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Topic Review
Kerb Construction
Concrete kerbs can be prepared by precast and cast in situ methods. The precast concrete kerbs can be manufactured by conventional (using a vibrator), dry-pressed and wet-pressed methods and can be installed in almost all weather conditions. Possible rainfall, temperatures and sunlight hours are considered in casting in situ kerbs, and they are more labour-intensive compared to the precast variations. However, cast in situ kerb can better handle sudden changes of direction. There is no study found comparing different aspects of in situ casting and precast kerb. Both types of concrete kerb are suggested for construction by all authorities, such as the Austroads and AASHTO. The precast kerbs require manual placement and have been a major source of workplace injury in the United Kingdom. Past studies have suggested that the use of special lifting equipment (such as vacuum lifters, lifting clamps or stone magnets), reduction in kerb section length, reduction in kerb foundation depth, use of a lightweight or hollow concrete section or other lightweight materials, such as polymer, can reduce the likelihood of such workplace injuries and may also lead to quicker construction as well as better construction quality.
  • 3.5K
  • 28 Mar 2022
Topic Review
Probabilistic Slope Stability Evaluation
Evaluating the stability of slopes in soil is an important, interesting, and challenging aspect of civil engineering. Despite the advances that have been made, evaluating the stability of slopes remains a challenge. Slope failures are often caused by processes that increase shear stresses or decrease shear strengths of the soil mass [4, 9]. Water plays a role in many of the processes that reduce strength; water is also involved in many types of loads on slopes that increase shear stresses. Another factor involved in most slope failures is the presence of soils that contain clay minerals. In concept, any slope with a factor of safety above 1.0 should be stable [6, 10]. In practice, however, the level of stability is seldom considered acceptable unless the factor of safety is significantly greater than 1.0. In this study an attempt has been done to perform stability analyses corresponding to several different conditions, reflecting different stages in the life of the new railway embankment found in Ethiopia. As various parameters are involved and determined based on correlations, the probabilistic approach was employed to scrutinize the effects of uncertainty on the likelihood of failure. There is no problem with performing a single analysis in which the embankment is considered to be drained and is treated in terms of effective stresses, and in which the clay foundation material is considered to be undrained and is treated in terms of total stresses (during end-of-construction analysis). This is because equilibrium in terms of total stresses must be satisfied for both total and effective stress analyses [2]. The inertia slope stability analysis was used. Since the foundation materials are overconsolidated cohesive soils such as stiff to very stiff clays that tend to dilate during the seismic shaking. The embankment is also expected to be well graded compacted granular material [12]. The critical factor of safety for the railway embankment during short term analysis was found to be 2.199. However, it has increased by 17.6% during the long term analysis (i.e., 2.585). Typical minimum factor of safety used in slope design are about 1.5 for normal long-term loading conditions and about 1.3 for end-of- construction conditions.  Apart from that, the minimum short term and long term factor of safety were reduced by 44.5% and 35.9% respectively, due to the introduction of the horizontal seismic load in the limit equilibrium analysis. According to Hynes-Griffin and Franklin (1984) criteria [8] the minimum factor of safety for ~1m tolerable displacement is 1. However, the minimum factor of safety during the pseudostatic analysis (i.e., 1.221) was found to be 22% higher than the required minimum factor of safety. Beside, Newmark’s deformation analysis has been done to predict slope displacement. However, the analysis predicted zero permanent slope displacement. Since; the Newmark (1965) method assumes no deformation of the slope during the earthquake if the pseudostatic factor of safety is greater than 1.0. The more realistic probability of failure is likely in between of 0% and 6.9 %. The sensitivity analysis showed that, the cohesion of the clay layer (i.e., layer II) governs the stability of the railway embankment.
  • 3.4K
  • 30 Oct 2020
Topic Review
Application of Artificial Neural Networks in Construction Management
Artificial neural networks (ANN) exhibit excellent performance in complex problems and have been increasingly applied in the research field of construction management (CM) over the last few decades. This paper aims to provide a comprehensive understanding of the application of ANN in CM research and useful reference for the future.Content analysis is performed to comprehensively analyze 112 related bibliographic records retrieved from seven selected top journals published between 2000 and 2020. The results indicate that the applications of ANN of interest in CM research have been significantly increasing since 2015. Back-propagation was the most widely used algorithm in training ANN. Integrated ANN with fuzzy logic/genetic algorithm was the most commonly em-ployed way of addressing the CM problem. In addition, 11 application fields and 31 research topics were identified, with the primary research interests focusing on cost, performance, and safety.
  • 3.3K
  • 27 Oct 2021
Topic Review
Earthquake Early Warning Systems
An Earthquake Early Warning Systems (EEWS) is the combination of different elements, such as seismometers, sensors, communication appliances, computers, and alarm systems, able to detect and warm of the arrival of seismic waves. It serves to mitigate damages and losses , to be used primarily in moderate and high seismically active regions.  
  • 3.3K
  • 25 Feb 2021
Topic Review
Basic Oxygen Furnace Slag Characteristics and Properties
Basic oxygen furnace slag is an significant environmental liability produced by the steel industry, considering the volume of material produced and its specific physical and chemical characteristics. To further understand the advantages and limitations of BOF slag aggregate and to establish its role in the replacement of natural sand in Portland cement concrete, the slag was characterized in depth in terms of both its physical and morphological properties.
  • 3.3K
  • 10 May 2023
Topic Review
Bitumen Aging and Rejuvenation Chemistry
Bitumen aging and rejuvenation include a series of chemical transformations that the material undergoes and that results in the variation of its physical characteristics.
  • 3.1K
  • 30 Jun 2021
Topic Review
Types of Insulation Materials
Insulation materials are classified into three main categories depending on material composition, material technology, and material sustainability index.
  • 3.1K
  • 11 Jan 2023
Topic Review
Prestressed Concrete Girders
Prestressing methods were used to realize long-span bridges in the last few decades. For their maintenance, dynamic nondestructive procedures for identifying prestress losses were mainly developed since serviceability and safety of Prestressed Concrete (PC) girders depend on the effective state of prestressing. In fact, substantial long term prestress losses can induce excessive deflections and cracking in PC bridge girders. However, old unsolved problematics exist since a variation in prestress force does not significantly affect the vibration responses of such PC girders. As a result, this makes uncertain the use of natural frequencies as appropriate parameters for prestress loss determinations. Thus, amongst emerging techniques, static identification based on vertical deflections has preliminary proved to be a reliable method. In fact, measured vertical deflections take accurately and instantaneously into account the changes of structural geometry of PC girders due to prestressing losses. Given the current state of methodologies, the manuscript represents a state-of-the-art review of some important works on determining prestress losses. The attention is principally focused on a static nondestructive method, and a comparison with dynamic ones is elaborated.
  • 2.9K
  • 05 Nov 2020
Topic Review
Early-Age Cracking in Concrete
Cracking is a common problem in concrete structures in real-life service conditions. In fact, crack-free concrete structures are very rare to find in real world. Concrete can undergo early-age cracking depending on the mix composition, exposure environment, hydration rate, and curing conditions.
  • 2.9K
  • 27 Jun 2021
Topic Review
Types of Steel Liners
There are significant levels of concern about both the safety assessment and financial evaluation of the whole hydropower system, especially at early project stages. In addition, there is a variety of reliable and accurate methods for analysis, design, and optimization of steel pressure liners in hydropower plants. Several countries have developed specific regulations and codes for the design, installation, and safety evaluation of under-pressure piping, as well as estimates of the potential risks associated with failure. This article reviews the current methodologies and codes available for design and safety assessment of either unstiffened or stiffened pressure steel liners in hydropower plants.
  • 2.8K
  • 28 Mar 2022
Topic Review
Civil Construction Sector Supported by Industry 4.0 Technologies
The civil construction sector is under pressure to make construction processes more sustainable, that is, aligned with economic, social, and environmental sustainability. Civil construction faces the challenge of reducing the consumption of natural resources, ensuring safe work, and optimizing processes, especially handwork. However, the insertion of Industry 4.0 Technologies into civil construction has allowed sensors, robots, modelling and simulation systems, artificial intelligence, and drones to have their productivity, efficiency, safety, strategic and environmental management enhanced. Furthermore, Industry 4.0 Technologies can contribute to civil construction through innovative, sustainable, and technological solutions focused on the flow of work, which can provide growth through the balance of costs/benefits in the management of projects and works.
  • 2.8K
  • 22 Mar 2022
Topic Review
Wind Turbines
Wind turbines (WTs) are large devices utilized to convert the wind's kinetic energy into electricity. There are several different typologies of WTs, the most common type being the so-called Horizontal Axis Wind Turbine (HAWT) systems. In this configuration, the rotation axis of the rotor is parallel to the ground. Specific attention must be paid to the orientation with respect to the wind direction, which is different from other types of wind turbines such as those with a vertical axis (VAWT), whose orientation is independent of the prevailing wind direction. For HAWT, the three-bladed upwind configuration is the most common one, with the rotor facing the incoming wind. WTs can be deployed both on- or offshore and have very different blade lengths, which result in different sizes (especially regarding the tower height) and power output. Due to fatigue and exposure to outdoor elements, WT monitoring and diagnostics are strictly needed to reduce structural and mechanical failure and achieve cost-effective energy production. This requires both the Structural Health Monitoring of the WTs load-bearing components (tower, blades, foundations, etc) and the Condition Monitoring of their mechanical parts (gearbox, generator, etc).
  • 2.8K
  • 02 Mar 2022
Topic Review
Energy Piles
Energy piles are a relatively new technology that have dual function as heat transferring and load bearing. Due to the influence of temperature cycles, additional thermal stress and relative displacement of the pile will be generated; this is different from the load transferring mechanism of the conventional pile. In order to study the thermodynamic characteristics of the energy pipe pile under dual working conditions and temperature cycles, field tests were carried out on the PHC (prestressed high-strength concrete) energy pipe pile without constraining on the top of the piles. Displacement gauges were arranged on the top of the pile, and concrete strain gauges (temperature, strain) were embedded in the pile.
  • 2.7K
  • 31 Jul 2021
Topic Review
Sustainable Housing in Rwanda
Baked clay bricks (Impunyu) is the dominant wall construction material in Rwanda. Clay deposits in the country’s lowlands are utilized for baked clay bricks. Despite the ongoing campaign, the use of wood by some local brick producers is unfriendly to the environment. Recent research has called for alternative methods in order to reduce the cost and impact on the environment. Earlier efforts with compressed earth blocks were saddled with weight and a substantial use of cement for good surface texture and adequate resistance against surface erosion. This research explored the potentials of using an appropriate dose of clay (from Muhanzi), volcanic light aggregate (Amakoro, (from Musanze)), and cement to produce unbaked shelled compressed earth blocks (SCEB). SCEB is a compressed earth block with an outer shell and inner core of different cement content or materials, compressed into a unit block. The result is a masonry unit with a higher surface resistance, durability, and desirable architectural effect produced with a 60% reduction in cement content. A weight reduction of 12% was achieved with an optimum content of 33% of the volcanic lightweight aggregate. A cost reduction of 25% was recorded over conventional compressed earth brick walls and a 54% over sand-cement block walls. Possible future trends were also identified with appreciable prospects in earthen architecture. 
  • 2.5K
  • 29 Jul 2021
Topic Review
Evaluation of Externalities of Highway Infrastructures
Various externalities caused by highway infrastructures, such as promoting economic development, traffic congestion, and air pollution, are becoming more and more important. Currently, there is no multi-dimensional quantitative evaluation of the externalities of highway infrastructures, hindering the sustainable planning and development of highway infrastructures. A summary of the status of the evaluation of the externalities of highway infrastructures is from four perspectives: social evaluation, economic evaluation, ecological evaluation, and comprehensive evaluation.
  • 2.5K
  • 11 Mar 2022
Topic Review
Sustainable Road Infrastructure
The implementation of sustainability in road infrastructure has become dependent on providing measurements and guidance for including sustainable principles in road projects, resulting in a dozen voluntary certification and rating systems to evaluate the level of sustainability of road design, construction, and maintenance. The predominance of issues which analyse the life cycle assessment of road infrastructures in its both environmental and economic dimension as a way to mitigate their effects on climate change, including the reduction of resources and energy consumption, or of energy consumption and greenhouse gases emissions during the construction and operation stages, respectively.
  • 2.5K
  • 27 Dec 2022
Topic Review Peer Reviewed
Challenges in Sewer System Maintenance
A sewer system is an important infrastructure of every settlement. A sewer system is a set of construction facilities used for the quick removal of wastewater from the humans’ immediate environment and its transport to a wastewater treatment plant or direct discharge into an appropriate recipient. In order for the sewer system to perform its purpose properly, its proper maintenance is required. Maintenance of a sewer system is very demanding since the system is mostly underground which makes it difficult to be accessed and maintained. The maintenance of a sewer system can be preventive (regular) or corrective (reactive). The regular maintenance occurs at certain intervals, whereas the reactive maintenance occurs in the case of some unforeseen event. This paper presents the history of sewer systems, as well as basic and alternative types of sewer systems. Furthermore, challenges that arise during sewer system maintenance and difficulties that maintenance employees face in their work are presented in this paper, as well as the ways in which sewer systems are maintained.
  • 2.4K
  • 20 Jan 2023
Topic Review
Properties and Characteristics of C6F12O
In order to cope with the problem that no gas fire suppressant can be used in the future, perfluoro-2-methyl-3-pentanone (C6F12O), also known as FK-5112, Novec 1230 or Novec 649, with its environmentally friendly performance, zero ODP, GWP of approximately one and atmospheric lifetime of up to two weeks (as shown in Table 1), has been considered as the next generation of halon alternatives. C6F12O belongs to fluorinated ketones which is different to HFCs. Its nontoxicity, noncombustibility, excellent insulation properties and fire suppression efficiency have attracted worldwide attention. The thermophysical parameters, safety and environmental issues and other properties such as the dispersion characteristics of C6F12O are important indexes to evaluate whether it is appropriate to replace the halon. Meanwhile, these properties and parameters are critical to determine the application scenes of fire suppressant, the selection of fire extinguishment facilities and the engineering calculation of the fire extinguishment system.
  • 2.3K
  • 18 Apr 2022
Topic Review
Hydrological Model Uncertainties
Hydrological models are a simplified representation of the natural hydrological processes. These models are developed to understand processes, test hypothesis, and support water resources decision-making. However, as they are simplification of the natural processes, they are inherently uncertain. Their uncertainty primarily stems from their structure, parameter, input and calibration data observations. While parameter and structural uncertainties are related to both data information content and process conceptualizations, input and calibration data observations are a result of data information content. In order to enable an improved process understanding and better decision making, a systemic uncertainty analysis of all of the four sources is critical. 
  • 2.3K
  • 08 Jan 2021
Topic Review
Remote Sensing Methods for Flood Prediction
Floods are a major cause of loss of lives, destruction of infrastructure, and massive damage to a country’s economy. Floods, being natural disasters, cannot be prevented completely; therefore, precautionary measures must be taken by the government, concerned organizations such as the United Nations Office for Disaster Risk Reduction and Office for the coordination of Human Affairs, and the community to control its disastrous effects. Floods are uncertain depending on several climatic and environmental factors, and therefore are difficult to predict. A classification framework is presented which classifies the remote sensing technologies being used for flood prediction into three types, which are: multispectral, radar, and light detection and ranging (LIDAR). 
  • 2.2K
  • 21 Mar 2022
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