Articles in This Issue
Abstract
The objective of this paper is reduced the electrical energy which used in air-condition system by replaced the common roofing system by the another which more suitable for hot climate area. The researcher was build (1x1x3)m sample room at 3rd floor in building at Baghdad city (33.2 °N) for 200mm polystiran thermal insulation for other room surfaces and air-conditioner of 0.5 Ton of refrigeration capacity is used to maintain the standard thermal comfort, the roof thermal behavior study for 15 hr/day, at day 21 from five each months (Jan, March, June, July & September). It was found the suggested roofing system reduced the dead load by 300kg/m2 and the electrical energy which used in air-conditioning system reduced by 37% when used open air gap was used, and become 30% when has used closed air gap has used and became 27% relation to ordinary system.
Abstract
In this study, eight rectangular reinforced concrete beams strengthened by bottom steel plates firmly interconnected to them by headed-stud shear connectors are manufactured using self compacting concrete and tested up to failure under two point loads to demonstrate the effect of steel-plate thicknesses, lengths, and the shear-connector distributions on the behavior, ductility and strength of this type of beams. A trial mix conforming to the EFNARC Constraints had been successfully carried out to satisfy the three fresh tests of SCC, these tests are flowability, passing ability and segregation resistance. The results show that there is a substantial improvement in the flexural resistance, increasing the flexural stiffness and decreasing the ductility ratio due to thickening steel plate, On contrary, increasing the spacing between shear connectors to 50% had slight effect on the flexural resistance, but subsequent increase of their spacing to 100% had seriously lowered that resistance, The spacing between shear connectors has a primary effect on the average flexural stiffness and ductility ratio. In regard to the steel plate length, its shortening has reduced the flexural resistance significantly, decreased the average flexural stiffness and had increased the ductility ratio. The experimentally determined ultimate flexural strength had been compared with its corresponding one computed by the "Strength Method" using ACI requirements where high agreement gained between them due to the nearly perfect interaction provided by SCC. The eight composite beams had also been analyzed by the non-linear three dimensional Finite Element Analysis employing ANSYS program (release 12.1),where high agreement is achieved compared with experimental results.
Abstract
Very little attention was given to study learning curves phenomenon in the construction industry, for many reasons related to the nature of production in this industry and also because of the variety of factors which affect these works. This research aims to measure the amount of improvement in the acquired production by the workers on the repeated construction operation because of the experience and learning in Iraq compared with a neighboring country (Syria).The measurement technique involves recording the time required to achieve every unit and finding out the mathematical relation which represents the learning curve for each item of production. The study involves six items (activities) of construction as follows: 1- Ceramic tiles (20 × 20 cm) for walls. 2- Paving the pavement of the street with concrete blocks. 3- Tiling the rooms with mosaic (30 × 30 cm). 4- Building the walls with concrete blocks (20 × 20 × 40 cm). 5- Coating the walls with emulsion paints. 6- Finishing the walls with gypsum The most important results of the research are that the amount of learning varies from 4.2% to 8.6% in Iraq, and 3.3% to 11.8% in Syria, which considered little compared to the developed countries.
Abstract
The present study, concern about an experimental work to study the stress-strain relationship of steel-fiber reinforced polymer modified concrete under compression. Four different mixes with weight proportions of (1:2:4) were used as; normal weight concrete (NC), polymer modified concrete (PMC) with (10%) of cement weight and two mixes of steel-fiber polymer modified concrete with (1%) and (2%) volume fraction of steel fiber, (SMPC). The influences of polymer and fiber addition on peak stress, strain at peak stress and the stress-strain curve were investigated for concrete mixes used. For all selected mixes, cubes (150×150×150mm) were made for compressive strength test at (28) days while stress-strain test was caried out on cylinders (150 mm 300 mm) at the same age. Results showed an improvement in compressive strength of polymer modified concrete (PMC) over reference mix, the maximum increase of it was (13.2 %) at age of (28) days. There is also an increase in compressive strength with increasing of steel fibers content with comparison to normal concrete, the maximum increases of it were (19.6% and 25.2%) of mixes with 1% and 2% fiber content by volume respectively. In terms of modulus of elasticity, the addition of polymer and the presence of fibers cause a significant increase in it. The peak of stress- strain curve for normal strength concrete (Mix No.1) was linear whereas it was more sharp for the other mixes. The behaviour of normal strength concrete (Mix No.1) was linear up to 20 % of ultimate strength, while for the mixes with the higher strength i.e. polymer modified concrete and fibers reinforced concrete (Mixes No.2, 3 and 4) the linear portion increases up to about 50 % of ultimate strength
Abstract
The study included evaluating water ten wells in the area Dabaa within the western region of Iraq for agricultural use, as has been the study of water quality of these wells during the year by conducting a full analysis of water samples and assess suitability for irrigation depending on the standard specifications of the Food and Agriculture Organization. As the analysis results showed that all the studied wells located within the water of light to moderate in terms of the seriousness of Electrical conductivity if used for irrigation, and sodium adsorption ratio values for all water wells studied were within the Has no influence soil permeability. It turned out that the Toxic Effect of these water plants were mild to moderate effect for sodium either chloride was degree selection of non-toxic to light moderate, and that the use method Piper for the classification of water showed that it quality predominantly Na+, Mg +2, Ca+2 - Mg+2 , Ca+2 for positive ions and water quality sulphurous HCO3-, SO4 = predominantly basal in terms of negative ions.
Abstract
This research includes producing compacted concrete by rolling method and the possibility for using in highway construction field with studying the influence of adding waste plastic fiber resulting from manual cutting for bottles used in the conservation gassy beverage on different characteristics of this type of concrete. For the purpose of selecting mix proportions appropriate for rolling compacted concrete (RCC). Approved design method for ACI-committee (5R-207 .1980) was selected for this research. Destroying plastic waste by volumetric rates ranging between (0.5%) to (2%) was approved. Reference mix was produced for comparison. Tests were conducted on the models produced from rolling compacted concrete like compressive strength, flexural strength and split tensile strength. The analysis of the results showed that the use of plastic waste fibers (1%) has led to improve the properties of each of the compressive strength and flexural strength and split tensile strength compared with reference concrete. Compressive strength in 28 days with fiber ratio (1%) is higher than (52.15%) from compressive strength in 28 days of reference concrete. It can be also observed that each of the flexural strength and split tensile strength increases by (17.86, 25.61)%, respectively, from flexural strength and split tensile strength for the reference mix
Abstract
The concern over increasing needs for drinking water and awareness for development of systems to improve water quality both for drinking purposes and for effluents from wastewater treatment and industrial facilities have provided incentives to develop new technologies and improve performance of the existing one. Adsorption technology has many advantages over other treatment methods such as simple design, low investment cost, limited waste production, etc. Synthetic water with a dosing of artificial copper solution (Cu No3) was passed through a PVC column (15 cm diameter, 100 cm length) containing limestone as a filter media in three different sizes, using three different hydraulic rates, and three initial influent copper concentrations (7.04, 4.39, 1.72) ppm .For this study, three experiments have been conducted; continuous batch and field experiment. The up flow roughing filtration is the suitable technique to recover heavy metals present in aqueous solutions, without the need of adding further substances. The filtration results demonstrated that the smaller size of filter media (3.75) mm gave higher removal efficiency (93.75 – 98.80) % than larger filter media (9.50) mm which gave removal efficiency of (67.61 – 94.0) %. This is due to the large specific surface. The smaller size of limestone achieved the longer detention time (49) min, so the removal of Cu was more than (90) % for the (50) min of experiment. At lower flow rate (0.16) L/min, the removal efficiency was higher than at higher flow rate (0.77) L/min. At high flows, there is a reduced period of surface contact between the particles and copper solution. This study also involved three different batch experiments .The removal efficiency was (93- 97) % for the three types of limestone which indicates the importance of limestone media in the removal process. This also indicates that the removal efficiency was increasing with the increase of the limestone volume. Field experiment has been conducted using wastewater from Al- Dura Electric Station on the three types of limestone so that to ensure the laboratory tests. It was achieved good removal efficiency range from (87.5) % to(97.5) % at the high adsorbent dose .To calibrate the physical model, a computer program of multiple regressions is used to assess the relative importance of the predicted variables. The partial correlations indicate that influent concentration of copper, surface loading (flow rate), and detention time are the most important variables while the size of limestone is not important as others.
Abstract
The present research focuses on the evaluation of the Tigris river water quality within the city of Baghdad. Thirty samples were collected monthly from ten sites (each site contains three positions center of river, Rasafa side, Karkh side) on the Tigris river within Baghdad city along one year (from Feb.2010 to Feb. 2011). Samples were analyzed for eleven water quality variables including physical, chemical, and biological parameters. The results showed increases in pH, TDS, TSS, Cl-1, SO4-2, and BOD values in some of the sites through study area, but all values remain within the allowable Iraqi and WHO limits except of SO4-2, it was exceeded the allowable limits in multiple sites.