Split Cylinder Research Articles

Quality Management In Ready-Mix Concrete Production In Zambia

The construction industry, a significant contributor to global economies, is projected to yield substantial economic output by 2030 of around $135 trillion. Central to construction is concrete, a widely used material. Ready-mix concrete (RMC), a specialised form of concrete, is gaining prominence due to its rapid setting and superior quality. In Zambia, the increasing demand for RMC highlights the need for stringent quality management to hedge potential structural risks. This study aimed to determine the quality management in ready-mix concrete production in Zambia. Employing a parallel convergent mixed-methods research design to achieve the objectives, qualitative data was collected through semi-structured interviews and desk study and quantitative data was gathered through a structured questionnaire and an observation checklist. The findings of the study reveal that while guidelines exist, adherence varies. Regulatory bodies for standards, engineering and construction play pivotal roles in overseeing RMC quality. However, their execution faces inconsistencies and challenges due to limited resources and a lack of sense of responsibility. Quality control practices were investigated unveiling variations in forward, immediate, and retrospective control phases. Notable trends in proper storage and equipment calibration showed a commitment to precision. Immediate control practices, encompassing sampling and non-compliance management, demonstrated both positive aspects and areas for improvement. Retrospective control showed commitment to comprehensive strength testing and minimal towards split cylinder testing and on-site slump evaluation. In the realm of quality assurance (QA), RMC facilities show substantial adherence to documented QA standard operating procedures and thorough raw material inspections. However, deficiencies in batching and mixing practices and limited adoption of modern weighing systems require improvement. The study recommends creating an industry association for collaboration, enhancing standardised practices, introducing third-party quality audits, and proposing compulsory RMC standards to boost progress in the Zambian RMC industry. Key Words: Quality Management, Ready Mix Concrete, Observation, Desk Study, Zambia.

Exploring engineering properties of sustainable multi‐grade concrete: Materials, structural, and environmental aspects

AbstractThrough experimental and theoretical studies, this research explores the materials, structural, and environmental aspects of multi‐grade concrete (MGC), a potentially sustainable structural concrete. The experimental part investigates the compressive, split cylinder, flexural, and shear strengths of MGC, essential parameters for the design of structural members composed of MGC. It also provides the relationships between various strengths. The compressive behavior is correlated with the cracking pattern and the confinement effect caused by the end platens. The theoretical study involves determining the carbon emissions (CEs) and modifying ASTM/ACI expressions for the flexural tensile strength (FTS) and shear capacity applicable to MGC. Three uni‐grade concretes (UGCs) with distinct materials, properties, and grades: grade 17 (G17), grade 25 (G25), and grade 30 (G30), were poured in layers of varied thicknesses to make two variants of MGC. Experimental investigations showed that the higher‐strength concrete (HSC) confined the lower‐strength concrete (LSC) part thus increasing the compressive strength. Replacing 50% of LSC with HSC led to an increase in compressive and shear strengths by 21% and 40%, respectively. The shear strength values of reinforced MGC beams observed experimentally are aligned with those obtained through the modified expressions developed by the authors. A trade‐off analysis among the strengths, CEs, and costs of UGC and MGC can aid in selecting MGC customized to specific requirements, thereby contributing to the development of sustainable structural concrete.

Numerical simulation study of steel wire winding split ultra-high pressure die.

In this paper, a new type of large-cavity two-anvil ultra-high pressure die structure is proposed to solve the problem that the large-scale of the two-anvil ultra-high pressure die is limited by the difficulty in machining the large-size tungsten carbide. The die is mainly composed of an internal split cylinder with an inner cone and its support ring and the external steel wire winding layer. The stress distribution and cavity dimensional stability of the split cylinder are studied by using the finite element method and compared with those of the integral cylinder. This suggests that although the cavity-dimensional stability of the split ultra-high pressure die is reduced, the split ultra-high pressure die has greater advantages in improving the pressure-bearing capacity, processing, and manufacturing.

Adhesive characteristics of novel greener engineered cementitious composite with conventional concrete substrate

Engineered cementitious composite (ECC) is a high-graded advanced construction material that can be used to strengthen and repair structural composites owing to its high mechanical and durability properties. Nevertheless, the ability of ECC to strengthen and repair concrete surfaces depends on the interfacial bond between the conventional concrete (CC) substrate texture and ECC overlay. It ensures sufficient adhesive or bonding ability over a lifetime under various loading and environmental conditions. The present study investigates the bond strength between CC substrate and modified ECC with agro-industrial by-products, such as ground granulated blast furnace slag (GGBS), bagasse ash (BA), and rice husk ash (RHA). The bond strength is determined using three types of tests, namely the slant shear, split cylinder, and split prism tests. A mathematical model has also been developed to predict the bond strength of the different ECC mixtures. The results indicate that incorporating 40% GGBS, 10% BA, and 10% RHA in ECC helps in attaining the maximum interfacial bond strength with cross-hatched textures under all types of testing. According to the ACI standard, ECC with agro-industrial by-products ranging from 10% to 55% achieved the required bond strength in all three tests. Correspondingly, the outcomes of the present research are compared with those obtained from previous studies to gain further insights into various applications, which are highly relatable. Furthermore, the experimental outcomes were strongly correlated with the mathematical modeling with great accuracy.

The study of steel wire winding split type ultrahigh pressure die based on different winding methods

ABSTRACT We propose a novel structure of ultrahigh pressure die which consists of a split compression cylinder, a support ring, and steel wire winding, and the impacts of various steel wire winding methods on the ultimate cylinder pressure-bearing capacity are investigated. The investigations are conducted on the pre-stressing dies using the equal tensile stress (ETS), equal shear stress (ESS), and constant tangential stress (CTS) winding approaches. First, it is determined theoretically what the maximum cavity pressure and the necessary number of winding layers would be. The shear stresses of the cylinder and the support ring, the displacements of the cylinder, and the axial stresses of the steel wire layer are then examined using the finite element method. The results of the theoretical calculation and simulation are compared and discussed. The findings indicate that the ESS winding is a better option.

An Optimized Design Method and Experimental Study of Belt-Type Ultra-High-Pressure Dies

In this study, various structures are designed to improve the bearing capacity of belt-type ultra-high-pressure dies. Via theoretical analysis, numerical simulation, and destructive experiments, the stress distribution, bearing capacity, and failure principle of various dies are analyzed. The results demonstrate that the positive and negative values of the third invariant of the deviatoric stress tensor J3′ determine the deformation mode of the cylinder; when J3′ > 0, the cylinder is in the tensile deformation state, and when J3′ < 0, the cylinder is in the compressive deformation state. The third invariant of the deviatoric stress tensor of the belt-type cylinder is J3′ > 0, which causes tensile failure and rupture due to excessive circumferential stress. The use of a split cylinder can significantly reduce the circumferential stress, thus effectively reducing the maximum shear stress and von Mises stress and improving the pressure capacity of the cavity. However, when J3′ > 0 for the split cylinder, the pressure capacity is affected and the cylinder experiences tensile failure. A tangential split cylinder has a compressive deformation of J3′ < 0, which can fully utilize the properties of hard alloy materials and significantly improve the pressure-bearing capacity of the cylinder. This article provides an effective optimization design theory for belt-type dies, and the effectiveness of this method is proven through experiments.

Measuring device for systems of technical vibro-diagnosis of power equipment

RELEVANCE. Among the various methods for assessing the technical condition of power equipment, vibration diagnostics occupies an important place. Therefore, improving the quality of hardware for vibration diagnostics is currently extremely important. THE PURPOSE. To develop a vibration sensor with a new principle of operation for systems of technical vibration diagnostics of power equipment, as well as to theoretically substantiate the performance of the proposed sensor. METHODS. When solving the set goal, the main provisions of the theory of vibration diagnostics were applied. RESULTS. A design of the vibration acceleration sensor has been developed, the peculiarity of which is that it is excited by means of constructive coupling capacitors, the first electrode of which is made in the form of a thin-walled metal split cylinder, the role of the second electrodes is performed by the lower row of the winding of each measuring coil, and the function of the inertial element is performed by a screen made in the form of a metal ring fixed on a suspension in the form of a membrane. Based on the electrical equivalent circuit of the sensor, a theoretical substantiation of its operability and efficiency was made. Variants of circuit solutions for the primary and secondary measuring transducers of the measuring device for vibration diagnostics systems have been developed. The primary measuring transducer contains directly a vibration displacement sensor, a sinusoidal voltage source, an input differential measuring amplifier and an analog filter containing a narrow-band filter, a broadband amplifier and a buffer amplifier. The secondary measuring transducer contains a quadrature detector of information signals, an output buffer amplifier and a quadrature reference voltage driver. A block diagram of the hardware solution for the vibration acceleration registration system is also proposed. CONCLUSION. The developed sensor has improved output characteristics and can be used not only for vibration control of power equipment, but also for measuring mechanical vibrations in technical diagnostic systems of various other machines and mechanisms, as well as for tasks of spectral seismic exploration.

Analytical approach for bursting cracking analysis of post-tensioned anchorage zone

In prestressed concrete structures, improper design and detailing of the anchorage zone frequently cause bursting cracking along the tendon path. Due to the complex stress state in the anchorage zone, it is difficult to estimate the actual cracking load, even in well-controlled experimental tests. Previous studies on anchorage zone cracking are mainly based on numerical simulation. There is still a lack of explicit approaches for practical use. This study aims to provide an analytical approach for predicting the first bursting cracking loads in the post-tensioned anchorage zone. It is found that the stress ratio of compression to tension is significantly higher in the anchorage zone than in the split cylinder. Thus, a strength correction factor is derived to compensate for the tensile-strength reduction due to the effect of biaxial stress state. Besides, a tension chord model is developed to quantify the contribution of bursting reinforcement in enhancing the tensile strength of concrete. After clarifying the effect of biaxial stress state and the contribution of bursting reinforcement, direct equations are proposed for predicting the first bursting cracking loads in the anchorage zone. The analytical approach is compared with existing test data and is applied in the cracking analysis of an actual bridge, indicating that it is accurate and convenient for application.

The numerical simulation of standard concrete tests and steel reinforcement using force flux peridynamics

AbstractPeridynamics is a numerical particle‐based solid mechanics method that enables the simulation of brittle and quasi‐brittle materials, as well as ductile materials. It allows cracking to appear spontaneously in the arms joining the particles and can therefore be used to simulate progressive fracture. In this article, we apply our version of peridynamics, which we call force flux peridynamics, to the simulation of concrete where the appearance of cracks plays an important role in the global mechanical properties. It is not difficult to modify the material parameters in peridynamics to achieve a given tensile strength or a given compressive strength. However, it is much more difficult to choose parameters which will model all the strength parameters of a material within the same model. When concrete fails in compression it may split or spall showing a complex relationship between compressive and tensile failure. We therefore set ourselves the simple task of producing a single peridynamics model which can predict the stiffness and strength behavior of concrete in standard compression and tension tests for which we chose the American Society for Testing and Materials standards for the cylinder compression test, the split cylinder test, and the modulus of rupture test. A parameter sensitivity study was performed based on the cylinder compression test to tune the key peridynamics parameters that determine the global material behavior. The compressive and tensile strengths were then determined from the combined simulation data. While the fracture modes, crack branching pattern and also the stress–strain curve show promising results, the maximum tensile strength was found to be significantly larger than physical experiments suggest. This is probably due to imperfections within real concrete at the interface between aggregate particles and cement paste and it shows that the detailed numerical modeling of the failure of concrete is highly complex with a large number of unknown material parameters.

An alternative approach for measuring the mechanical properties of hybrid concrete through image processing and machine learning

Image processing (IP), artificial neural network (ANN), and adaptive neuro-fuzzy inference system (ANFIS) are innovative techniques in computer science that have been widely used to predict the properties of materials in structural engineering. The stability of reinforced concrete structures mainly depends on the mechanical properties of concrete, i.e., its compressive strength fc and tensile strength ft. Different kinds of inexpensive cement replacement materials (CRM) can be used to form hybrid concrete (HC) with enhanced mechanical and other properties. In this study, the IP, ANN, and ANFIS methods are properly combined and used to predict the mechanical properties of hybrid concrete. For this, 162 cylindrical specimens of HC with 0%, 15%, and 25% silica fume and fly ash as replacement material with three mix ratios, 1:3:6, 1:2:4, and 1:1.5:3 were cast at 14 days and 28 days curing. The specimens were divided into three equal sets as follows: (i) the first to find the compressive strength, (ii) the second to find the split cylinder strength, and (iii) the third to develop a database of images. For the image acquisition, each cylinder of the third set is cut into three slices using a stone cutting saw, resulting in six faces and a total of 324 images (6 × 54). Photos (digital images) are then taken in fully controlled lighting conditions from a height of 600 mm between the concrete surface and the camera lens. The acquired images are pre-processed (converted to grayscale, cropped, and resized to 256 × 256 pixels), and the statistical features are extracted to predict the fc and ft by using ANN and ANFIS techniques. Finally, the predicted values are tested and validated through nondestructive testing methods. The actual values of the compressive and the tensile strength of concrete were compared to the corresponding values estimated by the proposed methods, i.e. (IP, ANN) and (IP, ANFIS). The accuracy of the results largely depends on the data set. The accuracy obtained by IP/ANN is 99.7% while the one obtained with IP/ANFIS is 97.8%.

Recycling of Waste Facial Masks as a Construction Material, a Step towards Sustainability.

Amid the COVID-19 pandemic, a sudden surge in the production and utilization of disposable, single-use facial masks has been observed. Delinquency in proper disposal of used facial masks endangers the environment with a new form of non-biodegradable plastic waste that will take hundreds of years to break down. Therefore, there is an urgent need for the resourceful recycling of such waste in an environmentally friendly way. This study presents an efficient solution by using waste masks in fibered or crushed form to produce environmentally friendly and affordable green concrete. This investigation assessed the mechanical and durability properties of waste masks-incorporated concrete. A total of six mixes were prepared for standardized tests to determine compressive strength, split cylinder tensile strength and rapid chloride penetration test (RCPT), and freeze-thaw resistance. The percentage of mask fibers used were 0.5, 1, 1.5, and 2% of concrete by volume, while crushed masks were used at 0.5% only. The mask waste in both forms was found suitable to be used in concrete. One percent of waste mask fibers was found as an optimum value to increase compressive and tensile strength, reduce chloride permeability, and increase freeze-thaw resistance. Besides this, 0.5% crushed mask fiber also performed well, especially for producing less permeable and highly durable concrete. It is thus corroborated that waste masks that increase pollution worldwide can be utilized sustainably to help build green buildings. By reutilizing waste masks to produce improved concrete with better strengths and higher durability, circular economy and sustainability are achieved, along with efficient waste management.

Testing the Bromide penetration resistance of concrete: substitution of NaCl by NaBr in Rapide Chloride/Bromide Migration Test (RCM/RBM)

The chloride migration coefficient of concrete describes the resistance of concrete against chloride ingress. This important material variable can be determined with the rapid chloride migration test (RCM). During the test, chloride ions penetrate concrete by means of an applied electrical field. If the concrete has already been exposed to chlorides before the test starts, the test set up has to be adapted to achieve reliable results. Due to repeated exposure to the same salt (e.g. NaCl), there is no direct possibility to distinguish the chloride ions from the test procedure and the exposure before this, within the initial test procedure. Therefore, the RCM-test setup has been adapted by replacing NaCl through NaBr in the same molar amount. Consequently, this adapted test setup is called the rapid bromide migration test (RBM). The indicator silver nitrate AgNO3 forms sparingly soluble silver salts (AgCl, AgBr) in the presence of halogen ions (e.g. Cl-, Br-), which form a white precipitate in areas with Cl- or Br- ions. The penetration depths are measured at two split cylinder halves. In case the RBM-specimen has previously been exposed to NaCl, an analyzation technique has to be available for the two elements Cl and Br to enable a differentiation. As the white precipitate areas - a result of the formation of AgCl and AgBr - have a quite similar visual appearance, a differentiation cannot be achieved and other analytical techniques have to be considered. With laser-induced breakdown spectroscopy (LIBS), it is possible to determine the depth-dependent ion quantity (wt.-% of Cl or wt.-% of Br). In this study, it is shown by test results that it is possible to exchange NaCl by NaBr in the RCM test, since the penetration behavior of both ions (Cl-, Br-) is very similar in the migration test.

Temperature sensor tag based on supercavity mode of dielectric resonator

This paper presents a wireless temperature sensor design based on the excitation of a high-Q supercavity mode in a dielectric resonator. Narrow resonance bandwidth improves sensor performance enabling accurate temperature measurements. The sensor consists of a half split ceramic cylinder attached to a metal sheet. The resonator parameters which lead to the excitation of a supercavity mode were obtained numerically. When the ambient temperature increased continuously from 23 to 120°C the notable shift of the resonant frequency was experimentally demonstrated.

Stress analysis and experiment on a split-type ultra-high-pressure die for synthesizing diamond.

In order to obtain a higher pressure-bearing capacity and a larger sample volume and prolong the life of the high-pressure die, a novel high-pressure die for synthesizing gem-grade diamond is investigated with the finite element method. This device is the split-type die, and the cylinder is a combined type. Furthermore, this paper studies the stress distribution of the split-type cylinder and compares it with that of the traditional belt-type die. According to the simulation results, the split-type cylinder has much smaller stress than that of the belt-type cylinder, and it can bear much higher pressure. Meanwhile, the experimental tests also show that the high-pressure die with a split cylinder has a stronger pressure-bearing capacity than the belt-type die. Apart from that, the split-type cylinder has a better performance in easy manufacturing, strong pressure-bearing capacity, and replaceable performance.

Experimental Study on Influence of Methylcellulose on Tensile and Flexural Strength of Normal Strength Ordinary Portland Cement Concrete

Current study explores the possibility of improvement in various categories of concrete’s strengths (including tensile strength, flexural strength etc.) by using methylcellulose as an additive. The effect of methylcellulose on concrete’s compressive strength has also been investigated experimentally. Concrete samples were casted with several methylcellulose to binder ratios varying from 0.002 to 0.01 by weight of cement. Several tests were performed on concrete specimens including concrete cylinder and cube compression tests, split cylinder tests and modulus of rupture tests. Results showed that addition of methylcellulose increased the tensile strength of concrete. Addition of 0.2% of methylcellulose increased the tensile strength of concrete by 16%. This increase in tensile strength reached up to 73% of the control sample on addition of 1% methylcellulose. It was observed that the effect of methylcellulose on compressive strength of concrete depends upon the type of samples being tested (cube or cylinder). The compressive strength of concrete cylinders showed a plateau behavior with peak at 0.4% methylcellulose content with an increase of 18.7%. Effect of methylcellulose on concrete cylinder strength becomes insignificant beyond 0.6%. It was observed that addition of methylcellulose reduces the modulus of rupture values. The reduction in MOR was only 3% at 0.2% methylcellulose content but it grew to 30% at 1% methylcellulose content. The research presents an effective way of increasing tensile strength of concrete but without significant effect on concrete’s compressive strength and modulus of rupture values. These findings can be used to determine optimum content of methylcellulose to achieve desired performance from concrete depending upon the intended use.

Contact parameter analysis and calibration in discrete element simulation of rice straw

Discrete element method was used to study and analyze the interaction between rice straws and between rice straw and agricultural machinery parts, thereby providing a scientific basis for post-harvest paddy field processing. Calibrations of rice straw-rice straw, rice straw-agricultural machinery part contact parameters (collision recovery coefficient, static friction coefficient and rolling friction coefficient) constitute an important prerequisite for the discrete element research process. In this study, the collision recovery coefficients of rice straw-steel and rice straw-rice straw were 0.230 and 0.357, respectively, which were calibrated by the collision method. The static friction coefficient and rolling friction coefficient of rice straw-steel were 0.363 and 0.208 respectively, which were calibrated by the inclined plate method and the slope method. The static friction coefficient and rolling friction coefficient of rice straw-rice straw were 0.44 and 0.07, respectively, which were calibrated by the split cylinder method. The paired t-test showed insignificant differences between calibration parameter simulation results and the physical test values (p>0.05). Taking the angle of repose that reflecting rice straw flow and friction characteristics as the evaluation index, the verification tests of the above calibration values indicated that the simulated angle of repose has no significant difference from the physical test value (p>0.05). The side plate lifting test on rice straw of different lengths showed no significant difference between the simulated angle of repose and the physical test value (p>0.05). This study can provide a basis for contact parameters choice in discrete element simulation analysis with rice straw-rice straw and rice straw-agricultural machinery parts as the research object. The calibration method can provide a reference for the contact parameter calibration of other crop straws. Keywords: rice straw, discrete element simulation, contact parameter, parameter calibration, angle of repose DOI: 10.25165/j.ijabe.20211404.6435 Citation: Jia H L, Deng J Y, Deng Y L, Chen T Y, Wang G, Sun Z J, et al. Contact parameter analysis and calibration in discrete element simulation of rice straw. Int J Agric & Biol Eng, 2021; 14(4): 72–81.

Effectively Tunable Bandpass Waveguide Filter Based on Incorporation of Coupled Cylindrical Resonators Cut in Half

A novel mechanically tunable waveguide dielectric filter is presented in this paper. The resonant structure of the filter is made of a rectangular waveguide cavity and an H-plane dielectric cylinder cut in half. The resonating frequency of the proposed structure can be significantly changed by moving two split cylinder parts. The coupling matrix synthesis technique is used to create the required bandpass filter. A drawback of the proposed structure is that the tuning process invokes a mismatch between the feeding structure and the filter. To overcome this drawback the tuning screws between the coupling irises are used. A filter with the proposed geometry has a large frequency tuning range as well as relatively constant passband bandwidth.

Hydrodynamic Studies on Split Cylinder Reactor: Experimental and CFD Technique

Hydrodynamic Studies on Split Cylinder Reactor: Experimental and CFD Technique - written by T. Bhalamphiga Arasi , K. Saravanan , N. Deepa Priya published on 2020/05/13 download full article with reference data and citations

Numerical simulation and research of the split ultrahigh pressure cylinder

The pressure capacity of an ultrahigh pressure cylinder is the bottleneck of the development of ultrahigh pressure vessels. In order to improve the pressure capacity of the cylinder, the finite element software was used to analyse the single-layer thick-walled cylinder and the split cylinder under the same load. Research results show that the split cylinder has higher pressure capacity than that of single-layer thick-walled cylinder. Simulation of the different number subsections of the same size split cylinder show that the number’s increase of the subsections can effectively reduce their Von Mises stress under the same load.

Concrete properties for ultra-thin continuously reinforced concrete pavements (UTCRCP)

Ultra-Thin Continuously Reinforced Concrete Pavement (UTCRCP) is an innovative road paving technology that can have significant advantages over traditional road paving techniques. Tests have shown that UTCRCP can carry in excess of one hundred million E80s (standard 80 kN axle loads). The laboratory tests used for quality control of conventional concrete are not adequate to fully capture the effects of the steel fibres added to the high strength concrete used in UTCRCP. In this study the concrete strength and fibre content were varied and the mechanical and physical properties of the concrete were measured. The tests included compressive strength, split cylinder, modulus of elasticity and four-point bending slab tests. The results of these tests are reported in this paper, and the suitability and shortcomings of the tests are discussed.