Concrete pumping, integral to building construction, governs pipeline durability and overall construction efficiency. This study advances the traditional methods by employing the CFD-DEM coupling technique, a pioneering approach that integrates the irregular shape of coarse aggregates, capturing the intricacies of concrete pumping in pipelines. Beyond identifying primary wear areas and quantifying wear magnitudes, this research unveils a quadratic progression in average wear over time. The most pronounced wear appears in the pipeline’s bent sections. Notably, pumping speed, more influential than aggregate volume fraction, is pivotal to pipeline wear. Minimized speeds increase blockage risks, notably at elbows, while augmented speeds intensify wear. An optimal speed range between 2 and 3 m/s is deduced. Additionally, as the aggregate volume fraction surges, wear amplifies and blockages frequent. Hence, an aggregate volume fraction between 15 and 20% emerges as the recommendation. Therefore, it is widely used in the construction fields such as houses, bridges, and roads. However, with the escalating utilization of concrete pump trucks and pipelines, certain challenges associated with pipeline wear have emerged6. In the process of concrete transportation, the long-term impact of aggregate will lead to the easy wear of the transportation pipeline. The light wear of the pipeline will lead to concrete leakage, while the heavy wear will affect the pumping efficiency and safety of the whole transportation pipeline. Meanwhile, in the process of concrete transportation, it will inevitably lead to the loss of pumping pressure. If the pressure loss is large, it will easily lead to serious problems such as bleeding and segregation, and coarse aggregate congestion9. Therefore, the research on concrete pumping has important theoretical significance and practical values.With the rapid development of infrastructure construction in China, the concrete pump truck has a series of functions such as high construction efficiency, drivability, and pumping10 constructed a dynamic monitoring system for the stress and strain of the pumping pipeline, and continuous experimental monitoring is carried out on the strain data of the pipeline under real pumping conditions, and the dynamic strain data of each measuring point of the pipeline are obtained. The results indicated that the circumferential strain and axial strain of the pipeline show obvious periodic changes with the piston stroke movement, and the circumferential strain is significantly greater than the axial strain, and the circumferential strain and axial strain gradually decrease with the pumping length extension. Chen et al.11 tested the working performance and viscosity change of concrete in a super-long pipeline by horizontal coil, and the pressure change along the pipeline was also detected. The results showed that the slump spread of self-compacting concrete before and after pumping through the horizontal pipeline lost 12 cm, the plastic viscosity decreased by 82%, the yield stress increased by 86%, and the average pressure drop in the horizontal pipeline was 0.012 MPa/m. Jacobsen et al.12 explored the flow changes of different materials  on the cross section of the pipeline are investigated. The results show that the flow velocity is the largest near the center of the pipeline, while the flow velocity at the wall of the pipeline is lower. Wu et al.13 developed field detection equipment for concrete pumping viscosity resistance, which can quickly and accurately detect the pumping resistance of concrete. The results show that the higher the label of high-strength and high-performance concrete, the greater its adhesion coefficient and velocity coefficient, indicating that the greater the pressure required for concrete to flow from a static state in the pipeline. In addition, the greater the friction resistance between concrete and the pipe wall with the increase in pumping speed, which provides a basis for the optimal layout of the transportation pipeline. Wu et al.14 explored the influence of silica fume, admixture, and fiber lamp components on concrete pumping through experiments. The results show that the increase in steel fiber infiltration obviously affects the working performance of high-strength concrete. The plastic viscosity of ultra-high-strength concrete mixture decreases with the increase of bead infiltration, and the effect of the viscosity reducer is not as good as that of high-permeability beads, which provides technical guidance for the high-performance design of high-strength concrete and promotes the large-scale application process of high-strength pumping concrete.For concrete pipeline transportation, many researchers at home and abroad have done many experiments. Ye15 employed the SPH (smoothed particle hydrodynamics) approach to simulate the rheology of concrete. SPH, an advanced computational fluid dynamics method, relies on inter-particle interactions rather than a fixed computational grid, making it apt for simulating fluid flows with intricate boundaries and significant deformations. In his study, both the slump test and L-box test of concrete were simulated, with the Bingham model serving as the material constitutive model for concrete. The close alignment between the simulated outcomes and experimental results underscores the feasibility of this numerical method in assessing the flow properties of concrete. Tan et al.16 established the discrete element model and predicted the distribution of pipe wall wear. The results show that the pipe wall wear increases rapidly with the increase of pumping speed and steadily with the increase of elbow angle. Based on the on-site coil pumping experiment, Li et al.17 simplified the concrete into two-phase flow, and the flow characteristics of concrete in the conveying pipe are simulated, and compared with the experimental results and theoretical calculation results of the coil. It is found that the pressure loss value is basically consistent, which verifies the effectiveness of the computer numerical simulation results. Using PFC2D software, Wang18 simulated the pressure loss of concrete in different conveying pipes by discrete element method, and the movement law and stress characteristics of concrete are studied. The findings show that the numerical simulation results of horizontal straight pipe are different from those of code, but the law is consistent, and the numerical simulation results of conical pipe are 2–3 times that of horizontal straight pipe. Yuan and Guo19 proposed a new elliptical particle model of concrete. Jiang et al.20 employed the CFD-DEM coupling technique to simulate the pumping process of fresh concrete in various pipelines. This method utilizes CFD to represent fluid dynamics and adopts DEM to model solid behavior, rendering it suitable for analyzing intricate flow regimes where particles and fluids are concurrently present. He also investigated the influence of varying pipeline structural Parameters and inclination angles on pressure loss. Taking the minimum pressure loss as the goal, the objective function of pressure loss is established, and an optimization method based on the CFD-DEM coupling model and the single objective optimization algorithm is proposed. The results show that the pressure loss of the pump truck conveying pipe is reduced by 5.45% and the average velocity of coarse aggregate at the outlet of the pipeline is also reduced under the optimization model.Due to the development of computer technology and the improvement of numerical algorithms, many researchers also use numerical simulation to study the fluidity of concrete. Wu et al.To summarize, given the diversity of concrete types and the complexity of its constituents, existing studies employing numerical simulations for concrete pipeline pumping often overlook the rheological properties of concrete or the irregularities in aggregate shape, frequently relying solely on either two-phase flow or discrete element methods for simulations. While multiphase flow methodologies have been extensively adopted, they still face challenges, particularly in scenarios with high solid volume fractions, especially in capturing intricate interactions between particles and between particles and the liquid phase. Moreover, when applied standalone, the discrete element method (DEM) exhibits a pronounced sensitivity to model parameters; even minor parameter deviations can compromise simulation stability. A review of the current literature reveals that many studies focus on pressure loss in pipeline pumping, with a paucity of systematic investigations into wear issues or the effects of specific factors on wear. Accordingly, this study employs a CFD-DEM coupled approach, a novel methodology that accounts for the irregularities of coarse aggregate shapes. By conceptualizing concrete as a solid–liquid biphasic system of mortar and coarse aggregate, we simulate the flow dynamics of concrete within the conveying pipeline and subsequently evaluate pipeline wear and dynamic responses. This research not only introduces a fresh perspective from a methodological standpoint but also underscores the academic significance of systematically studying wear and its influencing factors. Through this integrated approach, scholars can delve deeper into the wear mechanisms during the concrete pumping process, especially under intricate flow conditions, thereby offering insights and guidance to optimize concrete pumping efficiency in practical engineering scenarios.21. They are as follows:αf, ρf, Uf, and pf are the volume fraction, density, velocity vector, and pressure component of the fluid, respectively. τ is the viscous stress tensor; g is the local gravity acceleration, taking the number of 9.81 m/s2; Fpf is the force exerted by all the rock slag on the fluid; T is the temperature, kT, and cP are the heat transfer coefficient and specific heat capacity of the fluid; and sT is the viscous consumption phase.The process of fluid flow and heat transfer follows the laws of mass conservation, momentum conservation and energy conservation, and their mathematical models are continuity equation, Navier–Stokes equation and energy conservation equation, respectively22. The Bingham model can be considered a simplified representation of fluid characteristics to some extent. While there are more precise models available, such as the H–B model, the Bingham fluid model is deemed appropriate when considering computational efficiency and the practicality of the model. The rheological equation is as follows:In nature, fluids can be divided into Newtonian fluids and non-Newtonian fluids. Water and air are the most common Newtonian fluids. Fluids such as propolis, asphalt, and concrete are non-Newtonian fluids, which often show different rheological properties from Newtonian fluids, and their rheological equations are also different. The commonly used rheological models of non-Newtonian fluids include the H–B model, power-law model, and Bingham model, and Bingham rheological model is adopted in this Paper20.Among them, the yield strength is 270 Pa and the plastic viscosity 23. The calculation formula is as follows:κ is turbulent energy, ε is turbulent dissipation rate, µt is turbulent viscosity, Gκ is turbulence kinetic energy caused by average velocity gradient, and Cε1, Cε2, Cu, σκ, and σε are empirical constants.Because of the existence of large irregular stones and high flow rate, the flow of concrete belongs to typical turbulence. The two-equation k–ε turbulence model proposed by Launder and Spalding is recommended to simulate turbulence24. They are listed as follows:mi, Up,I, Ii, and ωi are the mass, velocity, inertial motion and angular velocity of rock slag i, respectively. Fc,ij, Fd,ij, and Tij are the contact force, viscous damping force and torque between the slag i and other slag respectively. Fc,iw, Fd,iw, and Tiw are the contact force, viscous damping force and torque between the rock slag i and the inner wall of the slurry discharge pipe respectively. Ff,i is the force of fluid phase acting on rock slag i.In the process of pipeline transportation, rock slag is affected by other rock slag, mortar and pipe wall, which can be described by Newton’s second law of motion and the discrete element method originally proposed by Cundall and StrackConcrete is composed of coarse aggregate, mortar, admixture and other components, which are different from traditional discrete-phase particles, and its components are more complex. Therefore, when simplifying concrete, it can be roughly divided into coarse aggregate and mortar. Coarse aggregate mainly contains stones with different particle sizes, and mortar mainly contains water, fine aggregate and other materials. In EDEM software, coarse aggregate can be characterized by special-shaped particles, which is more in line with the actual working conditions, as shown in Fig. Its particle size is expressed by the formula as follows:Wherein, 20, three foundation contact Parameters of fresh concrete obtained by simulation are shown in Table According to Jiang et al.Common contact models are JKR model, Bond model and Hertz no slip model. In this Paper, Hertz no slip contact model is selected because of the coupling method of CFD-DEM.25:In order to explore the wear of conveying pipe, this Paper adopts the built-in wear model of EDEM software, that is, Archard-wear model. The idea of this model comes from the fact that the amount of material removed from the surface is proportional to the friction work done by particles moving on the surface, and its wear equation is as followsFB, drag FD and pressure gradient FP, and the formula for calculating the equal force of coarse aggregate is as follows:Up is the speed of coarse aggregate, µe is the effective viscosity of fluid, ρp is the density of coarse aggregate, and dp is the particle size of coarse aggregate. The Reynolds number Rep and drag coefficient CD of coarse aggregate are calculated as follows:Re is the Reynolds number of the fluid; a1, a2, a3 are constants, defined by Morsi and Alexander26. They are as follows:The interaction force between coarse aggregate and mortar is mainly composed of buoyancy 27, the number of divided grids is 8641, as shown in Fig. In this Paper, Hypermesh software is used to mesh the geometric model of transportation pipeline, and the global mesh size is set to 20 mm3, the inlet condition is set to 3 m/s, the turbulence is set to intensity and Hydraulic Diameter, the turbulence intensity is 5, and the hydraulic diameter is set to 0.133 m. The outlet condition is set as pressure outlet, and the pressure value is 0, that is, it is connected with atmospheric pressure, and the turbulence setting is the same as the inlet condition. The wall attribute is set to non-slip wall to simplify the calculation. Transient calculation is adopted in the computing environment. Considering the gravity acceleration in the y axis direction, the value is 9.81 m/s2. We select standard k-epsilon model.In fluent software, according to the actual pumping condition of concrete, the fluid density is 2100 kg/m3, and Poisson’s ratio is 0.25. The Young’s modulus of the pipeline is 2.1e+11 Pa, the density is 7850 kg/m3, and Poisson’s ratio is 0.3. A circular particle factory is set at the inlet of the conveying pipeline, with the particle generation rate of 16.2547 kg/s, the initial particle velocity of 3 m/s and the particle diameter of 5–10 mm.For EDEM software, the shear modulus of particles is 1e+08 Pa, the density is 2600 kg/m28. In this Paper, the fluent time step is set to 1 The setting of time step in CFD-DEM coupling calculation has an important influence on the accuracy of calculation results. The time step of fluid is generally 10–100 times that of solidFigure Figure In order to describe the movement state of concrete particles, all Parts of the conveying pipeline are named in this Paper, as shown in Fig. Figure Figure Figure Firstly, this study investigates the influence of varying pumping speeds on pipeline wear. When the particle volume fraction is 15%, the solid particle size is 8 mm, and the time is 2 s, the pipeline wear is simulated and analyzed at different initial pumping speeds, in which the initial flow rates are set to 1 m/s, 2 m/s, 3 m/s and 4 m/s, respectively. Figure From the above analysis of motion characteristics, it is concluded that the motion state of solid particles will change dramatically when they Pass through the elbow 3, which is the most obvious change compared with other positions of the conveying pipe. Figure Figure Subsequently, the study delves into the impact of different coarse aggregate volume fractions on pipeline wear. When the pumping speed is 3 m/s, the particle size of coarse aggregate is 8 mm and the simulation time is fixed at 2.9 s, the wear of conveying pipes with different volume fractions of coarse aggregate is numerically simulated and analyzed. The generation rate of coarse aggregate is related to the volume fraction and initial speed of coarse aggregate, so the volume fraction of coarse aggregate is expressed by changing the generation rate, and the volume fraction of coarse aggregate is set to be 10%, 15%, 20% and 25%, respectively. Figure 27. Furthermore, an increase in the volume fraction reduces the compressive strength, tensile strength, and flexural strength of the concrete29.Due to the material properties of concrete, an excessive volume fraction of aggregates can lead to stratification, while a deficient volume fraction can result in segregation and bleeding. Consequently, most existing studies on the variation range of coarse aggregates are conducted within the 10–25% range. Notably, wear is more pronounced at the bend locations in pipelines. The wear is also influenced by different bending angles of the bend pipe. However, even with varying bending angles, current research indicates that the wear rate increases in a quadratic function with the volume fraction, which is consistent with the findings of this studyFigure Figure During the pumping of concrete, the outer side and bottom of the bent pipe exhibit pronounced wear, with the wear amount increasing quadratically over time from 0 to 1.42E−06 mm. Therefore, enhanced inspection of these areas is recommended.In bent pipes, particles predominantly move along the outer wall, whereas their motion in straight pipes is more uniform.The wear amount is correlated with the initial pumping speed and the volume fraction of coarse aggregates. For optimal results, it is recommended that the initial pumping speed be set between 2 and 3 m/s, and the volume fraction of coarse aggregates be maintained at 15–20%.In this study, the CFD-DEM coupling approach was employed, considering the irregularity of coarse aggregate shapes, to simulate the concrete pumping process within conveyance pipes. The specific conclusions are as follows.While this study accounted for the irregularity of coarse aggregates, future research can further investigate the effects of different aggregate materials, shapes, grain sizes, and gradations on pipe wear and pumping efficiency.


This combination increased the concrete’s compressive strength by 12.5%, tensile strength by 48.4%, and decreased the average permeability height by 63.6%; (3) The collective introduction of these three materials notably augments the hydration reaction of the cement, resulting in denser concrete microstructure, enhanced bonding between fibers and matrix, and improved concrete strength and durability.This research paper systematically investigates the combined influence of fly ash, cementitious capillary crystalline waterproofing (CCCW) materials, and polypropylene fibers on the mechanical properties and impermeability of concrete through comprehensive orthogonal tests. Microscopic morphological changes in the concrete induced by different composite materials are examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) testing. The objective is to facilitate a beneficial synergetic interaction among these materials to develop highly permeable, crack-resistant concrete. Key findings of this study are: (1) The study unveils the impact of the concentration of three additive materials on the concrete’s compressive strength, tensile strength, and penetration height, thereby outlining their significant influence on the mechanical properties and impermeability of the concrete; (2) An integrated scoring method determined the optimal composite dosage of three materials: 15% fly ash, 2% CCCW, and polypropylene fibers at 1.5 kg/m As transportation networks continue to develop and expand, the frequency and scope of tunnel construction projects are increasingly growing. Concurrently, various issues, such as lining leakage, concrete cracking, falling debris, structural cracking, and damage due to freezing drainage systems, are persistently emerging. Of these, the common problem of tunnel lining leakage is the most prominent , and it Currently, the primary method of tackling these issues involves designing an appropriate mix ratio, incorporating mineral admixtures and admixtures, which can enhance the impermeability and crack resistance of concrete structures. This approach aims to make the structure itself waterproof . StructuSeveral scholars have performed extensive research on the enhancement of concrete’s crack resistance by the addition of appropriate amounts of mineral admixtures to concrete mixtures. Zheng et al.  investig3 of polyvinyl alcohol fiber (PVA), 5 kg/m3 of imitation steel fiber (FST), and 32.8 kg/m3 of CSA expansive agent. This combination led to an 8.96% boost in compressive strength, a 28.2% rise in splitting tensile strength, and an 86.643% enhancement in impermeability. Liu et al. [3 to high-performance concrete containing fly ash and slag powder could improve the concrete’s waterproofing capabilities and increase polypropylene content. Zhang et al. [3, the permeability height of the concrete was reduced by 59.44% compared to standard concrete. In addition, numerous researchers have investigated the effect of adding permeable crystalline waterproof material on the impermeability and mechanical properties of concrete. For instance, Zheng et al. [Adding mineral admixtures to concrete can trigger autogenous shrinkage, making it necessary to incorporate a specific amount of admixtures into the concrete to enhance its various properties. Numerous researchers have pursued extensive experimental and theoretical investigations into the impermeability and crack-resistant properties of fiber-reinforced concrete, yielding many significant results. Desmettre, C, et al.  probed tu et al.  found thg et al.  exploredg et al.  comparedg et al.  introducg et al.  added a g et al. .In conclusion, numerous researchers have confirmed the beneficial effects of various concrete-reinforcing materials ,29,30,31Before employing the orthogonal design, it is essential first to devise the mix proportion of the benchmark concrete. Based on the benchmark mix proportion, the cement consumption is replaced by an equivalent quantity of fly ash and cementitious capillary crystalline waterproofing materials, ensuring the water–cement ratio remains consistent across all test piece groups. The benchmark concrete can also act as a blank control during the experiment, used to gauge the modification effect of each group of the samples in the orthogonal experiment. By calculating the benchmark mix ratio and carrying out trial mixing, the workability and mechanical properties of the concrete are ensured, forming a critical foundation for the entire experiment.The cement utilized for concrete pouring is P·O 42.5 ordinary Portland cement, and its physical performance indicators are detailed in Tunnel secondary lining concrete possesses unique attributes, including low strength, high fluidity, and superior impermeability . Unlike Owing to variations in the properties of raw materials, the mix proportion computed as per the specifications cannot be directly utilized for specimen preparation. It is crucial to conduct trial mixing for the calculated mix ratio, determining the final trial mix ratio to guarantee the concrete mixture’s workability and fundamental mechanical properties.A forced mixer with a 50 L capacity is used for concrete mixing, as illustrated in Through trial mixing, it was discovered that the concrete prepared according to the calculated mix ratio exhibited bleeding, necessitating adjustments to the calculated mix ratio. The first approach was to reduce the water–cement ratio while maintaining the same dosage of cementitious materials. However, it was observed that a decrease in water usage significantly impacts the concrete’s fluidity, yielding a slump value of only about 94 mm. The second approach was to increase the sand ratio, consequently increasing the concrete’s specific surface area, which, in turn, raises water demand and reduces free water content, all while maintaining the same slump. Through trial mixing, it was discovered that, after increasing the sand rate by 2%, the concrete mixture has good workability, and that the 7-day compressive strength was 32.3 MPa, satisfying the early strength and workability requirements of tunnel-lining concrete. Thus, the test mix of benchmark concrete can be established, as shown in Before undertaking the orthogonal design of experiments, it is essential to first define the purpose of the test, proposing test indicators to evaluate the quality of the test results for this purpose. This experiment’s objective is to simultaneously add different materials to concrete, enhancing the concrete’s impermeability and crack resistance for the secondary lining structure of tunnels. Three test indicators, namely, concrete compressive strength, splitting tensile strength, and penetration height, are proposed for this experimental purpose. Compressive strength ensures the lining structure’s load-bearing capacity, splitting tensile strength is a standard indicator for evaluating concrete’s crack resistance performance, and the penetration height of concrete can reflect its ability to resist water penetration.Upon determining the experimental indicators, the factors that may influence the experimental results and establish the corresponding levels are selected. Factor selection often requires a certain amount of practical experience and literature support. Through comprehensive analysis and a summary of existing research findings, this article selects fly ash as a representative material of mineral admixtures, polypropylene fibers as a representative material of fibers, and cementitious capillary crystalline waterproofing materials as a representative material of additives. These are selected as three factors to improve the concrete’s impermeability and crack resistance. Based on an exhaustive review of the pertinent literature, the corresponding levels of these three factors are established as shown in 9(34) orthogonal table is the most sensible choice for arranging the experiment. The mix ratio of concrete specimens is based on the C35 test mix ratio. To maintain a constant water–binder ratio, fly ash and permeable crystalline waterproofing agents are added to the mixture in equal amounts to replace the cement. The final mix proportions of nine sets of specimens and the benchmark concrete for the orthogonal experiment are shown in After determining the factors and levels of the orthogonal experiments, an appropriate orthogonal table can be selected for meter design. The orthogonal table should neither be too large nor too small. An overly large orthogonal table not only fails to significantly contribute to the experimental results but also impacts work efficiency, while a small orthogonal table may affect the experiment’s accuracy. Given that three factors and levels are involved in this experiment, the LThe pouring of concrete specimens also utilizes a forced mixer. Before pouring, the weight of each part of the material should be accurately measured, and the mixing mechanism is similar to that of the benchmark concrete. That is, the cementitious material, sand, and polypropylene fibers are first put into the mixer for dry mixing for 2 min to evenly distribute the fibers and avoid agglomeration; then, water is added and mixed for another 2 min to form cement mortar. Afterward, crushed stone and water-reducing agent are added and mixed thoroughly for 2 more minutes. After mixing, the mixture is poured into a mold, compacted using vibrating, and allowed to stand for 24 h. Then, the mold is removed, labeled with a number, and placed in a standard curing box for 28 days of curing. The mechanical properties were tested using 100 mm After 28 days of curing the concrete specimens, mechanical performance tests should be conducted promptly, and the test method should refer to the Standard for test methods of concrete physical and mechanical properties GB/T50081-2019 . The preThree concrete specimens with the same number form a group, and the average value is taken as the final compressive strength value. Since the specimens used in this experiment are non-standard specimens, the average compressive strength value should also be multiplied by a reduction factor of 0.95. The specific calculation method is carried out according to Equation (1).2).Among themThe tensile strength of concrete plays a significant role in its anti-cracking performance. In structural design, tensile strength is an important indicator for assessing the crack resistance performance of concrete, and it is also employed to evaluate the bonding strength between the concrete matrix and steel bars. The splitting tensile strength test is often used to determine the tensile strength of concrete. The “splitting tensile strength test” program in the press control system mentioned above is employed for the test, and the test equipment includes steel arc-shaped cushion blocks, plywood cushion strips, and straightedges. For C35 concrete, the loading rate should be between 0.05 MPa/s and 0.08 MPa/s , and 0.0The tensile strength value of concrete is also taken as the average of three specimens, and, for non-standard specimens, a reduction coefficient of 0.95 should be taken. The calculation method should be carried out according to Equation (2):2).Among them, This study uses a YC-HS4.0 intelligent concrete impermeability tester to measure and conduct experimental research on impermeability performance. This instrument has a maximum allowable working pressure of 4.0 MPa, and the pressurization method is automatic. Six specimens can be tested at once. The steel mold size is 175 mm in diameter at the upper mouth, 185 mm in diameter at the lower mouth, and 150 mm in height, complying with the requirements for the number and size of specimens in the Standard for the test methods of the long-term performance and durability of ordinary concrete GB/T50082-2009 .When using the penetration height method for testing, first, remove the specimen from the curing box and wipe it clean. Then, seal the specimen. Due to environmental concerns and the operational complexity associated with using paraffin as a sealing method, an alternative approach using rubber rings and glass glue was utilized in this study. Firstly, the rubber ring is placed at the upper and lower positions of the test piece. Then, glass glue is applied to the position of the rubber ring. Finally, use a press to press the test piece into the steel mold and let it sit for 12 h to complete the sealing. The operation process is shown in After the sealing is done, the testing can commence. Before installing the test piece, open the six water valves to fill the test tank with water, hence discharging the gas from the water pipe and test tank. During the installation of the test piece, ensure the screws are tightened properly to maintain the sealing of the entire instrument. At the beginning of the test, set the water pressure to 1.2 MPa and observe if there is any seepage around the specimen. If seepage is observed, the specimen should be removed and resealed. Close the outlet valve after a set of six specimens have undergone 24 h of exposure to 1.2 MPa water pressure, hence concluding the test. Subsequently, use a press to split the penetrated concrete specimen along its centerline, mark the water stains with a waterproof pen, and evenly divide the water stains into ten equal parts. Then, measure the penetration height and calculate the average value. The operation process is shown in The calculation of permeability height is carried out according to Equations (3) and (4):In the equation, After calculating the penetration height of each group of specimens, the relative permeability coefficient can be determined based on the water pressure and penetration time. This coefficient represents the impermeability of the concrete. The smaller the relative permeability coefficient, the stronger the concrete’s ability to resist liquid penetration. The calculation method is as follows :(5)SK=mDAmong them, The beauty of orthogonal experiments lies in their ability to carry out a comprehensive analysis using a minimal number of tests, thereby revealing the significant impact of various factors on the experiment indicators when they interact. The methods of analysis encompass range analysis and variance analysis.Compared to conventional C35 concrete, the compressive strength of concrete mixed with modified materials typically produces an enhancement. Notably, the strength of L2 concrete exhibits the highest surge of 28.8%, suggesting that the amalgamation of fly ash, polypropylene fiber, and CCCW contributes positively to the growth of concrete strength. Nevertheless, in the realm of orthogonal experiments, a mere comparison of each group of samples is not sufficient. It becomes imperative to perform range analysis and variance analysis on the experimental outcomes to decipher their inherent patterns of influence. 2 produced by the cement hydration reaction, generating denser hydrated calcium silicate and hydrated calcium aluminates, thereby elevating the structural strength. Moreover, the diminutive particles of fly ash augment the aggregate’s specific surface area, enabling the mix to have sufficient mortar to fill the pores between the coarse and fine aggregates. This plays a lubricating role, enhancing the mix’s workability and ultimately increasing the concrete’s strength, a phenomenon referred to as the micro aggregate effect of fly ash. The morphological effect alludes to the fact that most fly ash particles are spherical, with a smooth surface and minimal pores. This structure decreases the mix’s water demand, heightens its fluidity, and facilitates easier compaction of the concrete. It was found that the addition of fiber [When it comes to compressive strength, the three factors’ impact on the test results is primarily and secondarily ordered as A > B > C. This implies that the quantity of fly ash has the most substantial effect on the strength of the concrete, while the influences of polypropylene fiber and CCCW on compressive strength are not significant. The strength enhancement of concrete due to fly ash can be attributed to three factors: the volcanic ash effect , the micof fiber , shrinkaof fiber  to concrp-value of factor A is less than 0.05, indicating that the amount of fly ash has a notable impact on the concrete’s compressive strength. The inclusion of polypropylene fiber slightly impacts the compressive strength, whereas CCCW exerts a minimal effect on the concrete’s compressive strength. To summarize, for the compressive strength index, the optimal composite dosage of the three is A2B1C2. Verification experiments established that the average compressive strength of concrete with a factor level combination of A2B1C2 was 49.8 MPa, substantially enhancing the compressive bearing capacity of ordinary concrete.The calculation reveals that the The tensile strength of the benchmark concrete stands at 4.03 MPa, which represents the lowest value among the ten sets of specimens. The two sets of specimens with the highest tensile strength, L2 and L4, display values of 6.29 MPa and 5.92 MPa, respectively. In comparison to the benchmark concrete, their growth rates are 56% and 47%, respectively. Generally, the addition of fly ash, fibers, and waterproofing agents appears to enhance the concrete’s crack resistance performance. However, to delve into the three factors’ impact on tensile strength and ascertain the optimal dosage, it is imperative to conduct range analysis and variance analysis on the test results. The calculations suggest that the dosage of polypropylene fibers is the paramount factor influencing the concrete’s tensile strength, followed by CCCW. Conversely, fly ash does not have a significant effect on bolstering the concrete’s tensile strength. Unlike mineral admixtures, polypropylene fibers mainly modify concrete through physical processes. Once sufficiently mixed and subjected to friction, the fiber bundles disperse into thousands of individual fibers, uniformly distributed within the concrete, thereby forming a fiber network structure. This structure provides a significant “supporting” role , resultip-value is 0.02 < 0.05, statistically highly significant, suggesting that polypropylene fibers indeed play a crucial role in enhancing the tensile strength of the concrete. The p-value of factor C lies between 0.1 and 0.2, suggesting that permeable crystalline waterproofing agents also influence the concrete’s crack resistance performance to some extent. Further investigation is required to establish whether the two exhibit a “positive hybrid effect”, meaning whether the addition of waterproofing agents boosts the adhesion between the fibers and the matrix. The variance calculations indicate that factor B’s 3, the maximum tensile strength attained is 6.0 MPa. The tensile strength increases with the content of permeable crystalline waterproofing agents until it reaches 2% of the cementitious material, after which it starts to decrease. This decrease is because excessive CCCW can impact the hydration of the cement, leading to a reduction in the generated amount of hydrated calcium silicate cement, thus affecting the concrete’s crack resistance [3B2C2. Subsequent validation tests found that the concrete’s average tensile strength was 6.31 MPa with a combination of factor levels of A3B2C2. This represents a 56% increase in tensile strength compared to the benchmark concrete, enhancing the concrete’s crack resistance.The alteration in fly ash content does not induce significant fluctuations in the concrete’s tensile strength. Within a range of 15–25% of content, the maximum tensile strength fluctuation is merely 0.3 MPa. As the polypropylene fiber content increases, the tensile strength initially rises before descending. This is because an appropriate amount of fibers can, under the action of a mixer, form individual fibers that are evenly dispersed within the coarse and fine aggregates and mortar, thus enabling them to resist plastic shrinkage and cracking. The addition of excessive fibers not only curtails the mixture’s fluidity, but also leads to agglomeration, creating too many defects inside the concrete and significantly impairing its performance. This phenomenon is more likely to occur when the fibers have a larger aspect ratio. The experimental findings indicate that, when the dosage of polypropylene fiber is 1.5 kg/msistance . To summThe concrete impermeability test specimens are divided into six groups, and the average value of the water permeability height is taken as the permeability height of this group of specimens. Through statistical analysis and the organization of the test results, the permeability height and relative permeability coefficient of ten groups of specimens are obtained, as shown in −8 mm/s. The inclusion of fly ash, polypropylene fiber, and permeable crystalline waterproofing agent in concrete in specific proportions results in a significant decrease in their permeability height, thereby significantly enhancing the concrete’s impermeability. The most substantial reduction occurs in L6, which has a water permeability height of approximately 1/3 of that of the reference concrete and an 88% reduction in the relative permeability coefficient. The smallest reduction is in L3, but its relative permeability coefficient is only 43% of the benchmark concrete. Overall, the addition of the three materials significantly improved the concrete’s impermeability performance. However, to optimize the mix ratio and analyze the internal influencing laws, range analysis and variance analysis are also needed, as presented in The test results indicate that the permeability height of ordinary C35 concrete is 121 mm, and the relative permeability coefficient is 2.08 C > RB > RA. This suggests that CCCW is the most crucial factor affecting concrete’s impermeability, followed by the quantity of polypropylene fiber added, and, finally, the presence of fly ash. The p-values of factors B and C in the variance analysis are 0.05 and 0.02, respectively, demonstrating a significant impact of polypropylene fibers and CCCW on the impermeability of concrete. Furthermore, factor A has a p-value of 0.08, which, although greater than 0.05, is less than 0.1, implying that fly ash also contributes to improving the impermeability of concrete. Even though all three materials enhance the impermeability of concrete, their action mechanisms are distinct. Currently, the action mechanism of CCCW is broadly understood to be the “precipitation mechanism” or the “complexation precipitation mechanism” [2+ and oxides, generate insoluble crystals, and seal the pores and microcracks in the concrete. This process aids in waterproofing, enhancing the concrete’s resistance to water permeability. Polypropylene fibers improve the impermeability of concrete by minimizing defects during its hardening process, specifically by controlling the generation of shrinkage cracks and segregation cracks, preventing the formation of through-cracks inside the concrete [Through range analysis, we obtain the order of the three influencing factors as Rchanism” ,50,51. Uconcrete ,53. Conv3. The permeability height’s changing trend with the lateral change of CW is akin to that of polypropylene fiber, which first decreases and then increases. As the proportion increases, the permeability height decreases by 46%, 62%, and 41%, respectively. The optimal proportion is 2% of the cementitious material. The trend of the relative permeability coefficient changes aligns with the permeability height. Thus, for the penetration height indicator, the optimal combination of the three factors is A1B2C2.When increasing the fly ash content from 15% to 25% of the cementitious material, the penetration height initially increases and then decreases. The corresponding penetration heights at the three levels reduce by 53%, 45%, and 51% compared to the benchmark concrete, with the optimal content being 15%. Increasing fiber content causes the permeability height to first decrease and then increase, demonstrating yet again that excessive fiber content negatively impacts the internal compactness of the concrete. The permeability height corresponding to the three types of polypropylene fiber content is reduced by 50%, 56%, and 44% compared to ordinary C35 concrete, with an optimal content of 1.5 kg/mThe previous analysis considered a single indicator, and the optimal factor level combination obtained corresponded to a single indicator. Clearly, it did not fulfill the objective of this study, which is to prepare concrete with both high impermeability and high cracking resistance. Consequently, a comprehensive scoring method was employed to convert multiple indicators into a singular indicator. This method involves assigning different importance coefficients to each indicator based on the experimental purpose and each indicator’s independent analysis results. The product of each indicator’s experimental results and their importance coefficients are then added to calculate the comprehensive score of each combination. This enables the use of a single indicator analysis method to derive conclusions from a multi-indicator experiment . The keyIn this orthogonal experiment, the significance of the concrete’s compressive strength is relatively low. This is because the tunnel’s secondary lining structure mainly serves as a safety reserve, necessitating that its compressive strength merely meets the design requirements. However, both tensile strength and impermeability performance relate to the concrete’s durability, the key research objective of this study; therefore, their importance is relatively high. By taking various influencing factors into consideration, and based on the analysis results of different independent indicators, we can define the following score calculation method for each combination:Here, “150-penetration height” refers to the height of the impermeable specimen that remains unpenetrated by water. This calculation aims to ensure that a higher comprehensive score reflects the concrete’s superior comprehensive performance. Subsequent calculation provides the range analysis and analysis of variance for the comprehensive scores, as shown in 1B2C2. The variance analysis results indicate that the significance probabilities p of factor B and factor C are both less than 0.05, demonstrating that the addition of composite fibers and permeable crystalline waterproofing agents significantly impacts the mechanical and impermeable properties of the concrete. The optimal factor level combination obtained from both the single indicator analysis and multi-indicator analysis were simultaneously used for validation experiments, the results of which are shown in The extreme differences in the comprehensive scores for the three test indices suggest that the primary factors affecting the mechanical properties and durability of the concrete, in descending order, are C > B > A. The optimal factor level combination is A2B1C2 concrete displays the highest compressive strength improvement rate at 29.3%, and the A3B2C2 concrete has the highest tensile strength improvement rate at 56%. The concrete with a factor level combination of A2B1C2 is not only the optimal solution considering the single indicator of permeability height but also the optimal solution for a comprehensive evaluation. The verification test results indicate that the A1B2C2 concrete achieves the highest comprehensive score, its compressive strength meets the design requirements of tunnel engineering, and its tensile strength and permeability height are also at optimal levels. This greatly enhances the concrete’s resistance to cracking and permeability.Verification testing shows that the optimal combination of factor levels obtained through an analysis of individual indicators does indeed lead to the highest value of the corresponding indicator. When compared to the benchmark concrete, the AThe micro-morphological characteristics and material composition of concrete often dictate its macroscopic properties. Prior tests on mechanical properties and impermeability indicated that the inclusion of three modified materials significantly enhances the macroscopic properties of concrete. To further investigate the micro-mechanism of fly ash, polypropylene fiber, and cementitious capillary crystalline waterproofing materials during the hydration and hardening process of concrete, we performed scanning electron microscopy experiments and X-ray diffraction quantitative phase analysis experiments on concrete mixed with varying modified materials aged at 28 days. Through a comparative analysis, we aim to explain the modification mechanism of external materials and the interaction effect between these materials from a microstructural standpoint.3, the dosage of fly ash is set at 15% of the cementitious material, and the dosage of CCCW is set at 2.0% of the cementitious material. The mixing proportions and specimen numbers for the four groups of concrete are shown in In order to study the influence of different additive materials on the microstructural characteristics of concrete , we prep(1)Microscopic Morphological Characteristics of Concrete Matrix at 28 Days of AgeWe observed four groups of concrete samples using a field emission scanning electron microscope (Thermo Scientific APREO 2C), focusing on the micromorphology of the concrete matrix and the bonding characteristics between polypropylene fibers and the matrix. We divided the observation results into the following categories for analysis:2 crystals, abundant clustered calcium silicate hydrates (C–S–H gel), and a small amount of needle-like ettringite distributed in pores and cracks characterize SEM-1 concrete’s microstructure, which is generally loose and porous. This microstructure inevitably impacts the concrete’s mechanical properties and impermeability.2 to generate more crystals to fill the pores and cracks, creating a denser microstructure and thereby improving the strength and durability of the concrete.The cementitious system of SEM-2 concrete comprises cement and fly ash. The resultant microstructure after the hydration reaction is denser than that of SEM-1, with significantly fewer pores and cracks. The hydration products are more integrated. The improvement in SEM-2 concrete’s microstructure results from the addition of fly ash, which enhances the cement’s hydration reaction while providing an effective filling effect and volcanic ash effect . Fly ashThe cementitious materials of SEM-3 concrete include cement and CCCW. Although its apparent morphology resembles that of SEM-1, it has a reduced pore structure. Compared to SEM-1, SEM-3 displays improved overall integrity and compactness, further supporting the notion that adding CCCW can enhance concrete’s internal structure and, thus, its impermeability.In the case of SEM-4 concrete, where the composite cementitious system consists of ordinary Portland cement, fly ash, and CCCW, the microstructural characteristics post-hydration reaction indicate significantly reduced crystal structure defects, thorough hydration reaction, and abundant C–S–H gel complexed into a whole. These characteristics suggest a significant improvement in structural compactness, demonstrating that the three cementitious materials have excellent compatibility and mutual coordination, collectively enhancing the microstructure of the concrete. This is also the main reason for the improvement in the macroscopic mechanical properties and impermeability of the concrete.(2)Microscopic Morphological Characteristics of the Transition Zone between Fiber and Concrete Matrix at 28 Days of AgeThrough comparing and analyzing the microscopic morphological characteristics of the four concrete groups at 28 days of age, we found that concrete with only cement as the cementitious material has many internal defects, including poor crystal integrity, more pores and crack structures, and an incomplete hydration degree. The addition of fly ash or CCCW can somewhat improve the microstructure of the concrete matrix and the bonding strength between polypropylene fibers and the concrete matrix. When cement, fly ash, and CCCW are combined as cementitious materials for concrete, the improvement effect is most significant, and the three display good compatibility characteristics.The influence of fly ash and CCCW on the cement hydration reaction was evaluated through XRD diffraction tests after preparing four sets of concrete specimens. These four sets include the reference concrete, single fly ash concrete, single CCCW concrete, and composite fly ash and CCCW concrete. As polypropylene fibers mainly play a physical role within concrete and do not affect the cement hydration reaction, they are not added to these test pieces. The specimen numbers and proportions for the XRD diffraction test are presented in The XRD diffraction patterns of the four concrete groups at 28 days of age can be obtained by analyzing and organizing the test data, as shown in 2, Ettringite Aft, CaCO3, and the non-hydrated cement components C3S and C2S. As the primary product of the cement hydration reaction—calcium silicate hydrate gel—is an amorphous phase [From us phase ,60, it c2 in the cement hydration products, after adding fly ash, slightly increases. This is because fly ash not only promotes the formation of gel-like hydration products but also acts as the activation center of Ca(OH)2 crystallization, enhancing the crystallinity of Ca(OH)2 and consequently increasing its characteristic peak strength [2 are positively proportional and that C–S–H gel is an important source of concrete strength and durability [3S and C2S can also illustrate this phenomenon.By comparing the spectra of No. 1 and No. 2, it is found that the diffraction peak intensity of Ca(OH)strength . The cherability . In the 2. This suggests that CCCW can improve the crystallinity of cement hydration products, making the hydration reaction more complete and generating more hydration products. This could improve the strength and durability of concrete to some extent. By analyzing the No. 4 spectrum, it is found that, although the proportion of cement in the XRD-4 sample is the lowest, its Ca(OH)2 diffraction peak intensity is still slightly higher than in the No. 1 and No. 2 spectra. This strongly suggests that the composite addition of fly ash and CCCW does not interfere with the hydration process of cement but instead enhances the crystallinity of its hydration products.When comparing the No.1 and No.3 spectra, it is apparent that the addition of CCCW significantly strengthens the characteristic peak of Ca(OH)(1)2B1C2) resulted in a compressive strength of 49.8 MPa, a 29.3% increase compared to standard C35 concrete;The relative impact of the three materials on concrete’s compressive strength is: fly ash > polypropylene fiber > CCCW. The optimal combination of these three components (A(2)3B2C2) resulted in a tensile strength of 6.31 MPa, representing a 56% improvement over the control concrete;The influence of the three materials on the splitting tensile strength of the concrete is as follows: polypropylene fiber > CCCW > fly ash. The optimal combination for crack resistance (A(3)1B2C2) decreased permeability by 63.6% compared to the control concrete. Moreover, A1B2C2 also provided the optimal solution in the multi-indicator analysis;The effect of the three materials on the concrete’s impermeability is: CCCW > polypropylene fiber > fly ash. The optimal combination for impermeability (A(4)The 28-day-old control concrete exhibited numerous internal voids and crack defects and a low bonding strength between the polypropylene fibers and the concrete matrix. The incorporation of either fly ash or CCCW led to a substantial improvement in the concrete’s microstructure, resulting in a denser distribution of hydration products and improved fiber-to-matrix bonding characteristics;(5)2, which improved the structure of the aggregate interface transition layer, ultimately augmenting the concrete’s strength and durability.The addition of fly ash and CCCW effectively enhanced the cement hydration reaction and increased the crystallinity of the hydration products. The secondary hydration reaction of the fly ash and the complex precipitation reaction of the CCCW materials consumed a portion of the Ca(OH)This study employs an orthogonal experimental design to investigate the effects of various quantities of fly ash, polypropylene fibers, and CCCW on the mechanical properties and impermeability of concrete. This design determines the optimal composite dosage for each performance indicator, conceives a specific mixture ratio accordingly, and conducts scanning electron microscopy (SEM) tests and XRD tests on the concrete. The key findings are as follows:


Nearly ⅓ of outpatient antibiotic prescriptions are unnecessary or inappropriate. QuizTime is a web-based application based on Test-Enhanced Learning Theory that delivers daily case-based questions to a learner’s email or cell phone. We performed a prospective cohort study to evaluate the impact of a QuizTime module on appropriateness of pediatric outpatient antibiotic prescriptions.Table 1). Participants were pediatric prescribers  in a primary care, urgent care, retail health, or emergency department setting. Antibiotic prescription data were collected during the “baseline” period  though 3 months after QuizTime participation (Jul 15 – Oct 15 2022) defined as the “post-quiz” period. Pre- and post-intervention data were analyzed in aggregate (not at the provider-level). Significance was determined by calculating a 95% confidence interval (CI) for the difference of proportions. Outcome measures are listed in Table 1.Participants received one question daily for 10 days starting in July 2022. Quiz topics included age-appropriate antibiotic duration for acute otitis media (AOM), empiric antibiotics for uncomplicated urinary tract infections (UTI), and empiric antibiotics and duration for community-acquired pneumonia (CAP) . AOM guideline-concordant antibiotic duration was significantly higher among participants than non-participants (Table 2). There were encouraging trends towards improvement in secondary outcomes .Eighty clinicians participated in QuizTime totaling 13,478 antibiotic prescriptions  compared to 776 non-QuizTime clinicians totaling 43,321 antibiotic prescriptions  (Clinicians who participated in a QuizTime module on pediatric outpatient antibiotic prescribing showed improvement in antibiotic appropriateness suggesting web-based microlearning modules are an effective tool for disseminating antibiotic stewardship education. Creation, dissemination, and evaluation of additional QuizTime modules is ongoing.Ritu Banerjee, MD, Ph.D, bioMerieux: Grant/Research Support|bioMerieux: company is providing partial support for an ongoing trial unrelated to submitted abstract Sophie E. Katz, MD MPH, Dolly Parton Pediatric Infectious Diseases Research Funds: Grant/Research Support|Optum: Advisor/Consultant|Pfizer: Grant/Research Support


Rt) for the fast neutrons and the total mass attenuation coefficients (mµ), the half-value layer (HVL), the mean free path (MFP), the effective atomic number (effZ), and effective electron density (effN) for photons inside the materials. The model considered the radiation source energy and the material properties of the concrete types. The results revealed that the serpentine-containing concrete exhibited the highest ∑Rt with 12 cm of concrete thickness needed to attenuate an incident neutron flux to 1/100 of its initial value. In addition, the BC shows the highest mµ with a 38 cm concrete thickness needed to attenuate the 3 MeV energy X-ray flux to 1/100 of its initial value. This study suggests that a 40 cm thickness of SC or BC adequately shields the radiation generated from an IECF system with a maximum particle production rate of up to 1 × 107 n/s.A radiation source based on the inertial electrostatic confinement fusion (IECF) system is being developed for multidisciplinary research applications. The radiation outputs from the IECF system are 2.45 MeV fast neutrons and the associated co-generated X-rays with an energy less than 3 MeV. A radiation shielding study has been performed on five types of concrete to define the most efficient material for the shielding design of the system. The proposed materials were ilmenite-magnetite concrete (IMC), ordinary concrete-1 (OC-1), barite-containing concrete (BC), ordinary concrete-2 (OC-2), and serpentine-containing concrete (SC). A numerical model was applied to determine the effective removal cross-section coefficients (∑ Since the discovery of nuclear radiation, such as X-rays by Rontgen in 1895, γ-rays by Paul Villard in 1900, and neutrons by Chadwick in 1932 ,5,6,7. T3 lab in the Physics Department at Assiut University. The central technology is integrated with other facilities for multidisciplinary applications, including material science, medicine, and radiography. The planned IECF system will generate 2.45-MeV neutrons and hard X-rays from the deuterium-deuterium fusion occurring inside the system, with concurrent particle scattering interactions within the system components. Determining the shielding requirement and the necessary concrete thickness to attenuate the radiation to 1/100 of its initial value is the central core of the present study. An essential parameter for radiation shielding in a material is the attenuation efficiency (% reduction in flux) compared to incident radiation. The attenuation of the neutrons in the shielding materials changes based on the neutron energy and the microstructure of the shielding material [A radiation facility based on an inertial electrostatic confinement fusion (IECF) system ,19,20,21material ,23, whicmaterial ,25,26. Mmaterial ,28,29.Simulations using MCNP-6 and/or PHITS are planned to confirm the numerical calculations expected from the presented work to track the individual neutron and photon interactions. In the simulation, the chosen material will be investigated further in addition to the following considerations: (i) the effect of the anode material, (ii) the possibility of having a water jacket around the anode for both cooling and moderating the generated neutrons, (iii) the optimal thickness of the water jacket (0.5~7 cm) combined with concrete shielding, and (iv) modelling of a potential lead (Pb) layer after the concrete shielding to block any photons generated through the concrete by neutrons interactions. In the current work, five different types of concrete are investigated to determine their suitability as a shielding material for the proposed IECF system. The paper is arranged as follows; second 7 n/s DD neutrons. The IECF operation requires several tens of mA current and tens of kV voltage to be applied on the cathode to establish a potential well between the cathode and anode. Thermionic electrons are generated from the cathode; these electrons ionize the D2 gas, start a glow discharge between the electrodes, and subsequently ‘spike’ a D plasma inside the system. The D ions in the plasma are then accelerated by the steep potential field gradient towards the centre of the cathode. Thus, fusion occurs in this central collision zone between ions and/or electrode surfaces, generating neutrons and protons, as shown in Equation (1).The proposed radiation source in this study is a fusion system based on IECF . The str3, 60 cm from the floor, and 130 cm from each side with 200 cm from the top. A schematic drawing for the vacuum vessel, including the electrode dimensions, observation windows, and the fusion traces in the vessel are given in Of the particles generated, only the high-energy neutrons (2.45 MeV) can escape outside the system after passing through the anode. Due to the electrical properties and the small mean free path of the generated protons, they interact with the system components and lose their energy through the collision, scattering, and release of photons with different energies. Fast neutrons with a 2.45 MeV energy and photons with energy less than 3 MeV are the main types of radiation escaping the system and hence, are the subject of this study. He and T in Equation (1) are internally consumed or collide with the system components and lose their energy. The most critical factor for reducing the effect of the emitted radiation is determining suitable shielding materials. Five different types of concrete with high strength and long lifetimes that are widely used in Egypt are investigated in this study. The concrete types are (1) ilmenite-magnetite concrete (IMC), (2) ordinary concrete-1 (OC-1), (3) barite-containing concrete (BC), (4) ordinary concrete-2 (OC-2), and (5) serpentine-containing concrete (SC). The chemical compositions, mass numbers, and atomic numbers of the elements, as well as the fractional weights, partial densities, and densities of the concrete materials are shown in I0 and I are the incident and attenuated neutron intensities before and after passing through the distance x (cm) of shielding material. The value ∑t (cm−1) is the physical quantity that describes the neutron attenuation in the matter, while it is called the total macroscopic cross-section, which can be given as [ρ (g cm−3) is the material density, aN (Mol−1) is Avogadro’s number, tσ (cm2) is the microscopic cross-section that includes the scattering- and absorption-microscopic cross-section (ρt = ρs + ρa), and A (g mol−1) is the atomic mass number. One can see that the value of the total macroscopic cross-section in Equation (3) depends on the material’s properties and the incident neutrons through the macroscopic cross-section, which changes based on the neutron energy. Therefore, another parameter to describe the neutron attenuation called the removal cross-section ∑R (cm−1), is widely used [R is the probability that a fast or fission energy neutron takes a first collision, which removes it from the group of penetrating uncollided neutrons [R = ∑t, while for a small fraction of hydrogen, the value of ∑R = 2/3 ∑t for energies between 6 and 8 MeV [Rt) is given in the form [iw and iρ (g cm−3) are the fraction by weight  and the density of the medium material, respectively, and (∑Ri/ρ)i (cm2 g−1) is the mass removal cross-section of the ith constituent. The partial density of the ith constituent is given by iw = (it)/(ρ), and (it) is the fractional weight of the ith constituent. The effective removal cross-section of the proposed concrete shielding materials can be calculated from Equation (4).As they are electrically neutral, neutrons can only interact with the nuclei of obstructing atoms when passing through a material medium, imparting some or all of their energy. The interaction occurs here in different ways: collision or scattering, and energy absorption by the nuclei it collides with. The probability of each event depends on the neutron energy and the material properties . Fast negiven as ,40,41:ΣRt=Σlµ (cm−1), defined as how easily a beam of photons can penetrate 1 cm of the shielding material. From a radiation protection standpoint, the greater the attenuation exhibited for a small thickness x (cm) is, the better the material is at shielding the photons. So, the selection of shielding material for photons depends mainly on the attenuation properties it exhibits. The relation which describes a photon beam penetrating matter is given in a form similar to the neutron attenuation:I0 and I are the incident and attenuated photon intensities, respectively, the latter of which decreases exponentially with the distance inside the material x (cm). Another parameter linked to the material properties is introduced, called the mass attenuation coefficient mµ (cm2 g−1), which takes the density of the medium into account for photon attenuation and is given in the form:The critical factor for evaluating the effect of photons on the shielding material is the linear attenuation coefficient iw is the fractional weight given in HVL) and the mean free path (MFP). The HVL is defined as the thickness of the concrete specimens that will reduce the photon beam to half, while the MFP is the average distance travelled by photons between two events . Equations (8) and (9) give the values of the HVL and MFP based on the mass attenuation coefficient [The mass attenuation coefficient for a medium composed of different elements can be calculated by ,50:(7)μmfficient ,16,51,52effZ) is equivalent to the atomic number but is used for compounds and mixtures of different materials, and this along with the effective electron density (effN) are critical parameters for selecting the shielding materials. The effective electron density is derived from the effective atomic number and is defined as the number of electrons per unit mass. The following expressions introduce effZ and effN for the composite materials:iZ, iA, and iw are the atomic number, atomic weight, and the weight fraction of element i in the material, respectively. The mass attenuation coefficient, linear attenuation coefficient, half-value layer, mean free path, effective atomic number, and electron density for the photons passing inside the proposed shielding materials are estimated using Equations (6)–(11) at different energies expected from the IECF: 3, 2, 1.5, 1, 0.5, 0.2, and 0.05 MeV.In addition, the effective atomic number , tritium (T), hydrogen (H), and helium (He), inside a potential well to generate subatomic particles . The outIn the present study, it was planned that only DD fusion takes place in the system to generate 2.45 MeV neutrons and 3.03 MeV protons. The protons have a small mean free path inside the system; they interact with the vessel materials, then lose their energy or impact with the electrode surfaces and generate photons with different energies, while the 2.45 MeV neutrons travel outside the system passing through the anode wall. Indeed, 2.45 MeV neutrons and different photon energies are generated from the system and must be shielded. In the present model, we assumed that the neutrons and photons are generated from the surface of the vacuum vessel of the system due to the fact that a large percentage of the fusion takes place at the anode surface of the IECF system . The modσ)i of the concrete elements were collected at 2.45 MeV and then inserted into Equation (3) with the properties of the materials listed in Ri) values for each element of the materials were calculated, and the results are shown in Rt ranges between 0.09989 and 0.36635 cm−1.The IECF system is an isotropic radiation source, and a significant percentage of the neutrons are generated from the anode’s inner surface; therefore, we assumed that the neutrons are generated with 2.45 MeV from the outside shell of the system. The fast neutron removal cross-section of the air was ignored in this study, and neutrons travel 130 cm and reach the concrete wall without attenuation. The total microscopic cross-section values (4), with the Ba (Z = 56) adding to the overall density of the concrete. In this context, barite can be considered an additive for increasing concrete density. Serpentine-containing concrete contains serpentine minerals as a particulate additive to the aggregate. Serpentine has the generalized formula: 2–32O5(OH)4, and therefore constitutes an additive source of H in the concrete in addition to the CSH mineral content.Concrete is an engineering material that simulates rock properties and is composed of particles closely bound together using cement. From a simplistic perspective, it is a blend of aggregates, normally natural sand and gravel or crushed rock, which is held together by carbonate and calcium–silicate–hydrate (CSH), which is formed when the cement is initially wetted, and the concrete is cast into a shape. The CSH binder is the primary source of H in the concrete with regard to neutron attenuation. For the barite-containing concrete, a proportion of the aggregate used in the concrete mix is the mineral barite, also known as barium sulphate  and the high total microscopic cross-section of the element, with high scattering and absorption cross-sections for fast neutrons in comparison to the other elements such as O  in the same concrete type. On the other hand, even though OC-2 also includes H in the constituent mineral compounds, its contribution to the ∑Rt was only 17% due to the relatively small element fractional weight, 0.56% of the total density, compared to the O . The effective fast neutron removal cross-section values for IMC and BC were almost the same, which could be attributed to the relatively small fractional weight of H, of less than 1% of the total density, in comparison to the high fractional weight of other elements such as O with 38 and 31% of the total density, which reduces the total microscopic cross-section (σ)i and hence the total effective fast neutron removal cross-section values. It is essential to mention that none of the concrete types under investigation included boron, which has a high affinity for neutron absorption. The value of ∑Rt calculated from the present methods was in good agreement with other methods presented in the literature [Rt = 0.36635 cm−1. This concrete type was expected to attenuate neutrons better than other concrete types.Based on the modelling, SC showed the highest ∑terature . As seenUsing Equation (2), one can estimate the thickness needed to attenuate neutrons passing through the concrete materials. The effective fast neutron removal cross-section values for the five concrete types, listed in the bottom row of γ-rays inside the shielding materials. These processes include photoelectric absorption, Compton scattering, pair production in the nuclear field, and pair production in the electric field [mµ given in Equation (5). The mass attenuation coefficients for the constituent elements of the concretes listed in Different photon interaction processes characterize the attenuation of X- or ic field ,62,63,64miµ for the elemental compositions of the concrete materials for an X-ray at 1 MeV and 200 keV energies are shown in mtµ values for the concrete materials for an X-ray at 1 MeV and 200 keV energies are shown in 2 g−1, for which SC and BC exhibited the most significant and smallest total mass attenuation coefficients, respectively, among the concrete types at a 1 MeV X-ray energy. At different X-ray energies, from 0.2 MeV, the total mass attenuation coefficients for the shielding materials were calculated using the same technique, and the results are also given in mtµ values depend on the photon energy and the chemical composition of the concrete material. In addition, it was found that the variations in mtµ with the incident photon energy for all five concrete materials followed a similar trend. The values of mtµ decreased with the increased photon energy. Moreover, the relation between the photon energy and the mtµ values was not linear. The values of HVL, MFP, effZ, and effN of the photons in the shielding materials were calculated, and examples at 0.2 and 1 MeV energies are listed in HVL and MFP values; in contrast, OC-2 had the highest values. The value of mtµ calculated from the present methods is in good agreement with other techniques in the literature [The values of terature ,57,58,59mtµ from −3, compared to the other types.The X-ray attenuation curves of the concrete types were calculated using Equation (5) for all expected energies from the IECF system. The attenuation curves at 1 and 0.2 MeV X-ray energies are plotted as an example in mtµ, µL, HVL, MFP, and effZ in general, and especially at low photon energy, which can be attributed to the barite atoms inside the concrete, while OC-1 and OC-2 had the smallest values. In addition to the effective attenuation of the concrete types, the price may influence the selection of the shielding material.The thickness of the shielding concrete needed to attenuate the photons to 1/100 from the initial value was calculated from the data in Before constructing the facility, MCNP-6 and/or PHITS simulations are planned to confirm the numerical calculations presented herein and track the individual neutron and photon interactions. In the simulation, (i) the effect of the anode material will be considered, (ii) the possibility of having a water jacket around the anode as a means of both cooling the anode surface and moderating the generated neutrons will be investigated, (iii) the optimal thickness of the water jacket (0.5~7 cm) combined with concrete shielding will be considered, and (iv) the modelling of a potential lead (Pb) layer after the concrete shielding to block any photons generated through the concrete through neutrons with concrete will be performed.A final consideration of using SC for neutron shielding applications is that the precursor serpentine material would need to be elementally screened before making the concrete. This is because serpentine minerals are well documented to contain minor amounts of chromium, manganese, cobalt, or nickel, with the latter two elements providing potential routes for generating Co-60. It would be highly undesirable for the shielding material to become significantly activated (and gamma-emitting) during the lifetime of the planned facility. Further work could also explore the BC and SC formulations to further optimize the neutron and photon attenuation properties in them. It is expected that a very significant substitution of barite and serpentine for the typically used aggregate minerals in concrete  would lead to a detrimental reduction in the mechanical properties. An optimal formulation needs to be proven from both a radiation attenuation and structural performance standpoint.Rt) for fast neutrons and the total mass attenuation coefficients (mtµ), half-value layer (HVL), the mean free path (MFP), the effective atomic number (effZ), and the effective electron density (effN) for X-rays were determined for each material type and compared. The results obtained from this study show that the material density, chemical content, and total mass attenuation coefficient strongly affected the values of ∑Rt and mtµ. Serpentine concrete (SC) was found to have the highest ∑Rt value, while ordinary concrete-2 (OC-2) had the lowest value. At the same time, barite concrete (BC) and ilmenite-magnetite concrete (IMC) had almost the same values of ∑Rt for neutron attenuation. The obtained attenuation curves show that SC and BC would need the smallest material thickness to attenuate an incident neutron and photon flux to 1/100 of their initial intensities, respectively, compared to the other concrete types. The neutron attenuation curves for BC, OC-1, OC-2, and IMC were similar to that of SC. Moreover, the X-ray attenuation curves are very similar for SC, OC-1, OC-2, and IMC, with the BC being the most effective photon shield at lower incident energies.Five concrete materials of different densities and elemental compositions were investigated in this study to assist in the selection of a shielding material for a planned radiation generator based on IECF technology. The effective removal cross-section (∑One can conclude from this work that serpentine concrete is a good material for neutron shielding applications, whilst barite concrete is slightly better than other concrete types for shielding X-rays. In addition, 40 cm of serpentine or barite concrete is deemed sufficient to attenuate the neutrons and photons generated from the planned IECF system to 1/100 of their initial intensities. Further, more advanced simulations are needed using MCNP and PHITS to confirm the calculated parameters before constructing the facility.


Antimicrobial resistance is a public health challenge affecting all aspects of healthcare systems. Policies to reduce antimicrobial resistance should be implemented and monitored in community pharmacies, because they are patients' first point of care. Public awareness of relevant knowledge and attitudes on antimicrobials is a feasible strategy to mitigate the spread of antimicrobial resistance by exploiting the relationship between pharmacists and patients in the community pharmacy setting. The study evaluated and determined predictors of antibiotic knowledge and attitudes toward antibiotic use and resistance in community pharmacy patients.p < 0.05. Logistic regression was used to identify predictors of patients’ knowledge and attitude to antibiotic use.A cross-sectional design was used to retrieve data in five randomly selected community pharmacies in Lagos and Abuja using a self-administered questionnaire. Descriptive and inferential statistics were utilized for characterizing and determining the associations between predictors and outcomes at p value: 0.044], urban residence  and age 34  were strong predictors of knowledge on antibiotics, while community pharmacy location , urban residence , and antibiotic recommender  were predictors of respondents’ attitude to antibiotic use.A total of 964 clients participated in the study: 526(54.7%) were females, and 358(37.3%) were aged 25–34. chlorpheniramine–maleate and levonorgestrel were wrongly identified as antibiotics by 621 (64%) and 490 (50%) respondents, respectively. Many respondents, 448(46.5%), strongly agree that antibiotic creams should be mixed with body creams. The result of the multivariable logistic regression showed secondary education [Odds Ratio (OR): 0.31, 95% CI 0.10–0.97, The study established that sociodemographic factors could impact community pharmacy clients' knowledge and attitude toward antibiotic use and resistance and should be considered when developing policies to curb the spread of resistant microbes. Community pharmacies should educate community pharmacy clients on the dangers associated with the misuse of antibiotics with stringent antibiotic stewardship programs and restrict access to antibiotics over-the-counter. Advancement in science and technology has informed the growth of the human population over the century and the emergence of new diseases . The incAntibiotics are prescription-only medicines in Nigeria according to the national guideline and should be dispensed under the supervision of a certified medical professional. Unfortunately, due to poor prescription monitoring, antibiotics are regularly dispensed over the counter in community pharmacies and patent proprietary medicines vendors (PPMVs) with little or no oversight . The tenMany factors have contributed to the prevalence of antimicrobial resistance including but not limited to the misuse and overuse of antimicrobials, lack of awareness, poor knowledge and lax public health policies . The repCountries and regions worldwide need to develop a viable and reliable framework for monitoring and assessing the public's knowledge of antibiotic use and misuse to reduce resistance . Such a The study was a cross-sectional questionnaire-based survey conducted in five randomly selected community pharmacies in Lagos and Abuja, Nigeria. The data were collated over 3 months (July to September 2021) in five different districts: Utako (Abuja), Kubwa (Abuja), Yaba (Lagos), Victoria Island (Lagos), and Ajegunle (Lagos).The study was conducted in Lagos and Abuja. Lagos is the economic center of Nigeria and the most populous city in Sub-Saharan Africa, while Abuja is the Federal Capital Territory. Both locations have many community pharmacies dispersed in rural and urban areas. The percentage of urban to rural pharmacies used in this study was 60–40%. Three of the community pharmacies were in an urban setting, while 2 were in a rural location.The estimated study population for a month  was 10,000, from which a sample size of 370 was determined using the Raosoft Online Sample Size calculator, assuming a 5% error and 95% confidence interval. Data collection was conducted for 3 months to improve the robustness of the sample (1110). A proportionate distribution of 1110 was done among the four sites, although 964 respondents consented and completed the questionnaire (response rate of 86.8%).Adult clients who visited the community pharmacies during the period of the study were randomly invited to participate in the study. Researchers verbally informed the clients about the ongoing study, and leaflets were presented to seek their interest. Interested participants were directed to read the consent information imprinted on the front page of the questionnaire carefully before filling it. Further interpretations were given to a few respondents who found it difficult to understand the information on the consent page. Only those who consented with their signature were given the study instrument to complete.A self-administered questionnaire with 2-point and 5-point Likert-scale domains was used to determine the knowledge and attitude of respondents on the use of antibiotics, respectively. The questionnaire was revised from previous studies and modified to assess the study’s research questions , 14.Prior to data collection, the face validation of the instrument was done in collaboration with research experts from the University of Nigeria and community pharmacists practicing around the study settings. Researchers ensured that community pharmacists selected for face validation were not in proximity to the study sites and had no affiliation with them. Five willing participants were randomly selected to test the questionnaire at each test site. The content validation of the items of the adjusted questionnaire was determined using the viewpoint of the panel of clinical pharmacy experts according to the method outlined by Yusoff . The insThe Likert scales to assess respondents’ attitudes were Strongly Disagree = 1, Disagree = 2, Neutral = 3, Agree = 4, and Strongly Agree = 5, with a minimum sum score of 13 and a maximum sum score of 65. Respondents who correctly answered questions on antibiotic knowledge were given a score of 1, while those who chose wrongly were scored 0. Correct identification of commonly used antibiotics was assessed with a Yes/No question using their generic and trade names. Any antibiotic that was wrongly identified was given a score of 0, while a score of 1 was for correct identification. Hence, the minimum sum of the score for knowledge was 0, and the maximum sum of score was 23.Demographic and occupational characteristics of respondents.Knowledge of antibiotic use and antibiotic resistance.Attitude toward antibiotic use and resistance.The questionnaires were distributed to the respondents, self-administered, and retrieved from the respondents on the same day. The patients that visited the community pharmacies were approached, and those that gave their consent were administered the questionnaire. This was done on weekdays within the specified period of the survey. The filling exercise was adequately monitored to ensure prompt return. The questionnaire was made up of three sections:p value of 0.05.The data collected was analyzed using Statistical Package for Social Sciences (version 28). Descriptive statistics was used to evaluate measures such as frequencies, percentiles, and means of the sociodemographic characteristics of respondents. Binomial logistic regression was also conducted as appropriate. Univariate analysis established the relationship between the sociodemographic predictors and outcomes. Multivariable logistic regression was used to determine the odds of outcomes between predictors and outcomes. All statistical values were set at a threshold Negatively worded questions in the knowledge section of the questionnaire were adequately re-coded and transformed during analysis to ensure that they were correctly scored. Knowledge and attitude were dichotomized into poor and good, using the median of the respondents’ sum of scores. The sum of knowledge scores greater than or equal to 14 was categorized as good knowledge, while the sum of knowledge scores less than 14 was labeled poor knowledge. For attitude, a sum of score greater than or equal to 42 was categorized as good attitude, while a score less than 42 was poor attitude.The total number of respondents that filled the questionnaires was 964. Descriptive analysis of the socio-demographic data Table  showed tWhen asked if they had sought counsel from a health professional before using an antibiotic, only 640 (68%) of the respondents agreed that they used antibiotics on the recommendation of a health professional. Most respondents correctly identified common antibiotics, such as metronidazole, ampicillin/cloxacillin, sulfamethoxazole/trimethoprim, and ciprofloxacin. However, 621 (64.4%) and 490 (50.8%) of the respondents wrongly identified chlorpheniramine and levonorgestrel as antibiotics, respectively  for knowledge of antibiotics, 60.2% had good knowledge of antibiotic use. In comparison, 39.8% had poor knowledge   of having good knowledge about antibiotic use and resistance compared to respondents from Kubwa, Abuja. The odds of respondents between the age brackets of 25–34  and 45–54  having good knowledge of antibiotic were 1.547 and 1.966, respectively, relative to the reference age. In addition, urban residence had a strong statistical association with participants’ good knowledge of antibiotic use. Analysis showed that the odds of good knowledge on antibiotic use was 45% greater in urban residents  than in rural residents. Participants who took antibiotics for over 1 year  had 2.08 greater odds of having good knowledge of antibiotic use and resistance than those who took it in less than a month  except the period antibiotic was used and marital status.Univariable analysis in Table Some predictors showed a significant relationship with participants' attitudes toward antibiotic use with the multivariable logistic regression Table .. Among Few studies in Nigeria have concurrently evaluated community pharmacy clients' knowledge and attitude toward antibiotic use and resistance in different regions. Previous studies on antimicrobial resistance were restricted to single locations, such as tertiary hospitals, rural communities, or community pharmacies in a state –20. ThisIn a multi-country antimicrobial survey, the WHO estimated that over one-third of the participants took antibiotics within the past month. Egypt topped the list, while nearly half of Nigeria’s participants attested to taking antibiotics within the last month . SimilarMost of our respondents purchased antibiotics from pharmacies, which allows pharmacists to interact with and educate patients on antibiotic use. Such intervention can be explored when enacting policies toward curbing increasing resistant microbes. This strategy has been proven to improve public knowledge and perception of antibiotic use and resistance .The results on antibiotics identification are consistent with similar findings in a study among civil servants in Uyo, Nigeria, where the five most commonly used antibiotics reported were ampicillin/cloxacillin, metronidazole, sulfamethoxazole/trimethoprim, ciprofloxacin and amoxicillin . EmpiricA previous study showed that some people take antibiotics before and after sex to prevent sexually transmitted infections . StrikinThere is little difference between the participant’s good and poor attitudes toward antibiotic use. The belief that antibiotics could cure symptoms of cold and sore throat faster and their ability to prevent symptoms of cold from getting worse correlates with a study, where majority showed a negative attitude using antibiotics for cough, cold and skin wounds . A similAntibiotic creams are widely misused for bleaching/toning skin color in Nigeria. Popularly branded triple-action creams by pharmaceutical companies, antimicrobial creams contain antifungal, antibacterial, and steroidal agents and are readily available over the counter in Nigeria. It is a popular culture among community pharmacy clients in Nigeria to mix and use triple actions creams with regular body creams to enhance their skin tone. Hence, most participants strongly agreed that it is good to mix body creams with antibiotic creams to tone/bleach the skin for babies and adults, as seen in this study. The ease of obtaining antibiotics over the counter in developing countries is also a significant concern . Almost The findings from the univariate and multivariable analyses supported the study’s hypothesis that community pharmacy patients’ characteristics are predictors of knowledge and attitude toward antibiotic use. Educational status was among the predictors of respondents’ knowledge on antibiotic use and resistance. This is consistent with a study conducted in Jos, Nigeria, among consumers of antibiotics in community pharmacies . With a Lekki is a suburb of Lagos with people of high economic status and levels of education. It was no surprise to see higher odds of good attitude and knowledge toward antibiotic use, because the area possesses top-notch health facilities with qualified health professionals in Lagos. In addition, this location is also an urban residence which resonates with the result of the analysis which showed that respondents living in urban areas are more likely to have good attitudes and knowledge about antimicrobial resistance and use.Attitudes toward antibiotic use between male and female participants have shown conflicting evidence in previous studies . This stThe study evaluated the knowledge and attitude of respondents to antibiotic use in two major cities in Nigeria and, at the same time, compared it to their sociodemographic factors. A high percentage of participants showed good knowledge of antibiotic use, while the percentage difference between poor and good attitude was significantly small. Greater efforts need to be channeled into antimicrobial resistance campaign to address the misuse and abuse of antibiotics. It revealed that health professionals, especially community pharmacists have active roles to play, because they are at the epicenter of the medication distribution system and should uphold strict antibiotic stewardship when attending to patients. Analysis established that factors such as educational status, age, gender, and residence have strong statistical association on respondents’ knowledge and attitude to antibiotic use. To this end, educational institutions are one of the best settings to carry out antibiotic sensitization programs to educate young people on the appropriate and rational use of antibiotics and the dangers associated with indiscriminate use. Health policymakers could leverage on this information to enact laws and create programs that will reduce the abuse and misuse of antibiotics in the hospital and community pharmacy settings.This observational study is cross-sectional and comes with its limitations. Close associations between predictors and respondents’ attitude and knowledge do not mean causality, because data were collected once for each participant. Though the study population was drawn from five community pharmacies in different geographical locations in Nigeria, the findings do not generalize to other community pharmacy clients. There might be variations in findings if a similar study was done in other parts of the country. Respondents were prone to recall bias when asked about the last time and last place antibiotic was used and retrieved, respectively. It was reduced by increasing the interval between each sub-variables under the time and place predictors and aggregating them as categorical variables.