bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Static Balancing of Mechatronic Systems - An Overview
Authors: Ciupitu Liviu
Published: November 2015

Static balancing of a mechanical system can be regarded as the total or partial cancellation of the mechanical effects (force or moment) of static loads to the actuating system of it, in all configurations, respectively in a finite number of configurations, from functioning domain, under quasi-static conditions. Active balancing is taking into consideration the variation of static loads during the functioning of mechanical systems. As a consequence the active balancing requires an adaptive controlling system and a dynamic model of mechatronic system. In this article, some aspects of the active static balancing problem of mechanical systems are surveyed.
Velocity Characteristics of Movement of Chassis with Special Wheels for Overcoming Stairs
Authors: Bobovský Zdenko , Krys Václav , Kot Tomáš , Mostýn Vladimír
Published: November 2015

During the research dealing with design of a special wheel for movement on stairs it was discovered by simulations and tests on a scaled prototype that velocity of the chassis relatively to the stairs slightly oscillates when the rotation speed of the wheels is constant. The article describes a way of determination of required angular velocity of the shaped special wheels that would ensure constant velocity of the chassis during movement on stairs. To solve this task, contact kinematic simulations in the CAD system SolidWorks 2014 were used.
Gripper with Average Continuous Reconfigurability for Industrial Robots
Authors: Jitariu Sebastian , Staretu Ionel
Published: November 2015

Anthropomorphic grippers for robots are used increasingly in robotic applications for handling and assembly. Currently there are several versions of anthropomorphic grippers as projects, prototypes or commercial variants that due to high prices or even for very high ones, are not available for current applications. Among them, high functionality at a relatively low complexity can be noticed in the case of reconfigurable grippers with high reconfigurability, Barrett Hand type. In this context, it is justified finding alternative solutions at lower prices at a lower reconfigurability, with acceptable functionality for current robotic operations. The paper presents an original version of modular anthropomorphic gripper continuous average reconfigurability, with three fingers. There are mentioned, briefly, major structural, kinematic and static issues, a CAD model and CAD simulation for gripping several types of pieces. Furthermore, we intend to achieve a prototype and test it by mounting on an industrial robot.
Change of Thermo-Mechanical Properties of Optical Fibers Aged in CTAC Aqueous Solution
Authors: El Abdi Rochdi , Dumitrache Rujinski Alexandru
Published: November 2015

Fiber-optic sensors are mostly used for in situ measurements of diverse chemical composition of industrial surfactants employed in industry as detergents, emulsifying and dispersing agents, coatings, and pharmaceutical adjuvants. These optical sensors are often used in wet chemical environments in which the temperature can be high.The purpose of this work is to study the mechanical behaviour of optical fibers in contact with CetylTrimethylAmmonium Chloride in aqueous solution (CTAC) at different immersion durations and different temperatures.Optical fibers were submitted to dynamic bending test under different velocities.Result analysis demonstrates that immersion in CTAC drastically decreases the fiber strength particularly when immersed for long aging periods at high temperatures.
The Experimental Analysis for the Localization of a Mobile Platform Equipped with a Multi-Antenna GNSS System
Authors: Ghelmeci Radu
Published: November 2015

This paper is experiencing the localization of a mobile platform through a multi-antenna GNSS-RTK system in order to implement the system for the localization of the mobile construction robots. The approach introduced here shows the components of the system and a manner in which the localization coordinates and errors are determined. Furthermore, it establishes the accurate localization errors based on an experiment in which the mobile platform moves in similar conditions to those of a construction site.
RES Storage Solution for Clean Electrification of Passive House
Authors: Badea Gheorge , Felseghi Raluca Andreea , Răboaca Simona , Aşchilean Ioan , Bolboacă Andrei , Mureşan Dan , Şoimoşan Teodora
Published: November 2015

This paper illustrates the results of comparative study regarding two RES storage solutions for a energen hybrid system that power supply a passive house. In this case-study was used sun and wind as a primary sources and their storage was realized in S1 scenario through electrolytic hydrogen and in S2 scenario through battery. The aim of this research was to demonstrate the capability of hydrogen to integrate renewable energy sources in green electricity production for stationary applications, especially to new concepts of low energy buildings. As main results was found that on S1 is harnessed 77% of total energy production of the system to obtain hydrogen and on S2 just 10%. Storage by electrolytic hydrogen generates 55% reduced amounts of CO2 emissions compared with storage by battery. Total S1 NPC was with 45,6 % higher than S2 due to conversion equipment of hydrogen into electricity.
Instrumented Gait Analysis for Assessing the Efficiency of a Complex Rehabilitation Program in Patients with Stroke – A Case Study
Authors: Cojan Carlea Nida Alexandra , Badea Ruxandra Ileana , Iliescu Alina Nela , Ciobanu Ileana , Berteanu Mihai
Published: November 2015

Annually, 15 million people worldwide suffer a stroke. Establishing the disability status after stroke is the key for the Physical and Rehabilitation Medicine point of view. 90% of those who have suffered a stroke show multiple impairments. The post stroke walking pattern has a major impact on the patient’s activity and participation capacity and to regain a functional gait is one of the most important goals of the rehabilitation intervention. The instrumented gait analysis is the key for accurately assessing the efficiency of a gait rehabilitation program and may be an important tool for designing personalized training. The aim of this study is to evaluate the effect of a complex rehabilitation program on the walking pattern in patients with after stroke hemiparesis.
Cytostatic Solution‘s Flow Control for a Hyperthermic Intraperitoneal Chemotherapy Device
Authors: Clitan Iulia , Abrudean Mihail , Mureşan Vlad , Moga Daniel , Lungoci Corneliu
Published: November 2015

The authors present by means of this paper a transfer function model for the flow of a cytostatic solution and the design of a flow classical controller for a Hyperthermic Intraperitoneal Chemotherapy device, that they intend to develop. An analytical approach is used in order to obtain the model of the solution’s flow and a classical controller is designed for the flow control structure, in order to minimize the cost and obtain an affordable device.
Analysis of Reliability Aspects of Railway Accident Precursors: An Italian Case Study
Authors: de Felice Fabio , Petrillo Antonella , Zomparelli Federico
Published: November 2015

The Railway transport system is experimenting a deep transformation nowadays. The continuous technological evolution and the raising the standard of living of the population have led today to an increase in the volume of rail traffic, both referred to the passenger and freight transport. Despite railways being a statistically safe form of transportation (due to guidance per rails, professional drivers, etc.) rail accidents may still happen. Safety in railway infrastructure must be understood as the safe performance of their functions by the main components. From this perspective it denotes a growing interest in the issue of safety in railway tunnels. In particular, the analysis of the structural aspects of reliability and maintenance goes to correlate safety analysis. The papers aims to ensure a proper level of safety in railway tunnels, through the adoption of measures of prevention and protection finalized at the reduction of critical situations. In the present study a rigorous methodological approach is proposed for a “typical” Italian railway tunnel.
Optimization of Transportation for Hazardous Waste Disposal from Medical Units
Authors: Debita Mihaela , Musat Carmina Liana , Rus Madalina , Mereuta Elena , Mereuta Claudiu
Published: November 2015

The paper presents some technical considerations regarding the medical waste transportation and an optimization calculus for minimizing the transportation costs of a company specialized and authorized in collecting, transporting and final disposal of medical waste generated by healthcare facilities. The calculus revealed that it is possible to significantly reduce the transportation costs (up to 65.52%), but there are also other analysis possibilities like considering the in-between points from sources to destinations, alternative paths, limits to the amount of medical waste on each path, time.
Decrease in Power Consumption of Hydraulic Systems of Modern Machine Tools
Authors: Prodan Dan , Bucuresteanu Anca , Motomancea Adrian , Balan Emilia
Published: November 2015

This paper shows several issues related to decrease in electric power consumption for hydraulic systems of modern machine tools, especially CNCs. A core element in the structure of such systems is the pneumo-hydraulic accumulator. Here, examples are shown for hydraulic systems destined to locking and unlocking of skids and to opening of tool holders. This paper shows mathematical models, diagrams, simulations and certain experimental executions.
Influence of Non-Stationary Thermal Field on the Hardness of Welded Samples
Authors: Grigore Nicolae
Published: November 2015

The ends of the welding beads are the site of certain non-conformities due to the transitory regime used for welding. In these start and end areas of the welding beads, the thermal field is propagated in non-stationary regime, as opposed to the portions from the middle of the welding bead where the heat is propagated in quasistationary regime.This paper proposes to present the influence of non-stationary thermal field from the welding ends on the hardness values performed in such critical areas, by comparing these values with the values of hardness performed on the middle portions of welding beads. A similarity comparison is made with the situation of the welding works performed within the reconditioning process by welding, when the welding works are of short length executed with multiple rows, were the thermal field is also propagated in non-stationary regime.
Determining of the Wear Traces for Sliding Couplings
Authors: Petre Ivona Camelia , Cîrstoiu Carmen Adriana
Published: November 2015

Abrasion wear is a mechanical process when the surfaces of a friction coupling decay and which occurs with material removal from the softer surfaces that get into contact with the asperities of the harder surface located in the space between the coupling elements. The paper aims to determine the wear trace remained on a softer surface following the slidding of a harder one, for a brass/iron coupling. The lubrication of coupling and the processing way of the coupling surfaces are factors that directly influence the tribological behaviour of the friction coupling.
The Reduction of Errors of Bridge Crane Loads Movments by Means of Optimization of the Spatial Trajectory Size
Authors: Shcherbakov Vitaly , Korytov Mikhail , Volf Elena , Breus Irina
Published: November 2015

The article dwells upon the results of study of theshape influence of size of load’s motion using the sigmoidal functions of traversingsingle obstacle on the arc with suppression of load’s oscillations to theaccuracy figure of the trajectory’s realization. The possibility of thereduction of the maximum and average error by means of the little changing of the value ofthe arc’s lateral deformation for a fixed traveling time is shown in thisarticle. The functional dependencies of the maximum and average errors oftrajectory implementation from corrected value of the maximum arc’sdisplacement of required load's trajectory in lateral side to bypass obstaclesand from increasing of corrected value of the maximum displacement of the arcare given too.
Enhancement of Wear Properties on High Speed Steel Tool Using PVD Coating Technique
Authors: Malarvannan R. Ravi Raja , Moorthy T.V. , Hariharan P. , Ravi Samraj
Published: November 2015

Engineering industries are currently using many tool materials such as ceramic,carbide, high speed steel, Cubic Boron nitride and diamond. In most of the small scale industries, the lathe machines are consuming High Speed Steel (HSS) Tool. The HSS tools are easily available and cheapest one. In this present investigation, the Tungsten HSS Single point cutting tool was taken as substrate material. Two substrate HSS Tools were coated with two different combinations of TiAlN composite material using Physical Vapour Deposition coating technique. The surface roughness and hardness were determined for the tools in same condition. The tools were used in lathe machine in same operating condition. The weights of the tools were checked using standard equipment after each machining trials. The loss of tool weight for each trial was determined and the percentage of weight loss was calculated. The life of the Titanium Aluminium Nitride (Ti 70% , Al 25%) coated tool increased by 3.74 times than uncoated tool. The life of the Titanium Aluminium Nitride (Ti 55% , Al 35%) is increased by 2.71 times than uncoated HSS tool.
Effective Fuel Consumption by Improving Cooling Water Flow Rate in IC Engine
Authors: Kumar K.M. , Venkateswaran P. , Suresh P.
Published: November 2015

The coolant (water) pump assumes an important role of cooling system in IC engines. With upgrading of the engine power by turbocharging and turbo inter cooling, the water pump capacity needs to be increased corresponding to the power. This capacity enhancement has to be achieved without calling for a major change in the existing water pump, envelop and related fitment details. This requires a clear understanding of centrifugal pump for its performance parameter. One such engine is upgraded by turbocharging from 195PS to 240PS @2200 rpm. Improving water pump flow by changing the impeller dimensions, impeller casing, increase the suction, delivery pipe diameter had been done. Validation of the water pump in its actual engine installation was taken up as a part of the research work. Flow rate comparison of the new pump with the existing pump was made and the results were analyzed. The new water pump gives better flow rates for the engine speeds up to1800 rpm, beyond which the flow rate is slightly lesser than the existing pump.
Discussions about the Thermodynamic Entropy Property and its Existence in Vehicle Dynamics of Automobiles for Improving the Mileage
Authors: Arulanantha Samy S. , Shanmuganathan T. , Godwin John J.
Published: November 2015

The recent vehicle management systems have been developing to improve the quality of the combustion process and transmission systems. In thermodynamic approach, the water molecule can exists in different phases like ice, water, wet steam, dry steam, and superheated steam. The phase change occurs in the steam formation process can be compared to the various stages of any vehicle dynamic system such starting, idling, normal speed, high speed and very high speed. There may be an identical value in the increment of energy level in both steam formation process and any vehicle dynamic system. Thermodynamic approach always deals with system, surroundings, boundary and energy transformation across boundaries. Entropy is a very good property which is used to find the energy degradation in a particular system, and this property existence in the vehicle dynamics of automobiles will be used to improve the efficiency of the control module of a vehicle management system. This paper initiates a new angle research in the field of vehicle dynamics to study and investigate the kinetic energy transformation and distance moved by the vehicle thermodynamically. From this paper, Entropy is found as a very good property for increasing the mileage of the vehicle. In the vehicle health monitoring, there should be an entropy measurement to reduce the unavailability of energy as it is the measure of the distance travelled by the vehicle per unit energy supplied to the same vehicle at various operating speeds. In manual transmission method, it has been found that driver is not able to press the accelerator pedal continuously due to body strain. Driver has to run the vehicle at constant speed by pressing the accelerator pedal continuously. In automatic transmission, the data required for the ECU module is given by the thermodynamic relations such as enthalpy, entropy and internal energy. This paper aims thermodynamically to describe the speed, acceleration, fuel consumption, kinetic energy and various resistances offered to the vehicles. Generally, Thermodynamic system deals with heat and mass transfer, likewise vehicle dynamics deals with work and vehicle’s motion.
Multi-Response Optimization in Turning of AA6061 T6 Using Desirability Function Analysis
Authors: Jayaraman P. , Kumar L. Mahesh
Published: November 2015

This paper presents an ideal approach for the optimization of machining parameters on turning of AA6061 T6 aluminium alloy with multiple responses based on orthogonal array with desirability function analysis. In this study, turning parameters namely cutting speed, feed rate and depth of cut are optimized with the considerations of multiple responses such as surface roughness (Ra), roundness (Ø) and material removal rate (MRR). Multi response optimization of machining parameters was done through desirability function analysis. The optimum machining parameters have been identified by a composite desirability value obtained from desirability function analysis. The performance index and significant contribution of process parameters were determined by analysis of variance.
Study of the Emission Characteristics of the SCR System on CI Engine Fuelled with Diesel-Ethanol Blends and an Optimised Urea Injection System
Authors: Natarajan  , Sheshathri R. , Kamesh  , Avinash Alagumalai
Published: November 2015

The objective of this work is to determine the maximum reduction of NOx emissions by varying the concentrations of urea solution with a reduction catalyst, and optimization of the urea injection by the evaporation of the solution, using the CFD-Fluent solver. An aqueous solution of urea was injected in the engine exhaust pipe for reducing NOx emissions, in a single cylinder light duty, stationary, four stroke, air cooled DI diesel engine, fuelled with neat diesel and diesel-ethanol blends (10%). The concentration of the urea solution was varied from 30 to 35% by weight with constant flow rates, and tested with a Titanium dioxide (TiO2) coated catalyst, fitted on the engine exhaust pipe, which controls the by products of ammonia and water vapour. The results indicated that a maximum of 70% NOx reduction was achieved when the engine was fuelled with diesel-ethanol blends at a constant flow rate of 0.75 lit/hr with an urea concentration of 35%, and also that 66% reduction of NOx was achieved, using the Titanium dioxide catalyst in the Selective Catalytic Reduction system with neat diesel. From the simulation results,it was seen that only at 75% and 100% load,the evaporation point of the urea solution was higher than that of the boiling point (423 K), due to complete vaporisation of water.
Performance Evaluation of EGR in Two Stroke I.C. Engine
Authors: Ramakrishnan V. , Thamilarasan R. , Purushothaman K.
Published: November 2015

Petrol engines are known for their simplicity, low cost and maintenance. However nowadays use of two stroke petrol engines are fading away from the market. An attempt has been made here to revive the use of these old engines by using Exhaust Gas Recirculation (EGR) to improve performances.Short circuiting of fresh charge is an important contributing factor for reduction in performance in two stroke engines. Our project is aimed to reduce short circuiting of fresh charge by admitting cooled exhaust gas to pass through reed valves fitted at the upper end of the transfer passage, in a crank case scavenged two stroke engine. Reed valves were provided at the upper end of the transfer passage using a flange arrangement. Exhaust gas temperature at around 4000 was cooled using a heat exchanger to avoid pre-ignition inside the engine cylinder. The performance of the engine is tested using eddy current dynamometer. The study indicates an appreciable decrease in specific fuel consumption and in HC/CO emissions in a crank case scavenged two stroke engine.
Computational Analysis of an Early Direct Injected HCCI Engine with Turbocharger Using Bio Ethanol and Diesel Blends
Authors: Natarajan S. , Sundareswaran A.U. Meeanakshi , Arun Kumar S. , Mahalakshmi N.V.
Published: November 2015

In this paper the work deals with the computational analysis of early direct injected HCCI engine with turbocharger using the CHEMKIN-PRO software. The computational analysis was carried out in the base of auto ignition chemistry by means of reduced chemical kinetics. For this study the neat diesel and Bio ethanol diesel blend (E20) were used as fuel. The inlet pressure was increased to 1.2 bar to simulate the turbocharged engine operation. The injection time was advanced to 18° before top dead centre (BTDC) i.e., 5° BTDC than normal injection time of 23° BTDC. The equivalence ratio was kept at 0.6 (ɸ=0.6) and the combustion, emission characteristics and chemical kinetics of the combustion reaction were studied. Since pressure and temperature profiles plays a very important role in reaction path at certain operating conditions, an attempt had been made here to present a complete reaction path investigation on the formation/destruction of chemical species at peak temperature and pressure conditions. The result showed that main draw backs of HCCI combustion like higher levels of unburned hydrocarbon emissions and carbon monoxide emissions are reduced in the turbocharged operation of the HCCI engine when compared to normal HCCI engine operation without turbocharger.
Optimization of Operating Parameters on Wear Behavior of Manganese Phosphate Coated Die Steel
Authors: Ilaiyavel S. , Sheshathri R. , Sundram V.R. Alagu , Venkatesan A.
Published: November 2015

The aim of Manganese Phosphate coating is to convert the metallic surface completely into a non metallic surface. A Phosphating is a chemical conversion treatment which produces a porous surface layer of crystalline phosphate. High carbon high chromium steels are commonly used in applications requiring excellent wear resistance in tool and die making industries. The wear characteristic of the coated steel was evaluated through pin on disc test as per ASTM G99 standards using a sliding velocity of 3.0m/s under constant loads. Taguchi’s design of L09orthogonal array is followed selecting three parameters namely load, surface roughness, sliding distance. Optimal conditions are arrived by Signal-Noise ratio method with respect to coefficient of friction. The results are validated by analysis of variance (ANOVA) and the percentage of contribution of load, surface roughness and sliding distance for better coefficient of friction are determined.
Comparison of DEA Rank Based Method with Assignment Weightage Method in Optimizing the Process Parameters for Solar Seed Sprayer
Authors: Navas Kaja Bantha , Manu Kumar
Published: November 2015

This paper presents a novel approach for the optimization of process parameters on solar seed sprayer with multiple responses based on comparing DEA Rank based Method with Assignment weightage Method. These two methods have a series of steps from of proposed approach which are capable of decreasing uncertainty caused by engineering judgment in the Taguchi method. Experiments are conducted by varying the solar parameters related to solar radiation and solar panel area. In this study, process parameters namely solar radiation, solar panel areas are optimized with the considerations of multi responses such as voltage and current. Two factors and three levels were taken to conduct the experiments with the range 300-600 mW/cm2 for solar radiation and with solar panel area from 6.45 cm2 to 9.67 cm2. The two methods show a good convergence with the experimental data and the optimum process parameters combinations where maximum voltage and maximum current are obtained.Keywords: Solar Energy; Seed Sprayer, DEA rank based method, Multi Response Optimization.
Mechanical Behaviour of Engineered Cementitious Composites under Quasi-Static and High Strain Rate Applications
Authors: Tan Kang Hai , Yang En Hua , Kang S.B. , Wahyudi T.Y.
Published: November 2015

This paper presents a series of experimental studies on the behaviour of engineered cementitious composites (ECC) under quasi-static and high strain rate loads. Potential enhancement of ECC to the resistance and ductility of structural members was evaluated under column removal scenarios and impact loading conditions. Besides, dynamic increase factors for compressive strength and critical strain were derived according to experimental results under high strain rates. Finally, conclusions and recommendations were made in accordance with the use of these materials for different structural performances.
Chemical Resistance of Concrete-Polymer Composites – Comparison Based on Experimental Studies
Authors: Piotrowski Tomasz , Gawroński Piotr
Published: November 2015

One of the main advantage of Concrete-Polymer Composites (C-PC) in relation to Cement Concrete called Ordinary Concrete is its chemical resistance. There is no European standard for testing the chemical resistance of cement based concretes and C-PC. American standards ASTM provide varied concrete tests depending on exposure conditions and mechanisms of destruction of concrete structures but there is a lack of clear criteria for the evaluation of research results by these methods. There are also requirements for monolithic floors chemical resistance - ASTM C722-04 and the requirements of the standard EN 1504-2, but they involve coating materials and cannot be directly applied to the cement concrete and C-PC. The paper presents the experimental studies of chemical resistance of C-PC in relation to OC. The investigations has been made under different environment conditions. First the samples of Ordinary Concrete (OC), Polymer Concrete (PC-1) based on vinylester resin and Polymer-Cement Concrete (PCC-1) with polyacrylic dispersion used as a co-binder were immersed for a period of time up to 168 days in a distilled water, H2SO4, MgSO4, (NH4)2SO4 and mix of the mentioned. During the storage the pH was controlled. Additionally as a reference the samples were conditioned in a climate chamber (20°C, 60% RH). The compressive strength were tested after defined periods of time. Next experiment was performed on OC and three different PCC – first modified with synthetic latex, second with polyacrylic polymer dispersion and the last with epoxy resin. The samples were immersed in H2SO4 up to 90 days. Compressive strength and mass loss after 30 and 90 days of conditioning were measured. As a reference the water immersion was used. The results obtained in this experimental program showed high chemical resistance of Polymer Concrete. PC samples obtained continuous increases of compressive strength in all examined chemically aggressive environments. It is also confirmed higher chemical resistance of Polymer-Cement Concrete modified with vinylester resin in relation to Ordinary Concrete. The second part of the program showed that the best additive to PCC among poliacrylic dispersion, synthetic latex and epoxy resin was last one. Epoxy modified PCC samples obtained best results both in compressive strength and mass loss tests
Coefficient of Thermal Expansion of Polymer Concrete with Different Polymeric Binders
Authors: Yeon Kyu Seok , Kim Kwan Kyu , Kim Chul Young , Yeon Jae Heum
Published: November 2015

The coefficient of thermal expansion (CTE) is one of the material factors affecting the behavior of concrete structures. This study reports the typical range of CTE for polymer concrete with different types of polymeric binder based on extensive literature surveys. The results revealed the CTE of polymer concrete generally fell between 12.5 and 28.6 x 10-6/°C, which is about twice or three times higher than that of ordinary cement concrete, because the CTE of polymeric binder is much larger than that of cementitious binders. The findings of this study will provide useful information for the design and analysis of polymer concrete members and repair components.
Properties of VA/E/MMA Terpolymer Powder-Modified Mortars
Authors: Hong Sunhee , Kim Wan Ki
Published: November 2015

This study is to examine and clarify the quality of polymer-modified mortars using a VA/E/MMA terpolymer powder as compared with polymer-modified mortars using a VAE copolymer powder. Polymer-modified mortars using general commercial redispersible polymer powders are prepared with various polymer-cement ratios, and tested for flexural and compressive strengths, tensile strength, water absorption, chloride ion penetration, carbonation and pore size distribution by mercury porosimetry. Overall, the properties of polymer-modified mortars using a VA/E/MMA terpolymer powder were superior to those of polymer-modified mortars using a VAE copolymer powder. And VA/E/MMA terpolymer powder-modified mortars showed significantly improved mechanical properties and durability in comparison with unmodified mortar. It is concluded from the test results that the modification of cement mortar with redispersible polymer powder improves the properties of unmodified mortar, and VA/E/MMA terpolymer powder has higher quality than VAE copolymer powder.
Evaluation of Coating Properties Produced with Polyester Resins and Industrially Processed Components
Authors: Sacco Ana Cláudia Rosseto , Gorninski Jane Proszek
Published: November 2015

The objective of the present study is to investigate the behavior of floor coatings made of recycled isophthalic and orthophthalic type polyester resins along with industrially processed inorganic materials; gravel dust, that is the residue from crushed basaltic rocks, and fly ash generated in coal burning in power plants. The coatings were evaluated by the mechanical resistance tests: flexural strength, axial compression and abrasion and the durability tests: chemical attack, against many harmful agents, and also the water absorption test. The work proposes the use of these coatings as flooring, to be applied in the petroleum and petrochemical industry, which require high-strength materials with excellent chemical resistance. Two types of coatings were produced, one being composed of isophthalic polyester resin as binder, river sand as aggregate and fly ash as filler, and the other composed of orthophthalic polyester resin recycled from PET, river sand and gravel dust as aggregates and fly ash as filler. From the results, it was observed that the floorings reached flexural strength values of 26 MPa and 84 MPa for axial compression, and results below 0.17% for water absorption. The coatings were resistant to chemical attack from acids, bases, salt and hydrocarbons.
Study on Crack Bridging Ability of Polymer-Modified Cement Based Compounds for Waterproofing Material
Authors: Zhao Hong , Li Wei , Zhang Yong Ming
Published: November 2015

China's existing polymer-modified cement based compounds for waterproofing material standards are used for the tensile strength test and elongation at break test as the test method to evaluate the performance of the product extension. The elongation only reflects the extension ability of product, but cannot indicate the crack bridging ability of the product. In engineering applications, there is a requirement for higher bridging cracks ability of the products. In this paper, 9 samples of polymer-modified cement based compounds for waterproofing material were tested. Crack bridging ability was tested under the standards and methods in DIN EN 14891:2013-07. Tensile strength and elongation at break were tested according to the standards and methods in GB23445:2009. The crack bridging ability test results are between 0 to 2.08mm, in which 5 of them meet the requirements of greater than 0.75mm according to DIN EN14891:2013-07.The tensile strength test results are between 1.13MPa to 3.19MPa, the elongation at break test results are between 4% to 350%.The results show that higher tensile strength and higher elongation at break will have good ability of crack bridging. Samples with better crack bridging ability are close to type III product according to GB23445-2009 which requires tensile strength ≥ 1.8MPa and elongation at break ≥ 30%. Crack bridging ability directly reflects the product’s ability of crack bridging, and is more in line with the actual requirements in engineering applications. It is recommended that the crack bridging ability test method should be adopted in the formulation of China polymer-modified cement compounds for waterproofing material standards.
Comparison and Evaluation of Retrofitting Different Modes of Concrete Structures by FRP
Authors: Makhdoumi Hamed , Madani Seyyed Hesam , Shahraki Mehdi , Khodarahmi Mostafa , Nosratzehi Naser
Published: November 2015

Abstract. After recent earthquakes in the majority of seismic areas around the world including our country Iran and considering the irretrievable casualties and economic lost due to these earthquakes, natural catastrophic mitigation committees, research and scientific centers that are responsible for providing structural and seismic codes presented the concept of performance design, study of lifelines and retrofit and rehabilitation of existing and vital structures and the majority of researches in the field of earthquake engineering and structural engineering is focused on retrofit of structures considering economic and feasibility problems. Considering the increasing use of concrete structures in Iran and their substituting for steel structures ( due to weaknesses, constructional problems and defects) and considering the internal defects and failure modes, these structures should be retrofitted against earthquakes or preparations should be provided to decrease and minimize failure modes. concrete frames that consist of beam, column and connection is a essential part of concrete structures. Internal defect of concrete frame results in failure modes such as debonding and delamination in beams, buckling and torsion in column, local crashing in connection. Considering the several benefits of FRP sheets and their increasing use during years, these composites can be used for compressive-tensile, shear, bending, torsional retrofitting as well as for ductility increasing. In this study different types of failure modes of concrete frames and internal defects of them that lead to collapse are investigated. In addition different cases of retrofitting by FRP sheets to prevent failure modes and exciting defect are presented and these cases are compared.
Influence of Acrylic Emulsion on Polymer-Cement Waterproof Coating
Authors: Jiang Yong Jing , Li Lei , Wang Hong Song , Wang Rui , Tian Qian
Published: November 2015

In this study, effects of polymer-cement (P/C) ratio, glass transition temperature (Tg); amounts of functional monomers (acrylic acid, hydroxypropyl methacrylate, ammonium polyacrylate, diacetone acrylamide) on properties of polymer cement mortar were investigated. According of the tensile test, breaking elongation (ε) and the tensile strength (δ) of polymer latex-cement composites with low P/C ratio were mainly depended on Tg, differential Tg value between layer and shell in acrylic latex (ΔTg) and the amounts of functional monomer. Additionally, at a low P/C ratio, it was found that the cross-linking rate had small effect of tensile property. It was determined that the waterproofing coatings III with a low P/C (0.12) showed the excellent tensile property when the Tg and the ΔTg of the acrylic latex were controlled at -24°Cand -20°C, respectively.
Influence of Film Thickness and Ambient Temperature to the Protective Performance of Surface Coating Material
Authors: Sakuraba Hiroki , Miyata Atsushi , Kumagai Shinsuke , Sasaki Iwao , Nishizaki Itaru
Published: November 2015

Conditions such as the execution of repair works and ambient environment can affect the protective performance of surface coating material for concrete structures, and they are important in terms of exhibiting a long-term repair effect. This paper presents a fundamental study on the influence of film thickness and ambient temperature to the protective performance of surface coating material: oxygen, moisture vapor and chloride ion permeability. It was confirmed that as film thickness and ambient temperature increased, oxygen, moisture vapor and chloride ion permeation rates decreased and increased, respectively. Test results showed a good agreement with the behavior of polymer molecule membrane.
Fiber Reinforced Polymers in Civil Engineering: Durability Issues
Authors: Frigione Mariaenrica
Published: November 2015

In the last decades, the use of fiber reinforced polymers (FRP) composites to repair and/or upgrade existing buildings or infrastructure systems proved to be an effective solution, being able to overcome some of the drawbacks experienced with traditional interventions. The knowledge of durability behavior of polymer composite materials in terms of their degradation/aging causes and mechanisms is a critical issue for a safe and advantageous implementation of FRP. The durability of FRP employed in civil infrastructure applications mainly depends on the durability of any single component and on the environment (service conditions) in which the system operates. The components of FRP are: polymeric resins (more frequently thermosetting resins cured in service, i.e. at ambient temperature), fibers and the interface between them. Referring to the resins, heavy concerns arise from the behavior of “Cold-cured” thermosetting resins, often epoxy, used as matrices to manufacture (through wet layup technique) and adhesives to apply, also precured, FRP. The experimental studies present in current literature on the effect of environmental agents on the properties of FRP highlight the crucial role of the adhesive/matrix on the behavior of the whole system. Many other parameters (i.e. direction and disposition of fibers, direction of load application) are involved in the assessment of the durability of FRP. However, in the durability studies of FRP and their components, a lack of specific standards for such materials is recognized. In addition, the results of durability studies do not always agree, possibly due to different curing/conditioning conditions employed. The aim of this work is to critically illustrate the durability studies carried out on FRP for civil engineering applications and appeared in current literature, highlighting the issues that are not yet assessed and addressed.
Are Polymer Concrete Materials and Products Really Sustainable?
Authors: Fowler David W.
Published: November 2015

Sustainability is important in all engineering decisions. Every technical organization now has the objective to promote sustainability. Polymer concrete (PC), in order to have a rightful place in industry, must be sustainable. Based on several criteria, it can be shown that PC materials and products are sustainable. PC applications to be discussed include repair, concrete overlays, and precast products. When designed and constructed appropriately, PC materials and products are sustainable.
Apparent vs. True Bond Strength of Steel and PC with Nanoalumina
Authors: Douba Ala Eddin , Genedy Moneeb , Matteo Edward , Stormont John , Taha Mahmoud Reda
Published: November 2015

The bond of polymer concrete (PC) to a steel surface is a critical aspect in many infrastructure applications. Bond strength can be evaluated through several means including pull-off, flexural, twist-off, and slant shear tests. While pull-off strength tests are the most common method for evaluating bond for PC overlays in bridge and parking structures, slant shear tests are more suitable when vertical rather than horizontal bond lines are used. In this paper, we discuss the use of slant shear tests to examine bond of polymer concrete repair material to steel pipes used to ensure wellbore integrity of abandoned oil wells used for CO2sequestration.Bond strength of Novolac PC incorporating nanoalumina particles to a steel surface was measured using slant shear tests. Different amounts of nanoalumina were used in the PC to improve bond strength without significantly reducing PC flowability. Slant shear testing confirmed the ability of nanoalumina to improve the steel-PC bond strength. A finite element (FE) model using the ABAQUS simulation environment was developed to compare the apparent versus the true bond strength. A cohesive contact element surface was used to simulate bond along the interface line. The FE model showed that the stiffness mismatch between the PC and steel controls the maximum shear stress developed at the interface surface. The true bond strength extracted from the FE model appears to be about twice that of the apparent bond strength.
Comparison of Ordinary Pores with Internal Cured Pores Produced by Superabsorbent Polymers
Authors: Yang Jin , Wang Fa Zhou , Liu Yun Peng
Published: November 2015

Porous cementitious mixtures were prepared with two different spherical particles: expanded polystyrene (EPS) and superabsorbent polymer (SAP). The effect of EPS and SAP on the compressive strength, ultrasonic transmission, internal relative humidity and hydration degree under different volume fraction were studied. Results indicated that SAP matrix possessed much higher compressive strength (30-60%, 28d), ultrasonic transmission velocity, internal humidity (11-13%RH, 28d) and hydration degree (13-21%, 28d) than EPS matrix, which indicated that the desorption of SAP accelerated the hydration and increased the compactness of the surrounding cement paste. The internal cured pores left by SAP might have been strengthened which was different from ordinary pores produced by EPS.
Current Status of Expansion Joints Used for Road Bridges in Japan and an Advanced Buried Joint
Authors: Kawakami Makoto , Omata Fujio , Toyoda Atsushi
Published: November 2015

Expansion joints are indispensable for bridges to allow movement due to temperature, creep and other elements. Leakage of water from expansion joints causes damages to girder ends, shoes and abutments which poses serious durability issues. To overcome this problem, a buried expansion joint composed of epoxy resin mortar and ultra high strength fiber reinforced concrete used as flat panel was newly developed and investigated. Mechanical performance such as the bending strength and fatigue characteristic of this expansion joint in addition to the basic properties of epoxy resin mortar was clarified. Furthermore the durability of this expansion joint was confirmed by field tests on an existing bridge.
Effects of Long-Term Dry Curing on Strength Development of Initially Combined Wet/Dry-Cured and Steam-Cured Hardener-Free Epoxy-Modified Mortars
Authors: Ota Masahiro , Ohkubo Takaaki , Ochi Mitsukazu , Ohama Yoshihiko
Published: November 2015

It is clarified by the previous studies that even without any hardener epoxy resin can harden in the presence of hydroxide ions from calcium hydroxide in the cement mortars and concretes at ambient temperature. The strength development through the long-term curing of hardener-free epoxy-modified mortars and concretes has hardly been examined till now. Hardener-free epoxy-modified mortars using an epoxy resin (diglycidyl ether of bisphenol A) without any hardener are prepared with various polymer-cement ratios, subjected to (1) initial combined wet/dry curing plus long-term dry curing and (2) initial steam curing plus long-term dry curing, and tested for hardening degree of epoxy resin and strength development. As a result, the application of the initial steam curing rather than the initial combined wet/dry curing causes a marked strength development with increasing polymer-cement ratio and additional dry curing period. The flexural and compressive strengths of the initially steam-cured plus 336-d dry-cured hardener-free epoxy-modified mortars with polymer-cement ratios of 10% or more are about 1.5 to 2.0 times higher than those of the initially steam-cured unmodified mortar. This is proved by a marked increase in the degree of hardening of the hardener-free epoxy resin in the epoxy-modified mortars with additional dry curing period.
Concrete Crack Repair with Polymer Modified Mortars: The Status Quo in the South African Construction Industry and the Way Forward
Authors: Bester Jannes , Kruger Deon
Published: November 2015

In recent years, concrete repair has become an integral part of the construction industry. With the vast quantity of concrete used in the South African construction industry over the past 100 years, one can expect an increase in repair and rehabilitation requirements during the extended lifecycle of exposed concrete structures. Crack repair, re-profiling of spalled areas and surface sealing with polymer related materials forms the bulk of such repair and rehabilitation operations. Due to the complexity of these projects and the variety of professionals and other stakeholders involved from the diagnostics to the implementation phase (specialists consultants, contractors, suppliers and owners of the structures), considerable problems seem to have surfaced to ensure cost-effective but sustainable and durable outcomes. It has been found that in many concrete repair projects, the responsibility for the repair work, adequate quality control and the assessment of successful patch repairs are not fully embraced by the various stakeholders.This concern has led to the research as reported in this paper. The research entailed a series of questionnaires drawn up specifically for the four different stakeholder sectors of the concrete repair industry. The results indicate that, although there is agreement that concrete repair is a highly specialized field, there is not enough training in the correct use of the repair materials, nor enough knowledge regarding the diagnostics or material specification and selection processes. Knowledge on polymer modified mortar are also minimal. These problems are compounded by inadequate quality control and lack of ongoing monitoring of patch repair failure. The paper concludes with suggestions on the way forward.
Deformability of Mortars Incorporating Polyurethane Foam Waste under Cyclic Compression Fatigue Tests
Authors: Junco C. , Rodríguez A. , Gadea J. , Calderón V.
Published: November 2015

An experimental analysis is performed on the fatigue behaviour of composite specimens made with Portland cement, sand, water, and polyurethane foam wastes. Different mixtures were firstly prepared through the substitution of different amounts of sand by equivalent volumes of polyurethane. The test pieces underwent cyclic compression tests, to study the deformability of different strengths of mortars under fatigue. A total of 2,000 cycles of loading and unloading, estimated at between 55% and 65% of the breakage load were applied to each specimen. The experimental results indicate that the elastic properties of the polyurethane mortars remained practically constant in comparison with the standard mortar samples. In addition, a comparative study of the mechanical properties of these mortars was conducted before and after each fatigue test. Their compressive strength showed no reduction in ultimate compressive resistance, indicating good resistance to fatigue.