Roller Compaction Research Articles

Investigation of the Efficiency of Ultra High Range Water Reducing Admixture in Roller Compacted Concrete Production

In this study, roller compacted concretes were produced by using polycarboxylate-based third generation high-performance mortar and concrete admixture, which provides ultra-high range water reduction and long workability time. In roller compacted concrete production, the chemical admixture dosage was 1%, which was the maximum dosage recommended by the manufacturer, and the amount of water used was reduced by 10, 20, 30 and 40% compared to the concrete produced without the use of concrete admixture. The physical and mechanical properties of the roller compacted concrete specimens were investigated. When the ultra-high range water reducer was used as 1% of the cement weight in the production of roller compacted concrete, optimum values in terms of unit weight, compressive strength, water absorption, ultrasonic pulse velocity and dynamic modulus of elasticity were obtained by reducing the mixing water by 10%. Although the water/cement ratio decreased, further reduction in water amount resulted in a decrease in compressive strength and affected the concrete quality negatively.

Using a Model-based Material Sparing Approach for Formulation and Process Development of a Roller Compacted Drug Product.

The present work details a material sparing approach that combines material profiling with Instron uniaxial die-punch tester and use of a roller compaction mathematical model to guide both formulation and process development of a roller-compacted drug product. True density, compression profiling, and frictional properties of the pre-blend powders are used as inputs for the predictive roller compaction model, while flow properties, particle size distribution, and assay uniformity of roller compaction granules are used to select formulation composition and ribbon solid fraction. Using less than 10g of a model drug compound for material profiling, roller compacted blend in capsule formulations with appropriate excipient ratios were developed at both 1.4% and 14.4% drug loadings. Subsequently, scale-up batches were successfullymanufactured based on the roller compaction process parameters obtained from predictive modeling. The measured solid fractions of roller compaction ribbon samples from the scale-up batches were in good agreement with the target solid fraction of the modeling. This approach demonstrated considerable advantages through savings in both materials and number of batches in the development of a roller-compacted drug product, which is of particular value at early development stages when drug substance is often limited and timelines are aggressive.

Thermal Analysis of Roller Compacted Concrete Dam Utilizing a Probabilistic Model

Roller compacted concrete (RCC) dam safety evaluation requires a realistic definition of thermal condition during construction and operation. Seasonal variations of temperature induce significant tensile stress. Therefore, the required preparations should be made to control and limit the thermal stresses. In this study, the effect of thermal and mechanical parameters on RCC dam behavior is evaluated using a probabilistic model. ANSYS Workbench software based on the finite element method has been utilized. The Latin hypercube sampling (LHS) method was used for probabilistic and sensitivity analysis, in which the density of concrete, Young's modulus, Poisson ratio, thermal conductivity, and specific heat have been selected as input variables. Dam body temperature, total deformation, and maximum principal stress in the body were considered as output variables. To evaluate the structural performance of the case model of the RCC dam under thermal loading, the model sensitivity to selected input variables is investigated. Considering to obtained curves, it can be concluded that the mechanical and thermal parameters have different effects on the performance of the RCC dam under variation of body temperature. Also, the results show that the sensitivity curves of output parameters are linear or bilinear relative to input variables.

Crambe grain yield affected by compaction degrees of an Oxisol

Crambe is a new crop that produces oil used for biodiesel production. Soil compaction in a no-tillage (NT) system is one of the main challenges for sustainable grain production in soil clay. The objective of this study was to evaluate the effect of compaction degree on crambe grain yield over two years. The levels of artificial compaction were generated using a roller compactor (0, 1, 3, and 5 passes) under a NT system. The experimental design was a strip block, and soil density and crambe grain yield were evaluated. The passes of the roller increased the density from 0.98 to 1.24 Mg m−3 in the 0–0.1 m layer, and 1.03 to 1.15 Mg m−3 in the 0.1–0.2 m layer. As a result, the compaction degree increased from 53% to 66% in the 0–0.1 m layer and 54% to 61% in the 0.1–0.2 m layer. Five passes of the roller compactor reduced the crambe grain yield by 41% and 9% in the first and second years, respectively, compared to the NT system without additional compaction. The crambe grain yield was reduced when the compaction degree reached 53%; therefore, crambe is not suitable for compacted soils.

System model driven selection of robust tablet manufacturing processes based on drug loading and formulation physical attributes

Mechanistic process modeling presents an opportunity to reduce experimental burden, enabling relationships between process parameters and product attributes to be mapped out using in-silico experiments. A system model of a pharmaceutical tablet manufacturing process comparing dry granulation with direct compression is developed to answer key material and process design questions. The system model links API physical properties and formulation to process parameters to map out the robust operating space. To demonstrate the application of the model, several drug product formulation design questions were considered:•Which processing route is the most robust given the API material properties and dosage requirements?•How does drug loading and tablet size impact the robustness of the manufacturing process?•What process settings are required for a robust manufacturing route for the API material properties and drug loading requirements?A computational framework was developed using the system models to generate process classification and design space maps to aid robust pharmaceutical formulation and process decision making. Process classification maps were produced to assess the feasibility of roller compaction and direct compression for different material properties and formulations. Constraints on the critical quality attributes of the intermediate and final products were defined using the Manufacturing Classification System. Design space maps presented here demonstrate how system models can be used to support formulation and process design. The design space maps illustrate how the process operating space can be increased or decreased as the API mass fraction is varied.The process design and selection system model demonstrate how an understanding of the API physical properties can be used to model the impact of formulation and process design. Furthermore, these models can be instrumental in the dialogue with colleagues developing the API in order to set the requirements of the API physical properties to ensure successful and robust formulation and process designs.

FORMULATION AND DEVELOPMENT OF FIXED-DOSE COMBINATION OF BI-LAYER TABLETS OF EFAVIRENZ, LAMIVUDINE AND TENOFOVIR DISOPROXIL FUMARATE TABLETS 600 MG/300 MG/300 MG

Objective: This study is to formulate bi-layer tablet as a multidrug regimen against each reference listed drugs of Brand SUSTIVA® (efavirenz tablets 600 mg), EPIVER®(lamivudine tablets 300 mg), and VIREAD®(tenofovir disoproxil tablets 300 mg) to treat human immunodeficiency virus (HIV) infections. Which provides highly active antiretroviral therapy to provide effective treatment. Methods: Bilayer formulation was developed with each blend of layer-I (efavirenz) and layer-II (lamivudine and tenofovir disoproxil fumarate) through wet granulation process and roller compaction process, respectively. Further, both layers were compressed by using bi-layer compression followed by film coating. Layer-I and II formulations were developed by using various concentrations of diluents, surfactants, and disintegrants to improve the solubility of efavirenz and improve the flowability and uniformity of layer-II. Finally, the optimum formulation was developed to compare the in vitro dissolution with each branded formulation. Results: Drug-excipients interaction results revealed that the mixtures of three drug substances in 50 °C/75 % relative humidity (RH) resulted in an increase in tenofovir IMP-E and the highest unknown impurity was significantly increased and additionally decreased tenofovir assay in the presence of efavirenz. Sodium lauryl sulfate is very critical and it acts as a wetting agent and increases the solubility of efavirenz, and directly influences the dissolution of a drug product. Microcrystalline and croscarmellose sodium have a chance to affect the dissolution and friability of tenofovir. Powdered cellulose was acting as a diluent and flow property of the lamivudine part and it also affects the uniformity and dissolution. So, these ranges were optimized. X-ray diffraction (XRD) indicates there are no polymorphic changes for the optimized formulation and there is no interaction between the three active substances, and finally, in vitro dissolution results for the optimized formulation against the reference drugs. Conclusion: Optimum formulation yielded consistent drug release against each branded drug to treat human immunodeficiency virus (HIV1) infections. This formulation is robust and easily scale up for the next stage.

Relationship between powder properties and uniformity of ribbon property using feeding guider designs with thermography (PAT) in roller compaction

Roller compaction is a continuous dry granulation process in which two counter-rotating rollers compress the powder. The feeding of powder to the compaction zone has a significant effect on product quality in the process. This work aims to improve ribbon property uniformity using new feeding guiders and develop a relationship map. The feeding guiders were designed in a range of grades considering the different powder properties and process parameters to achieve a uniform powder feeding to the compaction zone. An online thermal imaging camera was used as a process analytical technology to monitor the powder compaction and the uniformity of temperature across ribbon width, which was indirectly related to the powder distribution. The uniformity of the ribbon temperature of all powders increased from 20% using the original design to about 70% using the optimum design of the guiders, which indicated better powder distribution during the compaction. A relationship was also investigated for different materials with varying properties, grades of feeding guider and roller forces, which is useful for the design of experiments and predicting relative temperature uniformity of other materials.

Evaluation of Different Types of Mannitol for Dry Granulation by Roller Compaction

Evaluation of Different Types of Mannitol for Dry Granulation by Roller Compaction

Micromechanical analysis of roller compaction process with DEM

This study applies the discrete element method (DEM) to the roller compaction process for the analysis of particle flow behavior, porosity distribution in the compaction zone and in the final ribbon, as well as the pressure distribution on rollers. The roller compaction setup was implemented utilizing a piston feeder and smooth roller surfaces. The parameters of the elastoplastic DEM contact model were calibrated by uniaxial compression tests, interparticle and wall shear tests. Finally, the simulation results were validated by micro-computed tomography measurements of porosity profiles of manufactured lactose ribbons. From performed studies, it was observed that the particles passing the smallest gap possess higher velocity than the roller surface, and peak pressure is reached before the smallest gap. Furthermore, due to lateral relaxation, the particles in the center of the ribbon are faster than on the walls. The lateral stress can act as a further possible reason for the transversal ribbon splitting.

Effects of High-volume Fly Ash on the Properties of Roller Compacted Concrete: A Review

Roller compacted concrete (RCC) is a kind of dry and water-poor concrete, which has the advantage of less water consumption, fast construction speed using roller compaction machine compaction and low cost. RCC is often used in water conservancy projects. This paper outlines the effects of fly ash on the impact of compacted concrete in terms of compressive properties, flexural properties, dynamic modulus of elasticity, impermeability performance and crack resistance based on the working mechanism of fly ash in concrete. In a certain range, the performance of RCC is improved with the increase of fly ash content. Finally, this paper puts forward some suggestions for the further research of RCC.

Pregled i kritička analiza matematičkih pristupa za karakterizaciju praškova i višečestičnih sistema u razvoju lekova

An understanding of material properties and processing effects on solid dosage forms performance is required within the Quality-by-design approach to pharmaceutical development. Several research groups have developed mathematical approaches aiming to facilitate the selection of formulation composition and the manufacturing technology. These approaches are based on material particulate, bulk and compression-related properties. This paper provides theoretical assumptions and a critical review of different mathematical approaches for processability characterization of powders and multiparticulate units. Mathematical approaches have mainly been developed for directly compressible materials, but sometimes other manufacturing technologies, such as roller compaction and wet granulation, are also considered. The obtained compact tensile strength has been implemented in the majority of approaches, as an important characteristic describing compact mechanical properties. Flowability should be also evaluated, since it affects sample processability. Additionally, particle size and shape, material density and compressibility, compactibility and tabletability profiles have been also distinguished as relevant properties for solid dosage form development. The application of mathematical approaches may contribute to the mechanistic understanding of critical material attributes and facilitate dosage form development and optimization. However, it is essential to select the appropriate one, based on the intended dosage form characteristics, in order to ensure that all relevant powder/multiparticulate units characteristics are implemented and critically evaluated.

Seepage Mitigation in Hydropower Dams by Optimization in Roller Compacted Concrete Interlayer (Monoliths) Joint Bonding Technology

Roller Compacted Concrete (RCC) has gained favorable recognition in hydropower and water resource dam construction. With optimization in construction technology and materials used for RCC Dams, cost is no longer a major disadvantage as compared to environmental impact, that is, wildlife habitat disruption. In as much as it has become optimal for investment in hydropower dam construction, the scourge for dam failure is still eminent, which is as a result of excessive seepage compromising the integrity of the mechanical properties of the dam. The aim of the paper is to highlight successful application methods in joint bonding to avoid excessive seepage and reduce the autogenous healing to a few years of operation. In view of optimization, this paper presents a comprehensive study on the influences of interlayer joints bonding quality from RCC mix performances and how it consolidates the RCC layers to withstand the shear strength along the interface, especially on the high dams. The case study is the RCC dam at the 750 MW Kafue Gorge Lower Hydropower Station. The scope of the study reviews the joint type judged by Modified Maturity Factor (MMF) with joint surface long time exposed in regions with dry and high temperature, technical measures of layer bonding quality control under condition of long time joint surface exposure, effects of joints shear strength and impermeability of the RCC layers when under the conditions of plastic and elasticity. The subtle observations made during the dam construction phases were with respect to the optimal use of materials in relation to RCC mix designs and the basis for equipment calibration for monitoring important data that can be referenced during analysis of shear forces acting on the RCC dam over time.

Experimental and mathematical analyses of process parameters for roll compaction of steel powder

To reduce these costs and energy consumption, direct powder rolling (DPR) is one of the promising techniques. In this research work, DPR is used at room temperature and the process is evaluated to find out the relation between the process and material parameters. The steel powder was compacted to a green sheet using laboratory-scale powder compaction two high rolling machine equipped with gravity feeder to supply the steel powder. Optical microscopy and image J software were used to determine the porosity (%). A mathematical model using Buckingham pi theorem was formulated to establish the significance of influencing parameters on sheet densification. 3D Surface plot and 2D contour were analyzed to define the maximum sheet densification parameter regime with respect to the employed process variables for powder roll compaction.

Simulation of radial oscillations of a spring-loaded roll in a roll compactor

Carried out simulation of oscillations of a spring-loaded roll in a roll compactor when interacting the powder being compacted with the rolls. Considering the separation of the feed and compaction areas in the contact area of the roll with the material being compacted, we obtain the dependence of the force acting on the roll on the gap size between the rolls. It is shown that this dependence is non-linear, and it can be described with a sufficiently high accuracy degree by an exponential function with a negative exponent in the working range. The given numerical solution of the equation of free nonlinear oscillations of the spring-loaded roll has shown that considering the deformation of the material being compacted leads to a reduction of the natural frequency of the system by 20–25 % compared to the case, where the pressure force of the powder on the roll is assumed to be independent of the gap size. The nonlinearity of the dependence of the pressure force on the gap also leads to the increase by 10 % in the calculated values of the maximum displacements. The developed approach to the calculation of oscillations of the spring-loaded roll in the roll compactor enables to take into account the peculiarities of deformation of the powder being compacted during its interaction with the rolls. In addition, it allows estimating the frequencies and oscillation amplitudes and setting the optimum range of spring rate values, at which the occurrence of resonance in the machine is not possible.

Effects of N-trimethyl chitosan-recombinant tissue factor pathway inhibitor complex on avulsion flap with roll compaction in rat

Effects of N-trimethyl chitosan-recombinant tissue factor pathway inhibitor complex on avulsion flap with roll compaction in rat

Correlating the Strength Properties of Roller Compacted Concrete

Prediction of the strength properties of roller compacted concrete from mathematical models is significant for rapid decision of the quality of the pavement. In the present assessment, roller compacted concrete slab samples have been prepared in the laboratory using 12 percentage of Portland cement by weight of aggregates. Cube, core, and beam specimens were extracted from the slab samples and tested for compressive, indirect tensile, and flexural strength at the age of 28 days. Strength test results were corelated among each other and mathematical models were obtained. It was observed that low significance of aggregates gradation type on the compressive and tensile strength exists. However, high influence of dense gradation on flexural strength could be detected. The flexural strength of dense graded mixture is higher than that of gap graded mixtures. The compressive strength of gap graded mixture is higher than that of dense graded mixture. It can be concluded that the flexural strength is higher than the tensile strength by (2.17 and 1.24) folds for dense and gap graded mixtures respectively. The compressive strength is higher than tensile strength by (5.72 and 4.87) folds for dense and gap graded mixtures respectively. The compressive strength is higher than the flexural strength by (3.4 and 2.49) folds for dense and gap graded roller compacted concrete respectively. The obtained mathematical models exhibit high coefficient of determination and may be implemented in verification of the specific strength property based on other measured strength properties of roller compacted concrete.

Experimental evaluation of multi-functional effects of fibers on mechanical and performance properties of Roller-compacted concrete pavements (RCCP)

The weak performance of asphalt pavements in different climatic conditions, quick decay of pavement, and lack of necessary durability have caused engineers and constructors to try to find Roller Compacted Concrete Pavement (RCCP) for use in various conditions and applications with outstanding properties such as higher durability, and lower maintenance costs. This paper aimed to investigate the mechanical and durability of RCCP by considering different types and amounts of fibers. Cylindrical specimens (with two diameters of 100 and 150 mm) and bending beams with four different fiber types (steel, Kortta Emboss, Kortta Twist, and Sinusoidal plastic) and different percentages were used and subjected to various tests. The compaction time (VB or Vebe) test on fresh concrete, the compressive strength, elastic modulus, the flexural strength, the Brazilian tensile strength, impact resistance, electrical resistance, and skid resistance tests on hardened concrete were conducted. A total of 17 fiber-reinforced concrete mixtures in addition to plain specimen were considered. The test results indicated that compressive, flexural, and tensile strengths of the specimen containing steel fibers were improved up to 27, 83, and 25%, respectively. Moreover, the flexural and tensile strengths of specimens containing Kortta Emboss fibers were improved up to 80 and 19%, respectively. The impact resistance of specimens containing steel and Kortta Emboss fibers were significantly improved up to 270 and 290%. Based on evaluating the results obtained from all tests, Kortta Emboss fiber was proposed as the best option among the studied fibers to improve the properties and functions of RCCP.

Microstructure evolutions in lithium ion battery electrode manufacturing

<p indent="0mm">Since its commercialization in the 1990s, the lithium-ion battery has been a huge success in the energy industry owing to its high energy density and long cycle life. They have been used in national strategic fields, such as satellites and unmanned aircraft, to promote a remarkable leap forward in new energy, new energy vehicles, and other emerging industries. Therefore, the development of lithium-ion batteries is a strategic high ground for competition among countries worldwide. The development and widespread use of lithium-ion batteries is driven by their high energy/power density, long cycle life, and low cost, which requires battery material innovation as well as advancements in manufacturing processes and equipment technology. Particularly, the power and energy storage applications require numbers of battery cells connected in series or parallel. High precision is required to ensure the consistency of the battery cell, to avoid module capacity loss and cycle life attenuation owing to the “shortboard effect,” and to ensure battery safety. Electrode manufacturing, which is the first critical process of lithium-ion battery production, consists of three critical steps: Mixing, coating, and rolling. The positive and negative electrode active materials, conductive agents, binders and solvents are mixed into slurry and coated on copper or aluminum foil. The positive/negative electrodes, which constitute the electrochemical reaction carrier and the battery’s core, are obtained after drying and roller compaction. The porous and multi-component electrode microstructure evolves and is constructed in a complex way during electrode manufacturing. The proportion of electrode slurry, mixing order, coating method, drying strategy, and rolling process can considerably affect the evolution of electrode microstructure, such as pore structure, active particle distribution and, conductive/bonding network. It also influences the lithium-ion battery’s electrochemical performance. Despite tremendous advances in high-energy-density materials, research on lithium-ion battery manufacturing lags, resulting in a large gap between laboratory and production scales. This requires an in-depth understanding of the manufacturing and the relationship between electrode microstructure evolution and battery performance. The advancement and application of cutting-edge slurry mixing, coating, and calendering technologies in electrode manufacturing are thoroughly reviewed in this paper. The evolution of electrode microstructure during manufacturing, in particular, and its impact on the battery’s electrochemical performance, are discussed in detail. Then, various novel electrode manufacturing techniques are summarized in terms of their significance and challenges, covering the innovations based on the current process (aqueous processing, simultaneous double-sided slot coating, multilayer co-coating and, multistage drying), dry processing (electron beam and ultraviolet curing forming, electrostatic dry-powder coating), three-dimensional printing, and template-based methods. We aim to gain a better understanding of electrode structure design, material preparation, and manufacturing processes through the perspective of the “Manufacturing-Microstructure-Performances” relationship and guide the development of high-performance lithium-ion batteries. Finally, perspectives on future developments toward accelerating electrode design and manufacturing process optimization are presented, including three main parts: (1) Developing the multiscale and whole-process simulation platform to connect the electrode manufacturing, microstructure, and battery performance; (2) constructing microstructure-controllable electrode manufacturing technology that is compatible with existing production infrastructure; and (3) researching the microstructure evolution of the post-lithium-ion battery manufacturing.

Laser triangulation as a fast and reliable method for determining ribbon solid fraction; focus on accuracy, precision, and measurement time

Roller compaction and dry granulation represent well-established unit operations in the pharmaceutical industry. The ribbon solid fraction is classified as a critical quality attribute, that directly impacts final product quality and performance. The development and evaluation of novel methods measuring ribbon solid fraction represent a subject of current research, since novel analyses strategies need to be established for at-, on–, or in-line process monitoring to overcome limitations of end product testing and to set the course for continuous manufacturing. In this study, a novel analytical device, using the principle of laser triangulation, was investigated to asses its potential being used as at-line process analytical technology tool during a roller compaction process. To this end, the laser triangulation device was compared with X-ray micro-computed tomography and powder based volume displacement measurement techniques using different statistical evaluation methods. Special focus was given to accuracy, precision, and total measurement time. The laser triangulation device was confirmed as highly accurate and precise, enabling the shortest total measurement time compared to the other methods. The findings of this study support the idea of implementing the laser triangulation device as a novel at-line process analytical technology tool into a roller compaction process.

Roller Compacted Concrete – Best Practice Of Lithuania

In these days constantly being looking for solution to reduce construction costs, the amount of materials used and the negative impact on the environment. Designing pavement structures with top layer of traditional concrete, the structures become very massive. An alternative to traditional concrete is roller-compacted concrete, the concrete with significantly larger fine aggregates which lead concrete mix to be non-slip. The roller-compacted mix can also achieve high concrete density and consolidation by rolling. Roller-compacted concrete is also an economical and fast-construction alternative for many pavement applications. In Lithuania, roller-compacted concrete as the top layer is an innovation and first application of it was few years ago. However, in recent years application of roller-compacted concrete increased in industrial areas and low-volume rural roads. The best practice of application of roller-compacted concrete was in Klaipeda Free Economic Zone, where roller-compacted concrete was used as the top layer of industrial area for heavy load traffic. Fresh roller-compacted concrete workability decreases with time, to reduce transportation time and avoid excessive moisture loss, which can cause problems in placement of roller-compacted concrete, mobile concrete batching plant used. Mobile concrete batching plant was located near construction site.