بحوث سكوبس — تميم محمد هاشم

Designing armor units that can withstand harsh marine environments while remaining cost-effective is a central challenge in modern breakwater engineering. This study introduces a newly designed artificial armor unit and evaluates its performance in comparison with established alternatives such as the accropode, core-loc, and conventional rock armor. The findings reveal that the new unit achieves a lower packing density, reducing the number of units required and thereby improving overall cost-effectiveness. Armor layers formed from the newly designed unit exhibited higher porosity than accropode but lower than core-loc, effectively avoiding the slender geometries that compromise durability. Structural analysis using STAAD.Pro confirmed that the new unit developed lower tensile stresses, with reductions of 15% compared to accropode and 35% compared to core-loc under flexure, torsion, and combined loading, demonstrating superior integrity. Hydraulic stability tests showed that the randomly placed newly designed units resisted failure at a stability number (Ns) of 1.4, lowering run-up by 50% and overtopping by 59%, while the uniformly placed newly designed units reached 1.5 without failure, with run-up and overtopping reductions of 30% and 37%, respectively. Collectively, these outcomes highlight the clear hydraulic and structural advantages of the new design over conventional systems, establishing it as a stronger and more resilient solution for breakwater protection. © 2026 by the authors.

Introduction: The accelerating growth of urban and industrial activities has led to mounting volumes of nonbiodegradable waste, posing urgent environmental challenges for modern societies. Recycling these wastes in stone matrix asphalt (SMA) mixtures helps reduce environmental impact while improving pavement performance. This study investigates the use of shredded cigarette filters (SCF) as fiber stabilizers and recycled medicine blister packs (RMBP) as aggregate replacement in SMA mixtures to enhance performance and support waste management. Methods: Laboratory testing included Superpave volumetric analysis, assessment of moisture susceptibility in terms of tensile strength ratio test (TSR), fatigue life evaluation, determination of rutting behavior in terms of Hamburg wheel-tracking test (HWTT), and service life modeling, to assess the effect of SCF and RMBP. Results: The recycled SMA mixture showed improvements compared to the control mix, including lower air voids, higher binder retention, enhanced moisture resistance (TSR of 86.7%), and improvements in stiffness and fatigue life (up to 20%). HWTT results revealed rut depth reductions of 19-31%, and service life modeling predicted an extension from 18.0 years for the control to 24.3 years for the recycled mixture under heavy traffic. Discussion: Incorporating SCF and RMBP into SMA mixtures demonstrated strong potential for enhancing pavement sustainability and aligned with ongoing advancements in waste-based asphalt technologies. The findings highlighted the broader value of recycled materials in improving mixture performance, although the work remains limited by the absence of certain durability tests and the reliance on controlled laboratory conditions. Conclusion: The findings suggested that incorporating SCF and RMBP into SMA mixtures can improve durability, moisture resistance, and service life, while supporting environmental sustainability through the recycling of postconsumer waste. © 2026 The Author(s). Published by Bentham Open., 2026. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Premature failure of hot mix asphalt (HMA) pavements in Iraq is typically caused by heavy loading, which requires frequent maintenance. Several approaches should be developed to prevent such failure and construct efficient and cost-effective pavements. In this study, a stone matrix asphalt (SMA) mixture is suggested as an alternative to reduce the damages in terms of rutting resistance and prolong the pavement’s service life. The SMA is a gap-graded mix of two ingredients, asphalt mortar and coarse aggregate. This study aims to design and evaluate SMA mixtures utilizing two kinds of asphalt binder (virgin and modified) and a stabilizing agent. Crumb rubber (CR) is a type of recycled rubber utilized as a binder modifier with four mixing proportions (5, 10, 15, and 20%). On the other hand, cellulose fiber pellets (CFP) are plant-based waste materials utilized as stabilizing agents with four percentages (0.2, 0.3, 0.4, and 0.5%). It is believed that incorporating these wastes into asphalt mixtures significantly impacts the environmental footprint. The generated Superpave SMA mixtures are assessed regarding their mechanical characteristics (air voids, voids filled with asphalt, and voids in mineral aggregate). Several lab tests were conducted to evaluate the performance of the produced SMA mixtures, including a drain-down test, tensile strength ratio (TSR) test, resilient modulus (MR) test, and flexural fatigue test. The findings indicated that the SMA mixtures with (0.4% CFP + 15% CR) had superior resistance to permanent deformation and moisture damage. In addition, at (0.4% CFP + 15% CR), the SMA mixtures achieved the lowest drain-down value and the highest resistance to flexural fatigue against the control mix. © The Author(s), under exclusive licence to Chinese Society of Pavement Engineering 2024.

In an era where sustainable infrastructure is crucial, self-healing asphalt emerges as a transformative solution to enhance pavement longevity and reduce maintenance costs, addressing the global challenge of deteriorating road networks. This study presents a pioneering investigation into the development and performance evaluation of encapsulated rejuvenators for self-healing asphalt, utilizing two distinct compositions; waste cooking oil (WCO) and Fischer-Tropsch bright stock oil (FTBSO), across three capsule sizes (1 mm, 2 mm, and 3 mm). Through the experimental tests on compressive strength, thermal stability, and rupture resistance under wet conditions, the ongoing study highlights the critical influence of capsule size and composition on the mechanical performance, as well as the resistance to degradation and oxidation under similar asphalt production conditions, including applied stresses and temperatures. The findings indicate the superior performance of 3 mm FTBSO-based encapsulated rejuvenators, which exhibit exceptional compressive strength (155 N), minimal weight loss (2% at 200° C after 1-hour short-term aging), and high rupture resistance (80 minutes to break under moisture at 100° C), making these capsules ideal for withstanding mechanical and thermal stresses, while ensuring effective crack repair. In addition, both 2 mm and 3 mm FTBSO-and WCO-based rejuvenator capsules demonstrated high resistance to compressive stresses, excellent thermal stability, and strong rupture resistance, making these capsules suitable for selfhealing asphalt applications. In contrast, 1 mm WCO-based rejuvenator capsules exhibited the lowest compressive strength (32 N), the highest weight loss (10% after 1 hour of short-term aging at 200° C), and the fastest rupture under moisture (18 minutes to break at 100° C), making these capsules the least suitable for self-healing asphalt applications. © 2025 by the authors.

With rising global temperatures and increasing sustainability demands, the need for advanced pavement solutions has never been greater. This study breaks new ground by integrating phase change materials (PCMs), including paraffin-based wax (Rubitherm RT55), hydrated salt (Climator Salt S10), and fatty acid (lauric acid), as binder modifiers within warm mix asphalt (WMA) mixtures. Moving beyond the traditional focus on binder-only modifications, this research utilizes recycled cigarette filters (CFs) as a dual-purpose fiber additive, directly reinforcing the asphalt mixture while simultaneously transforming a major urban waste stream into valuable infrastructure. The performance of the developed WMA mixture has been evaluated in terms of stiffness behavior using an Indirect Tensile Strength Modulus (ITSM) test, permanent deformation using a static creep strain test, and rutting resistance using the Hamburg wheel-track test. Laboratory tests demonstrated that the incorporation of PCMs and recycled CFs into WMA mixtures led to remarkable improvements in stiffness, deformation resistance, and rutting performance. Modified mixes consistently outperformed the control, achieving up to 15% higher stiffness after 7 days of curing, 36% lower creep strain after 4000 s, and 64% reduction in rut depth at 20,000 passes. Cost–benefit analysis and service life prediction show that, despite costing USD 0.71 more per square meter with 5 cm thickness, the modified WMA mixture delivers much greater durability and rutting resistance, extending service life to 19–29 years compared to 10–15 years for the control. This highlights the value of these modifications for durable, sustainable pavements. © 2025 by the authors.

Pavement deterioration is often the result of intense traffic and increased runoff from storms, floods, or other environmental factors. A practical solution to this challenge involves the use of permeable pavements, such as permeable interlocking concrete pavement (PICP), which are designed to effectively manage water runoff while supporting heavy traffic. This research investigates the effectiveness of PICP in two distinct surface patterns: stretcher bond and 45° herringbone, by assessing their performance in terms of water infiltration and runoff using two different methods. The first approach has been conducted experimentally using a laboratory apparatus designed to simulate rainfall. Various conditions were applied during the performance tests, including longitudinal (L-Slope) and transverse (T-Slope) slopes of (0, 2, and 4%) and rainfall intensities of (40 and 80 L/min). The second approach has been implemented theoretically using Surfer 2.0 software to simulate the distribution of infiltrated water underneath the layers of PICP. Moreover, the behavior of PICP has been analyzed statistically using artificial neural networks (ANNs). The results indicated that at a rainfall intensity of 40 L/min, equal infiltration was observed in both patterns on 0% and 4% T-Slope. However, the 45° herringbone PICP showed better infiltration on the 8% T-Slope. Additionally, at 80 L/min rainfall, equal infiltration was observed in both patterns on 0% L-Slope for 0% and 4% T-Slope. The 45° herringbone PICP also demonstrated higher water infiltration on the 8% T-Slope, and this trend continued as the L-Slope increased. PICP with a 45° herringbone surface pattern exhibited superiority in reducing runoff compared to the stretcher bond pattern. The statistical models for the stretcher bond and 45° herringbone patterns demonstrate high accuracy, as evidenced by their correlation coefficient (R2) values of 99.97% and 97.32%, respectively, which confirms their validity. Despite the variations between the two forms of PICP, both are strongly endorsed as excellent alternatives to conventional pavement. © 2025 by the authors.

The disposal of solid waste has become one of the critical issues facing governments due to its environmental impact due to the difficulty of its decomposition. Electric cable waste (ECW) is one of these wastes. Its production increased in Iraq over time due to the demolition and reconstruction of residential and commercial homes. Therefore, reusing it in other industries, such as concrete technology, is a promising solution. Limited studies have studied the utilization of these local wastes as a replacement for natural sand in the short and long term. Therefore, the aim of this study is to investigate the properties of mortar incorporating recycled ECW as a partial replacement for sand. The fine aggregate (natural sand) was replaced by weight with ECW ranging from 0 to 25 % in the step of 5 %. Flow rate, as well as mechanical properties (compressive strength, flexural strengths, and density), were executed at 7, 28, and 360 days. It was found that the best performance was obtained at a replacement ratio of 5 % of ECW with mechanical strengths close to or slightly less than the reference sample and a 17 % reduction in density. However, regarding sustainability, it is possible to produce a lightweight structural mortar with a density lower than 1700 kg/m3 and a compressive strength of 36 MPa at 360 days when replacing the natural sand with 25 % ECW. © Hasan, Z.A., Nasr, M.S., Kubba, H.Z., Hashim, T.M., 2025. Published by Peter the Great St. Petersburg Polytechnic University

Concrete is a brittle substance; thus, it is reinforced with rebars and fibers to enhance its ductility. On the other hand, the presence of waste from various industries negatively impacts the environment. The ongoing reconstruction in Iraq has resulted in an abundance of locally produced rebar-connecting wire (RCW) and copper electric wire (CEW) waste. To minimize the environmental impact of these wastes, they can be reused in other industries, such as the concrete industry. Few studies have dealt with concrete’s structural and mechanical properties containing these local residues. Therefore, this study included an experimental investigation of concrete columns with and without various types of industrial and waste fibers. Two types of industrial fibers (macro hooked-end; CH, and micro straight; CS) steel fibers and two types of waste fibers (RCW and CEW) were utilized. Six reinforced concrete (RC) columns (150 × 150 × 450 mm3) were cast: one control column without fibers and five columns with fibers. The fiber content within the columns was fixed at 0.75% of the concrete volume. The cracks pattern, load-deflection behavior and concrete strain for RC columns were investigated. Moreover, the mechanical properties in terms of compressive, splitting tensile, and flexural strengths tests were also conducted. The results revealed that all types of fibers used improved the mechanical and structural properties of the concrete. Moreover, although the hybrid synthetic fibers gave the best improvement compared to the reference sample, the waste fibers (especially RCW) showed a significant improvement that reached 30.91% in relation to the ultimate load and (10.1, 10.8 and 14.4%) in relation to the compressive, tensile, and flexural strengths respectively. © 2024, International Islamic University Malaysia-IIUM. All rights reserved.

Mineral filler is a mineral fine particle that passes through the No.200 sieve which plays a critical role in the performance of Hot-Mix Asphalt (HMA) mixes. A better understanding of how fillers affect the characteristics of HMA mixes is critical for good mix design and higher HMA performance. The main objective of this paper is to assess the impact of mineral filler on the mechanical characteristics of HMA using the Marshall mix design method. For this purpose, two different mineral filler types, namely, limestone and ordinary Portland cement (OPC) with three filler contents were utilized to prepare asphalt mixture samples. Optimum asphalt content was determined by the Marshall mix design method using six different asphalt contents (4.0%, 4.5%, 5.0%, 5.5%, 6.0%, and 6.5%). In this paper, the characteristics of two kinds of filler were assessed using three experimental tests: Marshall test, retained strength test, and indirect tensile strength test. This study considered three filler percentages: 4, 7, and 10% by aggregate weight. These percentages fall within the limit specified in the SCRB specification (SCRB, R/9, 2003). The results indicated that HMA containing cement filler resulted in higher stability levels, tensile strength, and index of retained strength values compared to the limestone dust. Therefore, the utilization of cement filler provides better performance for asphalt mixes. The addition of cement filler with 10 % and limestone filler with 7 % seem to be the optimum filler contents due to satisfying all SCRB specification requirements. © 2024 American Institute of Physics Inc.. All rights reserved.

Sustainability and reducing environmental damage caused by CO2 emissions have become issues of interest to researchers in the construction sector around the world. Reducing the cement content in concrete by partially substituting it with by-products or waste falls within this field as the cement industry is responsible for 7% of global CO2 emissions. On the other hand, self-compacting concrete (SCC) is one of the special types of concrete that contains a large amount of powder (most of which is cement) to ensure its flow under the influence of its weight without separating its components. Therefore, to produce eco-friendly SCC, many researchers have replaced part of the cement with clay brick waste powder (CBWP) since brick units are among the most widely used building materials after concrete. Accordingly, this study aims to review previous research that included using CBWP in SCC. The effect of these wastes on the fresh, mechanical, durability and microstructural properties of cement was reviewed. Additionally, a comparison between the environmental impacts of SCCs with different CBWP contents has been conducted using the life cycle assessment (LCA) approach. It was found that the highest value of CBWP that can be used without negatively affecting the different properties of concrete is 10% by weight of cement. Moreover, regarding environmental impact, using CBWP as a substitute for cement reduces environmental damage, and the lowest environmental impact that can be achieved per strength unit (MPa) is 37.5%. © 2023 by the authors.

A local scour is the removal of bed material from around the pier of the bridge. This bed removal is considered a big problem and is of great concern for hydraulic engineers. They should find economic solutions for this problem. The exaggerated local scour around bridge piers leads to many problems for the whole bridge structure, such as stability problems that may lead to the bridge's destruction. This paper aims to verify the scour depth around different shapes of uniform bridge piers for different flow conditions than those done by previous researchers using different prediction models. Where the consistency of previous experimental investigations is verified by multiple nonlinear regression analysis (MNLR), Gene Expression Programming (GEP) and Artificial Neural Network (ANN) models. In the comparison of values that were measured and predicted by the four models (CFD, MNLR, ANN, and Gene), it is seen that the ANN model has the ability to predict the Ys/b values higher than other models used in relation to the measured values. This makes the ANN model superior in predicting the Ys/b value over the other used models, followed by the Gene model. In comparison, the values of the R2 and RMSE for the four models that were used in this study, for the Ys/b model using the ANN had a value of 0.9978 and 0.0147, respectively, while those for the Ys/b model using the Gene model were 0.9800 and 0.0375, respectively. © 2023 by the authors. Licensee C.E.J, Tehran, Iran.

Carbon dioxide emissions are one of the problems that arouses the interest of scientists because of their harmful effects on the environment and climate. The construction sector, particularly the cement industry, is a significant source of CO2. On the other hand, solid waste constitutes a major problem facing governments due to the difficulty of decomposing it and the fact that it requires large areas for landfill. Among these wastes are LCD waste glass (WG) and used rope waste. Therefore, reusing these wastes, for example, in concrete technology, is a promising solution to reduce their environmental impact. Limited studies have dealt with the simultaneous utilization of glass waste as a substitute for cement and rope waste (nylon) fiber (WRF). Therefore, this study aimed to partially replace cement with WG with the addition of rope waste as fibers. Thirteen mixtures were poured: a reference mixture (without replacement or addition) and three other groups containing WG and WRF in proportions of 5, 15 and 25% by cement weight and 0.25, 0.5 and 0.75% by mortar weight, respectively. Flow rate, compression strength, flexural strength, dry density, water absorption, dynamic modulus of elasticity, ultrasonic pulse velocity and electrical resistivity were tested. The results indicate that the best ratio for replacing cement with WG without fibers was 5% of the weight of cement. However, using WRF increased the amount of glass replacement to 25%, with an improvement in strength and durability characteristics. © 2023 by the authors.

The difficulty of decomposing solid waste over time has made it a significant global problem because of its environmental impact and the need for large areas for disposal. Among these residues is the waste of the rendering mortar that is produced (falls to the ground) while applied to wall surfaces. The quantity of these materials may reach 200 to 500 g/m2. As a result of local urban development (in Iraq), thousands of tons of these wastes are produced annually. On the other hand, the emission of greenhouse gases in the cement industry has had a great environmental impact. One of the solutions to this problem is to reduce the cement content in the mix by replacing it with less emissive materials. Residues from other industries are considered a relatively ideal option due to their disposal on the one hand and the reduction of harmful emissions of the cement industry on the other hand. Therefore, this research aims to reuse rendering mortar waste powder (RMWP) as a possible alternative to cement in mortar. RMWP replaced the cement in proportions (0, 10, 15, 20, 25, and 30% by weight). The flow rate, flexural and compressive strengths, ultrasonic pulse velocity, bulk density, dynamic modulus of elasticity, electrical resistivity, and water absorption tests of the produced mortar were executed. Microstructural analysis of the produced mortar was also investigated. Results indicated that, for sustainable development, an eco-friendly mortar can be made by replacing cement with RMWP at a rate of 15%, resulting in a 17% decrease in compressive strength while maintaining or improving durability properties. Moreover, the microstructure became denser and more homogeneous in the presence of RMWP. © 2023 by the authors.

Pavement deterioration is mainly caused by high traffic loading and by increased levels of runoff water resulting from storms, floods, or other reasons. Consequently, this issue can be efficiently solved by employing permeable pavement, such as permeable interlocking concrete pavement (PICP) to control water runoff and endure increased traffic loads. This study investigates the performance of PICP, in both 45° and 90° herringboned surface patterns, in terms of the infiltration of volumes of water, runoff water volumes, and the ability of pavement to withstand static loading. All the related tests in this study were implemented using a lab apparatus that was fabricated as a simulator for rainfall. Various conditions were adopted during the performance tests, including the application of longitudinal slopes (0, 2.5, 5, and 7.5%), side slopes (0, 2.5, and 5%), and different rainfall intensities (25, 50, 75, and 100 L/min). The results indicated that at high rainfall intensities (75 and 100 L/min), PICP with the 45° herringboned surface pattern had the highest volume of infiltrated water and the lowest runoff water at all the adopted longitudinal and side slopes. In addition, PICP with the 45° herringboned surface pattern showed higher resistance to deflection under a static loading test than the 90° herringboned pattern under the same conditions. Therefore, PICP with a 45° herringboned surface pattern showed supremacy in terms of runoff reduction and load resistance in comparison to PICP with a 90° herringboned pattern. Even though there are differences between the two types of PICP, they are both strongly recommended as alternatives to regular pavement. © 2023 by the authors.

Challenges posed by industrial solid waste, particularly Electrical Cable Waste (ECW), have been increasingly recognized due to their environmental implications and substantial decomposition timelines. ECW, a byproduct of aggressive demolition and reconstruction in Iraq, has seen limited investigation regarding its potential use as an aggregate substitute and fiber additive in concrete applications. This study endeavors to repurpose ECW as a partial replacement for natural sand and as fiber reinforcement, with a focus on both short-term and long-term performance. A fixed ratio of natural sand was substituted with ECW (10%), and waste fibers were integrated at varying concentrations (0.5%, 1%, 1.5%, 2%, 2.5%, and 3%). For comparative purposes, a control mix devoid of ECW and fibers was also examined. Evaluations were conducted on the flow rate, along with compressive strength, flexural strength, and density at intervals of 7, 28, and 360 days. Results indicate that despite a reduction in flowability and a decrease in hardened density to under 2000 kg/m3, inclusion of ECW can yield a sustainable lightweight mortar without significant compromise on strength. This study thus underscores the potential of waste repurposing as a viable solution for waste management and environmental enhancement. Additionally, this approach can help mitigate natural resource depletion, such as that of natural sand, fostering a move towards sustainable construction practices. © 2023 Lavoisier. All rights reserved.

This study investigated the behaviour of permeable interlocking concrete pavement (PICP) in terms of water infiltration volume, surface runoff volume, and load resistance, using a specific lab apparatus, designed and manufactured as a rainfall simulator. The connecting pattern of the surface blocks is a stretcher bond pattern with a joint spacing of (5 and 10 mm) between the block pavers to be filled with a small-sized open-graded aggregate to finalise the permeable surface of joints. The adopted pattern has been examined under three rainfall intensities of (20, 40, and 60 l/min), four longitudinal slopes (0, 2, 4, and 6%), and three transverse slopes (0, 2, and 4%). The results showed that at high rainfall intensities (60 l/min), high longitudinal slopes (6%), and high transverse slopes (4%), the stretcher-bonded PICP with 5 mm spacing between the blocks infiltrates less water than the one with 10 mm. Furthermore, PICP with 5 mm spacing has higher surface runoff than PICP with 10 mm spacing at high rainfall intensities (60 l/min), high longitudinal slopes (6%), and all transverse slope percentages (0, 2, and 4%). In addition, the load resistance of stretcher-bonded PICP with 5 mm spacing between the blocks is higher than that of 10 mm at all the subjected loads in the load-deflection test. Despite the shown differences between both types of PICP, they are strongly recommended as an alternative choice for ordinary dense-graded pavement. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

It is essential to create more ecologically friendly and sustainable types of concrete due to severe emissions and the exhaustion of raw sources in cement manufacturing. The main objective was to determine if palmdate fibers were appropriate for use in wood-cement composite boards. A second objective is to improve the suitability of palmdate fibers for use in high-performance cementitious boards by pre-treatment procedures and carbon dioxide curing. The flexural strength and microstructural characteristics of the cement fiber boards were examined. In addition, durability tests including cycles of freezing and thawing, wetting and drying, and warm water immersion were also conducted. According to results, the use of treated palmdate fibers in high-performance cementitious boards was significant, because it increased flexural strength by 96%. Moreover, all CO2 cured boards showed higher flexural strength than control and pure carbonation curing 100% do not resulted in higher strength development. Also, X-ray diffraction patterns revealed, compared to control boards, CO2 cured boards showed more CaCO3 and lower Ca(OH)2 and according to SEM, aging exposures lead to make fibers rupture rather than pull out. © 2023 Trans Tech Publications Ltd, Switzerland.

Recycled aggregate pavement in bituminous can be repercussion to mitigation in the exhaustion of rudimentary aggregate and asphalt, orientation to alleviation in the quantities of tailings organized into the garbage dumps. This research aimed to investigate the performance of Hot Mix Asphalt (HMA) surface with recycled concrete aggregate (RCA) as a replacement to the natural aggregates (NA) of four substitution rates (0, 20, 40, and 60) % from natural coarse aggregate. Four HMA were designed by using the conventional Marshall method to investigate the density, air void, flow and stability. The results indicated the properties of mixes with RCA have a weaker impact on the performance asphalt mixture. Generally, the results articulate that the employment RCA in HMA lead to reduce the density and Marshall stability while procure to increase the air void percentage and flow values greater than its value in HMA with natural coarse aggregate. © 2023 Author(s).

Growing environmental pollution worldwide is mostly caused by the accumulation of different types of liquid and solid wastes. Therefore, policies in developed countries seek to support the concept of waste recycling due to its significant impact on the environmental footprint. Hot-mix asphalt mixtures (HMA) with reclaimed asphalt pavement (RAP) have shown great performance under rutting. However, incorporating a high percentage of RAP (>25%) is a challenging issue due to the increased stiffness of the resulting mixture. The stiffness problem is resolved by employing different types of commercial and noncommercial rejuvenators. In this study, three types of noncommercial rejuvenators (waste cooking oil (WCO), waste engine oil (WEO), and date seed oil (DSO)) were used, in addition to one type of commercial rejuvenator. Three percentages of RAP (20%, 40%, and 60%) were utilized. Mixing proportions for the noncommercial additives were set as 0–10% for mixtures with 20% RAP, 12.5–17.5% for mixtures with 40% RAP, and 17.5–20% for mixtures with 60% RAP. In addition, mixing proportions for the commercial additive were set as 0.5–1.0% for mixtures with 20% RAP, 1.0–1.5% for mixtures with 40% RAP, and 1.5–2.0% for mixtures with 60% RAP. The rutting performance of the generated mixtures was indicated first by using the rutting index (G*/sin δ) for the combined binders and then evaluated using the Hamburg wheel-track test. The results showed that the rejuvenated mixtures with the commercial additive at 20 and 60% RAP performed well compared to the control mixture, whereas the rejuvenated ones at 40% RAP performed well with noncommercial additives in comparison to the control mixture. Furthermore, the optimum percentages for each type of the used additives were obtained, depending on their respective performance, as 10%, 12.5%, and 17.5% of WCO, 10%, 12.5–17.5%, and 17.5% of WEO, <10%, 12.5%, and 17.5% of DSO, and 0.5–1.0%, 1.0%, and 1.5–2.0% of the commercial rejuvenator, corresponding to the three adopted percentages of RAP. © 2022 by the authors.

In dense-graded pavements, which are used for composing and recomposing roads in the paving industry around the world, failures occur due to increasing traffic loads and the rising runoff of water caused by storms or floods, or any other reason. Therefore, this kind of issue can be treated by adopting a permeable pavement system such as the permeable interlocking concrete pavement (PICP) to manage the runoff of water and tolerate the increasing loads of traffic efficiently. In this study, a laboratory apparatus has been designed and fabricated as an artificial rainfall simulator to investigate the behavior of different surface concrete block patterns under different rainfall intensities. Measuring the levels of runoff and the volume of infiltrated water are the fundamental factors in creating an essential comparison between the elected surface patterns. In this study, stretcher bond, 90º herringbone, and 45° herringbone patterns are chosen with (5 mm and 10 mm) joint spacing between the concrete blocks. All three surface block patterns are tested in terms of four longitudinal slopes (0%, 2.5%, 5%, and 7.5%) and three side slopes (0%, 2.5%, and 5%) under three rainfall intensities (25 l/min, 50 l/min, and 75 l/min). Based on the results, the stretcher bond pattern showed superior results to other bonds because it reduces surface runoff and spreads the water evenly under the permeable concrete block roadway. The 90° herringbone and 45° herringbone patterns, on the other hand, are the best for increasing the durability of roads. © 2022 The Authors

The Rapid reduction of energy resources and the escalated effects of global warming have created a strong motivation to find some new techniques in the field of paving construction. Adopting new technologies, such as warm-mix asphalt (WMA) or the recycling process of asphalt can be very helpful for the economy and have a significant impact on the environmental footprint. Thus, this research aimed to study the mechanical and durable characteristics of modified WMA mixtures using (1.0%, 1.5%, and 2.0%) Sasobit REDUX®, (0.3%, 0.4%, and 0.5%) Aspha-Min®, and (0.07%, 0.1%, and 0.125) ZycoTherm® additives corresponding to three percentages of reclaimed asphalt pavement (RAP) (20%, 40%, and 60%). Three mixing temperatures have been conducted in this study to generate WMA mixtures at (135 °C, 125 °C, and 115 °C) corresponding to three compacting temperatures (125 °C, 115 °C, and 105 °C). The mechanical properties of the developed WMA mixtures have been evaluated using the Superpave volumetric properties (air voids, voids filled with asphalt, and voids in mineral aggregate), while the durable properties have been investigated using the resilient modulus test (MR) at 25 °C, resilient modulus ratio (RMR), and Hamburg wheel-track test in terms of permanent deformation, moisture susceptibility, and rutting resistance. To make the WMA mixtures accept high quantities of RAP (>25%), an insignificant increase in the amounts of WMA additives was needed to produce mixtures carrying sustainability labels. Results indicated that all the used additives had pushed the WMA mixtures to achieve considerable mechanical properties, whereas the best properties for the WMA mixtures containing 0%, 20%, 40%, and 60% of RAP have been achieved by mixing with (1.0% Sasobit REDUX® @ 125 °C), (1.0% Sasobit REDUX® or 0.3% Aspha-Min® @ 135 °C), (1.5% Sasobit REDUX® @ 125 °C), and (2.0% Sasobit REDUX® or 0.5% Aspha-Min® @ 135 °C), respectively. On another hand, the best durable properties have been achieved by mixing the mentioned WMA mixtures containing 0%, 20%, 40%, and 60% of RAP with 0.07%, 0.07%, 0.1%, and 0.125% of ZycoTherm® at 153 °C, respectively. Using such additives in the recycled WMA mixtures made it possible to activate waste recycling in the paving industry. © 2022 by the authors.

Using the ABAQUS software, this article presents a numerical investigation on the effects of various stud distributions on the behavior of composite beams. A total of 24 continuous 2-span composite beam samples with a span length of 1 m were examined (concrete slab at the top and steel I-section at the bottom). The concrete slab used is made of a reactive powder concrete with a compressive strength of 100.29 MPa. The total depth of each sample was 0.220 m. The samples were separated into four groups. The first group involved 6 specimens with shear connectors distributed into 2 rows with different distances (65, 85, 105, 150, 200, and 250 mm). The second group had the same spacing of shear connectors as the first group except that the shear connectors were distributed with one row along the longitudinal axis. The third group consisted of six specimens with single and double shear connectors distributed along the longitudinal axis. The fourth group included six specimens with one row of shear connectors arranged in a staggered distribution along the longitudinal axis. Results show that the optimum spacing was 105 mm in all groups and the deflection in group four fluctuated up and down due to the non-symmetrical distribution of the shear connectors. © 2022 Yasar Ameer Ali et al., published by De Gruyter.

Geotextile reinforcement techniques have been widely used in paving works around the world and have proven to be effective in improving pavement performance. This study has focused on using different positions and numbers of geotextile reinforcement sheets between the layers of flexible pavement for rutting reduction. Fitting depth was measured in the field at seven constructed sections of the pavement of the road model. Each section has been strengthened with different reinforcement approaches. All road sections were subjected to a maximum load repetition of 10,000 cycles. The results indicate that using three layers of geotextile beneath each course of the designed road pavement sections (surface, binder, and base) reduced rutting by 96%. Traffic benefit ratio (TBR) has been employed in this study to reveal the behavior of geotextile reinforcement in increasing the service life of the road. TBR values are the load cycling ratio between the reinforced and unreinforced section for the exact recorded rut depth, it has been found to be minimally equal to 4 for the case of using one layer of reinforcement at interface I, and that value keeps growing up for other reinforcement cases. © 2022 Abdul Hadi Meteab AL Sa'adi et al., published by De Gruyter.

Reactive powder concrete (RPC) is one of the distinctive kinds of concrete whose benefits are high mechanical performance and durability. It contains a high content of cement, which means a high amount of carbon dioxide emitted during manufacturing. Scientists have tended to search for a way to reduce environmental damage, and one solution is to partially replace cement with mineral admixtures, waste from other industries, or by-products. There are restricted studies involving the use of high content of compounding mineral admixtures in the making of RPC. Therefore, this research aims to produce sustainable RPC with a low cement content (50%). The main objective of this research is to study the impact of substituting cement with 50% of silica fume (SF) + fly ash (FA) on the mechanical characteristics of RPC. Three mixtures containing various percentages of SF + FA were poured, in addition to the reference mixture. Flowability, flexural and compressive strengths, ultrasonic pulse velocity (UPV), and density were examined. The results showed that a sustainable RPC can be produced by substituting the cement with 10% SF and 40% FA with an improvement in workability and compressive strength and an insignificant reduction in other properties. © 2022 Mohammed Salah Nasr et al., published by De Gruyter.

In this study, a sustainable filler made from papyrus fiber ash (PFA) is used as a partial cement replacement in hot mix asphalt mixtures (HMA). The replacement levels used are 0, 5, 10, and 15% by weight of ordinary Portland cement. The hot mix asphalt samples were subjected to Marshal volumetric properties (stability, flow, and air voids) and service tests (tensile strength ratio test and immersion compression test) to predict the influence of the used filler modifier on the moisture sensitivity of blended HMA. Best results have been achieved by using 10% of PFA, whereas all the prepared samples with the mentioned percentage of the filler modifier showed a lower sensitivity to moisture in comparison with the control samples, which contained 0% of PFA. The used technique proved to be very efficient in keeping the pavement safe from deformation caused by moisture. At the same time, using sustainable filler materials proved to be an environmentally eco-friendly method. © 2022 Tameem Mohammed Hashim et al., published by De Gruyter.

This paper presents a numerical investigation for the behavior of simply supported T-section deep beams, which strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets. The used specimens were (1.8 m length), (450 mm width and 100 mm depth) flange dimensions, and (180 mm width and 360 mm depth) web dimensions. The specimens were divided into four groups. Mainly, the difference between specimens in each group is in the main reinforcement details. The control group consisted of six beams non-strengthen with CFRP, the other groups were similar to the control group but externally strengthened with CFRP sheets, which were (0.131 mm) thickness. In detail, the second group was strengthened with CFRP sheet at the bottom surface of the web. The third group was strengthened horizontally with CFRP sheets at both sides of the specimen's web. The last group was strengthened with three sheets of CFRP; one at the bottom face of the web and the others at the web sides. The results show that using CFRP at the bottom slightly increased the ultimate strength and changed the failure mode from flexural to shear. Using CFRP at the sides significantly increased both flexural and shear strength, while using CFRP at the sides and bottom of the web did not significantly enhance the ultimate strength in comparison with using CFRP at the sides only. © 2020 Trans Tech Publications Ltd, Switzerland.

Alum sludge (AS) is one of the final products from water treatment processes. Handling and disposal of alum sludge has become one of the major economic and environmental concerns. An experimental investigation was examined to study the possible utilization of alum sludge as aggregate substitute in asphalt mixtures for pavement construction applications. Five asphalt mixtures containing various contents of the AS, 0% (reference mix), 30%, 50%, 70% and 100%, as a replacement to the fine aggregate were prepared in this study. The results conducted that alum sludge is a suitable material for producing asphalt mixes that contains of AS ranging from 30% to 50% as partial replacement for fine aggregates to achieve almost all the standard requirements for aggregates in asphalt mixtures.. © Published under licence by IOP Publishing Ltd.