Articles in This Issue
Abstract
This study presents an investigation of the mechanical properties of normal concrete reinforced with discarded steel fibers (DSFs) resulting from tire manufacturing. DSFs were added to concrete in two different volume fractions of (0.25 %, and 0.5 %), and these fibers have dimensions of (40 mm length×0.92 mm diameter). The results showed that the compressive strength of the concrete was enhanced by (8.8%, and 3.3%) by adding of DSFs. However, the workability of concrete decreased at all added ratios. While the density is slightly changed. Also, the results indicate that the modulus of elasticity shows slight increases by (3.06%, and 2.25%). Additionally, the incorporation of DSFs improves the splitting tensile strength and modulus of rupture significantly. For concrete mixes having volume fractions of 0.25% and 0.5%, the splitting tensile increased by (7.89%, and 23.68%), and the modulus of rupture increased by (6.67% and 25.58%), respectively. It was concluded that using this type of discarded fibers can improve the mechanical properties of concrete as an alternative type for other types of industrial fibers.
Abstract
ABSTRACT. Hospitals pose a significant risk to human health due to the contamination of their environment with chemical elements. Exposure to these elements can have adverse health effects, such as neurological and developmental problems, cancer, and endocrine disruptors. To prevent and mitigate the risks associated with contamination, it is important to identify and control the sources of contamination. This study intends to investigate how chemical elements are contaminating hospitals, including the sources of contamination, possible health impacts of exposure, and preventative and remedial actions that may be done to lessen the dangers. To reach the aims of this study, water samples from three different spots at two different seasons (winter and summer) of the water flow through the hospitals (Hospital water on its first entry inside, Wastewater after use inside and around the hospital and Wastewater after passing through the treatment unit inside the hospital) have been collected. Magnetic suspended matter (TS), Total materials (T.D.S), Electrical Conductivity, and Turbidity tests have been done to the collected water samples. Additionally, heavy materials have been detected in the collected samples. The results showed that the pH function increased slightly and insignificantly for the alkaline after using the water, while the water conductivity, Alkalinit, hardness, and percentage of suspended solids (T.S.S) and dissolved solids (TDS) reached the highest in wastewater. From the results of this study, we can conclude that the stages of treatment are slow and inefficient.
Abstract
This study was conducted to examine the impact of plastic fibers (WPFs) in an effort to improve some of the features of self-compacting concrete (SCC) using Iraqi raw materials. Waste polyethylene terephthalate fibers (waste PET fibers) from used beverage bottles were added. Some tests were carried out to determine the effects of adding WPFs on the fresh properties of new concrete, while additional tests examined the mechanical properties of hardened concrete. Because of this, self-compacting concrete blends were created with a constant water-to-binder ratio of 0.32 and a binder content of 525 kg/m3. The designated plastic fiber percentages contents were 0%, 0.5%, 0.75%, and 1% of mix volume. Self-compacting concrete mixtures' fresh characteristics were assessed for slump flow diameter, T50 slump flow concurrently, V-funnel flow concurrently, and L-box height ratio. The 28-day density, compressive strengths and flexural strength of self-compacting concretes were also measured. The use of plastic waste fibers had a slight effect on reducing the density of the produced concrete and a negative effect on the fresh properties. The compressive strengths were improved by using WPFs, with the maximum improvement equal to (11.065%) when compared to those made from the reference mix
Abstract
In this study, the structural behaviour of RC-deep beams of glass fibre-reinforced polymer (GFRP) rubberized concrete is investigated. Rubberized concrete is manufactured by replacing fine sand aggregate with rubber crumbs in volumetric replacement ratios. The main variables were the crumb rubber content (0%, 10%, and 20%) and the main reinforcement ratio. Tested Six samples of deep beams with different dimensions (b = 150, h = 300 mm, L= 1400 mm) were under a four-point load until failure. The parameters under investigation were the mechanical properties of mixtures, load-midspan deflection curves, toughness, and the load-strain relationship. The results indicate that the increased crumb rubber content led to a decrease in the mechanical properties of rubberized concrete mixtures. It was found that the behaviour of all samples of rubberized concrete affected the deflection load curve, the ultimate load, and the increase in deflection. The sample R2-10% Rub showed the highest toughness among the tested samples, with an increase of 301.6% compared to the reference.
Abstract
Since evapotranspiration typically makes up the largest portion of the terrestrial water cycle, it is one of the most crucial factors in determining how much water is available. This study evaluated four models (Penman-FAO-24(PF), Penman-Monteith -FAO-56(PM), Penman-Kimberly(PK), and Jensen-Haise (JH)) utilized frequently to calculate monthly reference crop evapotranspiration (ET_0) values for Ramadi irrigation project (fourth stage). The statistical indicators considered were the root mean square error (RMSE), Mean Absolute Error (MAE), Relative Error (RE), Correlation Coefficient (R^2) and mean bias error (MBE), models were used to estimate evapotranspiration, and by calculating evapotranspiration for Al-Ramadi city according to the climate data available to us, The (PF) model had the lowest MBE = 0.02945, greatest RMSE = 29.369, and highest R = 0.9641 values among the four models, demonstrating that it is the best. The JH model, which achieved the highest values of MBE = 0.00978 and RSME = 58.509, was the least accurate of the models.. The study's conclusions may be useful to farmers, decision-makers, and local water organizations in assessing irrigation water requirements, planning, and effective use of water resources.
Abstract
The problem of discarded tires has received a lot of attention from many authors. Incorporation of rubber aggregate recycled from waste tires is one of the solutions to this issue. This research is based on evaluating fresh and hardened properties such as slump flow, T500, segregation resistance, and L-box tests, compressive strength, impact resistance, and flexural toughness. Rubber aggregate replacements in the self-compact concrete mixes was 10% by volume of fine aggregate. Additionally, both PET and steel fibers are utilized at a volume rate of 0.25%.The outcomes indicate that introducing rubber declines rheological and hardened properties, whereas incorporating hybrid fibers enhances hardened properties such as compressive strength, impact energy, and flexural toughness. The best increase impact energy was obtained at roughly 166.6% when 0.25% hybrid fibers and 10% rubber were used. 74.21 was the greatest increase in flexural toughness when 0.25% hybrid fibers (SCCH3) were used. As for the compressive strength, it was the highest by about 11%.
Abstract
There are various means of recycling agricultural wastes to maximize economic benefit from it. According to environmental statistics, agricultural wastes is one of the most dangerous types of wastes, especially in villages, because it is disposed of by burning. In this study, production of natural ash from agro wastes was carried out. Two types of agro waste ash were produced through burning and grinding process. waste date tree and waste reeds ash. The waste date ash (WDA) and waste reeds ash (WRA) were included in concrete by replacement of a specific portion of cement weight (5%, and 10%). Moreover, a blend of the two types of ashes were also considered. Furthermore, the natural ash was utilized in production of green concrete. Hardened density and compressive strengths at various ages (7, 28 and 56 days) were evaluated. The results in this research showed an excellent increase in compressive strength at ages (7,28 and 56) days. When measuring the compressive strength at the late age (56 days), DPA + WRA it was the best model used if it recorded the highest increase in it. Also, the use of WRA10% gave a good result, increasing its strength of the reference mixture and the rest of the mixtures also gave good and remarkable results in increasing the resistance, as the use of ash in these mixtures protects the environment from pollution and gives mixtures of higher resistance and can be used as a partial substitute for cement, except for DPA10%, so the usual mixture was better than it.
Abstract
This main aim of this study is evaluate wide range of fresh and hardened properties of sustainable self-compacting concrete containing various types of Cement Replacement Materials with optimum contents of Polyethylene Terephthalate PET waste plastic as fibers and fine aggregate replacement. This is to evaluate effect of the two forms of PET and to determine the best CRMs could be used with sustainable SCC. such as limestone, glass powder and fly ash with high replacement rate of 70% by weight of cement were used while fourth one (kaolin) was used with replacement rate of 20%. PET fibers were added to SCC with an aspect ratio of 24.4 and 0.7% volume fraction whereas fine aggregate partially replaced by 4% of waste plastic. Four reference mixtures contained FA, LP, GP and KA only, same four mixtures contained 0.7% PET fibers by volume, and the other same four mixtures contained 4% PET fine aggregate by volume. The obtained results all tested fresh properties, which include slump flow, T500, L-Box and segregation resistance were within the limits of the specification reported in EFNERC guidelines. Further, the forms PET have an adverse effect fresh properties of SCC. As for hardened properties (compressive strength, splitting tensile strength, flexural strength and impact strength). Further, this produced type of SCC showed an range of compressive strength (15.2-31.64 MPa) at 28 days. It can be from the current study the best CRMs to be used in SCC containing PET wastes was FA in terms of most tested properties.
Abstract
ABSTRACTStudies in geotechnical engineering have the nonlinear behavior of soils. An experimental study was carried out on models of piled rafts, and four piles with a diameter of 25 mm and a length of (300, 400, and 500) mm were taken, with a raft of (180x180) mm, and compared with the piled-raft system of 180 × 180 raft and nine piles of 19 mm and 500 mm in diameter and length respectively. They were tested for raft resistance, number of piles, length, and diameter while maintaining the spacing between piles. Test results showed the raft performance improved by 76% when adding piles. The increase in the (L/D) ratio for variable (L) length leads to an increase in pile share of 87% for the groups (2×2). Also, pile share was increased by 10% with a decrease in the diameter of piles and an increase in the number of piles in the group. Therefore, the increment in each pile’s skin friction results in an increase in the bearing capacity of each pile.