Articles in This Issue
Abstract
At the last period, the problems of the pre-cast concrete units have been increased rapidly due to its unconformity to the adopted specifications with regards to sulphate content. The high content of sulphate in Iraqi fine aggregate in many aggregate quarries, which are out of the Iraqi standard specification limits, causes many difficulties for most pre-cast concrete units Factories to provide an acceptable fine aggregate with regards to sulphate content. This study has been conducted to assess the possibility of using fine aggregate with sulphate content higher than the upper limit of the Iraqi standard (0.5%) to produce pre-cast concrete units: hollow concrete block and paving concrete brick, where the total amount of sulphate has been controlled by decreasing the fine aggregate content in the adopted mixes. The tests are conducted on reference mix with an acceptable fine aggregate according to the Iraqi standard (with regards to sulphate content) and three mixes with fine aggregates contain (1.19, 1.90 and 2.47%) of sulphate respectively. The hollow concrete block and paving concrete brick are produced from all these mixes. The results indicate the possibility of using unacceptable fine aggregate (those with sulphate content higher than 0.5%) to produce an acceptable hollow concrete block and paving concrete brick according to Iraqi specifications. This could be done by reducing the fine aggregate content in the mixtures within a specific limit.
Abstract
AbstractSolid waste data survey for the period from 1977 and 2002 has been collected andanalyzed, while the solid waste generated in six regions in Baghdad, which were selectedand estimated to be 1435 houses and 28643 households for the period 2000-2005 wasstudied. The growth of Baghdad's population, increasing urbanization and rising standardsof living have all contributed to an increase in both the amount and the variety of soliddomestic wastes.The amounts of waste generated and their sources, the type of materials in eachwaste stream, their properties, potential toxicity, and the hazards were evaluated. The lackof reliable time series on solid waste streams and rapid changes in the composition ofwaste streams are a serious impediment to setting priorities in solid waste management inBaghdad. The basic conclusions from this study are:-- The waste generated per capita in Rusafa, Kerkh and Baghdad increased from 0.32,0.46 and 0.354 kg/day in 1977 to 0.98, 1.37 and 1.11 kg/day respectively in 2002.- Municipal wastes in Baghdad have a higher proportion of organic matter and ash,higher moisture content and lower paper content. Organic matter and ash may account for between 76-89% of all wastes in low income settlements. Thepercentage of organic waste decreased from 91.17% in 1977 to 64% in 2002, whileplastic, paper, textile, metal, wood and glass wastes increased slightly at the sameperiod.- Collected solid wastes amounts were less than evaluated solid wastes amountsduring the period from 1977 to 2005 because of war and economic sanction.Keyword: SolidWaste management, Waste composition and characteristics, Baghdad city
Abstract
ABSTRACT An applied hydrological models were performed to model the rainfall-runoff relationship for Upper Adhaim River Basin. Three lumped integral models (hydrologic models) based upon the concept of the unit hydrograph were applied to analyze the rainfall-runoff relationship on a daily basis. These models are: the Simple Linear Model (SLM), the Linear Variable Gain Factor Model (LVGFM), and the Non-Linear Model (NLM). Five performance evaluation criteria have been used in this study. The application results of the (SLM) model showed a weak rainfall-runoff relationship. It was demonstrated that the linear assumption is valid only for the first four antecedent days. A considerable non-linear rainfall-runoff relationship was clearly observed from the results of (LVGFM) and the (NLM) models. Both models were satisfactorily identified at system memory of (17) antecedent days. However, the (LVGFM) was slightly superior to the (NLM). The (LVGFM) identified at system memory of seventeen antecedent days was used to simulate runoff flows. The simulation results show an acceptable applicability for the (LVGFM) in terms of simulating runoff events in time of its occurrence and volumetric fitness. The water budget for Upper Adhaim River Basin showed that an average of 73.4% from annual rainfall was evapotranspired, 8.0% was infiltrated and 18.6% was observed as direct runoff.
Abstract
This research work includes production of new type of light weight concrete and studies the mechanical and thermal properties. Several proportions of raw materials were used to produce this type of concrete. This study is intended to produce light weight concrete with low thermal conductivity so that it can be used for concrete masonry units. Polystyrene aggregate was added as percentages by weight of cement to improve the thermal properties of this type of concrete .Mechanical , and thermal tests with difference ages were made in this work .For polystyrene concrete with polystyrene cement ratio (p/c) of (2.67 – 6 )% , the28-day compressive strength range is from (4.31 – 2.67)MPa, flexural strength range is from (3.05-1.719 ) MPa , density range is from ( 1493-1213 ) kg/m 3 ,and thermal conductivity range is from ( 0.91-0.782)% as a percentage by that of reference mix. The study show suitability of this type of concrete to be used in concrete masonry units of non-bearing walls.
Abstract
In the circumstances interface Iraq wars and a lack of public services to citizens, water remains the most important requirements of daily life and must be accorded primary importance by ensuring that the processing of citizens with drinking water quality and conformity with the standard specifications, and that can be done not through the presence of plants To treat drinking water with high efficiency. In this research study of the Show a water Fallujah, which consists of the traditional liquidation of most water stations in Iraq , sedimentation and filtration and sterilization, has been studying each stage of the three phases through the collection of information and testing of each phase, has found that the plant Efficient (57%) of a deposition, and the efficiency (50%) of the nomination phase and the efficiency (40-90%) in the sterilization stage, within the World Health Standards for water quality characteristics , PH was equal to( 6.7), and equal to (3 turbidity unit international) turbidity, and electrical Alaissali (1100 μs/cm ), and the total salt concentration of TDS equal to (530mg/L) for drinking water out of the station, The concentration of suspended solids (40 mg / L) are not in conformity with the specifications
Abstract
Abstract:This paper presents exact probabilistic model as a complementary mathematicalbase for the traditional deterministic approach to quantify the selection of a factorof safety for each term of the load equation of friction piles in clay. The procedureof assigning a partial value of factor of safety for each clay layer using a quantifiedprobabilistic model instead of the use of a single global factor of safety for alllayers that based on arbitrarily judgments seems to introduce an enhancement toboth economical and safety consideration in the design procedure of the frictionpiles. it is suggested in this paper to derive probabilistic equation that describe eachlayer of the problem individually, each term of the pile load equation (clay layers) consists on a certain amount of uncertainty and each request assigning a certainvalue of factor of safety to eliminate this variability and to keep the probability offailure (which is more reliable risk index) at certain level. Exact probabilityequation is mathematically derived on the bases of the variability inherited in soilparameters (average un-drained shear strength and thickness of each clay layerinserted). The equation was verified using Monte carol simulation method andresults indicate excellent agreement in both, probability distribution shape andcalculated failure values. The relationship between factor of safety and probabilityof failure produced from the derived equation was inspected in addition to thesensitivity of the equation to the change of the variability of input parametersthrough a reference example.Keywords: Friction Pile, Load, Probability, factor of safety
Abstract
This research concerns, with studying the proposed of a simulation program, which is related with the process of movement and handling of construction materials on site. to reduce the handling wastes cost. This research deals with all factors affecting construction materials movement on site. Through a proposed program, weakness points of the mentioned factors can be specified and treated either with an applied program or Administrative procedures. Detailed literature survey was performed, detailed field investigation, analysis of collected data, and interviews with selected and well qualified and experienced management personal representing a wide variety of construction firms and companies. The results obtained from the mentioned actions confirmed the research hypothesis. A computer program was prepared, to simulate all construction materials movement stages affecting the movement and handling of construction materials. The proposed program, includes and perform several functions such as , simulation of construction materials management activities, evaluation of the existing status, finding out management solutions and training aspects, that helps in training engineers, possessing little experience in managing construction materials on site. To examine the capability extent of applying the proposed program at the site, the program function applied on tow construction projects and to be examined by experts. The examination was illustrated the program efficiency to reduce movement and handling costs of construction materials. The research recommended the applications of the proposed program to get its benefits and to achieve the research objectives. Further and future researches were proposed, such as expert system to evaluate and develop the performance of construction management in the field of on site materials management.
Abstract
Abstract:-This investigation studies the mechanical characteristics of carbon fiber reinforcedlight weight aggregate concrete, containing different percentages of fiber. The effect ofusing high range water reducing agent (SP) with 8% silica fume (SF) and 8% highreactivity Metakaolin (HRM), as a partial replacement by weight of cement, on thebehavior of (LWA) concrete is also studied.This investigation was carried out using several tests. These tests were workability freshand hardened density, compressive strength, splitting tensile strength and modulus ofrupture. Tests were performed for specimens at ages of (7,28,60,90 and 180) days . Thetest results indicated that the inclusion of carbon fiber to the light weight concrete mix didnot affect the compressive strength significantly, while the splitting tensile strength andthe modulus of rupture were improved significantly. The addition of silica fume andmetakaolin improves the compressive, splitting tensile , and modulus of rupture strengthsof carbon fiber light weight concrete. The average improvement was about (26.5%, 71%and 73 %) respectively for carbon fiber LWA concrete containing silica fume and (28%,72% and 75%) respectively for carbon fiber LWA concrete containing high reactivitymetakaolin.
Abstract
Abstract:This research studies the effect of high temperature which is reached to 600 °C onstructural lightweight and normal weight concrete. Lightweight concrete mix designedaccording to ACI committee 211-2-82 with mix proportion 1:1.12 :3.35 by volume .Thewc ratio equal to 0.5 by weight and cement content 550 kgm3. Mix proportions ofnormal weight concrete were 1:2:3 by weight with cement content 400 kgm3 and samewc. The design compressive strength at 28 days of normal weight concrete (NWC) andlightweight concrete (LWC) were 34.7 MPa and 22.62 MPa respectively. Compressivestrength tests were performed on 100 mm cubes exposed to high temperature 100,200,400and 600 °C. The normal weight concrete and light weight concrete test specimens wereexposed to high temperature for 10 minute suddenly at the required degree. Moreover,light weight concrete test specimens tested after graduate exposure to high temperaturereaching to the required degree with and without drying to examine the effect of moisturecontent.The results indicated that the structural lightweight concrete exhibits approximatelysimilar compressive strength loss compared to normal weight concrete up to 600 °C at 28days in graduate exposure .The percentage of reduction on compressive strength was30% in lightweight concrete compared to 28% in normal weight concrete at 600 °C .Insudden exposure to high temperature ,the opposite behavior was noticed .The percentageof reduction on compressive strength was 64.4% in lightweight concrete at 600°C .Drying of lightweight concrete specimens before graduate exposure to high temperaturessignificantly reduce the loss of compressive strength.
Abstract
AbstractWhen drivers are approaching a signalized intersection at the onset of ayellow change interval, they must decide whether to stop or cross theintersection. This can be a difficult decision when the vehicle is locatedwithin the dilemma zone and the result is sometimes a rear-end crash due to asudden stop. Dilemma zone is defined as an area close to an intersection inwhich a vehicle can neither stop safely before the intersection nor clear theintersection without speeding before the red signal comes on. This research studiesthe driver behavior during the amber onset in the signalized intersection.One signalized intersection was selected in Damascus city to collect data forthis purpose. Data was collected using video recording technique. Data wereabstracted, processed and analyzed using programs developed for this purpose. Thestudy examined 226 drivers on the amber onset, 42.47% of them were found to beconflicted by the dilemma zone phenomenon. 51.25% of them conflicted withaccelerating, 42.5% who stopped abruptly, and 6.25% who passed during the redsignal.Key words: dilemma zone, amber onset, clearing distance, stopping distance