bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydration characteristics and structure formation of cement pastes containing metakaolin
Authors: Dvorkin Leonid , Lushnikova Nataliya , Bezusyak Oleksandr , Sonebi Mohammed , Khatib Jamal
Published: February 2018

Metakaolin (MK) is one of the most effective mineral admixtures for cement-based composites. The deposits of kaolin clays are wide-spread in the world. Metakaolin is comparable to silica fume as an active mineral admixture for cement-based composites. In this paper, the rheological and mechanical properties of cement paste containing metakaolin are investigated. The effect of MK is more evident at “tight” hydration conditions within mixtures with low water-cement ratio, provided by application of superplasticizers. The cement is replaced with 0 to 15% metakaolin, and superplasticizer content ranged from 0 to 1.5% by weight of cementitious materials (i.e. cement and metakaolin). An equation is derived to describe the relationship between the metakaolin and superplasticizer content and consistency of pastes. There is a linear dependence between metakalolin content and water demand. Second-degree polynomial describe the influence of superplasticizer content. The application of SP and MK may produce cement-water suspensions with water-retaining capacity at 50-70% higher than control suspensions. The investigation of initial structure forming of cement pastes with SP-MK composite admixture indicates the extension of coagulation structure forming phase comparing to the pastes without additives. Crystallization stage was characterized by more intensive strengthening of the paste with SP-MK admixture comparing to the paste without admixtures and paste with SP. Results on the porosity parameters for hardened cement paste indicate a decrease in the average diameter of pores and refinement of pore structure in the presence of metakaolin. A finer pore structure associated with an increase in strength. X-ray analysis data reveal a growing number of small-crystalline low-alkaline calcium hydrosilicates and reducing portlandite content, when MK dosage increases. Scanning electron microscopy (SEM) data confirm, that hardened cement paste containing MK has crystalline structure with dominance of partially crystalized hydrosilicates and gel-like formations.
Challenges of the growing African cement market – environmental issues, regulative framework, and quality infrastructure requirements
Authors: Schmidt Wolfram , Ngassam Inès L. Tchetgnia , Breitschaft Gerhard , Virchow Stephen
Published: February 2018

The African cement, concrete and construction business is growing at rapid pace. The cement sales are expected to grow rapidly until 2050. The number of newly built cement plants increases dramatically and in addition more cements are being imported from outside the continent, e.g. from Turkey, Pakistan, Indonesia, and China, driven by overcapacities in the countries of origin. This causes a high number of potentials and challenges at the same time. Newly built cement plants can operate directly at best technological state of the art and thus incorporate more sustainable technologies as well as produce new and more sustainable products such as cements blended with sustainable supplementary cementitious materials such as calcined clays, and industrial or agricultural by products. At the same time the new variety of binding agent as well as the international imports, which are driven by price considerations, make the cement market prone to quality scatter. This puts pressure on the quality control regulations and institutions to ensure safety of construction, healthy application, and environmental safety for the population. The paper presents possible solutions to build up the rapidly increasing African cement production more sustainably than in the rest of the world as well as the related challenges and obstacles that need to be overcome. Based on experiences with a series of pan-African cement testing laboratory proficiency schemes conclusions are made on technical, regulative and political level.
Durable protection of the surface of wood used outdoors: material constraints, problems and approaches to solutions
Authors: Merlin A. , George B. , Malassenet L. , Podgorski L.
Published: February 2018

The aesthetic durability of wooden structures is a major challenge for the use of this material in construction. Wood is used for its technical performances but also for its architectural qualities and its aesthetic perception. The premature aging of the wooden structures is detrimental because these disorders, even if they do not affect the strength of the structures, are mostly irremediable. The surface protection of wood is generally ensured by the use of a finish, whose essential role is to protect wood from climatic aggressions (water, solar radiation, oxygen, ...). The secondary wood processing industry consists of a series of manufacturing and processing activities, each containing a portion of the added value of the product. The application of a finish on a wood-based work is usually the last and most visible step in this value chain.In outdoor use, the protection of the wood surface with transparent finishes is not yet sufficiently durable to be able to compete with materials used in industrial carpentry such as PVC or aluminum. Opaque finishes generally provide more durable protection but they mask the appearance of the wood sought by users.With the aim of positioning wood in this construction sector, research on transparent finishes has focused on the efficiency and improvement of the durability of the protection of the surface appearance of structures. Faced with climatic aggressions, the optimum conservation of a structure is not only linked to the performance of the finish but also to the characteristics of the wood material. In particular, in order to fulfill its protective function, the finish film must be able to follow the dimensional variations of the wood it covers without breaking and without detachment. In addition to the criteria for the effectiveness of finishes in the protection of structures, the environmental impact must be considered with increasing attention. Currently, more than 80% of composite or solid wood products are still protected with solvent-based liquid products, which are an important source of VOC emissions. Does the solution come from photo-polymerizable systems that can be formulated with 100% dry matter either in liquid phase in reactive diluents or powdered?
Research on the use of Ferro-Chrome slag in civil engineering applications
Authors: Al-Jabri Khalifa S.
Published: February 2018

Over recent decades there has been rapid increase in the industrial waste materials and by-products yields due to the progressive growth rate of population, development of industry and technology and the growth of consumerism. With the growing environmental pressures to reduce waste and pollution, Intensive research studies have been conducted to explore all suitable reuse methods. Wastes such as construction waste, blast furnace, steel slag, coal fly ash and bottom ash have been approved in many places as alternative materials in bridges, roads, pavements, foundations and building construction. The use of industrial solid waste as a partial replacement of raw materials in construction activities not only saves landfill space but also reduces the demand for extraction of natural raw materials. Ferrochrome slag is a by-product from the production of chrome. There are environmental and economic advantages in seeing slags as a potentially useful resource rather than as waste products. Slag management at ferrochrome producing companies has been influenced by the limited space available and financial cost implications of the slag dumps. Internationally, e.g. South Africa, India, Norway, Turkey, East Europe, China, Sweden and USA, ferrochrome slag is used commercially in the road and construction Industries. This material is being used for road construction, as aggregates in concrete industry, brick manufacturing, and in pavement construction as engineering fill and has recently been tried in cement. This paper presents an overview of the recent advances of the use of ferrochrome slag in various civil engineering applications such as road construction, and cement and concrete industries.
Towards more sustainable construction–application of superabsorbent polymers in cementitious matrices with reduced carbon footprint
Authors: Klemm Agnieszka J. , Almeida Fernando C.R.
Published: February 2018

Construction industry is constantly searching for sustainable innovations to mitigate negative environmental impacts. Ground granulated blast-furnace slag (GGBS) is a well-known supplementary cementitious material which contributes to reduction of energy and CO2 emissions from cement industry. However, its use in cementitious systems leads to materials with high cracking susceptibility due to their greater autogenous shrinkage triggered by self-desiccation processes. This problem is even more pronounced when concrete is exposed to severe dry-hot weather conditions, such as in North Africa. In order to mitigate this negative effect of cracking, internal curing agents in the form of Superabsorbent polymers (SAP) can be successfully used. This approach leads to more durable cement based materials and in turn more sustainable constructions.
Mineralogy of C-S-H belite hydrates incorporating Zn-Al-Ti layered double hydroxides
Authors: Amor F. , Diouri A. , Boukhari A.
Published: February 2018

Recently, the belitic cements with low alite content were the subject of several research works which aimed to replace the Ordinary Portland Clinker (OPC) for ecological reasons (reduction of CO2 emissions), so to understand the reactivity of this cement, the hydration study of the C2S “dicalcium silicate” phase is primordial research step. As well for a clean environment, the TiO2 photocatalyst has been extensively applied in the science of building materials because of its ability to degrade the cement surface pollutants. New photocatalyst based layered double hydroxides (LDH) associated with zinc, aluminium and TiO2 was introduced to increase the compatibility with mortars. The present work is subjected to investigate the effect of the layered double hydroxides on the hydration of C2S in following the evolution of hydration by X-ray diffraction at 2, 7, 28 and 90 days and analyzing the calcium/silicon ratio of different formed hydrates.
Valorization of glass and shell powders in the synthesis of Belitic clinker
Authors: Bouregba A. , Diouri A. , Amor F. , Ez-zaki H. , Sassi O.
Published: February 2018

In recent years, waste recycling has become a key issue in construction materials science for achieve the goal of sources of raw materials. The aim of this study is to use waste glass as source of SiO2 oxide and mussel shells consisting essentially of calcium carbonate as starting materials to synthesize belite rich cement. The elaborated clinker is chemically and structurally related to β-Ca2SiO4, by heat solid state activation. After grinding, the raw materials are mixed and heated up to 1050°C. The samples are characterized by X-ray diffraction (XRD) and Fourier Transformed Infrared spectroscopy (FT-IR). The mechanical strength of some sample was measured for 28 and 72 days. The results show the different mineralogical stapes of formation of clinker, the state reaction method allows the elaboration of a cementitious material by a simple heat treatment at relatively low temperature and low release of CO2. The hydration products are also identified by XR diffraction at 2, 7, 28 and 72 days.
Durability of the earth mortar: Physico-chemical and mineralogical characterization for the reduction of the capillary rise
Authors: Ammari A. , Bouassria K. , Zakham N. , Cherraj M. , Bouabid H. , D’ouazzane S. Charif
Published: February 2018

The stabilization of the earth material in the fields related to the earthen construction, in compliance with
the standards in force, allows strong results of strength and durability. The chemical and mineralogical elements play an important role, in the presence of an 'optimum' cement dosage, to strengthen the ties between the clays and the grains of the earth.. This approach targets the search for better performances in the use of natural materials resource in an eco-responsible habitat. This study presents the experimental results of the four techniques of mineralogical and chemical analysis on mortar specimens obtained from earth of the city of Fez. The results of the uni-axial compressive tests of the cylindrical specimens for this earth, associated by various percentages 0%, 4%, 7% and 10% by weight of cement, make it possible to analyze the effect of the mineralogical and chemical elements on the mechanical properties, namely Young's modulus, compressive strength and limiting deformation. However, we determine the water absorption coefficient of the mortar for different cement dosages in order to optimize the durability of the mortar against bad weather, rain and / or very wet climates. In the earth mortar of Fez, the strong presence of calcite (CaCO3), quartz SiO2 and dolomite CaMg (CO3)2 amplifies the improvement of the behavior of the material by the addition of cement. In fact, this strong presence of calcite stabilized the clay by cementing quartz and the cement matrix to strengthen the ties between the grains of the earth. In addition, with respect to the capillary rise, the water absorption decreases with the addition of cement. We also note that the evolution of the mechanical properties is of no importance except in the interval [4 to 7%] which represents the zone of effect for cement stabilization and which houses the optimum technicoeconomic cement dosing.
Influence of calcined mud on the mechanical properties and shrinkage of self-compacting concrete
Authors: Fatima Taieb , Nadia Belas , Omar Belaribi , Khalil Belguesmia , Rachid Hadj Sadok
Published: February 2018

The use of SCC has a particular interest in terms of sustainable development. Indeed, their specific formulation leads to a greater volume of dough than for common concretes, thus, a larger quantity of cement. However, for economical, ecological and technical reasons, it is sought to limit their cement content [1]. It is therefore necessary to almost always use mineral additions as a partial replacement for cement because the technology of self-compacting concretes can consume large quantities of fines, in this case calcinated mud issued from dams dredging sediments that can give and/or ameliorate characteristics and performances of this type of concretes. Four SCCs had been formulated from the same composition where the only percentage of calcinated mud of Chorfa (west of Algeria) dam changed (0%, 10%, 20% and 30%). The effect of calcinated mud on characteristics at fresh state of SCC according to AFGC was quantified. Mechanical strengths and shrinkage deformation (total, autogenous, drying) were evaluated. The results show the possibility to make SCCs with different dosages of calcinated mud having strengths that can defy those of the control SCC. The analysis of free deformations indicates the beneficial impact of the mud by contributing to decrease the amplitudes of the shrinkage compared to those of the control SCC.
Experimental study of a foam concrete based on local Tunisian materials
Authors: Ellouze Dorra , Miled Karim
Published: February 2018

The building sector in Tunisia is very energy-intensive, the largest share of energy consumption comes from factories of building materials namely brick and cement plants. This work is part of the reduction of the energy bill in the building envelope. Indeed, the foam concrete can be walls in single or double wall with better insulating power. This paper presents an experimental study on the technical problems related to the formulation and manufacture of a new cellular concrete in Tunisia, called "foam" concrete, from Tunisian local materials. Indeed, six varieties of sand of different provenance and grain size will be analyzed, the "good" sand is the one that is best suited for the manufacture of foam concrete. Two clean, fine-grained (0/2mm) rolled grain sands were retained. Then four foam concretes were formulated using each time a single type of sand and varying the density namely 0.8 and 1. These four formulations were tested mechanically and thermally. The results found showed that compressive strengths do not exceed 1.5 MPa at 28 days. Thus, the foam concrete can be used only as a filling concrete in non-load bearing elements such as partition walls. The guarded hot plate method was used to determine the thermal conductivities of the four foamed concretes studied. A low thermal conductivity was found of the order of 0.22 W/m°K which prove the insulating power of foam concrete.
Effects of Basalt Fibres on Mechanical Properties of Concrete
Authors: El-Gelani A. M. , High C.M. , Rizkalla S. H. , Abdalla E. A.
Published: February 2018

This paper presents the results of an experimental program carried out to investigate the effects of Basalt Fibre Reinforced Polymers (BFRP) on some fundamental mechanical properties of concrete. Basalt fibres are formed by heating crushed basalt rocks and funnelling the molten basalt through a spinneret to form basalt filaments. This type of fibres have not been widely used till recently. Two commercially available chopped basalt fibres products with different aspect ratios were investigated, which are dry basalt (GeoTech Fibre) and basalt pre-soaked in an epoxy resin (GeoTech Matrix) .The experimental work included compression tests on 96 cylinders made of multiple batches of concrete with varying amounts of basalt fibre additives of the two mentioned types, along with control batches containing no fibres. Furthermore, flexural tests on 24 prisms were carries out to measure the modulus of rupture, in addition to 30 prisms for average residual strength test. Results of the research indicated that use of basalt fibres has insignificant effects on compressive strength of plain concrete, where the increase in strength did not exceed about 5%. On the other hand, results suggest that the use of basalt fibres may increase the compressive strength of concrete containing fly as up top 40%. The rupture strength was increased also by 8% to 28% depending on mix and fibre types and contents. Finally, there was no clear correlation between the average residual strength and ratios of basalt fibres mixed with the different concrete batches.
Thermal treatment of desert sand to produce construction material.
Authors: Neumann Frank , Curbach Manfred
Published: February 2018

The concrete and reinforced concrete industry has refrained from using desert sand. The reasons for this are the rounded form of the particle, its grading and its chemical composition. This article provides an overview of the background, the constructability and technological challenges that the construction industry faces regarding construction sand’s shortage. Also, construction aggregates consumption and its influence on fresh and hardened concrete properties are described. The paper concludes by presenting several feasible approaches and provides a feasible technological solution.
Improvement of the mechanical performance of Fergoug dam sediments treated for reuse in road engineering
Authors: Abdelkader LAROUCI , Yassine SENHADJI , Laïd LAOUFI , Amar BENAZZOUK
Published: February 2018

The phenomenon of siltation is one of the main problems facing many dams throughout the world, and particularly in Algeria. The mud, before and even after extraction, is always harmful. Indeed, mud is a harmful material, first for dams, because it reduces their capacity of water storage, and second, for the environment following the desilting operations that generate large quantities of materials that occupy and sometimes pollute large areas. However, these materials can be exploited differently and used in other fields. The envisaged research work relates to real cases of silted dams, such as the dam of Fergoug (western Algeria) whose siltation rate is very high; it is estimated at 97% of its initial capacity which, according to the National Agency for Dams (Agence Nationale des Barrages - ANB), is equal to 18 million m3. The large quantities of silt extracted present an environmental problem, and its use as a local raw material for the manufacture of civil engineering materials can contribute to solve this problem. The vulnerable lands of the sub-catchment of Wadi Fergoug (Fergoug River) extend over an area of 122 km2, from a total surface of 8340 km2 for the dam catchment area. There is a great diversity of superficial formations with predominantly clay soils from marly formations. The rate of specific erosion has increased to 160 T/ km2/ year due to irregular annual rainfall resulting from a succession of dry and wet years. Sedimentary materials, which are found in considerable quantities, were collected at the foot of the dam, on its right bank. This study attempts to find a recycling pathway for these sediments. The objective of the present work is to investigate the behavior of silt from the dam of Fergoug (Algeria) for the purpose of using it in road construction (foundation and base layers). The method adopted is to reconstitute, in the laboratory, samples of mixtures containing road aggregates with different proportions of silt. These samples are then subjected to various tests (Normal modified Proctor, Atterberg limits, VBS, Particle size analysis, Sedimentation, DRX etc …). The results of the tests indicate that some of the prepared mixtures present very interesting properties. These results satisfy the current recommendations of the technical guides; they also corroborate their use in road construction.
Effect of reinforcement fibers on the collapse potential of clayey sands
Authors: Adjabi Souhila , Nouaouria Mohamed Salah , Betehi Cherif
Published: February 2018

The collapse of soils under wetting is a major problem in Geotechnical engineering. The erection of structures on these types of soils, located in arid and semi-arid zones, needs careful treatment of these soils. Soil reinforcement techniques have been rapidly increased during these two decades because of their effectiveness in geotechnical engineering. The aim of this experimental work is to investigate the collapsible soil behaviour in order to improve its characteristics. To achieve this goal, Polyethylene fibers, and Sisal fibers were used as Polyethylene fibers content in mass are varied from 0% (unreinforced samples) to 15%; and Sisal fibers content from 0.5% to 1%. The fiber reinforcement is combined with other processing procedures such as compaction and the addition of CPA cement to decrease the collapse potential.
The use of non-destructive tests to estimate Self-compacting concrete compressive strength
Authors: Djamila Boukhelkhal , Mohamed Guendouz
Published: February 2018

Until now, there are few studies on the effect of mineral admixtures on correlation between compressive strength and ultrasonic pulse velocity for concrete. The aim of this work is to study the effect of mineral admixture available in Algeria such as limestone powder, granulated slag and natural pozzolana on the correlation between compressive strength and corresponding ultrasonic pulse velocity for self-compacting concrete (SCC). Compressive strength and ultrasonic pulse velocity (UPV) were determined for four different SCC (with and without mineral admixture) at the 3, 7, 28 and 90 day curing period. The results of this study showed that it is possible to develop a good correlation relationship between the compressive strength and the corresponding ultrasonic pulse velocity for all SCC studied in this research and all the relationships had exponential form. However, constants were different for each mineral admixture type; where, the best correlation was found in the case of SCC with granulated slag (R2 = 0.85). Unlike the SCC with pozzolana, which have the lowest correlation coefficient (R2 = 0.69).
Effect of cement fineness and polycarboxylate dosage on the rheological and mechanical behavior of a mortar
Authors: Zahia Didouche , Karim Ezziane
Published: February 2018

The use of certain organic additives in the production of mortar and concrete influences the workability and the hydration kinetic of mortar. This results in a modification of some properties, namely rheological behavior and mechanical strength. The objective of this work is to evaluate the rheological and mechanical behavior of a mortar by varying the fineness of the cement and using the superplasticizer Polycarboxylate.
Experiment-based modelling of the mechanical behaviour of non-hazardous waste incineration bottom ashes treated by hydraulic binder
Authors: Sow Libasse , Bernard Fabrice , Kamali-Bernard Siham , Fadel Kébé Cheikh Mouhamed
Published: February 2018

Instrumented indentation tests have been carried out on an isolated 25 mm diameter particle of Non-Hazardous Waste Incineration bottom ash. These tests have enabled one to assess the intrinsic mean reduced modulus of elasticity “Er” of the particles. This result is used as input data for a 3D numerical model of Representative Elementary Volumes (REV) of a road gravel made with this kind of by-products. This numerical model is based on a multi-scale hierarchical modelling strategy. The aggregates treated with cement have been decomposed into two REV at the sub-mesoscopic and mesoscopic scales. The numerical simulations campaign (“virtual laboratory”) lead to the following results. At the sub-mesoscopic scale, we determined the input parameters for the Concrete Damaged Plasticity Model (CDPM) used at the mesoscopic scale. At the mesoscopic scale, the mechanical characteristics of the road aggregates usually determined through experiments have been found. The non-hazardous waste incineration bottom ashes treated by hydraulic binder was classified into mechanical classe 3.
Lightweight geopolymer composites as structural elements with improved insulation capacity
Authors: Kakali Glikeria , Kioupis Dimitris , Skaropoulou Aggeliki , Tsivilis Sotiris
Published: February 2018

This study concerns the development of lightweight fly ash based geopolymers which can be applied as alternatives to the traditional lightweight concrete. Different kinds of expanded polystyrene were used as lightweight agents. The results showed that lightweight geopolymers were successfully prepared, exhibiting compressive strength and density in the range 7.70 – 29.57 MPa and 0.97 – 1.57 g/cm3, respectively. The product containing 3% w/w of commercial expanded polystyrene possesses low thermal conductivity (0.16 W/mK) combined with sufficient mechanical strengths (11 MPa), excellent stability and fire resistance while its water absorption is comparable to that of conventional construction materials (cement mortars, concrete).
Ecofriendly bricks elaborated from coal waste of Moroccan Jerrada Mining
Authors: Ez-zaki H. , Diouri A. , Bouregba A. , Amor F. , Chhaiba S. , Sassi O. , El Rhaffari Y.
Published: February 2018

Solid waste generated during mining is one of the major environmental problems associated with this industrial activity. The best solution to overcome the environmental impact of this waste is to find recycling facilities in mass-produced products that can absorb the large quantities of these available byproducts. The present study shows the feasibility of using the coal waste of Moroccan Jerrada mining in the production of ecological brick. The first step consists of consecutive stages of crushing, grinding and heating at 650°C of the coal waste with a small amount of lime in order to promote the reactive products of elaborated binders. The second step of the process consists of mixing treated coal waste with a small amount of marble dust, sand, gravel, and water, then pressed and dried at room temperature to manufacture a laboratory ecofriendly bricks. The mechanical strength and thermal conductivity are investigated.
Identification of elasticity modulus by vibratory analysis (Application to a natural composite: Aleppo pine wood)
Authors: DAOUI Abdelhakim , ZERIZER Abdellatif
Published: February 2018

In this paper, we present a method for the determination of the elasticity modulus in the vibratory domain of materials. This approach is based on research and interpretation of the spectrum of natural frequencies resulting from natural vibrations based on the theory of elastic beams. The tests consist of classical tests of longitudinal vibrations of natural composite beams (Aleppo pine wood), long enough to observe some natural frequencies. This identification method showed a good correlation between the theoretical and experimental values, notably the evaluation of the modal parameter for the case of the resonant frequencies and the identification of the modulus of elasticity of the materials used.
Reinforcement of concrete by composite materials
Authors: Boulekbache Bensaid , Hamrat Mostefa , Gacem Nejma Imane , Halimi Kheltoum
Published: February 2018

This work was devoted to the material-scale study of the mechanical behavior of confined concrete by composite materials based on carbon fiber and glass under compression and bending loading. In this context, an experimental work on cylindrical and prismatic concrete specimens has been carried out. The obtained results permitted the identification of the mechanical behavior, strength, deformability and failure modes. The outcome of the present research indicates an increase in the bearing capacity and deformability in compression and in tension. The reinforcement by means of composite materials appears as a pertinent solution and therefore, makes it possible to obtain clear indication on the type of confinement to be considered according to the intended purpose.
Some physical properties of the date palm stem
Authors: Hakam A. , Elkhal M. , Ziani M. , Famiri A. , Fidah A.
Published: February 2018

The main objective of this study was to test some technological performances of date palm stem (Phoenix dactylifera L.) from the region of Marrakech in Morocco with a view to its use in housing construction in southern Moroccan regions. Physical characteristics were determined according to French AFNOR standards. The samples used were respectively 20 mm × 20 mm × 20 mm in the longitudinal, radial and tangential directions. All the results obtained were the average of the measurements on 50 samples. The results obtained showed that the moisture content has an average value of 15 % at the center of stem and 18 % at the periphery and the infradensity has a value of 0.18 g / cm3 in the center and 0.42 g / cm3 in the periphery. For samples from the center, the tangential, radial and longitudinal shrinkage were respectively 2.02 %, 1.77 %, and 0.42 %, while on the periphery of the stem the tangential, radial and longitudinal shrinkage were respectively 3.41 %, 2.98 % and 0.34 %. These results showed that the stem center has better dimensional stability compared to the peripheral region of the stem.
Parameters estimation of Drucker-Prager plasticity criteria for steel confined circular concrete columns in compression
Authors: Al-Kutti Walid A.
Published: February 2018

This paper explores the possibility to use Drucker-Prager model in Steel-Concrete composite section. Numerical simulation was conducted using finite element package to simulate the steel-concrete composite section subjected to uniaxial compressive loading. After calibration with experimental study, parametric study was conducted to evaluate the effect of the friction angle and the cohesion constant c on the stress-strain curve of composite section. Empirical relationship between the friction angle and the confined concrete compressive strength was developed and a range of cohesion constant c between 5-10 MPa was suggested for confined concrete strength range of 25 to 100 MPa, respectively.
Corrosion inhibition of austenitic stainless steel by clay in polluted phosphoric acid with presence of SiC abrasif
Authors: Skal S. , Kerroum Y. , El Aoufir Y. , Guenbour A. , Bellaouchou A. , Tabyaoui H. , Idrissi H.
Published: February 2018

Stainless steels have many properties mechanical and chemical resistances resulting from the formation of the protective layer (passive film) on their surface which prevents the metal to react with corrosive environments such as, phosphoric acid. This acid contains various impurities, including agressive agents and solid particles of gypsum, increase the risk of corrosion damage depending on the type of stainless steel used. In addition, it has been show that abrasion-corrosion causes an acceleration electrochemical process leading to a decrease in the resistance of materials. This work is to find a solution through an ecological inhibitor. That why we have been studied the effect of crude clay on corrosion behavior of Alloy 31 in polluted phosphoric acid with abrasive by electrochemical impedance spectroscopy (EIS) . The clay was characterized by X-ray fluorescence spectroscopy (FX), X-ray diffraction (DRX) and infrared spectroscopy (IR). EIS exhibited that resistance of Alloy 31 increased with increase the concentration of inhibitor.
Prediction models of mechanical properties for pet-mortar composite in sodium sulphateaggressive mediums
Authors: Kazi Tani Nabil , Benosman A.S. , Senhadji Y. , Taïbi H. , Mouli M. , Belbachir M.
Published: February 2018

In this research, an investigation was carried out on the effect of sodium sulphate attack on the durability of composites produced with waste polyethylene terephthalate (PET). Experiments were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced by various volume fractions of waste PET particles (6%, 12% and 17%). The test solutions used to supply the sulphate ions and cations were 5%sodium sulphate solution. Compressive strengths measured on specimens were used to assess the changes in the mechanical properties of PET-mortars exposed to sulphate attack at different ages, mainly the Young modulus of elasticity. Based on experimental compressive tests on PETMortar composite specimens and there densities, the evolution of Young modulus of elasticity has been analyzed in accordance with normative models given by (ACI-318) and (BS-8110) codes of practice. In addition, a comparative study has been carried out for corrosion resistance coefficients K of unmodified mortar to those modified with waste PET particles. It can be noticed that, for the composite immersed in a corrosive Na2SO4 solution, the corrosion resistance coefficients decrease with the increase of the immersion period. The corrosion sulphate resistance K based on Young modulus before and after immersion of PET-mortar composites is better than that of the control mortar. Therefore, for safety considerations of PET-mortar composites use, ACI 318 is recommended code for design and investigation works. Also, it can be concluded that adding waste PET by volume fractions (6%, 12% and 17%) to blend Portland cement renders this cement more resistant to the sodium sulphate aggressive medium. Therefore, composites materials based waste PET aare often presented as the materials of the future because of their potential for innovation and the advantages they offer. In fact, using waste PET as cement substitutes reduces the energy consumption. These modified mortars address problems related to environmental pollution by CO2 emissions, and are used to repair various reinforced concrete structures in sodium sulphate aggressive mediums.
Study of the Influence of an Air-Entraining Agent on the Rheology of Motars
Authors: Tebbal Nadia , Abidine Rahmouni Zine El , Rabiaa Chadi Lamis
Published: February 2018

The objective of this study is to analyze the effect of the air entrainment on the fresh rheological properties as well as on the compressive mechanical resistances of the mortars. The hardened concrete contains a certain amount of randomly spread air, coming either from a drive during kneading or from the evaporation of the mixing water. The air quantity is in the order of 20 l / m3, ie 2% of the volume. However, the presence of a large volume of air bubbles causes the mechanical resistances to fall in compression. On the other hand, the use of air entrainment could improve the rheological properties of fresh concrete.

Experimental studies have been carried out to study the effect of air entrainment on compressive strength, density and ingredients of fresh concrete mix. During all the study, water cement ratio (w/c) was maintained constant at 0.5. The results have shown substantial decreasing in water and mortar density followed with decreasing in compressive strength of mortar. The results of this study has given more promising to use it as a guide for mortar mix design to choose the most appropriate concrete mix design economically.
The effect of the addition of Alumina powder on the confinement properties of a cement mortar
Authors: Moutei L. , Benbrahim Y. , El ghailassi T. , Bouih A. , Labied S. , Guedira T. , Benali O.
Published: February 2018

Organic radioactive waste can occur in solid, liquid or rarely gaseous form. In general, organic components of radioactive waste Generally, the organic components of the radioactive waste have a contaminant effect stronger than most of the inorganic components, because of their low melting point, of their answer to the radiolyse or of their volatilitydu to their low melting point, to their answer to the radiolyse or to their volatility. This property can significantly affect the strategy adopted for their management. Organic radioactive waste results from the use of radioisotopes in the National Center for Energy, Nuclear Science and Technology (CNESTEN) and from medical applications. Organic radioactive waste requires management steps that take into account not only their radioactivity but also their chemical content. The aim of this study is the optimization of the stabilization of radioactive organic effluents in cementitious matrices. Thus, we study the effects of the addition of the alumina powder on the physicochemical and mechanical properties of the cement paste. The mortar was made by mixing Portland cement, sand, water and alumina powder (88 μm). The study showed that the addition of 12% alumina powder improves the compressive strength.
Alumina sludge's Influence on the physicochemical characteristics of CPJ55cement
Authors: Dahhou M. , Barbach R. , El Moussaouiti M.
Published: February 2018

Partial replacement of the Portland cement CPJ55 ingredients by various quantities of alumina sludge (AS), produced during drinking water plant sludge, was used in the preparation of mortar mold with dimensions 40×40×160 mm. The characterization of materials is carried out by X-ray fluorescence (XRF), Xray diffraction (XRD), free lime dosing, and the mechanical tests. Analysis of the chemical composition by XRF shows that the studied alumina sludge is mainly composed of aluminum oxide, silica, which is correlated with the principal mineral phases identified in the XRD analysis results. It is demonstrated that adding 5% of the alumina sludge in Portland cement does not affect the mineralogy of final product. Nevertheless, the compression and flexural strength tests (in 28 days) conducted on mortar sample comprising 5% sludge elucidate that it belongs to cement mortar class of type 32.5 R.
Influence of cement content on the thermal properties of compressed earth blocks (CEB) in the dry state
Authors: Zakham N. , El Rhaffari Y. , Ammari A. , Cherraj M. , Bouabid H. , Gueraoui K. , Samaouali A. , Mzerd A.
Published: February 2018

The Compressed Earth Block (CEBs) is one of the kinds of building materials which stabilized by cement. Soil is a basic component, a renewable, non-toxic and natural resource. Samples must be stabilized with a limited percentage of cement so that samples do not lose their natural properties including thermal comfort and on other hand offer high mechanical resistance. The objective of this work is to study the effect of cement content on thermal behavior of the building material of CEBs in the dry state, by studying variation of temperature with time, and measuring thermal conductivity and the specific heat, with respect to the various cement ratios added to the samples. This study is mainly an experimental and numerical, to determine how the thermal behavior evolves with the cement content in the samples CEBs. The soil was extracted from the famous city Fez in Morocco, Fez is known for its several historical monuments and buildings. After determining its granulometry and other specific characteristics, the CEBs are made by mixing soil with cement. The samples are put in plastic bags for two weeks, then removed the plastic bags from the samples and let them to dry again for an additional two weeks away from direct sun. The samples CEBs are taken cylindrical form (8 cm diameter with an average height of 12 cm).

The experimental method consists of a hot ring for which a numerical modelization was developed to fit the mathematical equations of heat diffusion and the boundary conditions. For the numerical model Bouabid and Cherraj have developed numerical model which allow, with a good accuracy, to quantify the evolution of the thermal behavior of the earth material in function of cement content.

Indeed, the study provides information on the influence of the cement percentage on the thermal behavior of the samples CEBs, the thermal behavior of samples increase with increase cement content.
Blast Resistance of Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires
Authors: Drdlová Martina , Sviták Oldřich , Bibora Petr , Popovič Miloslav , Čechmánek René
Published: February 2018

The utilization of waste steel fibres (coming from the recycling process of the old tires) in production of blast resistant cement based panels was assessed. Waste fibres were incorporated in slurry infiltrated fibre concrete (SIFCON), which is a special type of ultra-highperformance fibre reinforced concrete with high fibre content. The technological feasibility (i.e. suitability of the waste fibres for SIFCON technology) was assessed using homogeneity test. Test specimens were prepared with three volume fractions (5; 7.5 and 10 % by vol.) of waste unclassified fibres. SIFCON with industrial steel fibres (10% by vol.) and ultra-highperformance fibre concrete with industrial fibres were also cast and tested for comparison purposes. Quasi-static mechanical properties were determined. Real blast tests were performed on the slab specimens (500x500x40 mm) according to the modified methodology M-T0-VTU0 10/09. Damage of the slab, the change of the ultrasound wave velocity propagation in the slab specimen before and after the blast load in certain measurement points, the weight of fragments and their damage potential were evaluated and compared. Realized tests confirmed the possibility of using the waste fibres for SIFCON technology. The obtained results indicate, that the usage of waste fibres does not significantly reduce the values of SIFCON flexural and compressive strength at quasi-static load - the values were comparable to the specimens with industrially produced fibres. With increasing fibre content, the mechanical parameters are increasing as well. Using of the waste fibres reduces fragmentation of SIFCON at blast load due to the fibre size parameters. Using of low diameter fibres means more fibres in the matrix and thus better homogeneity of the whole composite with less unreinforced areas. Regarding the blast tests, the specimen with waste steel fibres showed the best resistance and outperformed also the specimen with commercial fibres. Using of waste fibres in SIFCON technology can reduce the price of this composite by 70 % by keeping the original SIFCON extraordinary properties, which makes it very competitive material in the concrete area.
Study of the mechanical characteristics and chemical degradation of concretes based on machining sludge
Authors: Kherbache Souad , Bouzidi Nedjima , Tahakourt Abdelkader , Moussaceb Karim
Published: February 2018

The main objective of this work is to study the mechanical characteristics and the chemical degradation of mortars and concretes made obtained by substituting the cement by the machining sludge. Several materials were carried out by substituting the cement with different amount of machining sludge (5, 10, 15 and 20%). The obtained materials are compared to those without substitution (ie: 00wt% of machining sludge). Mechanical and physical properties of the two materials (mortars and concretes) as flexural and compressive strengths were studied. Physical properties as shrinkage, the bloating effect, loss in mass, slump concretes and porosity were evaluated. In addition, chemical degradation is studied for the conservation of these concretes and mortars from machining sludge in different aggressive environment. Moreover, the addition of 5wt% of the machining sludge in the mixture of the mortar and the concretes seems to be interesting.
The use of ultrasonic pulse velocity to estimate the water permeability of concretes
Authors: Abdelhalim Benouis , Ali Mehamdia
Published: February 2018

In this work we investigated the possibility of estimating the water permeability of concrete from the ultrasonic surface wave velocity (Rayleigh's waves). This is a method for the non-destructive permeability diagnosis of the in situ auscultation of a structure. Four ordinary concrete compositions with different W/C ratios and two self compacting concretes SCC were used. This study showed a decrease in of ultrasonic pulse velocity with the increase in the W/C ratio, this is due to the increase in porosity. Curing in air of the concrete specimens produces greater permeability than curing in water. The increase in the permeability with the increase of W/C ratio is more important for curing in water than for the curing in air. SCC1 has a lower permeability than that of SCC2, this difference is respectively 20% and 10 % for curing in air and in water. The study show that permeability estimation with ultrasonic surface waves is more reliable for curing in water mode than tin curing in air. The correlations obtained between the permeability and the indirect ultrasonic velocity are linear, with an inversely proportional relation.
Physico-mechanical characterization of composite cementitious mortars modified by resin containing antifoam
Authors: Berkak Hichem , Makhloufi Zoubir , Bederina Madani , Demdoum Abdellah , Hadj Aissa Yacine
Published: February 2018

Nowadays, polymer-modified mortars (PMM) are generally used in the field of building as finishing materials. In general, The properties of the fresh and hardened PMC are affected by several factors that tend to interact each other: the nature of materials used as latex, cement and aggregates; the mix proportions (W/C, polymer/cement ratio, etc.); air content; type and amount of surfactants and anti-foaming; and curing methods. This present experimental work aims to study the influence of the rate of partial substitution of cement by resin containing anti-foaming on the properties of composite mortars in the fresh and hardened state particularly workability, tensile and compressive strengths at different times (3, 7 and 28 days) and module of static elasticity at 28 days. For that purpose, seven mortar combinations were developed from the various substitution percentages (0 to 15% by step of 2.5%). The treatment of the obtained results reveals that this partial replacement of the cement by resin improves, clearly, the workability of mortars and decreases the report W/C at the same time. Besides, the incorporation of resin affects significantly the mechanical strengths, and consequently, the addition by substitution of the polymer-latex improves, slightly, the mechanical behavior in tensile where the rates of increase range from 2.20% to 8.54% for replacement percentages of 2.5% and 15%, respectively. Furthermore, the compressive strengths of cement - resin composite mortars are lower compared to the reference mortar made with the cement Portland (CEM I). The notable decrease in compressive strength of polymer–modified mortars can be justified by the reduction of cementitious part, in hybrid materials, which is an indispensable and responsible part of improving compressive strength.