bluuebunny/crossref_metadata_2025 huggingface dataset:
Four-point technique development for measuring spherical surfaces of machine parts
Authors: Safarov D T , Kondrashov A G , Khafizov I I
Published: August 2019

The article presents the theoretical foundations of the four-point measurements of spherical surfaces of parts method, allowing to increase the efficiency of spherical structural elements of ball tips of various sizes control. Compared to the measurement method on the coordinate measuring machine, the developed technique can be used at workplaces of forming spherical elements. The technique ensures the efficiency of measurements and increases the efficiency of carrying out the cutting tool settings.
Promising methods for enhancing the performance of boiler plants of centralized, decentralized and individual type of heat supply
Authors: Safin T R , Konakhina I A , Khamidullina G R
Published: August 2019

The paper covers the methods of how to enhance boiler plants for centralized, decentralized and individual type of heat supply. The performance analysis uses technical and economic efficiency indicators, fuel and other types of energy resources saving.
Changes in the CoCr alloys surface relief during plasma electrolytic treatment
Authors: Saleeva L R , Kashapov R N , Kashapov L N , Kashapov N F
Published: August 2019

Development of dentistry is strongly correlated with the new treatment method development and construction of metal, polymer and ceramic materials. Metal-ceramic crown is a common dental prosthesis. The aim of work was determination the causes of the ceramic coating spalling from the cobalt chrome metal frame. It is proposed to replace the standard sandblasting method to plasma electrolytic treatment. The burning of single microdischarges occurs during plasma-electrolytic process. The formation of the microwells and increasing surface roughness observed in cathode mode. This is due to local melting of the surface. The treated surface does not contain impurity elements that can cause the formation of microcracks.
Development of a polymeric fuel tank with high barrier properties
Authors: Shafigullin L N , Sotnikov A M , Romanova N V , Shabaeva E S , Sarimov D R
Published: August 2019

The choice and justification of the polymeric material is made for the fuel tank. It is established a possibility of linear polyethylene application with technology of fluoration as material for production of the fuel tanks with high barrier properties, that is with low permeability in relation to hydrocarbons. The main technological operations for the production of plastic fuel tanks carried out by rotational molding are described.
Quantum chemical calculations of the vibrational spectrum of aliphatic nitro compounds. Cluster analysis of torsion oscillations
Authors: Shaikhullina R M , Hrapkovsky G M , Shaikhullina M M
Published: August 2019

The data of theoretical analysis of vibrational spectra in the long-wave range of different isomers of methyl nitrite, methyl, ethyl, n-propyl nitrate, as well as the electron density distribution obtained within the B3LYP Density Functional Theory method with the 6 - 31G(d) basis set are presented. The cluster analysis of charge distribution on carbon, oxygen, nitrogen atoms and torsion oscillation frequencies in the range of 10-400 cm-1 is carried out.
Revisiting the calculations techniques of the optimal planning methods for the local authority activities (on the Republic of Tatarstan example)
Authors: Shikhalev A M , Akhmetova I A , Vorontsov D P , Khananova A F
Published: August 2019

The indicators of Savrushinsky local municipal structures development in the Republic of Tatarstan (RT) are defined on the basis of creation, receiving and the analysis of the production function (PF). For the PF creation were collected the input statistical data for 2013 - 2017 on revenues of the studied local municipal district, fixed assets volumes and the staff number. After the logarithmation and receiving the simple multiple regression equation with the potentiation method was received the PF in a multiplicative look that allowed to estimate the degree of intensive and extensive development of the studied municipal structures and also to define its ratio. For the mathematically correct results obtaining beforehand was made the component analysis of future equation, and after its receiving was estimated the residuals autocorrelation existence. As a result was specified that the Savrushinsky local municipal office in the studied period was mostly developed due to the production efficiency increase, than from the production scale growth in which increase consists the positive experience of this municipal structures.
Highly effective composite materials based on waste of technogenic sulfur
Authors: Yusupova A A , Barayeva L R , Akhmetova R T , Khatsrinov A I , Bobryshev A A
Published: August 2019

The materials developed on the basis of technogenic sulfur of silicate and chloride zinc of akivator can be used as road materials (tiles, paving stones) for arranging the territory or inner rooms of enterprises for the machine-building complex in areas with aggressive media. X-ray, rheological and quantum chemical studies have shown that when sulfur interacts with zinc chloride, a system of strong thermodynamically stable compounds is formed, causing the formation of an effective material.
Application of neural networks in object recognition tasks for ADAS systems
Authors: Ziyatdinov R R , Biktimirov R A
Published: August 2019

Modern driver assistance systems (ADAS) require an environmental recognition function to inform the driver and for making management decisions. Neural networks are used to select and recognize objects in such systems. The paper presents the results of comparative analysis of various neural networks in object recognition problems. Experimental data showed that convolutional neural networks show the best results in recognition problems.
Performance-based seismic evaluation methods for the estimation of inelastic deformation demands
Authors: Zubritskiy M A , Ushakov O Y , Sabitov L S
Published: August 2019

The article presents experimental research and comparison of two performance-based seismic evaluation methods: nonlinear static procedure (NSP) / pushover analysis (PoA) and nonlinear time history analysis. It is established that nonlinear static procedure is good enough for prediction of plastic hinges localization, but difference between methods results is more than 15 % with a lack of seismic resistance.
Account for the contribution of higher modes under system seismic resistance estimation by nonlinear static method
Authors: Zubritskiy M A , Ushakov O Y , Sabitov L S
Published: August 2019

The article presents higher modes accounting method under estimation of system seismic resistance by nonlinear static method. As part of the study, in order to verify the proposed method for finding the inertial forces modified system a complex of dynamic and static calculations was performed. It is established that proposed inertial forces modified system can significantly reduce system seismic resistance lack.
The process control for improving the durability of the cutting edge of the teeth of the cutter at their recovery
Authors: Zvezdin V V , Hisamutdinov R M , Rakhimov R R , Saubanov R R , Israfilov I H
Published: August 2019

The features of the technology of laser deposition of wear-resistant powders on the cutting edge of the cutter tooth with control of the positioning of the focus of laser radiation are considered. The stabilization of the parameters of the laser technological complex and the positioning of the focus of the laser radiation makes it possible to increase the efficiency of the technological process of restoring the instrument, with its specified quality indicators.
Physical and mechanical properties of fiber reinforced gypsum-based composite
Authors: Mukhametrakhimov R Kh , Lukmanova L V , Gilmanshin I R
Published: August 2019

Formulations of effective gypsum-fiber and gypsum-cement-fiber materials modified with active mineral additives and superplasticizer have been developed in the present experimental work. The influence of the type and length of reinforcing polypropylene fiber, the conditions of hardening and molding on the physical and mechanical properties of the specimens was studied.
Investigation of mechanical properties of fiber-cement board reinforced with cellulosic fibers
Authors: Lukmanova L V , Mukhametrakhimov R Kh , Gilmanshin I R
Published: August 2019

The article presents experimental research on the development of the optimal composition of cement-fibrous composite material for the manufacture of autoclaved fiber-cement boards with high physical, mechanical and economic parameters. The effect of the cement-sand ratio of the matrix, the specific surface area of the sand and the cellulosic fibers content on the physical and technical properties of the material is shown. It is established that the optimum cement-sand ratio of the matrix associated with a specific surface area of quartz sand 310 m2/kg is 1:2. The optimal content of cellulosic fibers according to the criterion of increasing the strength is 5-7.5%.
Numerical analyses on seismic behavior of helical concrete columns
Authors: Al-habbobi Alaa M
Published: August 2019

This paper presents the behavior of the helical reinforced concrete columns (HCC) subjected to horizontal 2D seismic motion excitation combined with the static axial load. Helical concrete columns are new types of elements which arose in the new twisted buildings, providing a special geometry by twisting the top section by an angle (ϕ), furthermore, offsetting the top section by a considerable distance respecting to the bottom section. In order to study seismic behavior of the HCC under a seismic load of the short period using finite element software, numerical simulation is carried out in this paper using ANSYS V 18.1 software. A brief comparison of the HCC behavior was made between different cases of conventional reinforcement in the longitudinal and transverse directions, as well as the different twisting angles (ϕ) of column sections. The comparison illustrated that all columns response with giving the same mode shapes of vibration in the modal analysis with different values of natural frequencies and relative amplitude deformations. However, the difference be very noticeable when changing the section size of the columns comparably with changing the twisting angles of the section, where increasing the section size of HCC from 250 mm to 400 mm cause increase the natural frequency by 55.4% for second mode shape, while it cause decreasing the relative amplitude response of HCC by 52.5% for sixth mode shape. The transient analysis of the six types of HCC excited by horizontal 2D seismic motion indicates the tendency of HCC to increase its responses, like twisting and buckling deformations. The deform shape-time history of 6 HCC demonstrated that with increasing (shear stress path section distance) S of HCC column which depends up on (ϕ value), the top section would have less stresses.
Improvement of Multi-Lane Airport Highway in Baghdad-Iraq
Authors: Jrew Basim , Hadi Ahmed
Published: August 2019

Transportation industry is basically a service sector component. It is a great importance for traffic engineers and planners to understand and evaluate the quality of service provided by transport facilities. Highway Capacity Manual (HCM), with all its revisions since 1950, is the pioneer document in this area. It quantifies the concept of capacity for a transport facility and lays the foundations for estimating the level of service (LOS) being provided by that facility to its users. This study is an engineering project management. It is about evaluation and improving multi-lane highways in Iraq. The research study was conducted on one main multi-lane airport highway in Baghdad, including: Al- Dora intersection to Al- Rashid interchanges, where this highway is considered as a major highway with high traffic volume in Iraq. HCS-2010 program software was used to evaluate and improve the level of service and traffic conditions for the highway for existing conditions (year of the study-2018) and short-term conditions (2023). The evaluation shows that all segments are operating at LOS E or LOS F for existing conditions, short-term conditions. The segments that operated at LOS E or LOS F for existing, short-term and mid-term conditions improvements are suggested by modifying the geometric and traffic conditions and changing the highway to a freeway facility; in order to operate at better LOS. A management flow diagram was prepared for decision makers to be a guide for future planning programs.
Punching shear behaviour of solid and bubble reinforced light Weight aggregate concrete two-way slabs
Authors: habeeb Maha , Al-Azzawi Adel A , Al- Zwainy faiq
Published: August 2019

Punching shear is the most important problem in flat slabs, which usually required reducing the self-weight of the slab. A lightweight concrete as well as the bubble deck technology were used to allow for lighter self-weight of the structure. This study aims to investigate the use of lightweight aggregate concrete (LWAC) with the bubble deck technology in flat slab. The behavior of two- way LWAC voided slab (with and without shear reinforcement) under punching shear effect with respect to solid normal weight and solid LWAC specimen were studded. The behavior of six specimens having the same dimensions, slab thickness and flexural steel reinforcement were studded. The main changed variables were concrete type, percent of void and punching shear reinforcement existence. The results show that the load carrying capacity for light weight aggregate concrete voided slab without shear reinforcement decreased by (60%, 53%) with respect to solid normal weight and solid LWAC slabs without shear reinforcement respectively. In addition, the load carrying capacity for LWAC voided slab with shear reinforcement decrease by (67%, 47%) with respect to solid normal weight, solid LWAC slabs with shear reinforcement respectively. Also, for lightweight aggregate concrete, solid and voided slab, shear reinforcement existence did not significantly increase the slab capacity for punching shear. But cause a reduction in maximum deflection with respect to slabs without shear reinforcement.
Structural Behavior of Eccentrically Loaded R.C. Columns under Fire Temperature Loading
Authors: Kadhim A H , Rasheed M M , Jarallah H K
Published: August 2019

The main goal of this research paper is to investigate the response of the RC rectangular columns under loading simultaneously exposed to fire by using experimental study. The number of test columns were seventeenth columns. The dimension for these columns was 1600mm for length and 150mmx150mm for the cross-section. The columns were tested under axial load with two different types of eccentricity 60 mm 100mm, while the third type of loading is tested as a beam. The eccentric compression load was applied by using top and bottom cap with a column bracket. The eccentric load was applied simultaneously with fire. The test was performed under a high temperature of (400°C, 600°C, and 900°C) on the side of a compression face. At each temperature burning, cooling by two techniques of cooling, and normal cooling (by open air) and fast cooling (by direct water). The experimental results show decreasing in ultimate load capacity with increasing of temperature burning, ultimate load, load-deflection curve, strain profile, neutral axis, moment-curvature, and ductility.
Effect of Embedment Depth on Raft Foundation Settlement Under Seismic Load
Authors: A Hanash Abeer A , Ahmed Mahmoud D , Said Abdulmotalib I
Published: August 2019

Dynamic loads highly influence soil properties and may cause real damage to structures and buildings. This article reports the experimental results from 24 tests to study the settlement of flexible and rigid raft foundation with different embedment depth rested on dense sandy soil. A small scale building model of dimension 200*200 mm and 320 mm in height was performed with reinforced concrete raft foundation of 10 mm thickness for flexible raft and 23 mm for rigid raft, The shaking table technique was used to simulate the seismic effect, the shaker was sat to give three different excitation frequencies 1,2,and3 Hz and displacement amplitude equal to 13 mm, the foundation was placed at four different embedment depths (0,0.25B=50mm,0.5B=100mm, and B=200mm), where B is the raft side length. The results of the tests indicate that the foundation embedment have a positive effect for its ability to minimize the settlement for both flexible and rigid raft foundation and for all the excitation frequencies.
Effect of Hybrid Polypropylene - Carbon Fiber on Self-Compacting Mortar
Authors: Ali Muataz Ibrahim , Jabbar Jamel Asmaa Abdul , Ahmad Ahmed Mohammed , Ali Anwer Muneer
Published: August 2019

The present work, aims to improve the properties of fresh and hardened self-compact mortar (SCM) containing hybrid Polypropylene-carbon fiber. The hybrid fiber added as a percentage 0.1%, 0.5% and 1% by volume of self-compact mortar, five different mixture of 100-0%, 70-30%, 50-50%, 30-70% and 0-100% for every fibers ratios (Polypropylene to carbon). The effect of hybrid fiber on some physical and mechanical properties of (SCM) was also investigated as a compressive strength and modulus of rupture, which was examined at ages of 28 days. Results showed that the best added of hybrid fiber (50 P.P-50 C.F) % increased compressive strength with ratio 32%, so increased modulus of rupture for self-compact mortar with ratio 130% at hybrid fiber (0 P.P-100 C.F) %, also indicated that the added improve hard characteristic and decrease of fresh characteristic as a flow time, mini slump flow and specific gravity, when the volume fraction 0.5% and 1% for all hybrid fiber exceeded the limits of the standard because the largest flow time is 11 seconds.
Swelling Control of Expansive Soils Using Cement Dust
Authors: Almurshedi Alaa D. , Thajeel Jawad K. , Dekhn Hadeel Ch.
Published: August 2019

Expansive soils exist in many regions over the world including Iraq. Expansive or swelling soil contains minerals that are capable to absorb water easily causing an increase in its volume. In this research, an expansive soil that exists in some locations in the province of Karbala in Iraq was used. Limited data is available to investigate the effect of cement dust on engineering properties of expansive soils. For this purpose, samples have been prepared by mixing the expansive soil with different percentages of cement dust. The samples have been subjected to cycles of wetting and drying to investigate the swelling behaviour. Soil samples that are used were compacted at the optimum moisture content. Five different percentages of cement dust content are used in this study include: 4, 8, 12, 16 and 20%. Fundamental tests for all soil samples. It is concluded that the addition of cement dust to the expansive soils is successful method to improve their properties such as decreasing the consistency limits, increasing the maximum dry density corresponding to lower optimum water content, decreasing the swelling pressure and swelling potential.
Development of Risk Optimisation Model for Oil and Gas Transportation Pipeline Routes
Authors: Kraidi L , Shah R , Matipa W , Borthwick F , Hashim Khalid
Published: August 2019

Identifying safe routes for the pipelines that transport Oil and Gas (O&G) products is a challenging topic in the current environment; particularly in the insure countries. Because the relevant data about the probability and severity levels of the Risk Factors (RFs) that affect the safety of these pipelines are rare. Which makes the existing risk assessment tools ineffective to analyse these RFs and identify safe route for these pipelines. Hence, this paper aims to develop a risk assessment tool that can identify safe routes for the new O&G pipelines in Iraq in a systematic way using the following steps. Firstly, an industry-wide questionnaire survey was conducted to gather the data about the probability and severity levels of the RFs in such projects in Iraq. Secondly, the Fuzzy Inference System (FIS) in MATLAB was used to analyse and rank the RFs. Because the FIS can reduce the uncertainty in risk analysis, which results from the lack of data and the biasness of stakeholder’s judgments about the RFs. Thirdly, the existing information from the new pipelines projects were analysed to identify the potential RFs in the proposed routes for these projects. As the O&G pipeline network in Iraq is above-the-ground, this paper focused on the RFs that affect this type of pipelines. Fourthly, the safest route for the new pipeline was identified by optimising the risk index value for each route. While, the route that has less value of risk index is the safest route. This paper analysed the five routes that were suggested to build a new gas export pipeline in Waist in Iraq. The pipeline will transport the extracted gas from Badra filed to the shipping points in Iraq. It was found that route number 4 is the safest route for this pipeline.
Using LARS –WG model for prediction of temperature in Columbia City, USA
Authors: Zubaidi Salah L. , Kot Patryk , Hashim Khalid , Alkhaddar Rafid , Abdellatif Mawada , Muhsin Yousif Raad
Published: August 2019

Climate change has placed considerable pressure on the residential environment in different areas of the world. These issues have increased the motivation of researchers to analyse and forecast the changes in critical climatic factors, such as temperature, in order to offer valuable reference outcomes for management and planning in the future. This study set out to determine to what extent global warming would affect Columbia City, Missouri, USA. The Long Ashton Research Station Weather Generator (LARS-WG) model is used for downscaling daily maximum temperatures based on the SRA1B scenario. Seven General Circulation Models (GCMs) outputs are employed for three selected periods, 2011–2030, 2046–2065 and 2080-2099. The findings show that (1) statistical analysis confirmed the skill and reliability of the LARS-WG model to downscale maximum temperature time series; (2) the ensemble mean of seven GCMs exhibited an increasing based on yearly and monthly data for all periods compared with baseline period 1980-1999. The findings can contribute to a better understanding of the impacts of climate change on the urban environment and encourage planners and stakeholders to find the best solution for mitigation of these impacts.
Effect of void Ratio of Inner Steel Tube on Compression Behavior of Double Skin Tubular Column
Authors: Ali Hanaa A. , Salman Wissam D.
Published: August 2019

Hybrid double skin tubular columns (DSTCs) are a composite members that consist of outer FRP tube and inner steel tube and concrete filled in between. These three materials combination in one element have several advantages do not found in common columns. The total 12 circular DSTCs were poured and tested under axial load. Every specimen is average of a pair of samples of the variables, diameter and thickness of steel tube, to investigate effect of inner steel tube void ratio on compression behavior of hybrid DSTC. The void ratio was defined as a ratio between the two inner steel and outer FRP tube diameter. The test results show that the stress-strain behavior of concrete material in the hybrid DSTCs has a better confined by two tubes. While the DSTC with small diameter has similar behavior to concrete filled FRP tube (CFFT). Thickness of inner steel tube is slightly effect on concrete stress inside DSTC.
Effect of Wasit Thermal Power Plant on Water Quality of Tigris River Downstream to Al Zubaidiayh City
Authors: Alaa Hiba , Jaeel Ali Jwied
Published: August 2019

This study was directed at Wasit Thermal Power Plant (WTPP) to determine the water quality status. Nine sampling stations established along the reach of Tigris River, the first station was 500m upstream (US) to WTPP and it was a reference station, the second station at WTPP and seven stations downstream (DS) to WTPP for collection of water samples. Water samples were prepared for their physico-chemical characteristics at all sampling stations were compared with the reference station. Sampling of all stations (downstream to WTPP) showed higher water pH, total dissolved solids (TDS), electrical conductivity, and chemical oxygen demand (COD) than that of sampling station upstream to WTPP and lower water dissolved oxygen (DO). The results showed increasing of pH, TDS, EC, and COD by 68%, 166%, 60% and 478% respectively, and decreasing the value of DO by 66% indicated that discharge from WTPP increased pollution load in river Tigris.
Water quality index of Tigris River on Waist Governorate for aquatic life
Authors: Enad Huda Yousif , Jaeel Ali Jwied
Published: August 2019

In this study, a mathematical model Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) has been used. Several physical and chemical parameters are chosen to calculate the water quality index as follows: temperature, pH, total dissolved solids (TDS), turbidity, dissolved oxygen (DO), total nitrogen (TN) and total phosphorus (TP). The results showed that all stations received a poor assessment of the water quality index, indicating that the water of the Tigris River is highly polluted for aquatic life due to discharging of poorly treated wastewater from Al Azziziyah Wastewater Treatment Plant (AWWTP).
Effect of increasing floors number on the natural frequency compared with further masses added to steel building models
Authors: Alalikhan Ahmed A. , Habelalmateen Mohsen A. , Al-Tameemi Haider A.
Published: August 2019

This paper investigates the change in the natural frequency of whole building due to the increase or decrease of the number of floors of a steel building model. Five steel building models were adopted in the present study to investigate the natural frequency required to be identified in each model. The first model represents a one floor building model, the second building model contains two floors and so on. The first four models were subjected to further masses distributed upon four points within the last floor. Each model consists of the same structural details that are proposed in the other models such as details of the beams, columns and slabs. The herein parameters are the number of floors and the further added masses upon the models up to four floors. All models were analyzed using ANSYS software to identify the natural frequencies for the extracted modes of vibration about X, Y, and Z building axes. The study is aimed to produce a relationship between the change of floors number and the further mass addition in the field of structural frequency attenuation based on the indication of the first identified mode. Results show that higher masses required to be added to attenuate value of natural frequency for the one floor building model than the further masses required for building with two floors to achieve the same purpose. This relationship continues for the other models with higher number of floors but with less further required masses.
Recycling of disposal Polypropylene Blister Tablets and Strapping ties as fiber reinforcement for Pervious concrete
Authors: Ahmed Ahmed M , Hussein Ahmed H , Hammood Mohammed T
Published: August 2019

Pervious concrete (PC) was introduced as a solution for the runoff from rainfall. To insure high porosity, pervious concrete should contain limited quantities of fine aggregate, which adversely effects concrete mechanical properties. As an attempt to improve PC mechanical properties, fibers were added to concrete matrix. As PC is allows water to pass through it, metal fibers are uncourageous to be added to it. Plastic fibers were selected as an alternative to metal fibers to be added to PC. Concrete physical and mechanical properties were studied for mixtures containing different quantities of fibers. Tests results showed a slight improvement in concrete compressive strength (0.48% to 1.44%) as fibers were added. The addition of fibers improved splitting tensile strength by (6.36% to 27.67%). As adding fibers, concrete flexural strength increased by (11.37% to 24.17%) compared to the reference mixtures. of PC. Concrete physical properties (Density, Porosity and permeability) were also investigated. The addition of fibers to concrete has a slight effect on (density, porosity and permeability).
Influence of using alum sludge as an aggregate on hot mix Asphalt
Authors: Ali Dawood Sahar A. , Obaid Hayder Abbas , Hashim Tameem Mohammed , Jasim Hadeel Kareem
Published: August 2019

Alum sludge (AS) is one of the final products from water treatment processes. Handling and disposal of alum sludge has become one of the major economic and environmental concerns. An experimental investigation was examined to study the possible utilization of alum sludge as aggregate substitute in asphalt mixtures for pavement construction applications. Five asphalt mixtures containing various contents of the AS, 0% (reference mix), 30%, 50%, 70% and 100%, as a replacement to the fine aggregate were prepared in this study. The results conducted that alum sludge is a suitable material for producing asphalt mixes that contains of AS ranging from 30% to 50% as partial replacement for fine aggregates to achieve almost all the standard requirements for aggregates in asphalt mixtures..
Chitosan as a Widely Used Coagulant to Reduce Turbidity and Color of Model Textile Wastewater Containing an Anionic Dye (Acid Blue)
Authors: Abdullah Hala A , Jaeel Ali J
Published: August 2019

The study focuses on using chitosan as a widely used coagulant (a biopolymer) to treat model textile wastewater containing an anionic dye (acid blue). Jar test experiments had been used in the coagulation-flocculation process. Acid Blue was selected as a model dye for testing chitosan’s ability to treat model textile wastewater. Chitosan is found from chitin by deacetylation. The biopolymers, because of biodegradable properties, availability and low cost have been used as coagulants. The dosage impact, pH, settling time, decolorization and turbidity reduction of simulated textile wastewater were studied. Chitosan showed great performance to remove turbidity and color. The usage of chitosan as a primary coagulant would decrease the cost of wastewater treatment. Besides, it is eco-friendly coagulant without harmful impacts.
Comparison of Compressibility Behaviour of Lime-Cement Stabilized Lateritic Clay Soil Contaminated by Heavy Metals
Authors: Saeed K A , Kassim K A , Nur H , Yunus N Z M
Published: August 2019

The type of stabilizer, heavy metal and soil can typically affect the strength and compressibility development in the treatment of contaminated soils. This is due to the difference in chemical reactions and interferences occurring among the stabilizers, metals, and clay minerals. A standard consolidation test using an oedometer was carried out to investigate the cement–lime induced changes in the compressibility of clay soils contaminated with either copper or zinc. In this study, laterite clay soil obtained from the hilly area at Universiti Teknologi Malaysia was used. Control samples of cement-and lime-stabilized soils without heavy metals were compared with the treated contaminated stabilized soil at various contaminants contents. Such percentage of contaminants means that the soil falls under industrially contaminated soil. To highlight the effect of the two heavy metals on the consolidation behavior of clay samples treated with cement and lime, a comparison has been made at a curing period of 7, 28, 100, and 200 days respectively. It was found that the interference of heavy metals during the process of hydration (cement and lime) contributed directly to the inhibition of the compression development of the tested soil samples. Therefore, it is crucial to identify the type of stabilizer, heavy metal, and soil involved to ensure successfully and remediate treatment.
Experimental analysis of static capacity of fibrous concrete cambered slabs after impact loading effect
Authors: Ahmed Kamil Al Kulabi , Ali Adnan Al Zahid
Published: August 2019

Fibrous concrete is an enhanced material by adding fibers to the ingredients of normal concrete. This addition improved some properties of the regular concrete, which are growing concrete ductility, decreasing concrete shrinkage, and raising concrete resistance to the dynamic attacks. The aim of this paper is more investigating the properties of fibrous concrete by finding out the effect of impact loading induced by a free fall ball on flexural capacity of fibrous concrete from one side, and finding out the importance of camber construction in reducing the influence of impact loading on the flexural capacity of concrete slabs from another side. For that purpose, three concrete slabs of (80X80X4) cm dimensions were dynamically and then statically loaded. The three specimens had the same steel fiber dosage of 0.5%, but they had different slab camber at the mid span where one specimen had no camber, the second specimen had 10 mm camber, and the third specimen had 20 mm camber. In addition to the difference in the slabs‘ camber, the three slabs were subjected to a different number of impacts and from various heights to get a better explanation. Tests results showed that presence of fibers and increasing slab camber caused an improvement in the specimen resistance to both of impact and flexural loads, decreased the specimen crack width and number, and provided a safer residence for tenants.
The Effect of the Shear Connectors Layout on the Sustainable Lightweight Concrete Sandwich
Authors: Rasheed Laith Sh. , Ali Suad Abbas
Published: August 2019

Sandwich Slab is a modern shape of structural construction. It contains a low density layer known as the core layer confined by two strong layers. In the present study, the two layers of light weight concrete [LWC] were tied together by a cage of steel reinforcement named as shear connectors, sandwiched between them a layer of polystyrene. The experimental investigation was conducted on six slabs. Two parameters were investigated (the steel area of the shear connectors which is depended on the number of W-Shaped shear connectors and the layout of W-shaped shear connectors). The main reason for using crushed bricks as a lightweight aggregate was to the benefit from the recycling broken bricks as a sustainability material. The slabs were tested as simply supported under two line loads. Continuous truss-shaped shear connecter showed better behaviour than discrete W-shapes shear connectors. Experimental test results indicated that the presence of discrete shear connectors at the ends of the specimens in distance of one-fourth of span had significant better performance than at the center of the specimence.
Tire Rubber Waste for Improving Gypseous Soil
Authors: Snodi L N , Hussein I S
Published: August 2019

Each year large quantities of tire wastes are released to the environment in an undesirable way. Those waste materials cause many environmental and economic problems. This study introduces an attempt to improve Gypseous soil properties using rubber tires waste.

This paper presents an experimental study that explores the possibility of using rubber tires waste as an additive to improve the strength of gypseous soils. Different percentages of the waste material (2, 4, 6 and 8%) were mixed with the designated soil. The obtained results show that the angle of internal friction increases significantly with the addition of a different percentage of tire residues, unlike cohesion which was barely affected. In addition, the waste tires rubber minimizes the maximum dry density and optimum moisture content for this type of soil. The difference in optimum moisture content and maximum dry weight with the addition of waste fraction is linear.
Mechanical Properties of Lightweight Aggregate Moderate Strength Concrete reinforcement with Hybrid Fibers
Authors: Ibrahim Haider Araby , Mahdi Mohammed Bally , Abbas Basim Jabbar
Published: August 2019

This study aims to detect the mechanical properties of lightweight aggregate moderate strength concrete (LWAMSC) reinforced with single and hybrid fibers in various types and sizes. Moderate strength pumice lightweight aggregate concrete mix with compressive strength 40 MPa at 28 day age with silica fume and superplastizier was used. The fibers used include macro hooked steel fiber with aspect ratio 80, steel fiber with aspect ratio 60, and polypropylene fiber (P.P.F). Two groups of (LWAMSC) mixes were made with reference concrete mix (without fibers). The first group of mixes were substituted three (LWAMSC) mixes with different single fiber including, concrete mix reinforced with Polypropylene (P.P.F) about 0.75 % volume fraction (P1), concrete mix reinforced with macro hooked steel fiber type SF1 with volume fraction 0.75% mix (M1) and concrete mix reinforced with macro hooked steel fiber type SF1 volume fraction 1.5% mix (M2). The second group of fiber reinforcement (0.75% steel fiber type (SF1) + 0.75% steel fiber (SF2) mix (H1), (1% steel fiber (FS1)+ 0. 5% steel fiber type (SF2) mix (H2)),and finaly (1% steel fiber type (SF1)+0.5% PPF mix (H3)). Dry density, strengths of compressive, splitting tensile, and flexural of (LWAMSC) were examined. generally single and hybrid reinforcement fiber of (LWAMSC) show important increase at flexural strength and splitting tensile strength in comparison with reference concrete.The results also show that, the optimum added proportion of fiber steel type (SF1) was (1.0%) and with (0.5%) steel fiber type (SF2) that portion raised the strengths of compressive, flexural, and splitting tensile around (4.34%), (52.93%), and (297%) respectively comparison with control mixture.
Evaluation of the Performance of MBR-RO Technology for Treatment of Textile Wastewater and Reuse
Authors: Zahraa S H , Gzar H A
Published: August 2019

This study aims to evaluate the performance of membrane bioreactor (MBR) followed by the membrane of reverse osmosis (RO) for textile wastewater treatment and reuse. Firstly, study of the effect of hydraulic retention time (HRT) and the concentration of mixed liquid suspended solids (MLSS) on the removal efficiency of chemical oxygen demand, colour and turbidity were achieved by MBR system. The results showed that the MBR technology became increasingly effective in the treatment of textile wastewater with increasing HRT and MLSS concentrations The highest removal efficiencies were 86.7%, 77.67% and 96.74% for COD, colour and turbidity, respectively when HRT = 2days, while the highest removal efficiencies were 88.34%, 83.7% and 97.9% when HRT = 2.5days. The second step was studying the effect of operating pressure and RO feed temperature on the removal efficiency of COD and colour of the RO system. MBR effluent has been treated with RO membrane to remove the remaining pollutants. The results showed that, the increasing of the pressure and decreasing of the temperature have a positive effect on removal efficiency. The maximum removal efficiencies obtained for COD and colour were 99.3% and 99.8% respectively at a pressure of 10 bar and 25 °C RO feed temperature.
An experimental study of flow over V- shape crump weir crest
Authors: Mohammed Al-Khateeb Hasan Mahdi , Sahib Jumana Hadi , Hasan Al-Yasisri Huda Hadi
Published: August 2019

Weirs are considered important structures controlling flow conditions and measuring flow rates in open channels. Crump weir represent good solution tool to control flow depth in streams, especially where controlling fish zones is required. However, installing crump weirs in rivers and relatively wide streams may be accompanied with difficulty of controlling same water level over the entire weir crest length. This study aimed to modify the crest of crump weir to be V-shaped rather than normal crest. Four wooden crump weir models were adopted. Each of the four models had longitudinal equilateral triangle section with the same horizontal base length, L (78.5cm), width, W (29.5cm) and height, P (20cm), but they differ by the middle crest height, P’ as (20, 17.5, 15 and 12 cm) according to models 1, 2, 3 and 4, respectively.. The three v-shaped crested crumps and the normal crump were subjected to eight flow rates and five flow depths at steady state modular flow conditions. Data gathered were used to conclude a nonlinear multiple regression formula of discharge coefficient for the modified models tested. The formula concluded was calibrated and verified with very good determination factor (0.958). Effect of crest modification on water level was clear at relatively low flow rates and vice versa.
The effect on the interfacial strength of the length/width ratio of FRP sheet bonded to concrete
Authors: Al-Juboori W. , Weekesb L.
Published: August 2019

Fibre reinforced polymer laminates are commonly used for the retrofit of ailing reinforced concrete structures for both shear and flexure. Recent studies have been undertaken regarding bond behaviour, but these have not advanced significantly to apply in a general manner to FRP sheets. This paper presents the effect of the length/width ratio on the bond stress and strength between FRP laminates and concrete. The experimental and the theoretical study give the same effect of the length/width ratio. Experimental bond models were tested of 7 specimens with 3 bonding techniques and compared with predictions from finite element models. Mesh sensitivity studies were carried out for the FE modelling, and compatible crack patterns were observed between FE models and the experimental samples. The FE shows clearly the distribution of principal stress in the concrete and explains the failures observed in the experimental tests. This study shows that the width of CFRP sheet has more influence than the length. Also it can be concluded that increasing the CFRP sheet width leads to a propensity for concrete de-bonding. This also illustrates how existing expressions for bond strength match with the observed results. In general the results show that an increase in width provides more load capacity than a relative increase in length even some design methods do not interest to the effective of width/length sheet ratio.
Dependence of fracture size effect and projectile penetration on fiber content of FRC
Authors: Bažant Zdeněk P , Rasoolinejad Mohammad , Dönmez Abdullah , Luo Wen
Published: August 2019

The microplane constitutive model M7f for fiber reinforced concrete (FRC), previously calibrated by extensive material test data, is used in computational simulations of the size effect in geometrically similar notched specimens, and in simulations of penetration of projectiles into FRC targets. The M7f microplane model for fiber reinforced concrete is calibrated at the material level and then used to predict structural level behavior. The results show that, for any fiber volume ratio, the Type 2 size effect must be expected.
Fibre reinforced concrete with recycled concrete aggregate – inverse design approach
Authors: Broukalová I , Šeps K , Fládr J , Vodička J.
Published: August 2019

The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. The objective of the presented investigations was to verify the proposed breakthrough approach to utilisation of crushed waste concrete in construction of various types of structures. The traditional philosophy of the designing procedure – to find a suitable material for a given structure – is transformed into a new way of designing entitled “inverse design approach” that intends to find a suitable structure for a low-strength porous composite material that is obtained from available recycled rubble concrete. In the first stage, composition of concrete mix optimal from the point of view of mechanical properties, workability and economy is estimated based on the experience of the authors. The keynote is maximising of recycled aggregate use, minimising of cement consumption and providing competitive advantage of the composite made from concrete waste. Properties of the material are determined in laboratory tests. Possible applications of the composite in the construction industry are proposed. Finally, one of the possibilities is selected for verification. The results have shown that the introduced inverse design approach is applicable; it can lead to exploitation of significant amounts of construction waste in a useful way, to substantial savings of primary resources and to reduction of carbon footprint of the construction process.
Analytical model for rigid (steel) and flexible (synthetic) fibre mixing in concrete
Authors: Juhász K P
Published: August 2019

Quantity of the fibres intersecting the unit cross section is a relevant parameter. Firstly, the residual tension strength, which is the base of the material model of the fibre reinforced concrete, depends most on the number of fibres intersecting the cracked cross section. Secondly, by counting the fibres on the cross section of the broken test specimen the non-uniform distribution of the fibres can be examined and taken into account during the evaluation. Therefore, for most of the material model the initial parameter is the quantity of fibres intersecting the unit cross section.
Nonlinear modeling of SFRC beam using multilinear softening function obtained by inverse analysis
Authors: Benedetty C A , Oliveira L H , Almeida L C , Trautwein L M
Published: August 2019

The modeling of steel fiber reinforced concrete (SFRC) is a challenging task in comparison with the conventional reinforced concrete structures. Softening functions used to numerically reproduce SFRC fracture need to describe the effects associated with the post-cracking residual strength induced by the fibers in the concrete matrix. In order to do this, multilinear softening functions can be used to consider these effects. The work presents the results of a study in which the behavior of a SFRC beam tested in four-point bending test is compared with the responses obtained in nonlinear simulations using the finite element method. Multilinear softening functions are obtained through an inverse analysis technique, aiming to reproduce the phenomena of appearance and propagation of cracks. The simulations were performed using ATENA/GiD software. The technique adopted to find the softening function of SFRC allowed to reproduce, with a good agreement, the behavior reported experimentally.
Numerical validation of a simplified inverse analysis method to characterize the tensile properties in strain-softening UHPFRC
Authors: Mezquida-Alcaraz E J , Navarro-Gregori J , Serna-Ros P
Published: August 2019

In previous research a simplified closed-form non-linear hinge model based on the Third Point Bending Test (TPBT) developed by the authors to derive the tensile material properties of Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC) was numerically validated. This simplified non-linear hinge model was calibrated for UHPFRC that exhibits strain-hardening constitutive behavior. The aim of this work is the numerical validation of the simplified inverse analysis method to characterize the tensile properties of UHPFRC even with those UHPFRCs which exhibit strain-softening behavior. To get this objective a Finite Element Model (FEM) is carried out. The parameters to characterize the concrete properties from the simplified inverse analysis method by means of TPBT are used in the numerical modelling. The constitutive model for UHPFRC is modelled using a discrete crack approach for the macrocrack position. Different parameters are analysed to quantify the accuracy of the FEM. As a result, the model shows conservative load-deflection response when it is compared to the experimental curves.