bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

AbstractSandwich 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Simulation of mixed-mode fracture (I-II) on PFRC specimens with various fibre proportions using an embedded cohesive crack model
Authors: Suárez F , Gálvez JC , Enfedaque A , Alberti MG 
Published: August 2019

Abstract
The study of fibre-reinforced concrete (FRC) has become of increasing interest in the last decades. Although it is not a new technology, it has experienced a remarkable progress with the appearance of some recommendations in the standards. More specifically, the use of polyolefin fibres has proved to increase the tensile strength of concrete without the problems usually found with steel fibres, especially those related to corrosion. This type of fibres have been studied in depth and its fracture behaviour has been successfully simulated in the past by means of an embedded crack model using a trilinear softening function. Nevertheless, these simulations have been always focused on cases where fracture took place under pure mode I conditions, namely using the classical three-point bending test on notched specimens. In this study, such embedded crack model is used to reproduce the fracture behaviour on notched specimens subjected to a modified three-point bending test that induces fracture under a combination of modes I and II. Three PFRC mixes are analysed, all of them with the same proportions of concrete components but different proportions of polyolefin fibres. The experimental and numerical diagrams properly agree and allow identifying how the increasing proportion of fibres can be reflected in the trilinear softening function that numerically drives the damage evolution.
Advanced design methodologies for steel fibre reinforced concrete and new methodology of real time quality control
Authors: Hoekstra A 
Published: August 2019

Abstract
Steel fibre reinforced concrete has developed over years for the use in structural applications. The material itself has undergone development into higher performing steel fibre types and thus into higher performing steel fibre concretes. Whilst in regards to standards the development went from recommendations into building codes the way of designing – linear elastic design methods or yield line theory – and the way of quality control seemed to remain unchanged from the past. This paper shall emphasize the recent development in a design tool that enables a non-linear design methodology and a new advanced way of real time quality control.
New UHPFRC bridges in the Czech Republic
Authors: Marek J , Kolísko J , Tej P , Čítek D , Komanec J , Kalný M , Vráblík L 
Published: August 2019

Abstract
This paper deals with new UHPFRC (Ultra High Performance Fibre Reinforced Concrete) bridges produced or constructed in 2018 in the Czech Republic. The paper includes a short description of 3 unique pedestrian bridges with load bearing structure made of UHPFRC and 2 steel bridges over the railway track with lost formwork for bridge decks and cornices made of thin UHPFRC slabs. Focus is given on the testing of the material, comparison of test specimens and summary of results from UHPFRC production in real scale. The size effect of control specimen and the results analysis is given in the last chapter. The 3 mentioned unique pedestrian bridges are Footbridge over the Lubina river in city Příbor, Pedestrian and cycle bridge in the vicinity of Black Bridges in city Tábor and Footbridge over Dřetovice stream in Vrapice - a district of Kladno city. Thin panels as permanent lost formwork for two bridges over the railway tracks are in city Přerov. All new UHPFRC structures should be worthy of attention of bridge experts and community of specialists in the field of concrete engineering.
Steel microfibres in fly ash geopolymer for multifunctional conductive composites
Authors: Mizerová C , Kusák I , Rovnaník P , Bayer P 
Published: August 2019

Abstract
Steel fibres in construction materials not only enhance their mechanical and fracture properties but also increase their capability of electrical conductivity. This feature thus enables the material to obtain advanced multifunctional properties that can be utilized in self-sensing and other smart applications. Fly ash geopolymers with steel microfibres in 5−30% wt. were prepared to assess the influence of the fibres on selected electrical properties of the composite (resistance, capacitance and relative permittivity) with respect to mechanical performance. Microstructure and interfacial bonding of matrix and steel fibres was observed by electron microscopy imaging. Steel fibres caused an improvement in all assessed electrical properties but only above a certain frequency values. Furthermore, steel reinforced samples exhibited increase in both compressive and flexural strength.