Статті в журналах: "Compressible packing model"

1

Achour, Taoufik, Amara Loulizi, and Rim Achour. "Mechanical characterisation of aggregates using concrete compressible packing model." European Journal of Environmental and Civil Engineering 23, no. 8 (May 16, 2017): 945–56. http://dx.doi.org/10.1080/19648189.2017.1327889.

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2

Rocha, C. A. A., G. C. Cordeiro, and R. D. Toledo Filho. "Influence of stone cutting waste and ground waste clay brick on the hydration and packing density of cement pastes." Revista IBRACON de Estruturas e Materiais 6, no. 4 (August 2013): 661–80. http://dx.doi.org/10.1590/s1983-41952013000400009.

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The present work aims to study the replacement of Portland cement (PC) by stone cutting waste (SW) and ground waste clay brick (BW) in binary and ternary pastes. Thermogravimetry and differential thermal analysis tests were carried out at various ages in order to investigate the development of the cement hydration reactions in the presence of those wastes. The packing density was calculated in accordance with the Compressible Packing Model to understand the physical effect of those wastes. Compressive strength tests were also performed and the results were related to hydration and packing. Considering the substitution levels studied, the results indicated that the use of SW in the binary mixture accelerated the hydration reactions, and the particles packing density and compressive strength were maintained. The use of BW in the binary mixture caused a small acceleration in the hydration reactions and there was an indication of pozzolanic activity, although the compressive strength was reduced in comparison with the reference paste. In the ternary mixture, the combined effect of both wastes resulted in the maintenance of compressive strength for cement replacement content of 30%.

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3

Roquier, G. "The 4-parameter Compressible Packing Model (CPM) for crushed aggregate particles." Powder Technology 320 (October 2017): 133–42. http://dx.doi.org/10.1016/j.powtec.2017.07.028.

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4

Bala, Mokrane, Rachid Zentar, and Pascal Boustingorry. "Parameter determination of the Compressible Packing Model (CPM) for concrete application." Powder Technology 367 (May 2020): 56–66. http://dx.doi.org/10.1016/j.powtec.2019.11.085.

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5

Huang, Qiu An, Geng Guang Xu, and Jian Yu Chen. "Research of the Particle Gradation Technology of Components in PBX Explosive Based on CPM Model." Applied Mechanics and Materials 727-728 (January 2015): 366–69. http://dx.doi.org/10.4028/www.scientific.net/amm.727-728.366.

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Basedon the assumption of related parameters in compressible packing model, thecompressible packing model was used for the calculation of the explosivespacking efficiency. The accuracy of the calculation was verified by experimentsand the relative error was 2.49%. Besides, the influence of content offineparticles and particle size distribution in explosives on stacking efficiencywas discussed. The results show that the stacking efficiency was increasingwith the particle size distribution increasing from 0~300μm to 0~700μm. Thepacking efficiency reached it’s maximum value when we only increased thecontent of fine particles to 40%. Therefore, the packing efficiency has arelation with particle size distribution of raw materials.

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6

Baghaee Moghaddam, Taher, and Hassan Baaj. "Application of compressible packing model for optimization of asphalt concrete mix design." Construction and Building Materials 159 (January 2018): 530–39. http://dx.doi.org/10.1016/j.conbuildmat.2017.11.004.

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7

Xing, Chao, Zundong Liang, Yiqiu Tan, Dawei Wang, and Changhai Zhai. "Skeleton Filling System Evaluation Method of Asphalt Mixture Based on Compressible Packing Model." Journal of Transportation Engineering, Part B: Pavements 147, no. 4 (December 2021): 04021062. http://dx.doi.org/10.1061/jpeodx.0000320.

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8

Roquier, Gerard. "The 4-parameter Compressible Packing Model (CPM) including a critical cavity size ratio." EPJ Web of Conferences 140 (2017): 02009. http://dx.doi.org/10.1051/epjconf/201714002009.

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9

Gong, Jian Qing, Han Ning Xiao, Zheng Yu Huang, Jiu Su Li, Jing Nie, and Dan Mao. "Influences of Micropowder Gradation on Rheological Properties of Cement-Based Composite Pastes." Key Engineering Materials 353-358 (September 2007): 1398–401. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1398.

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The rheological parameters of cement pastes were investigated by varying the type and content of micropowders and the ratio of water to binder. Compressible packing model was used to calculate the packing density and to evaluate the influence of micropowders gradation on the rheological properties of fresh cement pastes. Results indicate that the higher the packing density is, the lower the yielding shear stress and plastic viscosity will be. When the ratio of water to binder is less than 0.20, the cement paste with 15% UFA and 15% SF has highest packing density and lowest yielding shear stress and plastic viscosity, which is beneficial to the workability of ultra-high performance concrete.

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10

Tanguy, P. A., and J. M. Grygiel. "A slightly compressible transient finite element model of the packing phase in injection molding." Polymer Engineering and Science 33, no. 19 (October 1993): 1229–37. http://dx.doi.org/10.1002/pen.760331902.

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11

Petrulis, Donatas, and Salvinija Petrulyte. "Packing Properties of Fibres in the Open-Packed Yarn Mode." Fibres and Textiles in Eastern Europe 25 (April 30, 2017): 57–61. http://dx.doi.org/10.5604/12303666.1228171.

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Theoretical observations of the packing properties of non-compressible round fibres for two idealized modifications of the open-packed yarn model are discussed. The modifications differ in the method of arrangement of fibres within the cross-sectional ring layer. Modification I has a number of fibres regularly increasing in further layers, and Modification II has the fibres maximum packed in the layers. A procedure for obtaining the number of fibres in the layers of Modification II was proposed. The investigation showed that with the beginning of the 5th layer, the above-mentioned modifications have different packing properties. Because of additional fibres in the layers of Modification II, packing fractions in the layers and yarn obtained were greater if compared with those for Modification I. Analysis of packing properties was made up to 12 layers of the yarn model and also was done for a case of an infinitely large numbers of layers or fibres in a yarn.

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12

HERMANN, A., E. A. LANGARO, S. H. LOPES DA SILVA, and N. S. KLEIN. "Particle packing of cement and silica fume in pastes using an analytical model." Revista IBRACON de Estruturas e Materiais 9, no. 1 (February 2016): 48–65. http://dx.doi.org/10.1590/s1983-41952016000100004.

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When added to concrete in appropriate content, silica fume may provide an increase in the mechanical strength of the material due to its high pozzolanic reactivity. In addition to the chemical contribution, physical changes can also be observed in concretes with silica fume due to an improvement in the particle packing of the paste. This is a result of their small size spherical particles, which fill the voids between the larger cement grains. However, it is necessary to properly establish the cement replacement content by silica fume, because at high amounts, which exceed the volume of voids between the cement particles, silica fume can promote the loosening of these particles. Thus, instead of filling the voids and increasing the packing density, the addition of silica fume will increase the volume of voids, decreasing the solid concentration. Consequently, this will impair the properties of the concrete. The objective of this paper is to use a particle packing analytical model, the CPM (Compressible Packing Model), to verify the maximum packing density of cement and silica fume, which could be associated with the silica fume optimum content in pastes. The ideal content of silica fume in pastes, mortars and concretes is usually experimentally determined. However, a theoretical study to contrast experimental data may help understanding the behaviour of silica fume in mixes. Theoretical results show maximum amounts of silica fume in the order of 18 to 20% of the cement weight, which is high considering recommendations on literature of 15%. Nevertheless, the packing model does not consider the effect of silica fume high specific surface on the agglomeration of particles or water demand. Hence, the packing density predicted by this model cannot be used as the single parameter in determining the optimum amount of silica fume in pastes.

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13

Yuan, Gaoang, Peiwen Hao, Dewen Li, Junli Pan, and Shi Dong. "Optimization design and verification of Large Stone Porous asphalt Mixes gradation using Compressible Packing Model." Construction and Building Materials 230 (January 2020): 116903. http://dx.doi.org/10.1016/j.conbuildmat.2019.116903.

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14

Baghaee Moghaddam, Taher, and Hassan Baaj. "The use of compressible packing model and modified asphalt binders in high-modulus asphalt mix design." Road Materials and Pavement Design 21, no. 4 (October 25, 2018): 1061–77. http://dx.doi.org/10.1080/14680629.2018.1536611.

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15

Sebaibi, Nassim, Mahfoud Benzerzour, Yahya Sebaibi, and Nor-Edine Abriak. "Composition of self compacting concrete (SCC) using the compressible packing model, the Chinese method and the European standard." Construction and Building Materials 43 (June 2013): 382–88. http://dx.doi.org/10.1016/j.conbuildmat.2013.02.028.

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16

Kuang, Tang Qing, and Kun Han. "Study on the Flow Behavior in Thin Cavity during Water-Assisted Injection Molding." Key Engineering Materials 467-469 (February 2011): 80–83. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.80.

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A numerical simulation model for the flow behavior of fluids in thin cavity during water assisted injection molding process is built up by adopting general Newtonian fluid model for the filling stage and non-Newtonian and compressible fluid model for the packing stage separately. Finite element/finite difference/control volume methods are adopted for the simulation of melt front, pressure variation at injection location, water thickness fraction and bulk temperature about a plate with trapezoidal cross-section. The simulated melt front location and shape have good agreement with experimental result. In comparison with the simulation results of conventional injection molding, it turns out that water assisted injection molding can obtain parts with low pressure requirement, perfect surface quality and rapid cooling.

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17

Roquier, G. "The 4-parameter Compressible Packing Model (CPM) including a new theory about wall effect and loosening effect for spheres." Powder Technology 302 (November 2016): 247–53. http://dx.doi.org/10.1016/j.powtec.2016.08.031.

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18

Schaeffer, D. G., T. Barker, D. Tsuji, P. Gremaud, M. Shearer, and J. M. N. T. Gray. "Constitutive relations for compressible granular flow in the inertial regime." Journal of Fluid Mechanics 874 (July 15, 2019): 926–51. http://dx.doi.org/10.1017/jfm.2019.476.

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Granular flows occur in a wide range of situations of practical interest to industry, in our natural environment and in our everyday lives. This paper focuses on granular flow in the so-called inertial regime, when the rheology is independent of the very large particle stiffness. Such flows have been modelled with the $\unicode[STIX]{x1D707}(I),\unicode[STIX]{x1D6F7}(I)$-rheology, which postulates that the bulk friction coefficient $\unicode[STIX]{x1D707}$ (i.e. the ratio of the shear stress to the pressure) and the solids volume fraction $\unicode[STIX]{x1D719}$ are functions of the inertial number $I$ only. Although the $\unicode[STIX]{x1D707}(I),\unicode[STIX]{x1D6F7}(I)$-rheology has been validated in steady state against both experiments and discrete particle simulations in several different geometries, it has recently been shown that this theory is mathematically ill-posed in time-dependent problems. As a direct result, computations using this rheology may blow up exponentially, with a growth rate that tends to infinity as the discretization length tends to zero, as explicitly demonstrated in this paper for the first time. Such catastrophic instability due to ill-posedness is a common issue when developing new mathematical models and implies that either some important physics is missing or the model has not been properly formulated. In this paper an alternative to the $\unicode[STIX]{x1D707}(I),\unicode[STIX]{x1D6F7}(I)$-rheology that does not suffer from such defects is proposed. In the framework of compressible $I$-dependent rheology (CIDR), new constitutive laws for the inertial regime are introduced; these match the well-established $\unicode[STIX]{x1D707}(I)$ and $\unicode[STIX]{x1D6F7}(I)$ relations in the steady-state limit and at the same time are well-posed for all deformations and all packing densities. Time-dependent numerical solutions of the resultant equations are performed to demonstrate that the new inertial CIDR model leads to numerical convergence towards physically realistic solutions that are supported by discrete element method simulations.

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19

Akonlula, A. "Preliminary Characterization of Co-processed Excipients of Okra (Abelmoschus esculentus) Mucilage and Pregelatinized Potato Starch." Nigerian Journal of Pharmaceutical Research 16, no. 2 (July 13, 2021): 119–29. http://dx.doi.org/10.4314/njpr.v16i2.14s.

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Background: Okra mucilage is highly viscous with good binding properties in tablets. Pregelatinized starches have significantly improved flow properties but produce tablets of poor mechanical strength.Objective: Preliminary evaluation of co-processed excipients of Okra mucilage and pregelatinized potato starch as directly-compressible excipients.Methods: Polymers were characterized for morphology (SEM), crystallinity (FT-IR) and flow properties. Coprocessed excipients were developed with Okra mucilage and pregelatinized potato starch at different ratios of starch: mucilage (95:5, 90:10, 85:15, 80:20, 70:30), using the co-fusion method. The flow, packing and compaction properties of the co-processed excipients were evaluated using density measurements, angle of repose, angle of internal friction, Kawakita model, consolidation index (C) and consolidation rate (K).Results: Larger agglomerates of the co-processed excipients indicated formation of a new polymer. FT-IR spectra showed retention of all the major peaks of individual polymers. Okra mucilage imparted swelling while starch improved flow in the co-processed excipients (Hausner’s ratio 1.12-1.20). Values from Kawakita plots revealedcohesiveness and compressibility were imparted to the co-processed excipients (a = 0.300–0.329; b = 0.078–0.361) suggesting good compactibility. Consolidation index and rate were observed to increase with Okra mucilage content, implying improved rate of packing as well as enhanced flow (C = 0.566-1.389; K = 0.123-0.424). The batch containing starch: mucilage 70:30 gave the best properties of good flow, cohesiveness and compactibility, essential parameters required in directly-compressible excipients.Conclusion: The co-processed excipients of Okra mucilage and pregelatinized potato starch could therefore be used as excipients for direct compression in tablet formulations.

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20

ZINCHENKO, ALEXANDER Z., MICHAEL A. ROTHER, and ROBERT H. DAVIS. "Gravity-induced collisions of spherical drops covered with compressible surfactant." Journal of Fluid Mechanics 667 (January 14, 2011): 369–402. http://dx.doi.org/10.1017/s0022112010004489.

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Gravity-induced collisions of two spherical drops covered with an insoluble surfactant at low Reynolds numbers are considered. Unlike in previous collision studies, the present work accounts for nonlinear coupling between the surfactant distribution and drop hydrodynamics by solving the full unsteady convective–diffusion equation for the surfactant transport. Our method includes high-order three-dimensional multipole expansions for hydrodynamics and a Galerkin-type approach for the surfactant transport with implicit marching. The efficiency of the algorithm allows for calculating thousands of trajectories to very close contact and determining the collision efficiency (related to the critical initial horizontal offset) by trial and error. The solution is valid for arbitrary surface Péclet (Pes) and Marangoni (Ma) numbers and sets limitations on approximations used in prior work for collision-efficiency calculations. Two limiting cases are observed: at smallPesor largeMa, the variation in surfactant coverage is small, and the results for the incompressible surfactant model are recovered, while for largePesand smallMa, the collision efficiency approaches the clean-interface value. For moderate drop-size ratios (radius ratiok≤ 0.5), the results generally fall between these limits. At larger size ratios, however, the collision efficiency may even exceed the geometrical Smoluchowski limit for both drops and bubbles. Moreover, with even moderate redistribution of the surfactant, equal-sized drops can move relative to one another and collide. These novel effects do not exist for clean drops or drops covered with an incompressible surfactant, and they are due to the nonlinear coupling between surfactant dynamics and flow. This surfactant-enhanced coalescence takes place, for example, in a physical system of air bubbles in water if the surfactant surface concentration is dilute (Γ ≈ 1×10−9mol m−2, much smaller than the typical maximum-packing value of 10−5−10−6mol m−2).

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21

Balthar, Vivian Karla Castelo Branco Louback Machado, Romildo Dias Toledo Filho, Eduardo de Moraes Rego Fairbairn, and Cristiane Richard de Miranda. "Durability of Lightweight Slurries for Oilwell Cementing." Key Engineering Materials 711 (September 2016): 203–10. http://dx.doi.org/10.4028/www.scientific.net/kem.711.203.

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In a deepwater environment, unconsolidated formations at seabed and naturally fractured carbonates at reservoir zones with high permeability are commonly found. In this context, the use of lightweight slurries is necessary to effectively cementing these formations, in order to mitigate slurry losses to the formations and to prevent their fracture. This work investigates the mechanical properties and durability of high performance lightweight slurries to be used in this environment. The mixtures were formulated within the framework of the Compressible Packing Model and were extended using hollow ceramic or glass microspheres. Tests were carried out to determine the slurries apparent density, rheology, free fluid, sedimentation, fluid loss, resistance to acid attack, sorptivity and total water absorption. A mechanical characterization was performed by uniaxial and triaxial compression and splitting tensile strength tests and were correlated with the durability tests. The reference slurry, extended with bentonite, presented a 1.46 g/cm3 density and compressive strength of 3 MPa (cure at 27oC/ 2.7 days). The slurries containing glass and ceramic microspheres were slightly lighter and presented a higher mechanical performance as compared to ordinary slurry. Besides, these mixtures presented a higher resistance to acid attacks and lower sorptivity, especially the lightweight slurry containing ceramic microspheres.

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22

Martins, A. P. S., F. A. Silva, and R. D. Toledo Filho. "Mechanical Behavior of Self-Compacting Soil-Cement-Sisal Fiber Composites." Key Engineering Materials 634 (December 2014): 421–32. http://dx.doi.org/10.4028/www.scientific.net/kem.634.421.

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The aim of this research is the development and mechanical characterization of self-compacting soil cement composites with the incorporation of fly ash, metakaolin and sisal fibers. The mentioned composites, based on natural raw materials (raw earth and vegetable fibers), which are abundant in nature and have low cost and low environmental impact could be used as a more sustainable alternative than conventional industrialized materials for applications that don ́t require high structural performance (minimum strength equals to 2 MPa). A residual soil, constituted by 35% of fines and 65% of granular material was selected and the matrix was designed using a computational routine, based on the compressible packing model (CPM). The rheology of the matrix was adjusted by the slump flow test having as a target the spreading value of 600 mm. The matrix presented uniaxial compression strength of about 3.3 MPa after 28 days of curing. After 240 days of curing it was noticed an increase in the compressive strength to 7.5 MPa. This can be traced back to the pozzolanic reactions that takes place in the system. The soil cement composites were produced with three different sisal fiber contents: 0.5, 1.0 and 1.5% (in relation to the weight of dry soil) and a fiber length (Le) of 20 mm. Under compression, the incorporation of fibers has significantly influenced the post-peak behavior, increasing the toughness and the strain capacity. Under four point bending loading, the presence of fibers have contributed to increase the peak strength and the residual strength with expressive gains of toughness. The composites presented strength values as high as 1.8 MPa (1.0% of fibers) when they were subjected to bending loads. The use of sisal fibers as reinforcement modified the fracture mechanisms of the composites, changing it from a brittle to a ductile behavior.

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23

Londero, C., L. A. Lenz, Í. M. R. dos Santos, and N. S. Klein. "Determinação da densidade de empacotamento de sistemas granulares compostos a partir da areia normal do IPT: comparação entre modelos de otimização de distribuição granulométrica e composições aleatórias." Cerâmica 63, no. 365 (March 2017): 22–33. http://dx.doi.org/10.1590/0366-69132017633652018.

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Resumo O empacotamento de partículas em concretos e argamassas adquire cada dia mais importância no âmbito técnico, uma vez que muitas das propriedades dos materiais compósitos são influenciadas pelo índice de vazios e concentração de sólidos. Este trabalho teve o objetivo de comparar a densidade de empacotamento de agregados miúdos, cujas curvas granulométricas foram obtidas pelo uso de diferentes modelos de empacotamento de partículas. A areia normal brasileira, fornecida pelo IPT, foi utilizada para verificação experimental dos resultados teóricos obtidos pelo uso dos modelos. As densidades de empacotamento das curvas granulométricas foram calculadas através do modelo de empacotamento CPM (do inglês, compressible packing model). A máxima densidade de empacotamento foi buscada pelo uso de modelos de empacotamento que resultam em uma curva granulométrica ideal, fazendo-se valer de ensaios preliminares que indicavam uma maior densidade de empacotamento na fração grossa da areia, de 1,2 mm. Desta forma, além das curvas granulométricas ideais, fez-se também um estudo com composições aleatórias onde houve aumento progressivo de 5% na fração grossa da areia com a devida compensação nas frações mais finas. Utilizou-se, como referência, a curva granulométrica que representa a média dos limites inferior e superior da zona ótima recomendada pela norma NBR 7211. Os resultados obtidos mostraram que é possível aumentar a densidade de empacotamento através do uso de modelos de empacotamento de partículas e composições aleatórias, com relação à curva média da norma. Esse aumento foi da ordem de 2% e 5% para as densidades de empacotamento real e virtual, respectivamente. A verificação experimental dos resultados teóricos demonstrou que o modelo CPM infravalorou a densidade de empacotamento em aproximadamente 10%.

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24

Bektimirova, Umut, Islam Mukhammedrakhym, Chang Seon Shon, Dichuan Zhang, and Jong Kim. "Effect of Aggregate Packing on Strength of Reactive Powder Concrete: Modeling and Experimental Evaluation." Materials Science Forum 998 (June 2020): 299–304. http://dx.doi.org/10.4028/www.scientific.net/msf.998.299.

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This research investigates the effects of aggregate packing degree on the strength of Reactive Powder Concrete (RPC) mixtures on the basis of the Toufar model. To optimize the packing degree of sand for strength development of RPC, various sand blends with the combination of different fraction size were used. In addition, 10 different blends that showed best packing degree were chosen to investigate the compressive strength of RPC. It was found that experimental verification results conform to Toufar model calculations. The test result shows that packing degree had a significant effect on the strength of RPC: Mixtures with higher packing degree can achieve higher compressive strength. Furthermore, Results indicate the Toufar model can predict packing degree of aggregate blends.

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25

Zhang, Li, Shufeng Zhang, Yuanxiang Jiang, Junyong Tao, and Xun Chen. "Compressive behaviour of fibre reinforced plastic with random fibre packing and a region of fibre waviness." Journal of Reinforced Plastics and Composites 36, no. 5 (October 14, 2016): 323–37. http://dx.doi.org/10.1177/0731684416674070.

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A critical limitation of fibre reinforced plastic is its large variability on mechanical performance, especially the longitudinal compressive strength. The influence of fibre random packing and waviness on the compressive strength of UD fibre reinforced plastic is studied in this paper. Three-dimensional geometrically non-linear finite element model is constructed to investigate the compressive behaviour, and an improved approach named Latin hypercube sampling based on random sequential expansion is proposed to generate random fibre distribution across the cross-section. Latin hypercube sampling based on random sequential expansion provides high computation efficiency and good distribution characteristics in comparison to previously proposed methods. Fibre waviness defect with different misalignment angles is also incorporated in the finite element model. It is shown that random fibre packing tends to result in a stochastic detriment of fibre reinforced plastic compressive strength in comparison with uniform fibre packing condition, and the stochastic variation of compressive strength tends to follow normal or lognormal distribution.

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26

Gao, De, Yu Wang, and Zhuang Liu. "A Set of Constitutive Models for a Kind of Corn Straw Fiber Based Composite Cushioning Packaging Material." Advanced Materials Research 174 (December 2010): 513–16. http://dx.doi.org/10.4028/www.scientific.net/amr.174.513.

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A static compressive model and a dynamic compressive model have been constructed based on Sherwood-Frost’s constitutive model for a corn straw fiber reinforced composite cushioning packaging material. In deriving the models, material density, shape function, strain and strain ratio are considered. The validity of models has been verified by static compressive and dynamic impact testing. The proposed models will provide important theoretic guideline for designing this kind of cushioning material.

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27

Cheng, Yun-Hong, Bao-Long Zhu, Si-Hui Yang, and Bai-Qiang Tong. "Design of Concrete Mix Proportion Based on Particle Packing Voidage and Test Research on Compressive Strength and Elastic Modulus of Concrete." Materials 14, no. 3 (January 29, 2021): 623. http://dx.doi.org/10.3390/ma14030623.

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According to the basic principle of dense packing of particles, and considering the interaction between particles, a dense packing model of granular materials in concrete was proposed. During the establishment of this model, binary particle packing tests of crushed stone and sand were carried out. The fitting analysis of the test results determines the relationship between the particle size ratio and the remaining volume fraction of the particle packing, and then the actual void fraction of the particle packing was obtained, based on which the water–binder ratio was combined to determine the amount of various materials in the concrete. The proposed concrete mix design method was used to prepare concrete, and its compressive strength and elastic modulus were tested experimentally. The test results show that the aggregate volume fraction of the prepared concrete increased, and the workability of the concrete mixture with the appropriate amount of water reducing agent meets the design requirements. When the water–binder ratio was 0.42, 0.47, or 0.52, the compressive strength of the concrete increased compared with the control concrete, and the degree of improvement in compressive strength increased with the decrease in water–binder ratio; when the water-binder ratio was 0.42, 0.47, or 0.52, the static elastic modulus of the concrete increased compared with the control concrete, and the degree of improvement in elastic modulus also increased with the decrease in water–binder ratio. The elastic modulus and compressive strength of the prepared concrete have a positive correlation. Findings show that the concrete mix design method proposed by this research is feasible and advanced in a sense.

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28

Zhang, Duzhou, Zhiguo Tian, Zhiqiang Chen, Dengyun Wu, Gang Zhou, Shaohua Zhang, and Moran Wang. "Compaction effects on permeability of spherical packing." Engineering Computations 37, no. 9 (May 6, 2020): 3079–96. http://dx.doi.org/10.1108/ec-01-2020-0015.

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Purpose The purpose of this paper is to investigate the evolution of the permeability of spherical packing during cold compaction by pore-scale modeling. Design/methodology/approach The discrete element method (DEM) is used to generate spherical packing structure under different compressive pressures and the Lattice Boltzmann method (LBM) is adopted to calculate the permeability of each spherical assembly. Findings It is found that the decrease of the porosity is the main reason of the reduction in permeability in the initial compression stage, but its influence becomes insufficient in the late compression stages. Besides, two empirical formulas are obtained, which describe the relation between the permeability and the equivalent mean diameter and the variation of normalized permeability with compressive pressure, respectively. Research limitations/implications In this study, the authors study the spherical particles and ignore the non-spherical effects. Besides, the classical contact model, the linear-spring-damping model, is used in DEM, so the plastic deformation cannot be considered. Originality/value The DEM and the LBM are well combined to study the compaction effects on permeability of spherical packing. Two simple expressions of the spherical packing structure with uniform diameter distribution are given for the first time.

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Liu, Yang, Lou Chen, Keren Zheng, and Qiang Yuan. "Improving Environmental Efficiency of Reverse Filling Cementitious Materials through Packing Optimization and Fiber Incorporation." Molecules 26, no. 3 (January 27, 2021): 647. http://dx.doi.org/10.3390/molecules26030647.

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To improve the environmental efficiency of the reverse filling system, three strategies aim to optimize the packing density, and the mechanical property were adopted in this study. Based on the compressive packing model (CPM), the relationship between the D50 ratio and maximum theoretical packing density for a reverse filling system with 25% and 30% superfine Portland cement was established. For comparison, silica fume and steel fiber were also added to the reverse filling system, respectively. The improvement of packing density by adjusting the D50 ratio was verified through the minimum water demand method, CPM, and modified Andreasen and Andersen (MAA) model. Compared to the reverse filling system added with 3 wt % silica fume, which possesses a comparable mechanical property with the optimized group (adjusted D50 ratio), the incorporation of steel fiber shows a more significant increase. The environmental efficiency of all the samples was quantified into five aspects through the calculation based on the mix proportion, compressive strength, and hydration degree. The comprehensive evaluation demonstrated that the optimized reverse filling system exerts a lower environmental impact and possesses a much higher cement use efficiency compared to the majority of ultra-high performance concrete (UHPC)/ ultra-high performance fiber-reinforced concrete (UHPFRC) reported in published papers.

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30

Yu, Zhihui, Lishan Wu, Cong Zhang, and Toshiyuki Bangi. "Influence of Distribution Modulus on the Compressive Strength of Ultra-High-Performance Concrete with Coarse Aggregate (UHPC-CA)." Advances in Civil Engineering 2022 (April 30, 2022): 1–14. http://dx.doi.org/10.1155/2022/7615616.

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The Modified Andreasen and Andersen model (MAA model) is commonly chosen to realize condensed particle packing in ultra-high-performance concretes (UHPCs). In the MAA model, the q (distribution modulus) is a parameter that plays a critical role in the UHPC matrix design. The objective of this study is to figure out the influence of the q for the compressive strength of UHPC-containing coarse aggregate (UHPC-CA). Therefore, a series of investigations were conducted, covering the following aspects: first, the traditional design procedure, based on the MAA model, of UHPC-CA is revised by taking water and steel fibers into account in the particle packing system. The results show that the revised design process of UHPC-CA yielded more excellent products with better workability and compressive strength. Second, different q values which are 0.2, 0.21, 0.22, 0.23, and 0.25 are employed. The results show that when q is 0.25, the maximum compressive strength can be achieved. However, the flowability decreases with the increase of the q value. Third, an empirical calculation of the optimal coarse aggregate content in the light of different q values and maximum size of coarse aggregate are proposed.

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31

Károlyfi, Kitti Ajtayné, Dániel Harrach, and Ferenc Papp. "Investigation of the Effect of Formwork Shape on Packing Density of Aggregates." Pollack Periodica 15, no. 3 (November 7, 2020): 125–34. http://dx.doi.org/10.1556/606.2020.15.3.12.

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Packing density of aggregate influences greatly the properties of concrete. Maximization of packing density increases the flowing ability and segregation resistance of the fresh concrete and the compressive strength of the hardened concrete. The determination of maximum density is difficult experimentally; therefore several models have been developed for that purpose. However, these models do not take the size of the formwork into account. In this study, 20 different formwork shapes were examined with defined aggregate fractions. Results show that increasing the formwork size increases the packing density of aggregate, and the growth depends on the formwork size and compaction method.

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32

Alkhaly, Yulius Rief, Abdullah, Husaini, and Muttaqin Hasan. "The Design of Reactive Powder Concrete (RPC) Mixtures Using Aceh Quartzite Powder." Key Engineering Materials 892 (July 13, 2021): 43–50. http://dx.doi.org/10.4028/www.scientific.net/kem.892.43.

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Original reactive powder concrete (RPC) consists of a large amount of cement, fine sand, crushed quartz, and silica fume, with a very dense matrix achieved by optimizing the granular packaging of the materials. This study, therefore, applied the modified Andreasen & Andersen particle-packing model using Aceh quartzite powder to design a densely compacted matrix and low cement content RPC mixtures. The research involved the preparation of two series of the mixture with different percentages of silica fume and Aceh quartzite powder and the 70.7 mm cube specimens were treated with combined steam curing and normal curing after which their compressive strength was tested at the age of 7 days and 28 days. The result showed the use of 61% local quartzite powder by weight of cement through an optimized mix design and cured treatment improves the RPC strength at any variation of silica fume.

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Díaz, Jesús, Jaime C. Gálvez, Marcos G. Alberti, and Alejandro Enfedaque. "Achieving Ultra-High Performance Concrete by Using Packing Models in Combination with Nanoadditives." Nanomaterials 11, no. 6 (May 27, 2021): 1414. http://dx.doi.org/10.3390/nano11061414.

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This paper describes the packing models that are fundamental for the design of ultra-high-performance concrete (UHPC) and their evolution. They are divided into two large groups: continuous and discrete models. The latter are those that provide the best method for achieving an adequate simulation of the packing of the particles up to nanometric size. This includes the interaction among the particles by means of loosening and wall coefficients, allowing a simulation of the virtual and real compactness of such particles. In addition, a relationship between virtual and real compactness is obtained through the compaction index, which may simulate the energy of compaction so that the particles are placed in the mold. The use of last-generation additives allows such models to be implemented with water–cement (w/c) ratios close to 0.18. However, the premise of maximum packing as a basic pillar for the production of UHPC should not be the only one. The cement hydration process affected by nanoadditives and the ensuing effectiveness of the properties in both fresh and hardened states according to the respective percentages in the mixture should also be studied. The characterization tests of the aggregates and additions (dry and wet compactness, granulometry, density and absorption) have been carried out in order to implement them numerically in the polydisperse packing model to obtain the compactness of the mixture. Establishing fixed percentages of nanoadditives in the calculation of the mixture’s compactness. The adequate ratio and proportion of these additions can lead to better results even at lower levels of compactness. The compressive strength values obtained at seven days are directly proportional to the calculated compactness. However, at the age of 28 days, better results were obtained in mixes with lower cement contents, fewer additions and lower compactness. Thus, mixes with lower cement contents and additions (silica fume and limestone filler) with a compactness of φ = 0.775 reached 80.1 MPa of strength at 7 days, which is lower than mixes with higher cement contents and number of additions (SF, limestone filler and nanosilica), which achieved a compactness of φ = 0.789 and 93.7 MPa for compressive strength. However, at 28 days the result was reversed with compressive strengths of 124.6 and 121.7 MPa, respectively.

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Ji, Tao, Bao Chun Chen, Feng Li, Yi Zhou Zhuang, Zhi Bin Huang, and Yong Ning Liang. "Effects of Packing Density and Calcium- Silicon Ratio of Ternary Cementitious Material System on Strength of Reactive Powder Concrete." Advanced Materials Research 261-263 (May 2011): 197–201. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.197.

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Aim & Goff model was used to predict the packing density of cementitious material including cement, ultra-pulverized fly ash and silica fume. The mix proportions of reactive powder concrete (RPC) with different packing density and calcium-silicon ratio of cementitious material were designed, and a strength test was carried out. The study results reveal that the flexural strength and compressive strength of RPC are related to the packing density and calcium-silicon ratio of cementitious material. For the mix proportion of RPC with the calcium-silicon ratio of 1.179, calcium hydroxide reacts with silicon dioxide fully, and the superfluous ultra-pulverized fly ash and silica fume fill the voids of RPC. The packing density of its cementitious material is the largest, and its strength approaches summit.

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35

Ji, Tao, Bao Chun Chen, Yi Zhou Zhuang, Zhi Bin Huang, and Yong Ning Liang. "Effects of Packing Degree and Calcium-Silicon Ratio of Cementitious Material on Strength of Reactive Powder Concrete." Advanced Materials Research 168-170 (December 2010): 1034–37. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1034.

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Aim & Goff model was used to predict the packing degree of cementitious materials including cement and silica fume. The mix proportions of reactive powder concrete (RPC) with different packing degree and calcium-silicon ratio of cementitious materials were designed and a strength test was carried out. The study results reveal that the flexural strength and compressive strength of RPC are related to the packing degree and calcium-silicon ratio of cementitious materials. For the mix proportion of RPC with the calcium- silicon molar ratio of 1.353 that is slightly less than the theoretical value of 1.42, where calcium hydroxide can react with silicon dioxide more fully, its strength of RPC approaches summit although its packing degree of cementitious material is not the largest one.

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36

Pyryev, Yuriy, Tomasz Zwierzyński, Edmundas Kibirkštis, Laura Gegeckienė, and Kęstutis Vaitasius. "Model to predict the top-to-bottom compressive strength of folding cartons." Nordic Pulp & Paper Research Journal 34, no. 1 (March 26, 2019): 117–27. http://dx.doi.org/10.1515/npprj-2018-0032.

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AbstractThis paper presents a proposed mathematical model, describing the calculations involved in deducting the critical compression force for rectangular, parallelepiped paperboard packaging, and permitting the minimisation of the thickness of the package sidewall. A comparison is given between the obtained calculations regarding critical force and the experimentally-determined results. This has shown a sufficient level of accuracy both for the theoretical and the experimental results. This means that the proposed mathematical engineering calculations model can be applied to the design of rectangular, parallelepiped paperboard packaging.

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37

McLachlan, D. S., M. B. Button, S. R. Adams, V. M. Gorringe, J. D. Kneen, J. Muoe, and E. Wedepohl. "Formation resistivity factors for a compressible solid‐brine mixture." GEOPHYSICS 52, no. 2 (February 1987): 194–203. http://dx.doi.org/10.1190/1.1442295.

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Formation resistivity factors were measured as a function of porosity for various rubber‐brine mixtures under uniaxial compression. Electrical measurements were made parallel and transverse to the direction of compression for regular crystal lattices (FCC and CsCl) and various random packings. Porosities from about 0.35 to as low as 0.03 were obtained. The formation factors ranged from about 5 to nearly 1 000. A new, effective media formula qualitatively, or in some cases even semiquantitatively, describes the results. The results agree reasonably well with calculations made on a model system, which the rubber‐brine mixture approximates. These calculations show, and the results from the rubber‐brine mixture confirm, a critical porosity below which the system is insulating.

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38

Tuan, Nguyen Van, Pham Sy Dong, Le Trung Thanh, Nguyen Cong Thang, and Yang Keun Hyeok. "Mix design of high-volume fly ash ultra high performance concrete." Journal of Science and Technology in Civil Engineering (STCE) - HUCE 15, no. 4 (October 31, 2021): 197–208. http://dx.doi.org/10.31814/stce.huce(nuce)2021-15(4)-17.

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The addition of supplementary cementitious materials (SCMs) to replace cement, especially with a high volume (> 50%), is an effective way to reduce the environmental impact due to the CO2 emissions generated in the production of ultra-high performance concrete (UHPC). Unfortunately, no official guidelines of UHPC using a high volume of SCMs have been published up to now. This paper proposes a new method of mix design for UHPC using high volume fly ash (HVFA), that is referred to the particle packing optimization of the Compressive Packing Model proposed by F. de Larrard. This proposed method also considers the heat treatment curing duration to maximize the compressive strength of HVFA UHPC. The experimental results using this proposed mix design method show that the optimum fly ash content of 50 wt.% of binder can be used to produce HVFA UHPC with a compressive strength of over 120 MPa and 150 MPa under standard curing and heat treatment, respectively. Moreover, the embodied CO2 emissions of UHPC reduces 56.4% with addition of 50% FA.

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39

Yang, Wen, Na Qian Feng, Ch’ng Guan Bee, and Xiao Deng. "Effect of Fineness of Fly Ash on Powder Packing Density and Paste Performance." Advanced Materials Research 701 (May 2013): 296–301. http://dx.doi.org/10.4028/www.scientific.net/amr.701.296.

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This paper discusses the effect of fineness of fly ash on powder packing density, compacting voidage, paste fluidity and compressive strength. The results showed that when the content of fly ash is between 0%~40%, the compacting voidage of the composite powder is reduced by adding the fly ash with D50 1.0μm and 3.0μm, not by the fly ash with D50 12.0μm. The results of pressured entities voidage are consistent with the calculated values by Aim-Goff model. The optimal content of fly ash with D50 1.0μm and 3.0μm are 30% and 25% respectively, which is more helpful to improve the dense packing density of composite powder. There are good corresponding relationships between compacting voidage, dense packing density and fluidity in composite powder or paste by adding the fly ash with D50 1.0μm and 3.0μm, the fly ash can reduce the dense packing voidage of composite powder, and improve the fluidity of fresh paste.

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40

Hela, Rudolf, and Lenka Bodnárová. "Development of Ultra High Performance Concrete Using Fly Ash." Materials Science Forum 987 (April 2020): 33–38. http://dx.doi.org/10.4028/www.scientific.net/msf.987.33.

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The experimental work presented in this article examines the possibility of lowering the economic cost of UHPC. The UHPC were designed using the Linear Packing Density Model. After 7 days, the UHPC compressive strength exceeded 120 MPa. Level of compressive strength after 90 days reaching 150 MPa had been obtained with a lower dose of cement (700 kg/m3) and with the use of secondary raw materials (fly ash), without the use of dispersed reinforcement. The successful design and production proved that the use of secondary raw materials is possible, thereby decreasing the economic cost of UHPC production.

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Lim, Jacob, Sudharshan Raman, Md Safiuddin, Muhammad Zain, and Roszilah Hamid. "Autogenous Shrinkage, Microstructure, and Strength of Ultra-High Performance Concrete Incorporating Carbon Nanofibers." Materials 12, no. 2 (January 21, 2019): 320. http://dx.doi.org/10.3390/ma12020320.

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The mix design of ultra-high performance concrete (UHPC) is complicated by the presence of many “ingredients.” The fundamental packing density allows a simpler mix design with fewer ingredients to achieve optimum packing density and dense microstructure. The optimum particle grading increases the flowability of UHPC and eliminates entrapped air. This study presents a simplified particle grading design approach that positively influences the strength, autogenous shrinkage, and microstructure characteristics of UHPC. Carbon nanofibers (CNFs) of superior mechanical properties were added to enhance the strength of UHPC and to reduce its autogenous shrinkage. In addition, ground granulated blast-furnace slag (GGBS) was used as a cement replacement material to reduce the amount of cement in UHPC mixes. Test results showed that the presence of homogeneously dispersed CNF increased the compressive strength and compensated the autogenous shrinkage of UHPC. The findings indicated that an ideal particle distribution, which is close to the modified Andreasen and Andersen grading model, contributed to achieving high compressive strength and CNFs were capable of providing nano-bridges to compensate the shrinkage caused by GGBS.

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42

Ling, Gang, Zhonghe Shui, Xu Gao, Tao Sun, Rui Yu, and Xiaosheng Li. "Utilizing Iron Ore Tailing as Cementitious Material for Eco-Friendly Design of Ultra-High Performance Concrete (UHPC)." Materials 14, no. 8 (April 7, 2021): 1829. http://dx.doi.org/10.3390/ma14081829.

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In this research, iron ore tailing (IOT) is utilized as the cementitious material to develop an eco-friendly ultra-high performance concrete (UHPC). The UHPC mix is obtained according to the modified Andreasen and Andersen (MAA) packing model, and the applied dosage of IOT is 10%, 20%, and 30% (by weight), respectively. The calculated packing density of different mixtures is consistent with each other. Afterwards, the fresh and hardened performance of UHPC mixtures with IOT are evaluated. The results demonstrate that the workability of designed UHPC mixtures is increased with the incorporation of IOT. The heat flow at an early age of designed UHPC with IOT is attenuated, the compressive strength and auto shrinkage at an early age are consequently reduced. The addition of IOT promotes the development of long-term compressive strength and optimization of the pore structure, thus the durability of designed UHPC is still guaranteed. In addition, the ecological estimate results show that the utilization of IOT for the UHPC design can reduce the carbon emission significantly.

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43

Yu, Wei, Hui Jian Li, Xi Liang, and Chang Jun He. "Studies on Mechanical Properties of Thin-Walled MHS Structure." Advanced Materials Research 189-193 (February 2011): 1321–24. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1321.

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Metallic hollow sphere structure cellular material is a type of super-light cellular metallic material. Its basic cell is thin-walled metallic hollow sphere. A series of quasi-static uniaxial compression experiments of two spheres array, three spheres array and tetrahedral packing structure were conducted. It is found that one sphere produces deformation at the contact place of two spheres, and the deformation is larger than that at the contact place of plates. The three spheres array and tetrahedral packing structure have the same phenomenon. Then, the Young’s moduli of these three models had been studied, and it is found that the tetrahedral packing structure has a larger value than the others. The compressive deformation behaviors of two and three spheres with the spheres glued together were studied too. These research findings can be the basis of the design of MHS structure cellular material.

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44

Mrówczyński, Damian, Tomasz Garbowski, and Anna Knitter-Piątkowska. "Estimation of the Compressive Strength of Corrugated Board Boxes with Shifted Creases on the Flaps." Materials 14, no. 18 (September 9, 2021): 5181. http://dx.doi.org/10.3390/ma14185181.

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In the modern world, all manufacturers strive for the optimal design of their products. This general trend is recently also observed in the corrugated board packaging industry. Colorful prints on displays, perforations in shelf-ready-packaging and various types of ventilation holes in trays, although extremely important for ergonomic or functional reasons, weaken the strength of the box. To meet the requirements of customers and recipients, packaging manufacturers outdo each other with new ideas for the construction of their products. Often the aesthetic qualities of the product become more important than the attention to maintaining the standards of the load capacity of the packaging (which, apart from their attention-grabbing functions, are also intended to protect transported products). A particular flaps design (both top and bottom) and its influence on the strength of the box are investigated in this study. An updated analytical–numerical approach is used here to predict the strength of packaging with various flap offsets. Experimental results indicated a significant decrease in the static load-bearing capacity of packaging in the case of shifted flap creases. The simulation model proposed in our previous work has been modified and updated to take into account this effect. The results obtained by the model presented in this paper are in satisfactory agreement with the experimental data.

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45

Arivoli, M., and R. Malathy. "Optimization of Packing Density of M30 Concrete With Steel Slag As Coarse Aggregate Using Fuzzy Logic." Archives of Metallurgy and Materials 62, no. 3 (September 26, 2017): 1903–13. http://dx.doi.org/10.1515/amm-2017-0288.

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Abstract Concrete plays a vital role in the design and construction of the infrastructure. To meet the global demand of concrete in future, it is becoming a challenging task to find suitable alternatives to natural aggregates. Steel slag is a by-product of steel making process. The steel slag aggregates are characterized by studying particle size and shape, physical and chemical properties, and mechanical properties as per IS: 2386-1963. The characterization study reveals the better performance of steel slag aggregate over natural coarse aggregate. M30 grade of concrete is designed and natural coarse aggregate is completely replaced by steel slag aggregate. Packing density of aggregates affects the characteristics of concrete. The present paper proposes a fuzzy system for concrete mix proportioning which increases the packing density. The proposed fuzzy system have four sub fuzzy system to arrive compressive strength, water cement ratio, ideal grading curve and free water content for concrete mix proportioning. The results show, the concrete mix proportion of the given fuzzy model agrees with IS method. The comparison of results shows that both proposed fuzzy system and IS method, there is a remarkable increase in compressive strength and bulk density, with increment in the percentage replacement of steel slag.

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46

Loza, Jerry, Doug Cash, and Benjamin Frank. "Importance of specimen preparation for edgewise compressive strength (ECT) testing." April 2018 17, no. 04 (May 1, 2018): 219–27. http://dx.doi.org/10.32964/tj17.04.219.

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While more than 50 years of published studies recognize the importance of rectangular, parallel edgewise compressive strength (ECT) specimens, none of the existing test methods address the degree to which a sample specimen is defined as sufficiently parallel. We present a detailed exploration of ECT results for specimens whose edges deviate from parallel with varying severity. We work to identify causes of variation in dimensional measurements and the corresponding ECT values across several industry standard cutters. These variations present a significant challenge to the industry in satisfying customer expectations for performance-based packaging, as well as to the development of improved predictive models for packaging performance.

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47

Chattaraj, Sandipan, and Sumit Basu. "Coarse-graining strategies for predicting properties of closely related polymer architectures: A case study of PEEK and PEKK." Journal of Materials Research 37, no. 1 (October 25, 2021): 1–12. http://dx.doi.org/10.1557/s43578-021-00332-0.

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AbstractThe ability of atomistic and coarse-grained models to discern between two polymers of very similar architecture is examined. To this end, polyether ether ketone (PEEK) and polyether ketone ketone (PEKK) are chosen. The difference in glass transition temperature and the similarity in compressive responses of the two polymers are captured by all-atom models. A coarse-graining scheme, with 6 beads per monomer and 3 types of beads, leads to a good approximation of the structure and packing of chains of PEEK and PEKK. The CG model reproduces differences in weakly rate-dependent properties such as $${T}_{\mathrm{g}}$$ T g . Comparison between strongly rate-dependent uniaxial stress–strain responses of these two polymers requires a knowledge of the scaling between physical strain rate in one to the effective rate in the other. The scaling can be approximately determined by comparing the variation of yield strength with strain rate, obtained from small-sized simulations. Graphic abstract

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48

Xie, Xiaogeng, Junqi Fan, Peng Guo, Haoliang Huang, Jie Hu, and Jiangxiong Wei. "Composition Design and Fundamental Properties of Ultra-High-Performance Concrete Based on a Modified Fuller Distribution Model." Materials 16, no. 2 (January 11, 2023): 700. http://dx.doi.org/10.3390/ma16020700.

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Both the discrete and continuous particle packing models are used to design UHPC, but the influences of a water film covering the particle surfaces on the compactness of the particle system were not considered in these models. In fact, the water film results in a certain distance between solid particles (DSP), which affects the compactness of the particle system, especially for cementitious materials with small particle sizes. In the present study, the mixture design method for UHPC was proposed based on the Fuller distribution model modified using the DSP. Then, the components of cementitious materials and aggregates were optimized, and the UHPC matrices with high solid concentrations were obtained. The results showed that the solid concentration, slump flow, and compressive strength of the UHPC matrix reached 77.1 vol.%, 810 mm, and 162.0 MPa, respectively. By replacing granulated blast furnace slag (GBFS) with quartz powder (QP), the flexural strength of the UHPC matrix was increased without reducing its compressive strength. When the steel fiber with a volume fraction of 1.5% was used, the slump flow, compressive strength, tensile strength, and flexural strength of the UHPC reached 740 mm, 175.6 MPa, 9.7 MPa, and 22.8 MPa, respectively. After 500 freeze–thaw cycles or 60 dry–wet cycles under sulfate erosion, the mechanical properties did not deteriorate. The chloride diffusion coefficients in UHPCs were lower than 3.0 × 10−14 m2/s, and the carbonation depth of each UHPC was 0 mm after carbonization for 28 days. The UHPCs presented ideal workability, mechanical properties, and durability, demonstrating the validity of the method proposed for UHPC design.

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49

NIU, XIAOYAN, GUOZHENG YUAN, ZHIGANG LI, and XUEFENG SHU. "STUDY ON DYNAMIC FAILURE MODEL OF LEAD-FREE SOLDERS USING SHPB TECHNIQUES." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1117–22. http://dx.doi.org/10.1142/s0217979208046402.

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The dynamic compressive properties of 96.3 Sn 3 Ag 0.7 Cu and 99.3 Sn 0.7 Cu solders were studied by means of a split Hopkinson pressure bar at strain rates ranging from 500 to 2000 s−1. Tests were conducted at room temperature and under uniaxial compressive conditions. Eutectic SnPb solders were used as the reference. From the data of tests, it was found that yield strength and flow stress increased remarkably with the increase of strain rate. On logarithmic scales, the yield strength increased linearly with strain rate. These lead-free solders revealed certain visco-plastic behavior and strain rate sensitivity, which predicted using Johnson-Cook material model. Related parameters in the model were determined from the experiment. Compared with the typical Pb -containing solder Sn63Pb37 , these lead-free solders showed some fine properties and could substitute some Pb -containing solder alloys in microelectronic components packaging and interconnects.

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50

Tiwari, Abhishek, and Shivam Tyagi. "Experimental study on lower cement content (LCC) concrete using continuous packing model: An Eco-Friendly and Sustainable Alternative for Construction Industry." International Journal of Current Engineering and Technology 10, no. 05 (October 31, 2021): 700–702. http://dx.doi.org/10.14741/ijcet/v.10.5.1.

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Now a day’s pressure is escalating on the construction industry to adopt more environmentally sustainable methods to reduce CO2 emissions. Portland cement often constitutes to quite two-thirds of the embodied energy of concrete, and its production generates 5% of worldwide greenhouse emission. One efficient strategy to scale back the cement content without sacrificing performance is that the use of particle packing models (PPM) to mix- proportion concrete mixtures with low cement content. This study aims to analyze and quantify the behavior of concrete mixtures designed with the use of the continuous PPM to increase binder efficiency in concrete. Three q factors were selected in this study and properties in the fresh (i.e. slump test) and hardened state (i.e., compressive strength) are measured and analyzed.

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