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  • Delayed ettringite formation in concrete

    Delayed ettringite formation in concrete

    By

    Nirmal Raj Joshi
    in

    Delayed ettringite formation (DEF) is a chemical reaction that occurs in hardened concrete, leading to internal expansion and cracking. This phenomenon typically arises due to the late formation of ettringite (a calcium sulfoaluminate hydrate) after the concrete has already set and hardened. DEF is a significant durability concern, particularly in heat-cured concrete structures, as it…

  • Effect of temperature on curing of concrete

    Effect of temperature on curing of concrete

    By

    Nirmal Raj Joshi
    in ,

    The curing of concrete is a critical process that significantly influences its strength, durability, and long-term performance. Temperature plays a vital role in the hydration process of cement, affecting the rate of strength development and the final properties of concrete. Concrete curing is the process of maintaining adequate moisture and temperature to ensure proper hydration…

  • Testing ASR in concrete before and after construction

    Testing ASR in concrete before and after construction

    By

    Nirmal Raj Joshi
    in ,

    Alkali-silica reaction (ASR) is a deleterious chemical reaction that occurs between the alkaline pore solution in concrete and reactive silica present in certain aggregates. This reaction forms an expansive gel that can induce cracking, reduce durability, and compromise structural integrity (Thomas, 2011). Given its long-term implications, ASR is a critical concern in concrete design and…

  • Erosion of concrete by wind and water

    Erosion of concrete by wind and water

    By

    Nirmal Raj Joshi
    in , ,

    Erosion by water The erosion of concrete caused by hard suspended particles in flowing water presents a significant challenge in the design and maintenance of hydraulic infrastructure. This degradation mechanism is particularly critical for structures such as spillways, stilling basins, and dam outlets, where high-velocity flows and sediment-laden water are common. Erosive processes are primarily…

  • N-of-1 trials

    N-of-1 trials

    By

    Wulandari Setiadewi
    in ,

    N-of-1 clinical trials, also known as single-subject trials, focus on identifying the most effective treatment for individual patients by employing rigorous, data-driven methodologies. This essay explores the potential of N-of-1 trials in advancing personalized medicine, their historical context, design considerations, and future directions, emphasizing their compatibility with the broader goals of evidence-based medicine. While they…

  • Safety of deteriorated structures

    Safety of deteriorated structures

    By

    Nirmal Raj Joshi
    in ,

    The collapse of various civil engineering structures-such as bridges, dams, and buildings-has become a common occurrence in recent years, often attributed to aging and material degradation (refer to relevant news reports). Many of these structures were constructed decades ago, with assumed service lives typically ranging from 50 to 80 years. For instance, the design life…

  • Use of genetic algorithm for optimum proportioning of concrete

    Use of genetic algorithm for optimum proportioning of concrete

    By

    Nirmal Raj Joshi
    in , ,

    Genetic Algorithms (GAs) have emerged as a robust optimization technique within civil engineering, particularly in the design of concrete mix proportions. Their inherent ability to address complex, multi-objective, and nonlinear optimization problems makes them well-suited for this application. Conventional mix design methodologies often rely on iterative, trial-and-error approaches that are both time-consuming and may fail…

  • Implementing AI in civil engineering

    Implementing AI in civil engineering

    By

    Nirmal Raj Joshi
    in , ,

    Artificial intelligence (AI) is rapidly transforming civil engineering by offering innovative solutions that enhance efficiency, safety, and sustainability across a variety of applications. From optimizing structural designs to predicting maintenance needs and improving construction management, AI technologies are reshaping traditional practices. By analysing vast datasets, AI enables engineers to make informed decisions, leading to smarter…

  • Fatigue stress and RC deterioration

    Fatigue stress and RC deterioration

    By

    Nirmal Raj Joshi
    in ,

    Fatigue stress represents a critical factor in the progressive deterioration of reinforced concrete (RC) structures, particularly under conditions involving repeated loading and corrosive environments. The synergistic interaction between fatigue and corrosion, commonly referred to as corrosion-fatigue, significantly intensifies the degradation of structural materials, thereby diminishing overall structural integrity and long-term durability. Fatigue stress originates from…

  • Radius of earth (classical trigonometry)

    Radius of earth (classical trigonometry)

    By

    Nirmal Raj Joshi
    in ,

    Suppose that, while lying on a beach near the equator watching the sun set over a calm ocean, you start a stopwatch just as the top of the sun disappears. You then stand, elevating your eyes by a height H=1.7m, and stop the watch when the top of the sun again disappears. If the elapsed…

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