The research of the operating mode of the concrete mixture plane depth compactor with a circular vibration exciter

2019 ◽  
Vol 1 (52) ◽  
pp. 5-12 ◽  
Author(s):  
Alexander Maslov ◽  
Janar Batsaikhan
Keyword(s):  
Vertical Plate ◽  
Operating Mode ◽  
Concrete Mixture ◽  
Vibration Exciter ◽  
Torsional Vibrations ◽  
Plate Movement ◽  
Concrete Mixtures ◽  
Linear Vibrations ◽  
Design Diagram ◽  
Made In

The paper proposes an essentially new design of a concrete mixture depth compactor made in the form of a vertical plate witha circular vibration exciter mounted on its upper part. A design diagram of the «plane depth compactor – concrete mixture»dynamic system is presented and the vertical plate movement equations describing its linear vibrations in the horizontal planeand torsional vibrations in relation to the center of gravity are provided. It has been determined the regularity of the verticalplate motion during the compaction of concrete mixtures. The provided results of the research enable the substantiation of therational parameters of the plane depth compactor performing spatial vibrations and the efficient modes of the vibratory actionon the concrete mixtures of different consistence.

Study of Rheological Properties of Modified Concrete Mixtures at Vibration

2019 ◽  
Vol 968 ◽  
pp. 96-106
Author(s):  
Oleksandr Pshinko ◽  
Olena Hromova ◽  
Dmytro Rudenko
Keyword(s):  
Mechanical Properties ◽  
Rheological Properties ◽  
Physical Nature ◽  
Concrete Mixture ◽  
Practical Significance ◽  
Vibration Displacement ◽  
Concrete Mixtures ◽  
Variable Quantity ◽  
Vibration Compaction ◽  
Mechanism Of Interaction

Study of rheological properties of concrete mixtures based on modified cement systems in order to determine process parameters. Methodology. To study structural-mechanical properties of modified concrete mixtures of different consistency at their horizontal vibrating displacement an oscillatory viscometer was designed. Results. The optimization of the process of vibration displacement of concrete mixtures with the specification of parameters of vibration impacts taking into account structural-mechanical properties of the mixture is performed. It has been established that the viscosity of the modified cement system of the concrete mixture is a variable quantity, which depends on the parameters of the vibration impacts. Scientific novelty. The mechanism of interaction of the modified concrete mixture with the form and the table vibrator during its vibration compaction is determined. On the basis of this, a model of concrete laying process control is proposed, that allows to predict the ability to form a dense concrete structure. Practical significance. Disclosed physical nature of the process of vibrating displacement of modified concrete mixtures using the principles of physical-chemical mechanics of concrete allows reasonably choose the best options for vibration impacts.

scholarly journals MAIN PROBLEMS OF MANUFACTURING ASPHALT CONCRETE MIXTURES IN LITHUANIA/ASFALTBETONIO MIŠINIŲ GAMYBOS SVARBIAUSIOS PROBLEMOS LIETUVOJE

2000 ◽  
Vol 6 (1) ◽  
pp. 39-45
Author(s):  
Donatas Čygas
Keyword(s):  
Asphalt Concrete ◽  
High Speed ◽  
Statistical Data ◽  
Concrete Mixture ◽  
Cement Material ◽  
Asphalt Cement ◽  
Concrete Mixtures ◽  
Concrete Quality ◽  
Regressive Analysis ◽  
Speed Gradient

The article describes the main problems of manufacturing asphalt concrete mixtures at the factories under Ministry of Communication in the Republic of Lithuania. The Lithuanian Road Network is up to 21.122 km of state roads. 1.455 km of them are motorways, 3.415 km—national roads and 16.251 km—regional roads. Half of the state roads in Lithuania are paved with asphalt concrete. 98% of the motorways and 36% of the regional roads have asphalt pavement. Asphalt concrete pavement resistance to corrosion can be increased by improving asphalt concrete mixture production technology: ie by updating technological equipment, changing technological conditions and developing new methods of asphalt concrete mixture production. Therefore, the updating of asphalt concrete mixture production technologies is a very important factor for improving road operating properties and ensuring proper duration of asphalt concrete pavements. Here is the essence of the new separate successive technology: crushed stone and sand are mixed with bitumen in the main asphalt concrete mixer, the amount of bitumen being calculated according to the bitumen absorption in the materials. Then the asphalt cement material produced in a separate high-speed mixer is passed, and the whole mixture is remixed in the main mixer and supplied to the customer. Both separate consequent technologies differ from each other in the order of supplying asphalt cement material into the main mixing unit. Separate successive technology was theoretically grounded by the correlation between the technological thickness of bituminous film and the chemical-mineralogical composition and size of constituents, by the correlation between the particle size and their capability to compose aggregates, by the emergence of the oriented binding material coating on the technological bituminous film encoating mineral particles. Special attention is given to the manufacturing of asphalt cement material in a separate high-speed mixer (3 Table). It was theoretically grounded that mineral filler passing through the intensive shift zone between the paddle ends of the high-speed mixer and the walls of mixing chamber disintegrate and new active surfaces become visible. The molecular structure changes and free radicals appear. This intensive mixing guarantees high bitumen adsorption on the surface of mineral filler, which increases asphalt concrete resistance to corrosion and its durability, improves ecological environment in the asphalt concrete plant. In order to confirm the reliability of research results and explain correlative and regressive regularity, statistical data were processed applying statistical data processing programming system “STATGRAPHICS”. The linear regressive analysis for determining close relations of separate asphalt concrete quality indicators with speed gradient of asphalt cement material shift in a high-speed mixer was performed. Therefore, the possibility to change shift speed gradient from 3000 to 5000 1/s is provided in terms of reference for manufacturing asphalt concrete mixing plant. Correlation between separate asphalt concrete quality indicators and asphalt cement material shift speed gradient as well as bitumen amount in the asphalt cement material was determined by multi-dimensional regressive analysis of experimental data. The calculated correlation factor squared (R2) and F criteria indicate the adequacy and reliability of the multidimensional regression model.

On the Non-Linear Dynamics of a Traveling Cable With Small Sag

1995 ◽  
Author(s):  
Christoph G. Reuter ◽  
Peter Hagedorn
Keyword(s):  
Equations Of Motion ◽  
Steady State Solution ◽  
Extended Model ◽  
Transport Velocity ◽  
Non Linear ◽  
Mechanical Models ◽  
Linear Vibrations ◽  
Technical Systems ◽  
Inertia Forces ◽  
Made In

Abstract Traveling cables or threadlines appear in a number of technical applications such as textile machinery, V-belts, ski lifts, funiculars and also in simple models of traveling webs in paper machinery. The mechanical models used so far, most often neglect the effect of sag due to the weight of the cable, although it is well known that in some cases it may be quite important. In this paper, the authors develop a particularly simple model for translating cables using the assumption that the longitudinal inertia forces are negligible in comparison to the transversal inertia forces if the sag of the cable is sufficiently small. This assumption has already been made in a study of linear vibrations of stationary cables in 1970 by Irvine & Caughey. This lead to surprising results which have also been verified experimentally in the laboratory. The extended model presented in this paper includes gyroscopic and nonlinear terms in the equations of motion, related to the cable transport velocity and geometric nonlinearities. As a particular case (zero longitudinal speed and linear theory) the model of Irvine & Caughey is again contained in the present analysis. The linear and non-linear vibrations about a steady state solution are studied. The results show some interesting features which may also be relevant to technical systems if the transport speed is sufficiently high.

DURABILITY PERFORMANCE AND DIMENSIONAL STABILITY OF POLYPROPYLENE FIBER REINFORCED CONCRETE

2018 ◽  
Vol 13 (2) ◽  
pp. 20-41 ◽  
Author(s):  
Ali Mardani-Aghabaglou ◽  
Süleyman Özen ◽  
Muhammet Gökhan Altun
Keyword(s):  
Reinforced Concrete ◽  
Dimensional Stability ◽  
Polypropylene Fiber ◽  
Pulse Velocity ◽  
Fiber Reinforced Concrete ◽  
Concrete Mixture ◽  
Fiber Reinforced ◽  
Concrete Mixtures ◽  
Durability Performance ◽  
Polypropylene Fiber Reinforced Concrete

In this study, the durability performance and dimensional stability of polypropylene fiber reinforced concrete mixture were investigated. For this purpose, two series of concrete mixtures, including a 0.45 water/cement ratio was prepared both in the absence and presence of fiber. A CEMI 42.5 R type portland cement and crushed limestone aggregate with a maximum particle size of 25 mm were used. In addition to the control mixture without fiber, three different concrete mixtures were prepared by adding polypropylene fiber as 0.4%, 0.8% and 1% of total volume into the mixture. The time-dependent fresh state properties, strength, ultrasonic pulse velocity, transport properties, drying shrinkage and freeze-thaw resistance of concrete mixtures, sodium sulfate attack and abrasion were investigated comparatively. Test results demonstrated that utilization of fiber affected the fresh properties of the concrete mixtures negatively. However, the 0.8% fiber-bearing mixture showed the highest performance in terms of durability and dimensional stability. Beyond this utilization ratio, the durability performance of the concrete mixture was negatively affected. The risk of nonhomogeneous dispersion of the fiber in the mixture was relatively high in the excess fiber-bearing mixture. Consequently, with the formation of flocculation in the mixture the void ratio of concrete mixture increased.

Compressive Strength of Concrete from Lightweight Bubbles Aggregate

2015 ◽  
Vol 754-755 ◽  
pp. 348-353 ◽  
Author(s):  
Norlia Mohamad Ibrahim ◽  
Leong Qi Wen ◽  
Mustaqqim Abdul Rahim ◽  
Khairul Nizar Ismail ◽  
Roshazita Che Amat ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Compressive Strength ◽  
Natural Resources ◽  
Concrete Structure ◽  
Concrete Mixture ◽  
New Materials ◽  
Concrete Mixtures ◽  
Compressive Strength Of Concrete

Compressive strength of concrete is the major mechanical properties of concrete that need to be focused on. Poor compressive strength will lead to low susceptibility of concrete structure towards designated actions. Many researches have been conducted to enhance the compressive strength of concrete by incorporating new materials in the concrete mixture. The dependencies towards natural resources can be reduced. Therefore, this paper presents the results of an experimental study concerning the incorporation of artificial lightweight bubbles aggregate (LBA) into cementations mixture in order to produce comparable compressive strength but at a lower densities. Three concrete mixtures containing various percentages of LBA, (10% - 50% of LBA) and one mixture used normal aggregate (NA) were prepared and characterized. The compressive strength of LBA in concrete was identified to be ranged between 39 MPa and 54 MPa. Meanwhile, the densities vary between 2000 kg/m3 to 2300 kg/m3.

Recycling of Waste Limestone as Fine Aggregate for Conventional and Green Concretes

2018 ◽  
Vol 928 ◽  
pp. 257-262 ◽  
Author(s):  
Trong Phuoc Huynh ◽  
Chao Lung Hwang ◽  
Si Huy Ngo
Keyword(s):  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Concrete Mixture ◽  
Engineering Properties ◽  
Fine Aggregate ◽  
Normal Concrete ◽  
Design Algorithm ◽  
Green Concrete ◽  
Concrete Mixtures

This paper presents the results of the experimental works to investigate the use of waste limestone from water treatment industry as fine aggregate in green concrete. Two concrete mixtures with a constant water-to-binder ratio of 0.3 were prepared for this investigation, in which, the normal concrete mixture was designed following the guidelines of ACI 211 standard, while the green concrete mixture was designed using densified mixture design algorithm (DMDA) technology. For comparison, both types of concrete samples were subjected to the same test program, including fresh properties, compressive strength, strength efficiency of cement, drying shrinkage, electrical surface resistivity, ultrasonic pulse velocity, and thermal conductivity. Test results indicate that both concrete mixtures showed the excellent workability due to the round-shape of waste limestone aggregate and the use of superplasticizer. In addition, the green concrete mixture exhibited a better performance in terms of engineering properties and durability in comparison with the normal concrete mixture. The results of the present study further support the recycling and reuse of waste limestone as fine aggregate in the production of green concrete.

Deicing salt scaling resistance of concrete incorporating supplementary cementing materials: laboratory and field test data

2008 ◽  
Vol 35 (11) ◽  
pp. 1261-1275 ◽  
Author(s):  
N. Bouzoubaâ ◽  
A. Bilodeau ◽  
B. Fournier ◽  
R. D. Hooton ◽  
R. Gagné ◽  
...  
Keyword(s):  
Field Evaluation ◽  
Outdoor Exposure ◽  
Test Procedures ◽  
Visual Evaluation ◽  
Deicing Salt ◽  
Supplementary Cementing Materials ◽  
Salt Scaling ◽  
Concrete Mixtures ◽  
Scaling Resistance ◽  
Made In

In this study, sidewalk sections were made in the field using seven concrete mixtures, applying a finishing and curing practice that is commonly used in Montréal, Canada. For each of the sidewalk sections, large slabs (1.2 m × 1.2 m) were cast from which specimens were cored and tested in the laboratory for determining their basic mechanical properties and deicing salt scaling resistance following ASTM C672 test procedures. Also, during the casting of the sidewalk, companion specimens were cast on site, using concrete from the same batch, and were subjected to the same tests as the “cored” specimens. The resistance to deicing salt scaling of these “laboratory specimens” was evaluated according to ASTM C672 and to BNQ NQ 2621–900 (2002 standard of the province of Quebec, Canada) test procedures. The results were compared with the performance of the sidewalk sections after four winters of outdoor exposure. The visual evaluation of the sidewalks after four winters has confirmed the severity of the ASTM C672 procedure and the adequateness of the BNQ procedure to better evaluate the deicing salt scaling resistance of concrete made with supplementary cementing materials (SCMs). The field evaluation should, however, continue for a longer period of time to increase the confidence in the BNQ test or to allow for changes as needed.

scholarly journals ADDITIVES FOR HEAVY CONCRETE BASED ON INDUSTRIAL WASTE FROM CHEMICAL INDUSTRIES

2021 ◽  
Vol 64 (4) ◽  
pp. 104-109
Author(s):  
Igor V. Polyakov ◽  
Mikhail V. Barannikov ◽  
Ekaterina A. Stepanova
Keyword(s):  
Research Work ◽  
Water Soluble ◽  
Concrete Mixture ◽  
Crystalline Hydrate ◽  
Cement Stone ◽  
Wetting Properties ◽  
Concrete Mixtures ◽  
Complex Additive ◽  
Corrosion Of Steel ◽  
Concrete Hardening

The effect of a complex additive containing superplasticizer C-3 on the properties of heavy concrete has been investigated. The efficiency of the plasticizing action of the specified additive at the stage of preparation of the concrete mixture and subsequent molding of concrete products has been revealed. It is proved that at the stage of concrete hardening, the investigated additive promotes to the formation of a more homogeneous colloidal-crystalline structure and the formation of dense crystalline hydrate complexes of cement stone by the time of completion of concrete hardening. The objects of investigation were samples of grade B22.5 concrete without additives; containing a monoadditive - superplasticizer S-3; containing the complex additive. When designing the composition of additives for heavy concrete, we proceeded from the fundamental provisions of construction science that the complexity of the action of additives lies in the optimal combination of two main opposite processes in time and volume of the concrete matrix. The use of the caprolactam oligomer synthesized in the course of this investigation makes it possible to solve the problem of involving concentrated wastes of caprolactam production in the production turnover. The obtained caprolactam oligomers can be used in construction as plasticizers of concrete mixtures, as inhibitors of corrosion of steel reinforcement in the production of reinforced concrete products. Water-soluble oligomers of caprolactam, which reduce the time of dissolution of the superplasticizer C-3 and the dispersion of low-temperature catalyst in the volume of the concrete mixture being mixed, were synthesized. It was found that in the presence of the oligomer caprolactam in an amount of 10 to 20% of the mass. the dissolution rate of S-3 superplasticizer in water at a temperature of 20-21 °C increases by 2.0-2.2 times. This contributes to a better mixing of the components of the concrete mixture, primarily to improve the dispersion of the complex additive in the volume of the concrete mixture. The caprolactam oligomer used in this research work is an effective water-soluble wetting agent for the surface of particles of cement, sand, and crushed stone, which is very important for activating hydration and sorption processes during mixing of a concrete mixture. The increased wetting properties of the caprolactam oligomer are characterized by a wetting angle of 19.6 °.

scholarly journals Life Cycle Assessment of Foam Concrete Production in Latvia

2019 ◽  
Vol 23 (3) ◽  
pp. 70-84 ◽  
Author(s):  
Zinta Zimele ◽  
Maris Sinka ◽  
Aleksandrs Korjakins ◽  
Diana Bajare ◽  
Genadijs Sahmenko
Keyword(s):  
Compressive Strength ◽  
Global Warming ◽  
Life Cycle Assessment ◽  
Foam Glass ◽  
Concrete Mixture ◽  
Foam Concrete ◽  
Recycled Glass ◽  
Concrete Mixtures ◽  
Alternative Materials ◽  
Aerated Concrete

Abstract Global warming being increasingly discussed, solutions for reducing emission greenhouse gases become more important in all industry sectors. The total energy consumed in the construction sector contribute up to 1/3 from all greenhouse gases emissions. Large part of it comes from the cement production – 5 % of the total global emissions. The foam concrete is lightweight concrete with good thermal properties and ability to reduce CO2 emissions by reducing the use of cement due to its low density. The aim of this study is to determine impact on the environment with the use of Life Cycle Assessment (LCA) with focus on Global Warming Potential (GWP) for two different compressive strength foam concrete mixtures produced in Latvia by unique intensive mixing technology – turbulence with cavitation effect. Afterwards, the selected foam concrete mixtures are compared with alternative materials with similar compressive strength – aerated concrete and hollow ceramic blocks. The foam concrete mixture having 12.5 MPa compressive strength showed higher CO2 emissions than hallow ceramic block. The majority of CO2 emissions comes from the Portland cement, which is a key element in its composition. On the other hand, the foam concrete mixture having 2.4 MPa compressive strength showed higher CO2 emissions than aerated concrete block. The majority of CO2 emissions are due to foam glass granules, which is the main element contributing to the increased insulation properties of the material. Comparison of each foam concrete with analogue building material by compressive strength shows that the chosen foam concrete mixtures produce greater GWP than alternative materials. This research allows to identify the environmental impacts of different foam concrete mixture components and to improve these mixtures to achieve similar properties with less impact, for example, by replacing foam glass granules with granules made from recycled glass or replacing cement with flay ash, silica fume or recycled glass powder.

Sign in / Sign up

Export Citation Format

Share Document