Flow Test Results Research Articles

Extrudability analysis of 3D printable concrete as a two-phase discrete flow

3D printing with concrete is primarily achieved through an extrusion process, where the material is precisely deposited layer by layer to construct structures. Proper control of extrusion ensures consistent material flow, accurate layer formation, and the overall stability of the 3D-printed structure. However, clogging during the extrusion process can occur as the nozzle size is too small relative to the aggregate size. To fundamentally understand the clogging mechanism and optimize the extrusion process, a precise two-phase discrete element model was established to simulate the extrusion process. A cluster of particles was used to model fresh concrete, with hard cores representing the aggregates and concentric soft shells representing fresh cement paste surrounding them. Five nozzles with different outlet diameters were designed and 3D printable concrete with different fineness modulus levels was formulated. The parameters of the two-phase discrete element model were determined based on rheological properties and calibrated using slump flow test results. The simulation results showed good agreement with the experimental pressure values and the quality of extruded filaments. Based on these results, it suggested that ensuring a proper balance between the aggregate fineness modulus and the outlet diameter of printing nozzles is essential for the extrusion process.

Comparative Analysis of Antibacterial Efficacy and Flow Characteristics of Three Root Canal Sealers.

Oral microflora containing microorganisms is responsible for the majority of orodental diseases as well as post-endodontic treatment failure. Even in the ideal root canal treatment cases, a small number of viable bacteria will remain in the dentinal tubule hence come the role of root canal sealers, which must offer and possess some degree of antimicrobial activity alongside adequate flowability to ensure excellent sealing of all lateral dentinal tubule canals to prevent the possibility of future reinfection. The present study aimed to examine the antibacterial efficacy against Enterococcus faecalis (E. faecalis) using an agar diffusion test (ADT) at different time intervals, as well as the flow characteristics of three different root canal sealers: Endofill (Produits Dentaires SA,Vevey, Switzerland), AH Plus (Dentsply De Trey GmbH, Konstanz, Germany), and the newly introduced GuttaFlow2 (Coltène/Whaledent, Altstätten, Switzerland). The antibacterial activity and flow characteristics of three root canal sealers, Endofill, AH Plus, and GuttaFlow2, were tested using ADT at three different time intervals (24 hours, 48 hours, and seven days). For this purpose,E. faecalis strains were used as the pathogen in this study. Flow characteristics were done using the standard flow test protocol recommended for endodontic sealers. Data were analyzed using one-way ANOVA and the Tukey post hoc test, with a p-value < 0.05 considered statistically significant. The results for antibacterial activity showed a statistically significant difference between Endofill and the other groups (p < 0.05). The antibacterial activity of Endofill increased over time from 24 hours to 48 hours and seven days. AH Plus demonstrated antibacterial activity only within the first 24 hours of mixing, while GuttaFlow2 showed no inhibition zones against E. faecalis. Regarding the flow test results, the Endofill group recorded the lowest flow values compared to GuttaFlow2 and AH Plus, which was statistically significant (p < 0.05). There was no statistically significant difference between GuttaFlow2 and AH Plus for flow values. Endofill demonstrated the highest antibacterial activity at all time intervals, while GuttaFlow2 showed no antimicrobial activity. AH Plus exhibited antimicrobial effects only within the first 24 hours of mixing. In terms of flow values, Endofill had the lowest flow, whereas GuttaFlow2 and AH Plus had the highest flow values.

The Effect of Rice Husk Ash as Cement Substitution on the Compressive Strength of Self-Compacting Concrete

Self-Compacting Concrete (SCC) is an innovative solution in today's world of concrete technology. Unlike traditional concrete, it does not require a vibrator for compaction, which makes concrete work easier. One of the key features of SCC is its high workability, which is achieved through the use of chemical admixtures and mineral additives. Rice husk ash is one such additive that can be used as a pozzolanic material for concrete mixtures, which is important as rice husk waste can cause environmental problems. The objective of this study was to investigate the effect of rice husk ash on SCC concrete. The study involved using Rice Husk Ash (RHA) as a partial replacement for cement in SCC concrete at varying percentages (0%, 5%, 10%, and 15% of cement weight). The results of the slump flow test showed that the highest value of 775 mm was achieved at 15% RHA, meeting the specifications of SCC concrete. In terms of compressive strength, the results showed that the SCC mixture without rice husk ash (0% RHA) had the highest average compressive strength, which was 30.56 MPa at 14 days and 31.66 MPa at 28 days of concrete. On the other hand, the average compressive strength of SCC concrete with rice husk ash mixture was highest at 5% RHA, with 25.04 MPa at 14 days and 28.81 MPa at 28 days. Overall, the study found that the use of rice husk ash in SCC concrete had a significant effect on its compressive strength, with the highest compressive strength being achieved at 5% RHA.

Unravelling the impact of ZIF-8, ZIF-67, and ZIF 8-67 on cement composites: insights into microstructure, mechanical strength and rheology

Zeolitic imidazolate frameworks (ZIFs) are a novel material, a sub-group of metal-organic frameworks (MOFs) with a sodalite-type structure similar to zeolites and are formed by the bridging of imidazole with metallic nodes or clusters which find applications such gas storage, energy storage, drug delivery, catalysis, and membrane technology. ZIF-8 denotes a MOF containing zinc metal ions; ZIF-67 comprises of cobalt metal linkers; and ZIF-8-67 signifies a MOF containing both zinc and cobalt linkers. In the present study, aforementioned nanomaterials are lab-synthesized and added to cement in concentration of 0.4%, 0.5%, 0.6%, and 0.7% by weight of cement and characterized using XRD, FTIR, and SEM analysis. Various fresh and hardened tests were conducted to evaluate rheology, flexural, and compressive strength. The flexural strength test resulted in an increase of up to 21.72% in ZIF-8-67 cement specimens. ZIFs tend to offer extra nucleation sites for the production of hydration products and result in strength increment and densification of microstructure. The optimum concentration among the selected trials was 0.5% for ZIF-8, 0.6% for ZIF-67, and 0.5% for ZIF-8-67 in cement based on the strength increment criteria. The flow test results indicated the hydrophobicity of the added nanomaterials, thereby increasing the workability.

Enhancing mechanical properties of three-dimensional concrete at elevated temperatures through recycled ceramic powder treatment methods

To promote the construction industry and establish a green environment, the integration of sustainable building materials is urgently required. This study presents the influences of three materials (silica fume, fly ash, and recycled ceramic powder (RCP)) and different RCP dosages (0%, 10%, 20%, and 30%) on the mechanical properties and microstructure of concrete at different temperatures. The study presents the results of comprehensive flow tests, printability assessments, mechanical evaluations under different loading directions, high-temperature analyses, digital image correlation, X-ray powder diffraction and scanning electron microscopy. The experimental findings indicate the successful printing of all samples, with wall structure failure occurring only at a height of 730 mm. Furthermore, compared to those of other materials, the RCP displays a superior heat resistance, with a significant increase in compressive strength (28.9%) to 53.9 MPa at 300 °C. Additionally, the introduction of the RCP into 3D-printed concrete results in an anisotropic behaviour, with an initial enhancement in the mechanical strength, followed by attenuation as the RCP content increases. Microstructural analysis reveals enhanced interfacial adhesion with RCP addition, albeit accompanied by the emergence of numerous pores. The optimal mixture, which is designated as RCP-2-0-1 with 20% of the cement replaced by RCP, exhibits a significant anisotropic compressive strength (55.9 MPa) and an adequate anisotropic flexural strength (12.49 MPa) and impressive heat resistance (11.7% increase in compressive strength at 300 °C). This renders it a suitable sustainable impact-resistant thermal material for use in structural applications.

Validation of the IDDSI funnel for liquid flow testing.

In 2017, the International Dysphagia Diet Standardisation Initiative (IDDSI) introduced the IDDSI flow test which enables patients, clinicians, caregivers, food service professionals and researchers to classify liquid thickness into five levels based on the volume of liquid remaining in a standard 10 mL slip tip syringe after 10 s of flow under gravity. Within a few months of publishing the IDDSI flow test instructions, several barriers emerged: (1) the preferred model of syringe (BD 303134) was not equally accessible around the world, causing some users to perform flow tests with alternate models of syringe; (2) differences in syringe geometry across models led to variations in IDDSI flow test results; and (3) the need to use a second syringe for sample loading added complexity and cost to end users. To address these barriers, IDDSI designed the IDDSI funnel, a novel device, which combines the geometry of the BD 303134 syringe with a kitchen funnel to facilitate easy loading of liquid samples without need for a second syringe. In this report, we compare the IDDSI flow test results across two devices: syringe BD 303134 and IDDSI funnel. IDDSI level classifications were in complete agreement with the syringe reference test results in 67/73 (92%) of the test fluids and temperature conditions with mean difference of residual liquid across devices of 0.2 (2% full scale). These results demonstrate excellent correspondence between the two devices.

Evaluation of the effectiveness of mixing hydrochloric acid and organic acid as stimulation fluids in a tight gas carbonate reservoir

AbstractMatrix acidizing is a widely used technique in carbonate formations to improve production and injection rates by restoring or improving permeability. This study evaluates the stimulation efficacy of organic and inorganic acid combinations in the Sarajeh carbonate formation, with a focus on improving permeability within this potential tight gas formation. Through solubility and continuous flow tests, a mixture of HCl 7.5% + HAc 2.5% was found to significantly outperform the traditional HCl 15% solution. The HCl 7.5% + HAc 2.5% mixture had a solubility rate of 59.27% and improved permeability by 4.4 times compared to HCl 15%, indicating a higher dissolving capacity. The results of continuous flow tests showed that the mixed acid had the best pore volume to breakthrough (PVBt) value of 2.574 at a controlled injection rate of 2 cc/min. This study demonstrates the superior performance of a lower concentration HCl‐HAc acid formulation in matrix acidizing carbonate formations and confirms its potential as a more effective alternative to high concentration HCl treatments for the Sarajeh reservoir.

Spline Model: A Hydrostatic/Non-Hydrostatic Dynamic Core with Space-Time Second-Order Precision and Its Exact Tests

We present a new explicit quasi-Lagrangian integration scheme with the three-dimensional cubic spline function transform (transform = fitting + interpolation, referred to as the “spline format”) on a spherical quasi-uniform longitude–latitude grid. It is a consistent longitude–latitude grid, and to verify the feasibility, accuracy, convergence, and stability of the spline format interpolation scheme for the upstream point on the longitude–latitude grid, which may map a quasi-uniform longitude–latitude grid, a set of ideal, exact test schemes is adopted, which are recognized and proven to be effective internationally. The equilibrium flow test, cross-polar flow test, and Rossby–Haurwitz wave test are used to illustrate the spline scheme uniformity to the linear scheme and to overcome the over-dense grid in the polar region and the non-singularity of the poles. The cross-polar flow test demonstrates that the geostrophic wind crosses the polar area correctly, including the South Pole and North Pole. A non-hydrostatic, fully compressible dynamic core is used to complete the density flow test, demonstrating the existence of a time-varying reference atmosphere and that the spline format can simulate highly nonlinear fine-scale transient flows. It can be compared for the two results of the density flow test between the solution with the spline format and the benchmark reference solution with the linear format. Based on the findings, the non-hydrostatic dynamic core with the spline format is recommended for adoption. When simulated for the flow over an ideal mountain, through the “topographic gravity wave test”, the bicubic surface terrain and terrain-following height coordinates, time-split integration, and vector discrete decomposition can be derived successfully. These may serve as the foundations for a global, unified spline-format numerical model in the future.

Enhanced stability of a three-dimensional graphene nanosheets networks modified asphalt mixture

To date, several concepts have been developed to enhance the mechanical and service life of asphalt pavements. Additives such as graphene, carbon nanotubes, carbon fibers and carbon black are used in the hot mix asphalt (HMA) or the asphalt binder (i.e., bitumen) for higher resistance to permanent deformations such as rutting, and transverse thermal cracking due to increased traffic volumes, vehicle mass and axle loads. In this study, graphene nanosheets (GNs) were used as potential modifier of bitumen binder in the HMA. The objective of this work is to investigate the impact of GNs modified bitumen on the Marshall stability and flow of the asphalt mixture using laboratory-compacted samples. The X-ray diffraction (XRD) study revealed a diffraction peak of GNs (002) at 2θ =26.5° along the bitumen’s γ-band and 10-band, which confirm a successful dispersion of GNs into bitumen binder. Furthermore, morphological analysis showed formation of a three dimensional (3d) interconnected networks of GNs between the bitumen micro-structures which could act as bridges for increased flexural strength of the binder. The Marshall stability and flow test results indicate that the mechanical properties of asphalt mixture were influenced by the addition of GNs to the bitumen binder. At 5% by weight of GNs modified bitumen (GNs-B), the compacted hot-mix Asphalt sample showed a higher Marshall stability of 11.7 kN recording 13.6% enhancement in comparison with the asphalt mixture with pure bitumen (P-B). In addition, when GNs-B was used, a lower flow of 1.4 mm was recorded which is desirable to prevent rutting and other forms of failure in asphalt pavements. This study underlines that adding GNs into asphalt binders such as bitumen could play a key role in enhancing the performance of asphalt pavements, which in turn extends their service life and saves maintenance expenses.

Fluid Flow and Effect of Turbulence Model on Large-Sized Triple-Offset Butterfly Valve

The performance a valve has been frequently estimated with numerical methods owing to limitations such as cost and place. In this study, for the triple-offset butterfly valves, the different sizes in various disc-opening cases was numerically conducted using different turbulence models of the two-equation turbulence models of k–ε, k-ω, and Reynolds stress model. The numerical calculations were validated against experimentally obtained valve flow test results. The numerical effect with the different turbulence models were analyzed with respect to the disc-opening cases. From the numerical analysis, the Reynolds stress model exhibits the most pronounced turbulence effects among the various turbulence models showing higher value of Reynolds normal stress near the valve disc region. The sensitivity of the turbulence model constants was examined using the 300 mm valve to observe the sensitivity of the turbulence model parameters in the two-equation turbulence models.

Properties of alkali-activated slag mortar and prediction of its compressive strength

An investigation was carried out on alkali-activated slag AAS mortar mixtures cast with three different water-to-binder ratios W/B; 0.35, 0.40, and 0.45, eight different silica modulus Ms, wide range of Na2O%, activated using a mixture of two different activators; waterglass and sodium hydroxide, and cured with two different curing methodologies; sealing and full immersion in water. The standard 70.6 mm mortar cubes were tested under compression at the age of 3 days and 7 days. Furthermore, their flow, setting time, and longitudinal shrinkage were measured. The results showed that not only the percentage of Na2O is important; but, its source. Additionally, curing methodology affected the compressive strength at both ages where the full immersion in water may cause early development of strength, with no later strength gain. Also, flow test results showed that although increasing the W/B ratio can cause an increase in the flow, however, the strength may be affected negatively at the highest W/B ratio. Drying Shrinkage of AAS mortar mixtures was also found to be very sensitive to the W/B ratio. Furthermore, four mathematical models were used to generate prediction equations of the compressive strength of AAS mortar based on the experimental data, and for both curing methods. A comparison between predictions of different mathematical models was made based on the highest coefficient of determination R2, score, and standard error. The models were verified using four AAS mortar mixtures that were casted and tested at the age of 7 days under compression. The results showed that two models closely predicted the actual strengths, except at compressive strength higher than 60 MPa, where the models were significantly conservative.

Mechanical Performance of Mortars with Partial Replacement of Cement by Aluminum Dross: Inactivation and Particle Size

Although the use of primary aluminum dross as cement replacement has shown promising results in mortars and concretes, there is a knowledge gap between the effect of the secondary dross inactivation process and particle sizes on the mechanical properties and consistency. So, by using X-ray diffraction, laser granulometry, and scanning electron microscopy, this article describes first the inactivation process applied to a secondary aluminum dross. Second, this manuscript presents the fresh and hardened properties of mortar mixes containing 5, 10, and 20% inactivated secondary aluminum dross with three different particle sizes (i.e., fine, intermediate, and coarse). Mortar flow test results indicate that compressive and flexural strengths of mixes containing up to 20% fine and intermediate aluminum dross as cement replacement were satisfactory, respectively. These results have the potential to reduce the environmental and health impacts caused by cement production and secondary aluminum dross disposal, respectively. Moreover, the durability aspects of the mortar mixes, as well as the effectivity of the investigated inactivation process, are identified as future research topics.

Ocena doświadczalna mieszanek mineralno-asfaltowych po częściowym zastąpieniu wypełniacza popiołami dennymi z elektrowni węglowej

The purpose of this study is to evaluate the performance of hot mix asphalt (HMA) prepared with coal bottom ash (CBA) as an alternative mineral filler. In this study, the effect of CBA on rutting, stiffness and fatigue resistance was experimentally evaluated. Combinations of conventional filler (stone dust) with different percentages of CBA (at 1.5%, 3%, and 4.5% by volume) were adopted. The HMA samples were prepared and tested using the Marshall mix design method. Following the Asphalt Institute MS-2 and the Pakistani National Highway Authority (NHA) General Specifications, sixty samples of HMA were compacted; stability tests at varying bitumen contents (3.5%, 4.0%, 4.5%, 5.0%, and 5.5%) were used to determine the optimum bitumen content (OBC) in the mixture for each percentage of CBA in the filler. For 0%, 1.5%, 3%, and 4.5% CBA, the optimum bitumen contents of 4.27%, 4.47%, 4.53%, and 5.0% were obtained, respectively. They were used throughout the study. Three samples with the optimum binder content were made for each of the four analysed CBA proportions. The wheel tracker test was run on 12 OBC samples, and the dynamic modulus test was run on 12 OBC samples. The Marshall stability and flow test results showed that the samples prepared with 3% CBA as filler and an OBC of 4.53% satisfied the NHA requirements for flexible pavement. It was noted that CBA greatly improves the rutting resistance and stiffness of asphalt mixtures. It also improved the fatigue life. Therefore, adding up to 3% CBA by volume to stone dust used as filler in asphalt concrete can minimize the need for stone dust and provide a suitable method of CBA disposal.

Optimization of alkali-activated binders using natural minerals and industrial waste materials as precursor materials

This paper presents the results of a study on developing optimized alkali-activated binders (AABs) utilizing selected natural minerals and industrial byproducts as precursor materials in addition to sodium hydroxide and sodium silicate as activators. Four selected precursor materials (natural pozzolana, limestone powder, red mud, and silicomanganese fume) were characterized in terms of their physical and chemical properties. The proportioning of the four precursor materials was optimized based on the results of flow, setting time, and compressive strength tests conducted on trial mortars. After reaching an optimal proportioning of the four precursor materials, the natural pozzolan was partially replaced by ordinary Portland cement (maximum 30% by wt.) to significantly enhance the properties of the AABs. The activator to precursor (A/P) ratio, sodium silicate to sodium hydroxide (NS/NH) ratio, sodium hydroxide (NH) molarity, and water to precursor (W/P) ratio, were varied from 0.3 to 0.6, 1 to 2.5, 8 to14 M, and 0.35 to 0.55, respectively. The influence of these activation parameters (at the optimally selected proportioning of precursor materials) on the physical and mechanical properties of AABs besides their mineral composition and morphology was investigated leading towards selecting the optimum AABs. The compressive strength at 28 days ranged from 28.5 to 32 MPa, 24.15 to 31.8 MPa, 24.2 to 33.1 MPa, 15.33 to 31.16 MPa, and 19.7 to 34.1 MPa, as A/P ratio, NS/NH ratio, NH molarity, W/P ratio, and curing method and duration were varied, respectively. XRD, FTIR, and SEM analyses of the AABs were conducted to validate the trends observed in the compressive strength results with variation in the activation parameters. The main phases detected by XRD included CSH, CASH, Mn-SH, KASH, and NASH. FTIR analysis showed bands that coincide with reported vibration and stretching of Si–O-M (M → Al, Si, or Mn) that are associated with geopolymerization, while SEM imaging showed dense microstructure with a homogenous distribution of polymerization gels that filled the microcracks and voids. Additionally, the effect of curing regimes (oven, steam and ambient-air curing) on the performance of AABs was also examined. The results of the present work enabled to identify the optimum proportioning of the selected precursor materials, optimum combination of A/P ratio, NS/NH ratio, NH molarity, and W/P ratio for producing the AABs with enhanced performance.

Chronic kidney disease, preoperative use of antispasmodics and lower resected prostate volume ratios are risk factors for postoperative use of adrenergic Alpha-blockers and antispasmodics.

Transurethral resection of prostate (TURP) and laser prostate surgery are common surgeries for benign prostate hyperplasia (BPH). We conducted an investigation using hospital database to evaluate the clinical factors associated with post-operative usage of alpha-blockers and antispasmodics. This study was conducted using retrospective clinical data from the hospital database, which contained newly diagnosed BPH patients between January 2007 and December 2012 who subsequently received prostate surgery. The study end-point was the use of alpha-blockers or antispasmodics for at least 3 months duration after 1 month of surgery. The exclusion criteria was prostate cancer diagnosed before or after the surgery, recent transurethral surgeries, history of open prostatectomy, and history of spinal cord injury. Clinical parameters, including age, body mass index, preoperative prostate specific antigen value, comorbidities, preoperative usage of alpha-blockers, anstispasmodics and 5-alpha reductase inhibitors, surgical methods, resected prostate volume ratios, and preoperative urine flow test results, were evaluated. A total of 250 patients receiving prostate surgery in the database and confirmed pathologically benign were included. There was significant association between chronic kidney disease (CKD) and the usage of alpha-blockers after prostate surgery (OR = 1.93, 95% CI 1.04-3.56, p = 0.036). Postoperative antispasmodics usage was significantly associated with preoperative usage of antispasmodics (OR = 2.33, 95% CI 1.02-5.36, p = 0.046) and resected prostate volume ratio (OR = 0.12, 95% CI 0.02-0.63, p = 0.013). BPH patients with underlying CKD were more likely to require alpha-blockers after surgery. In the meantime, BPH patients who required antispasmodics before surgery and who received lower prostate volume resection ratio were more liable to antispasmodics after prostate surgery.

Development of Cemented Paste Backfill with Superfine Tailings: Fluidity, Mechanical Properties, and Microstructure Characteristics.

Previous studies have shown that the effectiveness of superfine tailings cemented paste backfill (SCPB) is influenced by multiple factors. To optimize the filling effect of superfine tailings, the effects of different factors on the fluidity, mechanical properties, and microstructure of SCPB were investigated. Before configuring the SCPB, the effect of cyclone operating parameters on the concentration and yield of superfine tailings was first investigated and the optimal cyclone operating parameters were obtained. The settling characteristics of superfine tailings under the optimum cyclone parameters were further analyzed, and the effect of the flocculant on its settling characteristics was shown in the block selection. Then the SCPB was prepared using cement and superfine tailings, and a series of experiments were carried out to investigate its working characteristics. The flow test results showed that the slump and slump flow of SCPB slurry decreased with increasing mass concentration, which was mainly because the higher the mass concentration, the higher the viscosity and yield stress of the slurry, and thus the worse its fluidity. The strength test results showed that the strength of SCPB was mainly affected by the curing temperature, curing time, mass concentration, and cement-sand ratio, among which the curing temperature had the most significant effect on the strength. The microscopic analysis of the block selection showed the mechanism of the effect of the curing temperature on the strength of SCPB, i.e., the curing temperature mainly affected the strength of SCPB by affecting the hydration reaction rate of SCPB. The slow hydration process of SCPB in a low temperature environment leads to fewer hydration products and a loose structure, which is the fundamental reason for the strength reduction of SCPB. The results of the study have some guiding significance for the efficient application of SCPB in alpine mines.

Preparation and Performance Analysis of a Dimension-Controlled Nano-Drag-Reducing Agent for Low-Permeability Reservoirs

Graphene oxide (GO), as a derivative of graphene, is rich in reactive functional groups on its surface for modification, and the modified graphene oxide (M-GO) has excellent special properties. In this paper, the improved Hummer’s method was used to analyze GO by adjusting the amount of oxidant (potassium permanganate), oxidation time, and temperature, using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and laser particle size measurement. The successful synthesis of dimension-controlled GO in the range of 630–1000 nm was confirmed. On this basis, modified graphene oxide (O-M-GO) was prepared by grafting octadecyltrimethoxysilane (OCT). The successful synthesis of O-M-GO was confirmed by FT-IR and XRD. Through a contact angle test, the contact angle of GO before modification was 80 ± 0.5° and that of O-M-GO after modification was 105 ± 0.5°. Combined with SEM analysis, the change in the wettability of O-M-GO was clarified. Core flow test results showed that after O-M-GO was injected into the core, the subsequent brine injection pressure decreased by 14.21%, and the permeability was 1.166 times that before the brine injection. When the injection concentration was 50 mg/L, the drag reduction rate was 14%.

Leakage Dynamics of Glass Bottles on Container Closure Integrity Testing: Influence of Different Laser-Drilled Microhole Geometries

Container closure integrity testing (CCIT) is a critical step in ensuring package integrity and providing feedback on package designs. In practical applications, CCIT methods, namely physical and probabilistic methods, must be appropriately selected and validated to ensure their suitability for the intended use. However, the industry still lacks practical recommendations regarding the choice of CCIT methods and artificial leaks to set the acceptance criteria. The main reason is the lack of correlation between testing methods. Artificially introduced leak microholes are the only way to determine the sensitivity of a CCIT method and to implement the method correlation. However, the type of artificial leakage is a key factor because in most studies, leakage is described and valued using a single parameter, such as size. This can significantly affect the credibility of the relevant test results, especially in the case of microbial invasion, where the difference in test conditions and samples will severely affect the probability of microbial invasion. Therefore, it is vital to conduct a systematic study on the influence of leakage conditions on CCIT methods. In this study, the influence of the shapes of artificial leaks on the two kinds of testing methods was systematically studied based on a laser-drilled microhole—a highly potential and non-exogenous artificial leak manufacturing method that can fabricate different leakage geometries. The reason for the influence of the shape of an artificial leak on the CCIT is that the deterministic method takes defects as an idealized model and ignores the influence of the leak shape, wall thickness, and other factors on leakage and pollution risks. However, these factors seriously affect the dynamic process of leakage and microbial invasion. The pressure decay method is used to test the leakage flow rate of conical and straight holes. Microbial challenge tests are then used to verify the impact of leakage shapes on the pollution risk. The results of the tests indicated that the probability of microbial invasion in the conical holes is much higher than that in straight holes with the same flow test results and that the wall thickness can also affect microbial invasion. Thus, it can be proven that the risk of leakage and invasion or the sensitivity of different methods cannot only be compared through the leak diameter. Numerous influencing factors, including leakage geometry (e.g., shape and thickness), must be considered in practical applications.

Flow behavior of impounded fly ash slurries using flow test

Coal ash is one of the largest industrial waste products generated in the United States. Since 1967, several failures in ash impoundments have been reported, releasing millions of gallons of impounded fly ash slurry and resulting in loss of life and mass environmental destruction. Several studies have been carried out to understand the flow behavior of fly ash slurries. However, several questions remain unanswered regarding the flow behavior of fly ash slurries after containment loss. In this study, a new flow test, a miniature version of a cylindrical slump test, was developed to investigate flow behavior of six different fly ash slurries. The flow behavior of these slurries was evaluated based on the yield stress derived from the flow test results. The results showed that some fly ash slurries flowed at higher solids content (>60 %), while others flowed at lower solids content (<50 %) and stopped flowing at higher solid content. Furthermore, some slurries did not flow at all. It was found that the chemical compositions of fly ash, the state of hydration (hydrated or non-hydrated), original solids content when received, and initial solids content of fly ash slurries at the start of the flow test played a major role in the flow behavior of fly ash slurries. The interactions between these factors were complex, and it was difficult to identify the effect of a single factor. Most of the fly ash slurries showed shear flow, and some slurries at high solids content showed elongational flow. The fly ash slurries with shear flow had larger flow areas after containment loss. The addition of an anionic polyacrylamide significantly increased the yield stress by 2.8 – 3.5 times and decreased the flow of fly ash slurries.

Explainable Ensemble Learning Models for the Rheological Properties of Self-Compacting Concrete

Self-compacting concrete (SCC) has been developed as a type of concrete capable of filling narrow gaps in highly reinforced areas of a mold without internal or external vibration. Bleeding and segregation in SCC can be prevented by the addition of superplasticizers. Due to these favorable properties, SCC has been adopted worldwide. The workability of SCC is closely related to its yield stress and plastic viscosity levels. Therefore, the accurate prediction of yield stress and plastic viscosity of SCC has certain advantages. Predictions of the shear stress and plastic viscosity of SCC is presented in the current study using four different ensemble machine learning techniques: Light Gradient Boosting Machine (LightGBM), Extreme Gradient Boosting (XGBoost), random forest, and Categorical Gradient Boosting (CatBoost). A new database containing the results of slump flow, V-funnel, and L-Box tests with the corresponding shear stress and plastic viscosity values was curated from the literature to develop these ensemble learning models. The performances of these algorithms were compared using state-of-the-art statistical measures of accuracy. Afterward, the output of these ensemble learning algorithms was interpreted with the help of SHapley Additive exPlanations (SHAP) analysis and individual conditional expectation (ICE) plots. Each input variable’s effect on the predictions of the model and their interdependencies have been illustrated. Highly accurate predictions could be achieved with a coefficient of determination greater than 0.96 for both shear stress and plastic viscosity.