Peiman Kianmehr

This study evaluates the performance of slag-based alkali-activated mortar (AAM) under ambient curing, focusing on the effects of 2% nano-alumina, sodium hydroxide (NaOH) molarity (12, 14, and 16 M), and sodium silicate-to-sodium hydroxide (S.S/S.H) ratios (1.5 and 2.5). Fresh and mechanical properties, including flowability, compressive strength, and flexural strength, were investigated. Short-term chemical-exposure resistance was examined by measuring water absorption and sorptivity, and by assessing the compressive and flexural strengths of AAM specimens cured for 28 days and subsequently exposed for 28 days (56 days total specimen age) to 5% sulfuric acid, 5% magnesium sulfate, and 3.5% sodium chloride solutions. General linear model analysis of variance (GLM-ANOVA; α = 0.05) was applied to the strength data, with NaOH molarity, S.S/S.H ratio, and nano-alumina content as factors, and exposure condition included as a fourth factor for post-exposure compressive strength. The results indicate that flowability varied markedly with NaOH molarity, S.S/S.H ratio, and nano-alumina addition, while strength depended mainly on interactions among these factors (GLM-ANOVA). For fresh-state and unexposed mechanical performance, the mix with 12 M NaOH, S.S/S.H = 2.5, and nano-alumina addition achieved the best balance of workability and compressive strength. Flexural strength increased with NaOH molarity up to an optimum at 12 M, beyond which a decline was observed at 14–16 M, while increasing consistently with curing time up to 56 days. GLM-ANOVA showed significant NaOH × nano-alumina interactions for compressive strength at 28 and 56 days (p = 0.002 and 0.030, respectively), significant three-factor interactions for flexural strength (p = 0.004 and 0.022, respectively), and exposure condition as the largest contributor (32.2%) to post-exposure compressive strength. For short-term chemical-exposure resistance, mixes with 2% nano-alumina at 12–16 M and an alkali ratio of 1.5 retained superior residual compressive and flexural strengths after 28 days of exposure to sulfuric acid, magnesium sulfate, and sodium chloride, compared with their counterparts having a higher S.S/S.H ratio. Overall, no single mixture provided the best balance across all the properties investigated.

This study examines the global implications of a 1 m sea-level rise, with a focus on its impacts in the Gulf region, particularly Dubai. The literature review highlights Dubai’s vulnerability to both static and dynamic factors, including groundwater rise, wave action, soil erosion, and corrosion. The research estimates the cost of feasible preventive solutions to protect urban areas from these risks. Various construction strategies are evaluated to enhance resilience against flooding, erosion, and corrosion while maintaining long-term sustainability. The study assesses five mitigation techniques, land reclamation, wave breaking, sump pump installation, corrosion prevention, and landscape paving, across 10 areas in Dubai. Land is categorized by use (residential, commercial, recreational) and proximity to the shoreline. Average unit costs are estimated at $48.9/m² for residential, $46.4/m² for commercial, and $49.9/m² for recreational areas. Costs are higher near shorelines ($62.6/m²) than inland ($39/m²), largely due to seawall construction. Overall, the average remedial cost is about $48/m², approximately 2% of the average coastal property value, indicating economic feasibility. The total cost corresponds to about 0.5% of Dubai’s GDP and 5% of the construction sector revenue.

The high cooling demand in arid regions like the United Arab Emirates (UAE) necessitates sustainable alternatives to conventional air conditioning. This study investigates the performance of a horizontal closed-loop shallow geothermal ventilation (SGV) system, also Earth-to-Air Heat Exchanger (EAHX), for building cooling in the UAE's hot arid climate. An integrated methodology combining experimental measurements, analytical modeling, and Computational Fluid Dynamics (CFD) simulations was employed. Results demonstrate that lower airflow velocities (1.5 m/s) maximize temperature reduction, achieving differentials up to 16.6°C from a 45°C inlet. A critical finding for design optimization is that over 60% of the total cooling occurs within the initial 10–15 m of pipe length, indicating a point of diminishing returns. Integration with a conventional AC unit reduced the mechanical cooling load by over 50%, with net energy savings of up to 0.985 kW. A preliminary economic assessment indicates a promising payback period of approximately 6.7 years. This work provides empirically validated design guidelines for EAHX systems in arid, sandy environments, contributing to sustainable building practices in the Gulf region.

This study evaluates the performance of slag-based alkali-activated mortar (AAM) under ambient curing, focusing on the effects of 2% nano-alumina, sodium hydroxide (NaOH) molarity (12, 14, and 16 M), and sodium silicate-to-sodium hydroxide (SS/SH) ratios (1.5 and 2.5). Fresh and mechanical properties, including flowability, compressive strength, and flexural strength, were investigated. Durability was evaluated by measuring water absorption and sorptivity, and by assessing compressive and flexural strengths of AAM after 28 days of exposure to 5% sulfuric acid, 5% magnesium sulfate, and 3.5% sodium chloride solutions. Additionally, General Linear Model Analysis of Variance was conducted to assess the effects of NaOH molarity (12–16M) and 2% nano-alumina on the fresh, mechanical, and durability properties of alkali-activated mortar. Results indicate that NaOH molarity and SS/SH ratio significantly influence workability and strength. The optimal mix (12 M, SS/SH = 2.5 with nano-alumina) achieved a balanced improvement in workability and compressive strength. While flexural strength generally increased with molarity, higher concentrations did not always yield proportional benefits. The addition of nano-alumina greatly increased matrix densification through the filling of micro voids, reducing water absorption and sorptivity with improved mechanical performance and chemical resistance of alkali-activated materials. A manifest synergistic effect of nano-alumina amount and sodium hydroxide molarity was determined, with optimal mixes — namely those with 2% nano-alumina at 12–16 M and at the alkali ratio of 1.5 — showing superior compressive and flexural strength and improved durability against aggressive exposures to sulfuric acid, magnesium sulfate and sodium chloride. While high nano-alumina content marginally decreased workability, it increased cohesion in the mixes which also confirmed its effectiveness as an important ingredient in high-performance mix design. Overall, the interaction between NaOH molarity and nano-alumina plays a key role in enhancing AAM performance, highlighting its potential as a sustainable and durable alternative to conventional cement-based materials.

Due to the fact that a large number of farms are equipped with surface irrigation systems, the proper design and use of these systems increases their efficiency, which is of particular importance due to the current water crisis. In this context, it is possible to use models and tools that increase efficiency and reduce water wastage in these irrigation systems and achieve even higher efficiency than pressurized irrigation. Among the tools used in this field, we can mention floater valves. The performance of furrow irrigation is highly dependent on the inflow. One of the irrigation methods in this system is irrigation with constant inflow. To stabilize and create this state in the furrows, a flow stabilizing set is used at the head of the fields. One of these sets includes a stabilization tank with an overflow and a pump. Disadvantages of this method include excess water overflow from the tank and its wastage, as well as the need for excess energy for the pump. In this study, for solving these problems, the use of floating valves has been investigated to provide a constant inflow in furrow irrigation. For this purpose, a concrete platform was constructed on which the water storage sources were placed. A hydraulic slope was provided with a height difference of about 30 cm to transfer water from them to the flow stabilization tank. Inside the stabilization tank, two two-inch brass floating valves were used to stabilize the water level. Numerous field experiments and evaluations have shown that a height difference of 30 cm, before completely draining water from water storage sources, stabilizes the maximum inflow of 2.2 and the minimum of 1.3 L per second into the tank. Floating valves keep the water level inside the stabilization tank constant at a height of 50 cm from the outlet center of the stabilization tank with inflow of 0.8 L per second. Measurement of the inflow to the furrows by flow measuring instruments (flume) also confirmed that the intensity of the inflow to the furrows was always constant throughout the test. The main purpose of this study was to create a constant input flow in irrigation systems, especially furrow irrigation, using simple mechanical tools that can be used by all farmers. Also, reducing water loss in farms and water management in the field with the approach of reducing energy consumption is important. These goals were investigated during 60 furrow irrigation operations, and measurements showed that they could be achieved by gravity-free energy provided the minimum water head was observed and mechanical tools such as valves were used. Therefore, considering the importance of inflow in furrow irrigation, according to the results of this research, it is possible to use mechanical and piping tools, including valves, etc., in the facilities at the head of the farm to control the water entering the furrow, and one of these tools is a floater valve. In the furrow irrigation method with constant input flow rate, in order to reduce water wastage and also reduce energy costs in secondary pumping, a mechanical set that stabilizes the flow with the help of gravity energy can be used. This issue is very important due to the reduction of energy consumption and production of greenhouse gases, as well as the reduction of water wastage in the current water crisis. Therefore, the innovation presented in this current manuscript has economic, environmental, social and etc. importance.

Purpose: Schools should be adequately built and operated to protect students' health. Green building rating systems, including Leadership in Energy and Environmental Design (LEED), assist the construction industry in improving both the resource efficiency and indoor environmental quality of its buildings. Construction professionals may waive some green modifications and available optional credits due to their high costs or construction complexities. This study investigates whether cost-effective green modifications can adequately address the student health.Design/methodology/approach: In an effort to identify how school projects in Dubai, UAE prioritized LEED credits related to occupant well-being, the study identified eight LEED credits (called “Health and wellbeing” credits). Cost data from a sample of nine Dubai schools were used to develop an indicator, named the Feasibility Index Score (FIS), to quantify the attractiveness of LEED credits based on their cost and implementation complexity. Physical measurements taken from the sample schools give a window into current indoor environmental quality (IEQ) conditions of schools in the local region, while FIS provides insight into potential financial barriers towards improving these conditions.Findings: The authors identified eight “Health and wellbeing” credits, which may net up to 14 points or 13% of all possible LEED points. Despite this, assessments of the sample schools revealed that six of the “Health and wellbeing” credits exhibited relatively low FIS values. This may cause these credits to be waived when lower tiers of LEED certifications are desired.Research limitations/implications: A sample of nine schools was chosen for this research; further investigation using a greater sample size is recommended.Practical implications: The paper's IEQ assessment indicates the importance of health-related credits and suggests implementing them regardless of their FIS.Originality/value: This paper recognizes the importance of providing more weight to credits that directly impact the health of occupants, particularly when upgrading existing structures.

A range of thermal pretreatment conditions were used to evaluate the impact of high pressure thermal hydrolysis (HPTH) on the biodegradability of waste-activated sludge (WAS) under aerobic and anaerobic conditions. It was found that pretreatment did not increase the overall extent to which WAS could be aerobically biodegraded. Thermal pretreatment transformed the biodegradable fraction of WAS (X_H) to readily biodegradable COD (S_B) (16.5–34.6%) and slowly biodegradable COD (X_B) (45.8–63.6%). The impact of pretreatment temperature and duration on WAS COD fractionation did not follow a consistent pattern as changes in COD solubilization did not correspond to the observed generation of S_B through pretreatment. The pretreated WAS (PWAS) COD fractionations determined from aerobic respirometry were employed in anaerobic modeling and it was concluded that the aerobic and anaerobic biodegradability of PWAS differed. It was found that that thermal pretreatment resulted in as much as 50% of the endogenous decay products becoming biodegradable in anaerobic digestion. Overall, it was concluded that the COD fractionation that was developed based upon the aerobic respirometry was valid. However, it was necessary to implement a first order decay process that reflected changes in the anaerobic biodegradability of the endogenous products through pretreatment.