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Topic Review
Direct and Indirect Solar Gain Systems
The energy crisis, the risk of interruptions or irregular supplies of conventional energy carriers, and the need to protect the environment stimulate the search for new solutions to improve the heat balance of buildings with the use of solar energy. Based on the criterion of the storage, distribution, and discharge time of stored heat, passive solar gain solutions can be divided into direct and indirect solar gain systems.
  • 2.8K
  • 15 Dec 2022
Topic Review
Cost–Benefit Analysis for Road Infrastructure Projects
Cost–benefit analysis (CBA) is considered an effective evaluation method for fostering optimal decision-making and ranking of road infrastructures over decades. Eight distinct modelling categories used for CBA implementation were determined, each encompassing three different modelling approaches for capturing the data risk assessment (deterministic or probabilistic), CBA’s parameters interactive behavior (static or dynamic) and the considered economies (microeconomic or macroeconomic). In-depth content analysis led to the interpretation of the current status of extant models and the identification of three main knowledge gaps: the absence of the CBA’s inputs updating into a probabilistic environment, the deficiency of a dynamic interdependent framework and the necessity of homogenous cost datasets for road projects. Future research directions and a conceptual framework for modelling CBA into a microeconomic, probabilistic and dynamic environment are proposed providing decision-makers with new avenues for more reliable CBA modelling.
  • 2.7K
  • 29 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.
  • 2.5K
  • 05 Nov 2020
Topic Review
Architectural Perspective of Ant Nests
Ants are excellent architects in the animal kingdom. The activities of “design”, “material selection” and “construction” of their nests are full of magical secrets. After hundreds of millions of years of survival of the fittest, the nests of each species of ant are generally characterised by reasonable structure and good mechanical performance, and also reflect the law of “obtaining large and solid living space with the least amount of material”. The complex underground ant colony nest system is large in scale, stable in internal environmental characteristics, has excellent ventilation, appropriate humidity and temperature, and makes use of natural barriers, such as thin grasses, trees, sand and stone, around entrances and exits, as well as having good physical structure, resistant to pressure, water, heat and moisture. Ants have very strict requirements on the size, weight, lustre and colour of the building materials for the nest, such as soil particles. As social insects, ants are responsible for the site selection and materials selection of their nests, the design of the whole nest, organising and coordinating the grand construction process, and managing the nest. 
  • 2.4K
  • 26 Dec 2022
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.
  • 2.4K
  • 27 Jun 2021
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.
  • 2.3K
  • 30 Jun 2021
Topic Review
Cup Lump Natural Rubber
Cup lump is obtained when fresh latex is extracted by tapping into a long cut made in a rubber tree and letting the drips pour into a plastic cup.
  • 2.3K
  • 05 May 2023
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.
  • 2.2K
  • 31 Jul 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.
  • 2.1K
  • 11 Jan 2023
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. 
  • 2.1K
  • 29 Jul 2021
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