Engineering and Technology Journal

The inclusion of polyvinyl alcohol fiber (PVA) into an engineered cementitious composite (ECC) material is essential to impart mechanical and thermal properties, in addition to the enhancement of porosity and microstructural properties. Therefore, this improvement can be achieved by utilizing four different percentages of fiber (0.5, 1, 1.5, 2)%, replaced by volume. Five mixes of (PVA-ECC) of M25 grade strength were produced and tested at three different ages (7, 28, and 90) days. Because of the more porous structure of (PVA-ECC), the results demonstrated that adding 2% by weight of (PVA) fiber to (PVA-ECC) dramatically lowered its thermal conductivity by 36.5% compared to traditional concrete. However, more thermal energy can be captured and concentrated at the cement paste surface with the increasing amount of (PVA) fiber, causing an increment in thermal load and negatively affecting thermal insulating efficiency. Furthermore, compressive strength results revealed an upward trend as the fiber content increased up to 1.5% of (PVA) fiber, demonstrating the maximum improvement in strength. On the other hand, the achievement of 55% of the modulus of rupture by inclusion (2%) (PVA) fiber reveals that the modulus of rupture is mainly influenced by (PVA) fiber inclusion. Finally, there is confidence that the reduced thermal conductivity, hydrophobic surface nature, and improved mechanical characteristics of (PVA-ECC) can meet the demanding standards of environmentally friendly building construction.

The structural performance of reinforced concrete (RC) columns plays a pivotal role in ensuring the safety and stability of buildings and infrastructure. In structural engineering, the quest for optimizing the design and behavior of RC columns has been a persistent pursuit. This research is focused on the columns having a ―large‖ height that the secondary bending moments induced will affect the behavior of the RC column element. Therefore, one critical aspect that has garnered considerable attention is the influence of slenderness on the behavior of these columns, particularly when subjected to eccentric loading. As structures become taller and larger, slenderness is valuable to meet the demands of modern architectural design and urbanization, and understanding how slenderness affects the response of composite RC columns becomes increasingly vital. This study is focused on the strength of composite RC slender columns under eccentric loading. As such, it aims to contribute valuable insights to structural engineering, ultimately enhancing our ability to design resilient and efficient structural systems in a world where tall and slender buildings continue to shape our urban landscapes. Due to its numerous benefits, the concrete-steel composite column with a partially enclosed or full steel section encasement is currently more attractive to people than the reinforced concrete column. Strengthening RC columns by steel channel cross-section embedded in the column will contribute to the column stiffness for ultimate strength capacity and decrease the lateral deformation. Twelve RC columns were tested under eccentric loading, a rectangular cross-section of (150×200) mm. Six have a steel structural channel embedded in the cross-section, while the rest of the RC columns have the same cross-section properties but without a steel channel inside. The improvement in column capacity was (65 to 74)% for columns under moderate eccentricity axial loading and (35 to 50)% for columns under large eccentricity axial loading. Also, the improvement in column stiffness for the lateral deflection was (142 to 69)% for columns under moderate eccentricity axial loading and 84% to 87% for columns under large eccentricity axial loading.

This research seeks to improve the performance behavior of reinforced concrete (RC) beams by examining their load-deflection diagrams using ordinary and prestressed carbon fiber-reinforced polymer (CFRP) bars in place of standard steel reinforcement instead. Using CFRP bars as prestressed tendons to replace the bottom steel rebars, eight 1800-mm long RC beams with a 200 mm×300 mm cross-section were evaluated and split into three groups, evaluating critical loading phases (i.e., cracked, ultimate, and mid-span deflection). Relative to the reference beam, beams reinforced with CFRP had far higher load-carrying capacities and ductility. One beam, reinforced with regular CFRP bars, exhibited a mid-span deflection of 21.2 mm and an ultimate load of 157.2 kN, resulting in a cracked load of 57.7 kN. Another beam using regular CFRP bars also demonstrated improved performance with a mid-span deflection of 21.2 mm, an ultimate load of 160.6 kN, with a cracking load of 57.5 kN. Prestressed CFRP bars led to a significant decrease in mid-span deflection (7.3 mm), a rise in the ultimate load (254.2 kN), and a cracking load of 137.6 kN. Furthermore, the use of two different prestressed CFRP bars showed notable improvements. CFRP bars with these enhancements were employed instead of steel reinforcement in the tension zone, thereby greatly increasing the beam strength with respect to the bonding materials (cement grout and epoxy resin). Thus, using regular and prestressed CFRP bars in traditional steel reinforcement may significantly improve the load-carrying capacity and ductility, producing more robust reinforced concrete buildings.

Clay barriers have garnered much interest in environmental engineering because they successfully reduce various ecological dangers, including groundwater contamination, the migration of leachate from landfills, and waste disposal in landfills. This review paper aims to provide a comprehensive analysis of the features, uses, and performance of clay barriers in various environmental conditions. The problem this review paper addresses is the dangers of waste disposal sites, which emphasizes landfills' harm to the ecosystem and explains why natural clays are often employed as barriers surrounding landfills to keep out pollution. The paper aims to provide an update on essential subjects about barrier system performance difficulties for landfills and their function in reducing the effects of pollutants on the surrounding environment. When designing physical barriers, it is essential to account for a certain amount of material degradation and ensure that the barriers will work for the time needed to achieve landfill sustainability.Subsequently, the elements that affect clay barrier performance are discussed in the study. These variables include long-term stability, chemical compatibility, hydraulic conductivity, and compaction techniques. The usefulness of clay barriers in practical applications is shown via case studies and experimental results. This illustrates the role of clay barriers in preventing the spread of pollutants and safeguarding natural resources.The paper also covers current advancements and new directions in clay barrier technology. These advancements include the use of nanomaterials, barriers made of geopolymers, and innovative construction techniques. The paper also addresses challenges related to the effects of aging, maintenance needs, and regulatory issues. It also provides viable ways to address these obstacles.

The quantity of waste generated during construction and demolition keeps rising annually. Refractory bricks are wastes that have a detrimental effect on the environment. This paper investigates the reuse of refractory brick wastes to create environmentally friendly refractory concrete. To accomplish this goal, two percentages 10 and 25% of alumina cement will be substituted for bauxite powder, and alumina brick as the aggregate will be used instead of the natural aggregates. For each of the six types, a mix of refractory concrete (RFC), 14% water content, and a 1:3 cement/ aggregate ratio. The cast samples were stored at laboratory temperature for a full day while still in their molds. The cast samples were left for (24) hours at laboratory temperature in 100% relative humidity. After that, they were opened and placed in water for 7 days to cure. The specimens were placed in an oven to dry at 110 ℃ for 24 hours after seven days of curing in water. The samples were burned for two hours at temperatures between 1000–1100 ℃ at a rate of 3.33 ℃/min. After that, they were cooled to 25 ℃ before being tested. Then, the cast samples were tested to determine the bulk density, shrinkage, compressive strength, modulus of rupture, and weight change. The produced RFC performed almost comparably to those obtained on conventional RFC. This implies that waste alumina bricks as aggregate, with bauxite powder, can be used to manufacture RFC.

The behavior of subgrade materials plays a pivotal role in determining the longevity of transportation infrastructure. More often, interests had been focused on the mechanical behavior of treated soils prior to the failure stage, while the critical state conditions had received very little attention. This study focused on the critical state characteristics of two distinct lateritic soils (Sample 1, non-plastic and Sample 2, plastic) which were treated with rice husk ash (RHA). The chemical composition of the rice husk ash was examined using X-ray fluorescence. The two natural soils were characterized, and the X-ray diffraction technique was used to identify the soil minerals. The lateritic soils were subjected to varying percentages of rice husk ash treatment, which ranged from 0-21% at 3% intervals. The experiments on treated soils were compaction, California bearing ratio (CBR), and shear strength test. For both samples, the maximum dry density was reduced while the optimum moisture content increased with the addition of RHA from 0-21%. The maximum deviator stress attained values of 941.8k N/m2 and 769.06 kN/m2 at the application of 9% and 12% RHA for Samples 1 and 2, respectively. The CBR of Sample 1 was reduced by 81% with the addition of 21% RHA, while that of Sample 2 increased by 14.22% with the addition of 6% rice husk ash. The critical state parameter (M) for Sample 1 increased by 5.08% at the addition of 9% RHA, while that of Sample 2 increased by 13.09% at 12% RHA. The values are in the same range with some granular and unsaturated soils.

Climate change has significantly increased the risk of drought and natural disasters. Droughts are expected to become more frequent and severe globally, particularly in Iraq, due to decreasing precipitation, rising temperatures, reduced vegetation cover, and water scarcity. The extent and location of drought are primarily influenced by limited precipitation and scarce water resources. In Iraq, drought is a serious and recurring issue exacerbated by the mismanagement of water resources and insufficient precipitation. Drought indicators are utilized to monitor and evaluate drought conditions to address this issue. Drought models typically consider systematic patterns of precipitation shortages, temperature increases, and other factors over decades. This study employs advanced technologies, including remote sensing (RS) and geographic information systems (GIS), to assess drought-affected water surfaces in Iraq from 2000 to 2022 using the Land Surface Water Index (LSWI). The results demonstrate that LSWI effectively identifies hydrological droughts, especially during extreme drought events. Extreme drought conditions were observed in 2020 and 2021, with 43.9% and 43.3% of areas affected, respectively. Severe drought was prevalent in 2000 and 2001, with the highest recorded drought impact being 78.7% and 57.5% of the affected regions, respectively. Additionally, moderate drought conditions were notably high in 2019 and 2003, affecting 9.9% and 9.2% of areas, respectively. The findings of this research can support the development of effective drought alerts using remote sensing. The results confirm the usefulness of LSWI as a rapid and cost-effective index for monitoring changes in land surface water conditions and assessing the impact of drought.

The frequency and intensity of flash floods are expected to increase due to climate change, resulting in significant casualties and damage to infrastructure and the economy. Reliable and timely flood maps are essential for an effective disaster management plan. On December 17, 2021, a severe flash flood in Erbil City resulted in twelve fatalities and extensive damage to the affected area. The ability of synthetic aperture radar (SAR) images to penetrate clouds and heavy precipitation is vital for accurate flood imaging. This study analyzed Sentinel-1 satellite-based radar images before and after the flood to detect the inundation. Two change detection techniques, the Normalized Change Index (NCI) and the Ratio Index (RI), combined with semi-automatic thresholding were employed. Both methods successfully identified the flooded region with consistent findings. The overall accuracy of NCI and RI were 90.5% and 84.3% respectively. The accuracy assessment revealed that the NCI method outperforms the RI method in detecting the flash flood event in Erbil City. This model is viable for disaster management, enabling the evaluation of damage to critical municipal infrastructure and other assets, thus supporting effective urban governance and timely response to emergencies. At the final stage of disaster management, this model can be implemented to evaluate the extent of loss on major municipal infrastructure and other properties within the area.

The construction of hydraulic structures worldwide results in controlled hydrologic regimes through river impoundment. The studied area exhibits a fluctuation in climatic change and flow regulation by hydraulic structures, resulting in variations in flow patterns. This study investigates the variations in the water flow of the Euphrates River in the vicinity of Abbassia Barrage. Three flow scenarios, maximum flow 44.26 m3/s, average flow 28.69 m3/s, and minimum flow 19.67 m3/s for one year, were processed in HECRAS2D software and analyzed to view the impact of flow modulation on hydraulic river behavior between Al-Abbassia and Al-Shammia Barrages. The findings indicate that the hydraulic behavior of the entire river is influenced by changes in the river's hydraulic characteristics due to flow modulation, such as flow velocity, water surface elevation (WSE), and water depth. The flow velocity values ranged from 2.16 m/s, 1.83 m/s, and 1.55 m/s, while the water surface elevations were 19.2–29.4 m, 19.05–29.02 m, and 18.7–28.8 m for maximum, average, and minimum flow conditions, respectively. In terms of water depth, the values ranged from 2.85–7.94 m in straight river sections, and from 3.51–6.86 m in meandering sections, depending on the flow conditions. These results offer valuable insights into the future behavior of river channels under various flow scenarios, which can help in addressing issues arising from prevailing fluvial processes.

A significant amount of reclaimed asphalt pavement must be used to address the growing demand for sustainable road-building materials. One of the problems of employing RAP in mixes is that it makes them more rigid. The guideline specifies that when the amount of RAP is greater than 15%, softer-grade asphalt should be used; however, the asphalt used in Baghdad is 40–50 grade, and its high viscosity makes it challenging to mix when adding RAP. Sometimes, softer grades are not readily available and must be made upon request. Therefore, using some waste oil as a rejuvenator was the task. It is more economical and environmentally friendly. In this study, three asphalt grades (40-50, 60-70, and 85-100) are used, and three distinct types of fillers; hydrated lime, Portland cement, and limestone dust; with an aggregate gradation of maximum size (12.5 mm). Three percentages of recycled asphalt pavement (RAP) materials, 10%, 20%, and 30%, are used. Based on Marshal graphs, the optimum asphalt cement content for each grade was calculated. The samples in all blends were subjected to volumetric analysis, Marshall Stability, flow, and water sensitivity testing. The findings of this study showed that adding hydrated lime enhanced Marshall properties and reduced the sensitivity of asphalt mixes to moisture. Stability increases as the proportion of RAP increases. Asphalt (40-50) with 4% waste oil showed improved stability than the original asphalt mix and presented better Marshall properties than the softer grade (85-100). Additionally, mixes containing RAP may be less moisture-resistant than conventional mixtures.

Laser scanning systems are used to capture high-resolution 3D point clouds, thereby obtaining the object geometry. Terrestrial laser scanning (TLS) technology is an essential data capture tool for providing high-quality point clouds for industrial environments. However, TLS point clouds can be lacking and incomplete due to occlusions prevalent in complicated industrial environments. The static nature of the system makes it necessary to use a complementary data collection technique, such as cameras, to fill the gaps, enrich density, and improve data quality. Therefore, in this research, an integrated work frame was presented that would allow for the automatic and reliable direct co-registration of TLS data and photogrammetry of industrial objects. Combining TLS data and photogrammetric-derived SfM-MVS techniques makes getting a comprehensive dataset of complex objects possible. This is accomplished by employing individual approaches in situations that provide the most favorable conditions for operation. This research aims to detect deformation and determine the geometric features of oil plant equipment (tanks) in industrial sites. This was achieved by integrating TLS and UAV photogrammetry measurements of an oil plant in Basra City, Iraq. The gaps in the point cloud coverage introduced by TLS and UAV individual measurements are eliminated following the integration process. Detailed comparison analyses are performed on cross-sections, and the results are analyzed to show potential found to comply within a few millimeters. After data integration and accuracy analysis, the RMSE was withdrawn to reach 3 cm. This research approves the potential of data fusion to detect deformations in industrial sites.