Accepted Papers to Appear in Future Issues

Effect of Environment with Heavy Industrial Pollution on the Selection of Concrete Mix for Building Structures

Anwar Ul-Hamid, Huseyin Saricimen

Abstract
This study proposes durable concrete mix design suitable for use in superstructures of an industrial plant of a cement company located in an area marked by heavy industrial pollution.  Concentration of pollutants in the environment was recorded by undertaking ambient air quality monitoring along with an assessment of corrosivity of soil and ground water present at the site.  Type of reinforcement, concreting procedures and protection methods were determined for reinforced concrete that was intended to be used in conjunction with steel structures.  Experimental results indicated that soil and groundwater constituted no risk for the substructure.  However, air was highly polluted and deemed to be severely corrosive due to the presence of chloride and sulfate salts, SO2 and CO2 in concentrations recorded several times higher than at a comparable industrial area.  A concrete mix design suitable for observed conditions was recommended.  Additionally, it was suggested that concrete reinforced with black steel bars should be completely coated while that using FBE coated steel bars should be coated up to a height of 1.5m from the grade level for protection against ingress of salt and water.
Date accepted : 2019-10-05

Elaboration and characterization of spherical carbon nanoparticles
SEDIRA Sofiane

Abstract
In this paper, hydrothermal method was used to provide stable colloidal suspension of spherical carbon nanoparticles (CNPs) with good uniformity of size and shape. XRD analyses showed the formation of crystalline structure of carbon material. CNPs Raman spectrum indicates the high quality with a low content of structural defects and high graphitic degree. The formation of CNPs is confirmed by an absorption peak at 264 nm. XPS technique showed well a significant decrease of oxygen containing functional groups, indicating a low degree of graphite oxidation. The active surface area of CNPs was measured by BET technique. TEM images show that CNPs are nearly spherical in shape and the diameters varying between 50 and 120 nm. The CV behaviors showed that CNPs exhibit the higher specific capacitance values, and is greatly improved over that of previously reported carbon nanomaterials.
Date accepted : 2019-10-06

Reliability Based Robust Design Optimization Based On Sensitivity And Elasticity Factors Analysis

Naoual  Karar, Ahmed Felkaoui, Farhat Djeddou

Abstract
In this paper, a Reliability Based Robust Design Optimization (RBRDO) based on sensitivity and elasticity factors analysis is presented. In the first step, a reliability assessment is performed using the First-and Second Order Reliability Method (FORM)/ (SORM), and Monte Carlo Simulation. Furthermore, FORM method is used for reliability elasticity factors assessment, which can be carried out to determine the most influential parameters, these factors can be help to reduce the size of design variables vector in RBRDO process. The main objective of the RBRDO is to improve both reliability and design of a cylindrical gear pair under uncertainties. This approach is achieved by integration of two objectives which minimize the variance and mean values of performance function. To solve this problem a decoupled approach of Sequential Optimization and Reliability Assessment (SORA) method is implemented. The results obtained shown that a desired reliability with a robust design is progressively achieved.
Date accepted: 2019-10-08

Mechanical instability of saturated soils sampled in the Oran coast, Algeria

Mohammed BOUSMAHA, Mohamed BENSOULA, Renaud TOUSSAINT

Abstract
Soil liquefaction is a significant natural hazard associated with earthquakes. Some of its devastating effects include tilting and sinking of buildings and bridges, and destruction of pipelines. Conventional geotechnical engineering assumes liquefaction occurs via elevated pore pressure. This assumption guides construction for seismically hazardous locations, yet evidence suggests that liquefaction strikes also under currently unpredicted conditions. We show, using simulations and experiments, another mechanism for liquefaction in saturated sandy soils, without high pore fluid pressure. In this work, the objective is to follow and characterize the vertical displacement of an intruder on a dry and saturated mass of soil in laboratory experiments. The external excitation is operated by regular horizontal oscillations with controlled frequency and amplitude. The liquefaction is shown to have a direct impact on the vertical displacement of intruders. It can be concluded that the movement of the intruder depends essentially on the imposed acceleration and the relative density of soil.
Date accepted : 2019-11-10

Comparison of Compressive Strength and Flexural Capacity between Engineered Cementitious Composites (Bendable Concrete) and Conventional Concrete used in Bangladesh
Munshi Galib MUKTADIR, M I Fahim ALAM, Asifur RAHMAN, Mohammad Robiul HAQUE

Abstract
The Engineered Cementitious Composites (ECC) is made of the same ingredients as in regular concrete. The coarse aggregate is replaced with tiny Polyvinyl Alcohol fibres. This structure offers maximum flexibility and it is expected to cost less. It looks exactly like normal concrete, but under excessive strain, the ECC concrete allows, the specially coated network of fibre in the cement to slide within the cement, thus avoiding the inflexibility that causes brittleness and breakage. As this is a special type of concrete there are no defined codes for it, thus for these reasons, the parameters needed are to be obtained using trial and error method. During the composite preparation, sieve analysis was carried out. Composites were reinforced with Polyvinyl Alcohol (PVA) at the following ratios: 0 % (control), 0.5 %, 1 % and 1.5 %. The cylindrical specimens were subjected to compression and the slab specimens were subjected to flexural test using a Universal Testing Machine, while acquiring data with GOM Correlation Software. Test results reveal that fibre ratio 1% is most acceptable for attaining best compressive strength along with high flexural value. Even though 1% fibre content concrete in the flexural strength test showed 33% less strength of what 1.5% fibre content concrete gained, in the long run, for having the highest compressive strength value (almost 62% more than of 0% fibre content concrete and 15% more than of 1.5% fibre content concrete), 1% fibre content concrete is most suited for constructions.
Date accepted: 2019-11-10

Behaviour of ground cupola furnace slag blended concrete at elevated temperature
Stephen Adeyemi Alabi

Abstract
Fires adversely affect the performance of concrete when expose to extreme temperatures. However, it is important to study the effects of elevated temperature on the concrete properties. Concrete often contains other cementitious materials such as ground granulated blast furnace slag (GGBFS) and this has been successfully used to improve its properties. Hence, little or no study has been carried out on the use of ground cupola furnace slag (GCFS) in concreting. Therefore, this paper investigates the behavior of concrete blended with GCFS at elevated temperatures. A total of 300 samples were prepared with four different GCFS contents. The test specimens were cured for 28-d and 56-d and subjected to elevated temperatures ranging from 200oC to 800oC up to 24 h. The slump, residual compressive and tensile strength tests were carried out on fresh and hardened concrete. The results showed that the compressive strength and splitting tensile strengths of concrete generally increased with increasing % GCFS content but decreased as temperature increases. At 28-d and 56-d, the strengths were observed to be maximum at 10% replacement when the temperature is 200oC compared to other mixes. It can be concluded that the strength drastically decreased at temperature above 200oC. An analysis of variance (ANOVA) was also carried out to determine the effect of the elevated temperature and percentage replacement of cement with GCFS on the 28-d and 56-d compressive strength of concrete. The results showed that temperature and % GCFS content had a statistically significant effect on the concrete performance. Based on Tukey’s honestly significant difference (HSD), the effect of GCFS was found to be statistically non-significant for 4% and 6% GCFS content at 28-d; and 2% and 4% GCFS content at 56-d. The effect of temperature was also found to be statistically non-significant for 600oC and 800oC at 28-d; and 27oC and 600oC; 200oC and 400oC at 56-d.
Date accepted: 2019-11-19

The Effect of Masonry Infill Walls on the Reinforced Concrete Frames Behavior under Lateral Load
Ismail LAYADI, Ali MESSABHIA, Jean-Patrick PLASSIARD, Olivier PLE

Abstract
The reinforced concrete structures with masonry infill walls are widely used to construct buildings in Algeria, as in many parts of the world. According to earthquake analysis, this type of construction can undergo serious damage under seismic load. The interaction between the infill wall and the surrounding reinforced concrete structure is considered a key parameter, which could trigger damage and even collapse in self-stable frame buildings. To study the behavior of this type of structures and the wall–frame interaction, four half-scale single-storey, single-bay reinforced concrete infilled and unfilled frames were constructed and tested under in-plane lateral load. Furthermore, the experimental results were analyzed using the Digital Image Correlation (DIC) technique giving a detailed analysis of displacement and strain fields. The wall–frame interaction was evaluated in terms of displacement field evolution and interface slip in the contact contour. The masonry infill wall demonstrated a significant influence on the in-plane lateral response of this type of structure. The analysis of the results of the experiment are discussed in this paper.
Date accepted : 2019-12-02

Sensitivity Study of Load-Dependent Ritz Vectors on Modal and Seismic responses of Cable Stayed Bridges
M. OUANANI, B. TILIOUINE, N. BELKHERI

Abstract
In the present article, a 3D Finite Element Model (FEM) of a bridge structure under load dynamics is performed in order to assess the sensitivity study of Load-Dependant Ritz vectors (LDR) on modal and seismic responses of cable stayed bridges. In this context, two techniques are examined in the present study for solving structural dynamics problems; the Traditional Modal Superposition (TMS) technique and that of Load-Dependent Ritz orthogonal vectors (LDR). The latter is based on a very efficient algorithm allowing the systematic generation of Load-Dependent Ritz orthogonal vectors (LDR), the accuracy of this method is significantly influenced by the selection of LDR vectors used for the modeling of the structural behavior. The cable-stayed bridge connecting two districts in eastern Algeria, characterized by an expected Peak Ground Acceleration (PGA) equal to 0.275g in accordance with Algerian seismic design code is selected in order to perform critical modal properties such as, frequencies, shapes of the required vibration modes and effective mass participation as well as the dynamic response of the cable stayed bridge under earthquake loadings in three orthogonal directions (longitudinal, transversal and vertical).  The results of this study reveal that the LDR vectors method which has the important advantages of short Central Processing Unit (CPU) time as compared to traditional modal method is very efficient for modal and seismic analyses of cable stayed bridges.
Date accepted: 2019-12-15

Assessment of the ternary coarse aggregates for economic production of sustainable and low-cost concrete
Stephen Adeyemi ALABI, Jeffrey MAHACHI

Abstract
This paper study the effects of construction and agricultural wastes (CAW) as coarse aggregates in ternary blends on the properties of concrete. A concrete mix ratio of 1:2:4 by weight of cement, sand and granite was adopted with water-cement ratio of 0.50. Five different concrete mixes were prepared in this study; one natural aggregate concrete (NAC) and four concretes with 10%, 20%, 30% and 40% recycled aggregate and 40%, 30%, 20% and 10% palm kernel shell (PKS) contents in reverse order at constant 50% natural coarse aggregate (NCA). The results of slump tests showed an increase in workability as the percentage replacement level of RCA reduces and PKS respectively. The compressive strength of concrete mixes was observed to be less than the strength of lightweight concrete recommended by standards by 23.2%, 28.87%, 31.2%, 43.2% and 45.6% respectively. Based on the result of calculated thermal conductivity, it was observed that as the %RCA content reduces with increasing %PKS content significant amount of energy was saved. Also, an analysis of variance (ANOVA) was carried out to determine the effect of the % replacement and curing period on the compressive strength of concrete. It showed that % replacement had a statistically significant effect on the concrete performance. This type of concrete can be classified as lightweight concrete based on the strength and bulk density.
Date accepted : 2019-12-18

Trapping of oil in an epoxy-based polymer matrix with activated carbon and its effect on tribological behavior
Mustapha BELDI, Ali BILEK, kamel TOUAHIR

Abstract
The incorporation of lubricating oil at high levels in the epoxy composite materials makes it possible to obtain materials with low friction and wear. This article evaluates the wear behaviour of an epoxy-based composite obtained by the addition of lubricating oil and activated carbon. An oil content of up to 31wt% is trapped and maintained in the matrix by the presence of activated carbon. The wear experiments are carried out on a pin-on-disk type tribometer. The tests are carried out on pins of different compositions sliding on steel discs (XC48) under dry friction conditions. The effect of various parameters such as speed and loading has been investigated. The wear surfaces are analyzed by using a scanning electron microscope to observe the different wear mechanisms. The results show that the addition of activated carbon made it possible to trap large quantities of oil in the matrix. This decreased greatly the coefficient of friction and increased the capacity of the sample to withstand higher values of sliding velocities and pressures.
Date accepted : 2019-12-18