bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of self-compacting rubberized concrete
Authors: Hamza Bensaci , Belkacem Menadi , Said Kenai , Walid Yahiaoui
Published: February 2018

Used tyre rubber wastes present a serious environmental problem of pollution and storage. The recycling of this waste in the industry of construction could be an appropriate solution to produce an eco-concrete and could contribute to the improvement of some of its properties. This paper aims to study the possibility of using tyre rubber waste as fine aggregate replacement in self-compacting concrete (SCC). Fines rubber particles of 0-2 mm of waste tyres were added SCC mixtures as a partial substitution of the total volume of sand at different percentages (5, 10, 15, 20 and 30%). The influence of fines rubber of used tyres on fresh and hardened properties of the SCC was investigated. The fresh properties of SCC were performed by using slump-flow, T50 flow time, L-box, V-funnel and segregation resistance tests. Characteristics of the hardened state were obtained by compressive strength and thermal conductivity. The experimental results showed that the inclusion of fines rubber in SCC decreases the workability, reduced its passing capacity and increases the possibility of blocking. A decrease in compressive strength is observed with the increase in rubber content. On the other hand, the incorporation of the rubber fines aggregates enhances in a remarkably way the thermal conductivity.
Feasibility of backfilling mines using cement kiln dust, fly ash, and cement blends
Authors: Beltagui H. , Sonebi M. , Maguire K. , Taylor S.
Published: February 2018

Cement kiln dust (CKD) is an industrial by-product of the cement manufacturing process, the composition of which can vary widely. Recent years of using alternative fuels have resulted in higher chloride and alkali contents within CKDs; as such, this limits the applications in which CKDs can be utilised. Using a CKD containing a high free lime content of 29.5%, it is shown that this CKD is capable of activating pulverized fuel ash (PFA) due to its high alkalinity, which can be utilised in low strength un-reinforced applications. One potential application involves the backfill of mines, reducing the need for continuous maintenance of the mine. This study focuses on the compressive strength achieved by various blends of CKD, PFA, and cement. Samples were hand mixed and compacted in 100 mm x 50 mm diameter cylinders, and unconfined compressive strength measurements taken at 28 and 56 days. The hydration products were assessed through the use of x-ray diffraction and thermogravimetric analysis. Aiming to maximise the use of CKD at a water to binder (w/b) ratio of 0.2, it was found that the maximum CKD content possible to achieve the required strength was 90% CKD blended with 10% cement.
Influence of Fluorine on Clinker burnability and mechanical properties of CPA Moroccan cement
Authors: Bouregba A. , Diouri A. , Elghattas B. , Boukhari A. , Guedira T.
Published: February 2018

It has been found that the addition of certain components, despite their low concentration in raw mix, may accelerate and enhance the reactivity of the cement raw mix. The utilization of mineralizers to facilitate and quicken the process of clinkerization backpedals numerous years, the concept of using such mineralizers to burn normal raw mixes at a much lower temperature with the end goal of decreasing the fuel necessities of the furnace and to enhance the cement proprieties has become to be seriously considered over the most recent couple of years.

The subject of this paper is to investigate the impact of calcium fluoride as mineralizer on addition during the clinkerization process of industrial raw mixtures and its effect on chemical, mineralogical, and mechanical properties of CPA Moroccan cement. Five different raw meals were utilized and were burned with 2% of calcium fluoride. The resulting clinker was analyzed by X-ray diffraction (XRD) and fluorescence spectroscopy to determine the chemical phases of the obtained clinker, and the mechanical properties of resulting CPA cement were determined. The results show that the addition of 2% of CaF2to the clinker raw meal induced a decrease in the burning temperature and free lime, while improving the clinker phase formation and the mechanical properties of obtained cement.
Physical, mechanical and thermal properties of Crushed Sand Concrete containing Rubber Waste
Authors: Mohamed Guendouz , Djamila Boukhelkhal
Published: February 2018

Over the past twenty years, the rubber wastes are an important part of municipal solid waste. This work focuses on the recycling of rubber waste, specifically rubber waste of used shoes discharged into the nature and added in the mass of crushed sand concrete with percentage (10%, 20%, 30% and 40%). The physical (workability, fresh density), mechanical (compressive and flexural strength) and thermal (thermal conductivity) of different crushed sand concrete made are analyzed and compared to the respective controls. The use of rubber waste in crushed sand concrete contributes to reduce the bulk density and performance of sand concrete. Nevertheless, the use of rubber aggregate leads to a significant reduction in thermal conductivity, which improves the thermal insulation of crushed sand concrete.
Physical and mechanical properties of cement mortar made with brick waste
Authors: Mohamed Guendouz , Djamila Boukhelkhal
Published: February 2018

The development of new building materials is a current problem where researchers are trying to find the right materials for each region and returning cheapest countries. Recycling and recovery of waste are now considered as a promising solution to meet the deficit between production and consumption and protecting the environment. This work focused on the study of the effect of brick waste in the production of cement mortar with substitution rates ranging from 5-30% by weight of cement and to compare its performance with fresh and hardened state with ordinary mortar considered as control mortar. Compressive and tensile strengths up to 28 days of age were compared with those of controlled mortar. Water absorption was also measured at 28 days of age. The test results indicate the beneficial effect of brick waste powder on performance of cement mortar with an optimum of 15% of cement weight substitution.
The effective complex permittivity stability in filled polymer nanocomposites studied above the glass transition temperature
Authors: Elhaouzi F. , Mdarhri A. , Zaghrioui M. , Honstettre C. , El Aboudi I. , Belfkira A. , El Azhari M.
Published: February 2018

The temperature effecton the dielectric response of nanocomposite at low frequencies range is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate (EBA) polymer filled with three concentrations of the dispersed conducting carbon black (CB) nanoparticles. The temperature dependence of the complex permittivity has been analyzedabove the glass transition temperature of the neat polymer matrix Tg=-75°C. For all CB concentrations, the dielectric spectra follow a same trend in frequency range 100-106Hz. More interestingly, the stability of the effective complex permittivity ɛ=ɛ' -iɛ'' with the temperature range of 10-70°C is explored. While the imaginary part of the complex permittivity ɛ'' exhibits a slight decreasewith temperature, the real part ɛ' shows a significant reduction especially for high loading samples. The observed dielectric response may be related to the breakup of the three-dimensional structurenetwork formed by the aggregation of CB particles causing change at the interfaceEBA-CB.This interface is estimated bythe volume fraction of constrained polymer chain according to loss tangent data of dynamic mechanical analysis.
Effect of anionic polyelectrolytes on the flow of activated sodium bentonite drilling mud
Authors: Chalah Kaci , Benmounah Abdelbaki , Benyounes Khaled
Published: February 2018

Bentonite is often used in water-based drilling fluids. The xanthan gum is widely used as to increase the viscosity of the bentonite suspension. For the stabilization of the drilled layers, we use filtrate reducers: sodium carboxymethylcellulose low viscosity and cellulose polyanionic low viscosity. The objective of this work is to explain the effect of the polymers on the rheological behavior of the 5% bentonite suspensions. These results will provide practical recommendations for the rational use of different types of additives in water-based drilling muds. Our work is based on rheological trials on a viscometer. The results obtained on the bentonite 5%-xanthane suspension show a rheofluidifying behavior with yield stress conform to the Herschel-bulckly modal. While increasing the concentration of filtrate reducer decreases the yield stress and reduces the viscosity. The effect of CMC LV is more pronounced than PAC L.
Synthesis and crystal structure of two new phosphates with Alluaudite type structure: (M, Mn)3Fe(PO4)3 (M= Ca, Cd)
Authors: Alhakmi Ghaleb , Assani Abderrazzak , Saadi Mohamed , El Ammari Lahcen
Published: February 2018

Two new phosphates with alluaudite type structure (M, Mn)3Fe(PO4)3 (M= Ca, Cd), namely Ca1.54Mn1.46Fe(PO4)3 and Cd0.66Mn2.34Fe(PO4)3, has been synthesized by a solid state reaction and characterized by single-crystal X-ray diffraction. The two compounds crystallize in the monoclinic system with C2/c space group. Their open framework results from (Fe1/Mn1)2O10 units of edge-sharing (Fe/Mn)O6 octahedra, which alternate with M(1)O6 octahedra (M(1)=Ca1/Mn2 or Cd1/Mn2) that form infinite chains running along [10-1] direction. These chains are linked together through the common corners of PO4 tetrahedra giving rise to two types of tunnels occupied by bivalent cations Ca2+ or Cd2+ and Mn2+.
Synthesis and structure study of new manganese and indium based phosphate: (Ca,Ba)1.222Mn0.923In1.570(PO4)3
Authors: Benhsina Elhassan , Assani Abderrazzak , Saadi Mohamed , El Ammari Lahcen
Published: February 2018

Phosphates are an important class of materials which are well-known due to their structural diversity and their important potential application in many fields of sciences. A member of this family, represented by transition metal phosphates, is in the forefront of important researchers. A new manganese and indium based phosphate is successfully isolated by means of solid state reaction. Its corresponding crystal structure is isotypic to the alluaudite and crystallizes in the monoclinic system with the space group C2/c and cell parameters a=12.4697(5)Å ; b=12.9365(5)Å ; c=6.5625(3)Å and β=115.603(1)°. The framework of this phosphate is built up on the basis of MnO6, InO6 and PO4 polyhedra. The InO6 octahedra are linked together via common edge, leading to the formation of In2O10 dimers. The In2O10 dimers share edge with MnO6 octahedra, generating chains along the [101] direction. The PO4 tetrahedra connect two chains giving arise to a three-dimensional framework with hexagonal tunnels where the barium and calcium are located.
Synthesis and structural characterization of new cadmium, zinc and iron based pyrophosphate: (Cd,Zn)25Fe(P2O7)2
Authors: Khmiyas Jamal , Assani Abderrazzak , Saadi Mohamed , El Ammari Lahcen
Published: February 2018

The novel compound with the following nominal formulation (Cd, Zn)2.5Fe(P2O7)2 has been successfully prepared by the solid state reaction and characterized by single-crystal X-ray diffraction. This phosphate crystallizes in the orthorhombic system with the C2221 space group. Its crystal structure is formed by five types of cationic sites and by two unique (P2O7)4- anionic groups with a staggered conformation. In the structure, three sites are fulfilled by Zn2+ :(Zn(3), Zn(4)) and Fe(1)3+, the fourth site is localized in the Wyckoff position 4a (site symmetry 2 ‥) and is statically occupied by Cd2+ : Zn2+with ratio 0.586(2) : 0.413(8). The last site, localized in 8c Wyckoff position (site symmetry 1) is also occupied by a mixture of the two cations Cd2+ : Zn2+with occupancies of 0.444(6) : 0.555(4).Within this framework, the metallic polyhedra [MOn] (n = 5 or 6) form corrugated layers stacked along the b-axis, and intercalated by P2O7 groups.
High efficient photocatalytic activity of Zn-Al-Ti layered double hydroxides nanocomposite
Authors: Amor F. , Diouri A. , Ellouzi I. , Ouanji F. , Kacimi M.
Published: February 2018

This work establishes a simple method for synthesising layered double hydroxides (LDHs) powders with coprecipitation. The characteristics of the samples were investigated y X-ray diffraction (XRD), scanning electron microscopy (SEM) and spectrophotometer UV–Vis (DRS). Non-uniform distribution was shown for LDHs samples by SEM. Photocatalytic efficiencies were tested using methylene blue (MB) dye as a model contaminant under UV irradiation. In particular, Zn–Al-Ti LDH exhibited an excellent performance towards MB degradation compared with commercial TiO2 nanoparticles. Methylene blue removal percentage was reached at almost 100%, whereas commercial TiO2 reached a removal rate of only 66% under the same conditions within 20 min. The aim of the current work is to prepare Zn-Al-Ti layered double hydroxides nanocomposite and to evaluate their photocatalytic activity in the removal of methylene blue under UV irradiation.
Effects of the brake shoe friction material on the railway wheel damage
Authors: Hamdaoui Abdelmajid , Jaddi El Houcine
Published: February 2018

The wheels of a railway axle are the most critical components of a train. These wheels are subjected to several forms of deterioration, including wear, which significantly influences the safety of traffic as well as the dynamic stability of railway vehicles and the lifetime of wheelsets. The objective of this work is to compare the effect of two friction materials of brake shoes at the damage and the wear rate of the ER8 steel wheels.
Durability of mortars modified by the effect of combining SPA polymers and supplementary cementitious materials
Authors: Belbachir B. , Benosman A.S. , TaÏbi H. , Mouli M. , Senhadji Y. , Belbachir M.
Published: February 2018

Nowadays, the major concern of professionals in the field of building materials is to improve the properties induced by the addition of different additives (polymers) and mineral additions (Supplementary Cement Materials SCMs) and to eventually adapt them to a particular application. This race towards performance has resulted in mortar formulations that are increasingly complex and rich in diversified additions. This is an industry-friendly practice since it generally yields a mortar modified by the combination of a polymer and SCMs, at low cost and low environmental impact, with an improved sustainability in the long term. In order to improve the durability of SCM-modified repair mortars, it seemed interesting to evaluate the influence of adding the styrene polyacrylic (SPA) Latex on the properties of these mortars when exposed to aggressive media such as acids. Composite mortars based on pozzolanic mineral additions, containing different levels of 0.5%, 1% and 2%w latex, were stored in acid solutions, for various periods of immersion. The analysis of the microstructure of these mortars, after exposure to acid attack, was carried out by FTIR spectroscopy. The results obtained allowed to demonstrate the beneficial effect of adding the SPA polymer and the pozzolanic additions to the modified materials and to show their improved resistance to acid attacks, such as HNO3 and H3PO4 solutions at 8%. The best durability properties of the mortars modified by the combination of the polymer and the additional cementitious materials observed in this study indicate a longer service life of the repaired structure when using this type of Latex-modified repair materials.
Electrochemical behaviours of Eu(III)/E(II) and Ce(IV)/Ce(III) in H3PO4-H2O media : solvation and complexation reactions
Authors: Belqat B. , Belcadi S.
Published: February 2018

Many kinds of rare earth elements (REE) such as europium and cerium have been make them essential elements in many high-tech components. The electrochemical studies can be presented as an interesting indication for europium and cerium extraction from phosphoric solutions, including solvation and complexation reactions. The normal redox potentials of Eu3+/Eu2+and Ce4+/Ce3+systems have been determined in H3PO4-H2O media with various phosphoric acid concentration. The solvation of these elements in phosphoric media is characterized by their transfer activity coefficients "f" calculated from the corresponding normal redox potentials. The corresponding solvation increases with increasing the H3PO4concentration. For each REE, the electrochemical properties depend on its number of charges and on its basic properties. Results suggest that solvation and complexation of REE phosphates are important in controlling REE concentration.
Earth as Building Material – an overview of RILEM activities and recent Innovations in Geotechnics
Authors: Vyncke Johan , Kupers Laura , Denies Nicolas
Published: February 2018

This paper presents an overview of the different earth building techniques, the latest innovations and the normative aspects. The oldest man made earth constructions known to exist date back to 10 000 BC. Since then, earth has remained a popular building material throughout history. With time, different techniques evolved, starting from sundried adobe blocks to cob constructions, rammed earth walls and compressed earth bricks. Today these techniques are still being optimized and alternative binders, specifically adapted admixtures and surface treatments are being developed. Even though nearly one third of the world’s population lives in an earth construction, few specific building standards and testing methods exist. Many of the tests used today are based on tests for concrete and thus do not take into account the complex nature of earth constructions, such as their sensitivity to water. RILEM, the union of Laboratories and Experts in Construction Materials, Systems and Structures, set up a new Technical Committee in 2016: TC TCE (Testing and Characterisation of Earth-based building materials and elements). This committee, consisting of an international group of experts on the topic, aim to define testing procedures for earth as a building construction material. To end with, this paper also gives a short introduction to “Deep soil mixing”, an “earth” building technique dedicated to geotechnical engineering.
Safe Construction Works Made of Reliable Construction Products based on verified structural calculations
Authors: Breitschaft G.
Published: February 2018

Ensuring the safety of buildings and other construction works is a major public concern. This article gives an overview of the mechanisms and structures put in place in Europe, and more specifically Germany, to ensure safety in construction. The article identifies major risk factors and shows how the European and German governmental and private systems respond to these risks. The questions addressed include: How do regulators ensure the use of safe construction products and designs, and how is the execution of construction works monitored?
Recent Developments in Nanomaterials for Geotechnical and Geoenvironmental Engineering
Authors: Taha Mohd Raihan
Published: February 2018

Nanotechnology has provided enormous benefits to the industrial and developed world. Most fields of knowledge have been tapping, using, and applying the advantages of nanotechnology to improve systems and living standards. This cannot be said for civil engineering and construction particularly geotechnical engineering. Actually, soil mechanics have been involved with nano scale dimensions and materials for a very long time, i.e. before the term nanotechnology and nanomaterials were coined. From the basic clay structure and the water molecules which give rise to soil plasticity/cohesiveness, geotechnical engineers were exposed to these phenomena since the early days of the subject. Currently, developments in nanotechnology and nanomaterials in geotechnical engineering has been limited to its use as an improvement and clean-up materials. Recent results have shown that the use of a small amount of nanomaterials (<1% of dry weight of the original soil) have resulted in significant change and improvement in soil properties. This is important since efficient use of materials is one of the facets of sustainability related to prolonging the life of our depleting natural resources. Experiences with nano-soil, nano-clay, nano-silica, nano-alumina, nano-magnesium, carbon nanotube and nanofibers, and nano-lime will all be discussed with respect to its use in soil improvement and soil remediation.
Prevention of concrete structures from collapsing
Authors: Cechmanek R. , Nespor B. , Drdlova M. , Steffan P. , Machan L.
Published: February 2018

At the end of the 20th century requirements on using electrical properties of building materials emerged for application in heating of trafficable surfaces, grounding of electrostatic charges in floors, shielding of electro-magnetic fields and diagnosis of concrete structure state in the course of time. For this reason, it was necessary to design special fibre-cement elements able to transfer any mechanical impulse to an electricallymeasured signal detected as a change in electrical resistance with computer outputs. Regarding previous research studies, it was concluded that special fibre-cement composites are able to conduct electric current under specific conditions. This property is ensured by using of various kinds of carbon materials. Though carbon fibres are less conductive than metal fibres, composites with carbon fibres were evaluated as better current conductors than the composites with metal fibres. By means of various kinds of carbon particles and fibres it is possible to design cement composites with an ability to monitor changes in electrical conductivity of concretes. The designed composites are assembled with conductive wires and connected with a special electronic equipment for monitoring of changes in alternate voltage passing through the tensometer within mechanical loading of a concrete element in which the composite is integrated. The tensometers are placed preferably into parts of the concrete elements subjected to compression, such as simple reinforced columns or upper parts of longitudinal beams. Several tests of repeated loading and simultaneous monitoring of vertical as well as horizontal prefabricated concrete elements were carried out and evaluated.
Feedback of the behaviour of a silo founded on a compressible soil improved by floating stone columns
Authors: Bahar Ramdane , Sadaoui Omar , Yagoub Fatma Zohra
Published: February 2018

The coastal city of Bejaia, located 250 kilometers east of the capital Algiers, Algeria, is characterized by soft soils. The residual grounds encountered on the first 40 meters usually have a low bearing capacity, high compressibility, insufficient strength, and subject to the risk of liquefaction. These unfavorable soil conditions require deep foundations or soil improvement. Since late 1990s, stone columns technique is used to improve the weak soils of the harbor area of the city. A shallow raft foundation on soft soil improved by stone columns was designed for a heavy storage steel silo and two towers. The improvement of 18m depth have not reached the substratum located at 39m depth. The stresses transmitted to the service limit state are variable 73 to 376 kPa. A rigorous and ongoing monitoring of the evolution of loads in the silo and settlements of the soil was carried out during 1400 days that is from the construction of foundations in 2008 to 2012. After the loading of the silo in 2010, settlement occurred affecting the stability of the towers due to excessive differential settlements. Consequently, the towers were inclined and damaged the transporter. This paper presents and discusses the experience feedback of the behavior of these structures. Numerical calculations by finite elements have been carried and the results are compared with the measurements.
Search of the Optimal Position of Sails
Authors: Rafik MADI , Mohamed GUENFOUD
Published: February 2018

During its history, Algeria has suffered several destructive earthquakes. According to the observations made during these earthquakes, the Algerian seismic regulation: RPA 82, RPA 83 and RPA 99 revised en 2003, seems insufficient and the buildings have suffered considerable damage. Which explains the presence of failures and insufficiencies in the Algerian seismic code.To resolve this problem, several researchers have advocated the introduction of bracing sails to improve the behavior of structures against the earthquake. In the Algerian seismic regulation, no article is related to this parameter. The objective sought in this study is to study the influence of the position of bracing sails on the behavior of structures across: the ductility demand µD, inter-floor displacement Dp and stiffness Kp at the performance point, the elastic stiffness Ke and the overall degradation indicator of the structure Id. the results obtained showed that the best arrangement of the bracing sails is that which are placed at the end of the structure with perfect symmetry.
Development and study of mechanical behaviour reinforcing composites by waste BTP
Authors: kanzaoui M.El , Hajjaji A. , Guenbour A. , Boussen R.
Published: February 2018

Composite materials are used in many industrial applications for their excellent mechanical and electric properties and their low density compared to metal structures. Most countries are extremely rich waste materials such as white ceramic breakages which represents a potential to be developed. Ceramic breakages have exceptional properties and could be effectively exploited in the manufacture of composite materials for a wide variety of applications. The composite materials reinforced by construction waste materials, such as ceramic breaks which offer significant benefits and gains in strength and stiffness properties (Young's modulus E : a material whose modulus Young is very high is said rigid).This article covers the benefits of breakages as ceramic filler used for reinforcement in composites, as well as improve the mechanical response of these structural elements (test compression).
Comparative study of direct and inverse problems of cracked beams
Authors: Mahieddine Chettah , Rachid Lassoued
Published: February 2018

In recent decades, the analysis and evaluation of the cracked structures were hot spots in several engineering fields and has been the subject of great interest with important and comprehensive surveys covering various methodologies and applications, in order to obtain reliable and effective methods to maintain the safety and performance of structures on a proactive basis. The presence of a crack, not only causes a local variation in the structural parameters (e.g., the stiffness of a beam) at its location, but it also has a global effect which affects the overall dynamic behavior of the structure (such as the natural frequencies). For this reason, the dynamic characterization of the cracked structures can be used to detect damage from non-destructive testing. The objective of this paper is to compare the accuracy and ability of two methods to correctly predict the results for both direct problem to find natural frequencies and inverse problem to find crack’s locations and depths of a cracked simply supported beam. Several cases of crack depths and crack locations are investigated. The crack is supposed to remain open. The Euler–Bernoulli beam theory is employed to model the cracked beam and the crack is represented as a rotational spring with a sectional flexibility. In the first method, the transfer matrix method is used; the cracked beam is modeled as two uniform sub-segments connected by a rotational spring located at the cracked section. In the second method which is based on the Rayleigh’s method, the mode shape of the cracked beam is constructed by adding a cubic polynomial function to that of the undamaged beam. By applying the compatibility conditions at crack’s location and the corresponding boundary conditions, the general forms of characteristic equations for this cracked system are obtained. The two methods are then utilized to determine the locations and depths by using any two natural frequencies of a cracked simply supported beam obtained from measurements as inputs. The two approaches are compared with a number of numerical examples for simply supported beams including one crack. The theoretical results show that the accuracy of the Rayleigh’s method to predict natural frequencies decreases for higher modes when crack depth increases. It is also found that for the inverse problem, the transfer matrix method show a good agreement with those obtained from previous works done in this field.
Behavior of reinforced concrete beams pre-cracked and repaired by
composite materials under static loading
Authors: Hamrat Mostefa , Boulekbache Bensaid , Bouziane Halima , Benkara Hayet
Published: February 2018

This work constitutes a contribution to the analysis of the behavior of beams repaired by composite materials. To analyze the overall behavior and failure modes of the beams, an experimental study of nine reinforced concrete beams, pre-cracked and then repaired by composite materials was conducted. Six beams were pre-cracked and repaired in the tensioned part (bending repair) and in the other two beams on the tensioned and lateral parts with strips in the shape of U (shear repair). A comparative study was made between the ultimate moments measured experimentally and those calculated by the theoretical models. Compared to the control beam, the resistance gain for the beams repaired in bending is 50% to 90%, while that of beams repaired in shear is from 120% to177 %. The beams repaired in shear exhibit a ductile rupture in bending. However, the beams repaired in bending were failed by the lift-off of composite or by failure of concrete cover layer (except for beams repaired by fiber glass). BAEL99, EC2-04 and ACI318-08 models give the best prediction of the ultimate moments with a mean value of 1.16 for the ratio of MExp./Mtheor. and a mean standard deviation of 0.33.
Study of clay soils swelling by the new method based on Laser Interferometry and the classical Odometer test
Authors: Asselman Hassan , Daouidi Aouatef
Published: February 2018

Geotechnical engineering participates in the act of construction, which means that it must meet a double concern for securityand economy. Therefore, an essential part of the engineer's responsibility rests on the recognition of soils in order to determine their nature and properties (taking into account the flow of water). In the present work, we measure the swelling and the permeability by detection of the swelling, by our new optical method based on the interferometry-laser, invented by Hassan Asselman, within the team of Optics and photonics of sciences faculty, Tetouan-Morocco. This new prototype allows us to directly measure the following parameters: the permeability k (m / s), the Young module Eand the swelling index Cs. For the latter parameter, the evolution of the strain as a function of the stresses ρ (Pa) is measured for a given degree of saturation (Until saturation). Moreover, we will use the classical odometer test, which reproduces the conditions of deformation of the soils. Using the results of the latter by the graphic methods of Taylor and Gasagrande, it is possible to determine the value of the coefficient of consolidation of the soil Cv. According to the Darcy theoretical modelfor a saturated medium, Cv depends on the permeability, the compressibility coefficient mv (or the inverse of the model of Young odometric) and the voluminal weight of the water γw. These tests will be carried out at the GEORET Geotechnical Laboratory in Tetouan. To perform this work, we chose a sample of claydistrubed, already characterized by X-ray diffraction (whose clay fraction is illite). It is extracted from the so-called "Teffalin" quarry of the Tetouan region, used in the manufacture of pottery. Finally we give a comparison between our new patented method and the classic Odometric test
Analysis of some key aspects of soil/foundation interaction-Finite elements modelling
Authors: Ahmed Hamidi , Ali Bouafia
Published: February 2018

This paper is aimed to contribute to the analysis of three important aspects of soil-foundation interaction, which are not clearly investigated, by means of a detailed parametric study based on a finite elements modelling.

The first aspect focuses on the effect of the bedrock proximity on the load-settlement behaviour of a continuous or circular shallow foundation. It was found there exists a threshold distance between the foundation base and the top of the bedrock layer beyond which the foundation behaves as in an infinitely deep medium.

The second one deals with the behaviour of shallow foundation on a bi-layered soil where the effect of the underlying layer on the bearing capacity as well as on the settlements depends on the distance between the foundation base and the top of the underlying layer, and beyond a threshold value this effect vanishes.

The third aspect studied was the interference between two strip footings installed on saturated clay. It was shown within a threshold distance between these foundations, an important modification of the foundation behaviour may occur. Finally, the numerical results were fitted and interpreted which allowed suggesting simple practical formulae for shallow foundations design.
Influence of granular material characteristics in the behaviour of “Bouregreg Valley” soft ground improved with stone columns
Authors: Nehab Noura , Baba Khadija , Ouadif Latifa , Bahi Lahcen
Published: February 2018

The use of finite element analysis has become widespread in geotechnical practice as means of optimizing engineering tasks; it can be easily applied to the treated areas by stone columns, which are a method of improving the soil having low geotechnical properties and likely to deform significantly under load action, by incorporating granular material (commonly called ballast) compacted by remounting passes, so they act mainly as inclusions with a higher stiffness, shear strength than the natural soil. Moreover the stone columns are highly permeable and act as vertical drains facilitating consolidation of the soft soil improving the performance of the foundation. However the characteristics of this granular material influence the behavior of soft soils treated by the stone columns technique, especially: the friction angle, the cohesion, the modular ratio and the constitutive model. The choice of the constitutive model depends on many factors but, in general, it is related to the type of analysis that we intend to perform. Numerical modeling must consider the diversity of the materials nature, the complex geometry of structures-land and the behavior of materials generally nonlinear (permanent deformation). It is a simple and effective alternative to approach the real behavior of soils reinforced by stone columns and the influence of materials characteristics, it allows settlement analysis, lateral deformation, vertical and horizontal stresses in order to understand the behavior of columns and soil. It also has the advantage of integrating the settlements of the underlying layers. This paper aims to study the mechanisms of functioning and interactions of stone columns with the surrounding ground, and vis-à-vis the various parameters characterizing the granular material "ballast" and the surrounding soil, which influence the behavior of the improved soil, The paper presents, in the first part, soil conditions and the parameters associated with columns, is then presented 3D finite element analyses, so the parametric study was carried out varying several properties especially granular material properties.
Effect of cement on the stability and the wearrance of soils in earthworks
Authors: Karam Feth-Allah Bendimerad , Abdeldjalil Zadjaoui
Published: February 2018

The technique of soil treatment is known for a long time, currently, during the big motorway programs this technique is experiencing important to reach zero imprints and zero deposit in a context of sustainable development or the socio-economic and environmental challenges incite during the work of earthworks. Our work puts highlights the treatment of fine soils in westerns region of Algeria (wilaya of Tlemcen, a project to construct a payment station for the entry of the wilaya (sample n°1), electrical post 400/200 KVA in the locality Ain Fetah (sample n°2)), belonging to the class A3h (very plastic clay) according to the Technical Guide for Earthworks (GTR), whose use in the raw state would involve great risks of stability because of their plasticity (Ip > 20%) and their low capacity (CBR < 25) according to the Specification of the Algerian Loads, Technical Clauses (CSDCA-CT) by the incorporation of the stabilizing agents, for example the variant of locally manufactured CEM II / A42.5N composite cement, in order to define their behaviours by examining the variation of their characteristics determined according to the Algerian standards and at a ambient temperature according to the additive dosage and to contribute to the deduction of the interest of the method demonstrated previously. The results obtained clearly show a tendency the rearrange classification of the soils studied according to the unified system en proportion whit to the additive dosage (0 to 14%) in view of the appreciable change in the plasticity behaviour, which results in a decrease in the plasticity index, going up to 37.7% and the 11% of the maximum dry density accompanied by a satisfactory increase in the suitability of the materials to be supported a load with different moisture content and changes in water regime exceeds 100%. Given the unavailability of other exploitable deposits near the site and the experimental results obtained, the variant of the treatment seems feasible.
Modelling of fine soils railway embankments behaviour under real cyclic loads
Authors: GUESSOUS Soufiane , LAMDOUAR Nouzha
Published: February 2018

Before the development of regulations, standards and guides for infrastructure building, embankments were generally constructed, by reusing and compacting the excavation materials. Therefore, a large part of existing railway embankments, over the world, is composed of fine compacted soils such as clay or marl. However, the current international trend of the railway undertakings and transport contractors is within the intensification of traffic, and the increase of train’s load and speed. Therefore, infrastructure managers are always called upon to evaluate the bearing capacity of existing infrastructures and define the necessary reinforcement solutions. In this perspective, a better awareness and knowledge of the behaviour of fine soils railway embankments is required to define optimal and efficient reinforcement solutions. In that matter, the article will feature the results of finite elements modelling of instrumented railway embankments that were constructed in Morocco in 1920, with marl compacted soil. The model is based on real applied loads and hydraulic conditions monitored for the last three years, which allow to simulate the hydro-mechanical behaviour of the embankment for this period. The article will be also comparing real monitored deformations recorded by the inclinometers equipping the embankments, with the output of the model using different models and adjustments.
Neural networks and principle component analysis approaches to predict pile capacity in sand
Authors: Benali A , Nechnech A , Boukhatem B , Hussein M N , Karry M
Published: February 2018

Determination of pile bearing capacity from the in-situ tests has developed considerably due to the significant development of their technology. The project presented in this paper is a combination of two approaches, artificial neural networks and main component analyses that allow the development of a neural network model that provides a more accurate prediction of axial load bearing capacity based on the SPT test data. The retropropagation multi-layer perceptron with Bayesian regularization (RB) was used in this model. This was established by the incorporation of about 260 data, obtained from the published literature, of experimental programs for large displacement driven piles. The PCA method is proposed for compression and suppression of the correlation between these data. This will improve the performance of generalization of the model.
Seismic stability analysis of rock slopes by yield design theory using the generalized Hoek-Brown criterion
Authors: Belghali Mounir , Saada Zied
Published: February 2018

The stability of rock slope is studied using the kinematic approach of yield design theory, under the condition of plane strain and by considering the last version of the Hoek-Brown failure criterion. This criterion, which is suitable to intact rock or rock mass highly fractured regarded as isotropic and homogeneous, is widely accepted by the rock mechanics community and has been applied in numerous projects around the world. The failure mechanism used to implement the kinematic approach is a log-spiral rotational mechanism. The stability analysis is carried out under the effects of gravity forces and a surcharge applied along the upper plateau of the slope. To take account of the effects of forces developed in the rock mass during the passage of a seismic wave, the conventional pseudo-static method is adopted. This method is often used in slope stability study for its simplicity and efficiency to simulate the seismic forces. The results found are compared with published numerical solutions obtained from other approaches. The comparison showed that the results are almost equal. The maximum error found is less than 1%, indicating that this approach is effective for analyzing the stability of rock slopes. The relevance of the approach demonstrated, investigations are undertaken to study the influence of some parameters on the stability of the slope. These parameters relate to the mechanical strength of the rock, slope geometry and loading.
Study of primary creep behavior of clayey soils in landslide area : suction effect
Authors: Hachimi Dahhaoui , Naima Belayachi , Abdeldjalil Zadjaoui
Published: February 2018

Creep behavior of clayey soils plays an extremely important role in the landslide process. The soils that make up these sliding zones are often in unsaturated state. This point indicates the need to take into account the suction effect as hydric parameter on the long-term deformation of clayey soils. In this paper, a primary creep model named Modified Time Hardening (MTH) for unsaturated soils with different matric suction has been built. Based on the literature tests results[1][2], parameters C1 and C2 of the model have relations with suction and deviator stress level respectively. The primary creep strainwill be able to demonstrate unsaturated effect of the soils. comparison between the calculated results and the literature tests results shows a good coherence. The work underway at the university of Orleans will show later the relevance of model used in the present work.
Towards building a neural network model for predicting pile static load test curves
Authors: Alzo’ubi A. K. , Ibrahim Farid
Published: February 2018

In the United Arab Emirates, Continuous Flight Auger piles are the most widely used type of deep foundation. To test the pile behaviour, the Static Load Test is routinely conducted in the field by increasing the dead load while monitoring the displacement. Although the test is reliable, it is expensive to conduct. This test is usually conducted in the UAE to verify the pile capacity and displacement as the load increase and decreases in two cycles. In this paper we will utilize the Artificial Neural Network approach to build a model that can predict a complete Static Load Pile test. We will show that by integrating the pile configuration, soil properties, and ground water table in one artificial neural network model, the Static Load Test can be predicted with confidence. We believe that based on this approach, the model is able to predict the entire pile load test from start to end. The suggested approach is an excellent tool to reduce the cost associated with such expensive tests or to predict pile’s performance ahead of the actual test.
Assessment of Seismic Vulnerability of Reinforced Concrete Frame buildings
Authors: Fatiha Cherifi , Mohammed Farsi , Salah Kaci
Published: February 2018

The seismic activity remains strong in the north of Algeria since no less than 30 earthquakes per month are recorded. The large number of structures built before the introduction of the seismic standards represents a high seismic risk. Analysis of damage suffered during the last earthquakes highlighted the vulnerability of the existing structures. In this study the seismic behavior of the existing buildings in Tizi-Ouzou city, located in the north of Algeria, is investigated. To make this assessment, a database was created following a building inventory based on a set of technical folders and field visits. The listed buildings have been classified into different typologies. Only reinforced concrete frame buildings are considered in this paper. The approach adopted to estimate structures damage is based on four main steps: 1) construction of capacity curves using static nonlinear method “push-over”, 2) estimate of seismic hazard, 3) determination of performance points, and finally 4) deduction of damage levels.
Influence of Prior Distributions and Fragility assessment methods in the estimation of the Magnitude of a Historical Seismic Event
Authors: Morais Eduardo Charters , Vigh László Gergely , KrÄhling János
Published: February 2018

The production of fragility functions describing the probable behaviour and damage on historical buildings is a key step in a method for the estimation of the magnitude of historical seismic events that uses a Bayes'. The fragilities are estimated by integrating the structural capacity with the seismic demand using either static methods, as the Capacity Spectrum Method (CSM), or dynamic methods, as Incremental Dynamic (IDA) and Multiple Stripes Analysis (MSA). Uncertainties in both resistance, demand, and distance and magnitude models propagate to the posterior magnitude distribution. The present paper studies the effect of uncertainties related both to the production of fragility functions and prior distributions, in the estimation of the magnitude of the 1763 Komárom earthquake (in historical Hungary). In the XVIII century most of the structures in the region were built of earth, adobe, clay or stone masonry, which is complex to model. While micro or detailed macro-modelling strategies are computationally costly, simplified macro-approaches are often more efficient, but require a pre-identification of the failure mode(s) and the determination of the backbone curve. For this study, a simplified macro-model of a Hungarian peasant house archetype is calibrated for CSM and IDA. The physical and geometrical uncertainties are incorporated in the fragilities using Monte-Carlo simulation. Prior magnitude and distance distributions are studied. The final magnitude estimates are presented and discussed.