.5, NaOH (NH) concentration of 2, 4, 6, and 8M were used. The ratio of binder (B) to total liquid (TL) is 0.44. Alkaline-activated solutions mortar's (AASM) physical properties, such as its density and spread flow test, have been studied. Compression and flexural behavior strength are also measured after 28 days of drying in plastic sacs at 30°C. The results demonstrate that the optimal ratio may be 15% EAF slag. Since EAFS requires a higher curing temperature than ground granulated blast furnace slag (GGBFS), increasing the NH molar 2M-8M enhances fluidity and reduces density, but it also reduces the compressive strength of AASEAFS mortar. The presence of compounds like tricalcium silicate (C3S), tricalcium aluminate (C3A), and calcium aluminate ferrite (C4AF) affected the cementitious properties of the slag. The interactions between the OH- ions and the Ca2+ ions may products Portlandite (Ca(OH)2) then insufficient calcium silicate hydrate (C-S-H) or calcium-sodium aluminosilicate hydrate (C-(N)A-S-H) gels, though, because decreased Ca2+ ions and Na+ ions of EAFS. The mortars' strength and structure are significantly impacted by this effect.

Scour around bridge piers due to flooding is the leading cause of bridge failure. Numerous numerical and experimental studies have investigated local scour under various sediment properties, pier geometries, and hydraulic conditions. In this paper, we present the results of an experimental study on the influence of sediment grain-size distribution and disposition on local scour around a circular bridge pier. The study aims to qualitatively evaluate how various factors, particularly grain size distribution and sediment disposition, affect local scour in open-channel flow. Four factors were tested: flow rate, channel slope, grain size distribution, and sediment disposition. Results show that both sediment properties and their arrangement significantly impact the maximum scour depth. While channel slope also affects local scour, its influence is less pronounced than that of flow rate. The most significant changes in scour volume are attributed to sediment disposition in the channel. These findings highlight the critical role of sediment composition and arrangement in bridge pier scour mitigation and provide valuable insights for riverbed protection and hydraulic structure design.

The possibility of the synergic occurrence of the chemical and physical modes of sulfate attack at the evaporating front is one of the un-resolved issues concerning the case of the partially immersed concretes. Some of the past studies put the accent on chemical sulfate attack as the dominant mechanism, while others identified physical sulfate attack responsible for the degradation of the evaporating front. To fill out this knowledge gap and distinguish the dominant mechanism at work, the presented study focused on the role of climatic condition. Accordingly, visual characteristics, phase composition, and ultrasonic pulse velocity of the immersed and upper-dry regions of the partially immersed concretes in Na2SO4 solution were analyzed under different climatic cycles. The designed cycles offered low and high evaporation rates, allowing the thenardite/mirabilite transitions in the Na2SO4.nH2O system. It was found that regardless of the evaporation rate, the mechanisms of physical sulfate attack were favored over the chemical ones. Furthermore, the differences in the evaporation rates of the environments determined the location of the physical sulfate attack. Under high evaporation rate, such aggression was realized beneath the mortar layer of the concrete, leading to its internal microcracking and spalling.

The use of steel material has increased in developing countries causing surges in prices and affecting the environment. Researchers are endeavouring to find better and eco-friendly materials like bamboo as a better alternative to be used as reinforcement in concrete construction. This research purpose is to examine bamboo as a reasonable substitute for conventional steel serving as a reinforcement in concrete beams. Nine concrete cubes and prisms, and nine Bamboo-Reinforced Concrete Beams (BRCB) designed are subjected to compression testing. For longitudinal reinforcement, T12 steel rebars are utilized while for shear reinforcement R3 bars are used. Also, Bamboo-Reinforced Concrete Beams BCRBs are experimented with using longitudinal bars having a diameter of 20 mm and 8 mm thick steel bars. The results obtained show that bamboo is a viable alternative material and can be efficiently used as reinforcement in concrete beams in place of steel bars average strength is 34 Mpa. However, bamboo poles should be utilized in concrete construction rather than using bamboo slats because of severe durability concerns. There is a need to further investigate bamboo material to enhance its strength and durability while it is being used as a reinforcing material in concrete beams. This could be done by improving the treatment processes, examining the composite materials, or exploring new ways to improve bamboo efficiency and lifespan in concrete construction.

It has become essential to recycle materials to create a sustainable environment, the application of using brick dust and glass powder leads to the reduction in the emission co2 and environmental landfills caused by the production of cement, disposal issues relating to solid waste, and demolished structures. The outcome of this research observes that the use of brick dust and sawdust in concrete helps in reducing the cost of the product, decreasing the amount of emitted CO2 as well as providing a way for environmental byproducts to be reduced by utilized for better sustaining of the ecosystem. In accordance with this study the evaluation of several properties of concrete was determined, the properties include compression test, split tensile test, compacting factor, slump for workability, density in the fresh and hardened state, and the ultrasonic pulse velocity of the concrete. The study used 10% brick dust as cement substitute and 5% by volume as substitute for fine aggregate. The outcome shows that the incorporation of brick dust increases the compressive strength and tensile strength, reduces workability, and has excellent quality of compactness which is 0.91, the compacting factor of just sawdust is seen to be 0.86, sawdust reduces the strength of concrete, and can be almost designated as light concrete due to the low density obtained and when both materials are added in one concrete the properties values as they have a different effect on the concrete separately. Overall, the application of this material in the same concrete as replacement proves beneficial and can be applied for construction.

The bond mechanism between concrete and steel is an important input parameter in the design of reinforced concrete elements. The reuse of waste materials as aggregates in concrete has led to the discovery of different types of concrete with unique bond characteristics. This paper reports on the bond characteristics of concrete produced from waste automobile tire chips and palm kernel shell aggregates and deformed mild steel rebars. A total of 125 concrete cubes (150 x 150 x 150mm) with metal inserts were cast from 21 concrete mixes with varied content of PKS and waste automobile tire aggregates. Pullout test was carried out to evaluate the strength of the bond mechanism between the steel and the various concrete mixes. The results revealed that bond strength decreased with increasing PKS and tire content. Moreover, increasing the bar size and embedment length reduced the bond stress. The ratio of the bond stress and compressive strength was found to be averagely 63.88%. Regarding the bond failure mechanism, it was identified that failure of the specimen occurred through either rebar pullout or tensile splitting of the concrete. Based on the results obtained, it was concluded that PKS and tire can be used as partial replacement of granite aggregates in concrete since the resultant concrete can develop adequate bond with steel bars in structural applications.

This work consisted in characterizing of calcined laterite and oyster shell powder based blended geopolymer binders. To do this, raw laterite taken from Soa in the city of Yaoundé and oyster shells extracted from Mouanko in the Sanaga-Maritime were initially air-dried, then dried at 105 °C, before being calcined at 500 °C and 200 °C respectively for 2 hours. These samples were subjected to preliminary studies, i.e. determination of their chemical and mineralogical compositions, particle size distributions, densities, as well as thermal analysis for the synthesis of geopolymer binders. X-ray diffractometry, thermal and gravimetric analysis were carried out on the oyster shell powder and laterite, in order to elucidate the time and degree of calcination of the two samples, the evolution of the linear shrinkage, the setting time as well as the compressive and flexural strengths of the geopolymer binders. The results obtained show that oyster shells are rich in CaCO3 and contain crystalline phases, while laterite is rich in silica, iron (FeCO3) and alumina (Al2O3). The geopolymer samples: Lat + 0% oyster shells have a setting time between 125 and 168 min for a compressive strength of about 47 MPa. The peak strength is observed around 15% addition of oyster shell powder, i.e. 53.5 MPa at 28 days with an increased setting time. This strength was decreased from 25 % of addition of oyster shells, despite the increase observed in the setting time. It appears from this study that the addition of 15% oyster shell increases the compressive strength of the geopolymer, but also leads to a considerable decrease in absorption rate. Above this rate, the compressive strength decreases drastically and concomitantly the setting time increases.

Ground Granulated Blast-furnace Slag (GGBS) and Pulverised Fuel Ash (PFA) were used to replace up to 60% of Portland cement (PC) in concrete. The testing program of the concrete included the determination of the consistency of fresh concrete, the measurement of the density and compressive strength of the hardened products cured for up to 56 days and the evaluation of their durability via visual inspections and strength loss calculations after the freeze and thaw cycles. The results showed that the blend proportion and type had affected the consistency of the fresh concrete. Replacing the PC with 20% for PFA or 40% for GGBS had similar performances as the control mix. The durability of concrete subject to freeze and thaw had little effect on the concrete specimens. It was observed that the concrete without blends suffered the worst, resulting in chips along the edges of the cube and scaling of the faces compared to mixes with 20% GGBS and 20% PFA which resulted in increased durability. However, blended concrete exhibited more loss in strength compared to the concrete without cement blends.