Engineering and Technology Journal

This research discusses experimentally the shear strain of the reinforcement concrete hybrid beams composed of reactive powder concrete (RPC) at the peripheral and conventional concrete (CC) at the core beams under torsional strength tests. Shear strain is usually represented by is explained as the tangent of the angle and is be like the length of deformation at its maximum divided by the length of perpendicular in the plane of the force application. Twelve reinforced concrete beams are tested having the following dimensions: 100, 200 and 1500mm as width, height and length respectively with thickness of the RPC concrete were 40 and 20mm. The beams were cast and tested to failure in torsion by using two opposite cantilevers steel arms that contribute to transferring the torque to the centre of the beams. Two control (CC and RPC) beams were poured, and the ten other beams were all poured as hybrid ones. Experimental data of the three strain gauges locations in the middle of the beams in one of the side surface face, to calculate shear strain (). The percentage of shear strain at ultimate torsion capacity was reduced by about 76% for RPC (RP) to CC (NC) beams and 63% for hybrid beam (H1) to CC (NC) beam.

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

This study presents an experimental approach to investigate the structural behavior of normal and moderately high strength Self Compacted Concrete (SCC) voided slab strips under repeated loading system. The experiments were carried out on eight one-way simply supported slabs. Four of them have been tested under two types of repeated loading regime. The required number of cycles of the first load pattern (R1) to achieve permanent damage in the slab is more than 40 cycles, while the second type of repeated loading regime (R2) requires more than 20 cycles to achieve complete damage in the slab for the selected loading scheme. The remaining four additional slabs were tested under monotonically increasing loads. The loading techniques have been applied under the displacement control scheme. The experimental results show that for moderately thick reinforced SCC one way slab having (3 voids, dia. =75mm) under repeated load R1, the ultimate load is reduced by about 10% relative to the reference solid. In this research, the number of cycles required to achieve permanent damage is decreased by about 7% and the mid-span deflection at ultimate load is increased by about 3.4% relative to the reference solid slab. The ultimate load for slab having (3 voids, dia. =75mm) under repeated load R2 is decreased by about 6%, the deflection at ultimate load and the number of cycles are decreased by about 6.1%and 16.7% respectively concerning SCC reference solid slab.

Electro discharge machining (EDM) is one of a thermal process that is used for remove of metal from the workpiece by spark erosion. The work of this machine depends on multiple variables. One of the more influential variants on this machine is the change of polarity and the use of this variable is not wide and the research depends on the polarity of the machinist. Essentially, the polarity of the tool (electrode) is positive and the workpiece is negative, this polarity can be reversed. This paper focuses on the influence of changing the polarity (positive and negative) on the surface roughness and metal removal rate by using different parameters (current, voltages, polarity and Ton). Experiments show that the positive electrode gives (best surface roughness = 1.56 μm when the current = 5 Am and Ton = 5.5 μs) and (best metal removal rate = 0.0180 g/min when the current = 8 Am and Ton = 25 μs). Negative electrode gives (best surface roughness = 0.46 μm when the current = 5 Am and Ton = 5.5 μs) and (best metal removal rate = 0.00291 g/min when the current = 8 Am and Ton = 25 μs).

The present research paper is on photovoltaic air conditioning system using the direct drive method. The experimental system setup arranged in Iraq at Al-taje site at longitude 44.34 and latitude 33.432 during the summer season inside a room. The proposed off-grid system consists of an array of photovoltaic, battery used to store power, PWM (pulse width modulation) charge controller, and DC air cooler. During the examination of the system, proven success of this new type(dc air conditioner ) of client urges Iraq warm conditions as an alternative type used instead of the prevailing types of air conditioners (AC air conditioner )in Iraq which consume large amounts of electrical energy and gets a cooling system for the room full working on solar energy.

For a long time, the seismic examination of retaining walls has been contemplated by a few strategies dependent on the basic augmentation of Coulomb's limit equilibrium investigation. These techniques cannot gauge the removal of the refill soil upheld by the wall. A trial examination is completed to contemplate the vertical settlement on sandy soil under dynamic loads with other burden amplitudes, vibration frequencies, relative density, and various separations between the establishment and holding divider. The model balance utilized in this investigation is square. Dynamic burden test is done on cohesion less soil with three burden amplitudes (0.25 ton, 0.5 ton and 1 ton), three vibration recurrence (0.5 Hz, 1 Hz and 2 Hz), two density of sandy soil (30% loose sand and 70% dense sand) and three unique separations between the establishment and retaining wall. It has been seen that the change is increment with the burden of abundance and decreased by increasing the separation between the establishment and retaining wall. There is an unimportant result of recurrence on the aggregate settlement. The settlement decrement by incrementing the relative density.

The solar energy system is environmentally friendly and the utilization of photovoltaic thermal collectors, (PV/T) has attracted more attention, which directly converts solar radiation into electricity and thermal energy simultaneously. This study investigated the air biased Photovoltaic thermal hybrid solar collectors, (PV/T) trend for two cases, denominate case one (PV/T system fully covered with PV modules), and case tow (PV/T system partially covered with glass). The studied parameters were solar irradiance and the air mass flow rate. The investigation has been performed in terms of outlet air temperature, electrical power, thermal and electrical efficiencies. A numerical model was developed using the computational fluid dynamic program (CFD) and the results were compared with the experimental measurements that carried out from indoor conditions using a solar simulator. A good agreement has been achieved between experimental and numerical results. The performance of both cases one and case two concluded that the PV/T system should be operating at a moderate air flow rate of 0.013 kg/s, which is the best mass flow rate. In addition, it has been observed that for case tow the maximum outlet air temperature and electric powers were 44.3 oC and 26.6 W, respectively. For case one, thermal and electrical efficiencies were found 34% and 10%, respectively, based on the experimental data, while for case 2, the maximum thermal and electrical efficiencies were found to be 48.9 and 9.1%, respectively

The behavior of the erosion wear for samples manufactured by hand layup method of epoxy-supported fiberglass, eggshells and calcium carbonate particles were investigated. The test was performed in accordance with the experimental designs Taguchi (L 9) MINITAB (19) to select samples that have the resistance to erosion under the influence of factors. The erosion rate was assessed under the influence of three factors: weight fraction (2% to 8% eggshells and CaCO3 particles), sand size (450, 650, 850 μm) and angles (30º, 60º, 90º) with a fixed face distance of 30 cm, 10 hours and a flow rate of 45 L/min. The results revealed that the rate of erosion is lower for samples consisting of enhanced epoxy resins (eggshell molecules and CaCO3) with chopped fiber glass compared to unfilled samples. Also from these results, it should be noted that the maximum erosion rate was when the weight fraction (2%), the sand size of 850 μm and the angle of 90º, while the minimum rate of erosion was when weight fraction (8%), sand size 650 μm and 30º angle. In this work, the sample of composite materials behaves in a semi- ductile manner.

Natural materials have been extensively used as reinforcements in polymer matrices instead of non-degradable synthetic reinforcement such as carbon, glass or aramid. The use is because of their low density, good mechanical properties, availability, and biodegradability. Peanut shell is one such natural waste filler used, and it contains cellulose, hemicellulose, and lignin. Natural fiber/particle sources are not only strong and lightweight but are relatively very cheap. This paper offers the comparison of the flexural, and impact energy test properties of the peanut shell reinforced with the epoxy resin matrix. Peanut shells add into the epoxy resin matrix with various weight fractions (2%, 4%, 6%, and 8%) and have been fabricated by hand lay-up procedure. Flexural strength and flexural modulus changed from (140MPa) to (160 MPa), and from (2 GPa) to (7.79 GPa) respectively, impact strength, and fracture toughness changed from (2.5 KJ/m2) to (7 KJ/m2), and from (2.23 MPa.m1/2) to (7.07 MPa.m1/2), respectively as a function of the particle weight fraction. The highest flexural strength and modulus obtained samples (reinforced 4% wt. peanut shell), while samples (reinforced +8% wt. peanut shell) provided the highest impact strength and fracture toughness.

The requirements of minimum flexural reinforcement in the last decades have been a reason for controversy. The structural behavior of beams in bending is the best way of investigating and evaluating the minimum reinforcement in flexure. For this purpose, twelve singly reinforced concrete beams with a rectangular cross-section of (125 mm) width by (250 mm) height and (1800 mm) length were cast and tested under two-point loads up to failure. These beams were divided into three groups with different compressive strengths (25, 50, and 80 MPa). Each group consists of four beams with different amounts of tension steel reinforcement approximately equal to (0% Asmin, 50% Asmin, 100% Asmin and 150% Asmin), two bar diameters (Ø6 mm and Ø8 mm) were used as the longitudinal tension reinforcement with different yield and ultimate strengths, the minimum amount of reinforcement required is calculated based on ACI 318M-2014 code. The results show that for the reinforced concrete beams, the flexural reinforcement in NSC beams increases the first cracking load and the increment increased with an increasing amount of reinforcement, while for HSC beams the increasing in first cracking load are very little when the quantity of reinforcement less than the minimum flexural reinforcement and increased with the increasing amount above the minimum flexural reinforcement. The equation of ACI 318M-14 code gives adequate minimum flexural reinforcement for NSC and overestimate value for HSC up to (83 MPa), A new formula is proposed for HSC rectangular beams up to (90 MPa) concrete compressive strength by reducing the equation of ACI 318M-14 code for minimum flexural reinforcement by a factor depending on concrete compressive strength.

In the present study commercial zinc oxide (ZnO) nanoparticles in the size of 30 nm were utilized as an adsorbent for the removal of Ni (II) ion from synthetic waste aqueous solution. Adsorption capacity of ZnO for removing Ni (II) ions from aqueous solutions was measured at different pH, adsorbent dose, contact time, temperature and metal ion concentration. Moreover,  adsorption isotherms, kinetics and thermodynamics were studied to understand  the  nature  and  mechanism  of  adsorption. ZnO nanoparticles were characterized by X-Ray diffract analysis(XRD),Fourier Transform Infrared Spectroscopy(FT-IR), scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy(EDS) and Brunauer-Emmett-Teller (BET). The maximum amount of Ni (II) removal were found to be (98.71%) from its aqueous solutions by ZnO nanoparticles which was achieved at the evaluated optimum conditions. The experimental kinetic data were examined using the pseudo-second-order rate model with a high regression coefficient. The adsorption isotherm was well described to the equilibrium data by Langmuir isotherm model (R2=0.990). In addition, the calculated thermodynamic parameters, the standard Gibbs free energy ΔGo, the change in standard enthalpy ∆Ho and the standard entropy change ∆So showed that the adsorption of Ni (II) onto ZnO nanoparticles was feasible, endothermic and spontaneous respectively. The experimental results suggest that ZnO nanoparticles can be used as a potential adsorbent for the efficient removal of heavy metals from aqueous solutions than any other adsorbent because an economical and low- consumption energy due to its ambient operation conditions.

This paper presents the effect of spacing between boreholes heating on plasticity of expansive soils. The expansive soils used were prepared artificially by mixing Kut clay with different percentages of bentonite. Nine laboratory models of expansive soils having dry unit weight of 17.8 kN/m3 with 6% initial water content were prepared inside a steel box of (300 mm × 300 mm × 400 mm height). A special heating system generates 400 Co for six hours was designed and manufactured for this purpose using 12 mm diameter electric heaters inserted through boreholes. Square pattern boreholes of 170 mm length with spacing (4.16d, 6.25d and 8.33d) were used. A representative sample were taken after heating from the center of the square pattern for measuring the plasticity of the soils. The results showed that the plasticity index remarkedly decreases compared with that before heating and increases with increasing bentonite and the spacing. It is also indicated that an expansive soil could be changed from high to low plasticity

Cost overrun in construction projects is a common phenomenon in Iraq. This might occur due to diversity of factors. This study aims to identify the factors influencing construction projects cost that are potentially controllable by main contractors. A field study through a questionnaire survey was directed to a sample of related Iraqi professional engineers from general contracting companies at both public and private sectors. Their opinions on the impact and frequency of each factor were investigated. The questionnaire offered (59) factors classified in (8) categories namely; legislations, financial and economic, design, contractual, site management, material, labor and equipment. The factors were ranked according to the highest Relative Importance Index (RII). The study revealed (10) major factors that are potentially controllable by main contractors namely; labor productivity, sub-contractors and suppliers performance, equipment productivity, site organization and distribution of equipment, experience and training of project managers, scheduling and control techniques, planning for materials supply, planning for equipment supply, materials delivery and planning for skilled labor recruitment. Recommendations to aid contractors and owners in early identification of these factors are also included in this study.

In this study, the behavior of a Polyvinyl chloride (18 wt % PVC) hollow fiber ultrafiltration (UF) membrane for methyl green (MG) dye removal from aqueous solution was estimated by studying the influence of varying the operation conditions (the concentration of the dye and volumetric flow rate) to determine their impact on the separation processes (permeate flux and rejection coefficient) at constant pressure and temperature. The PVC membrane was characterized by scanning electron microscopy. Furthermore, tests of the UF were carried out with pure water and MG aqueous solutions as feed. Outcomes explained a notable influence of feed concentration and flow rate on the rejection and permeate flux, with the highest rejection coefficient value close to 75.2% of the membrane system, at neutral pH.

In this research, the composite material was prepared from untreated and treated corn cob powder by acetylation process and the physical and mechanical properties have been studied. Cellulose is extracted using the Kürchner-Hoffer method and then acetylated. Untreated corn cob powder and Acetylated corn cob powder were mixed with unsaturated polyester resin in different concentrations (0, 1, 2, and 3 wt. %). The Mechanical and the physical test results showed that there is an enhanced in mechanical properties (Tensile, Impact, Hardness, and Bending) with the treatment (Acetylation) by increasing treated corn cob powder mass fraction (1, 2, and 3wt. %) respectively.