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Introduction
Published in Sumit Sharma, Composite Materials, 2021
As said, “Need is the mother of all inventions,” the modern composites – that is, polymer composites – came into existence during World War II. During World War II due to constraint impositions on various nations for crossing boundaries as well as importing and exporting the materials, there was scarcity of materials, especially in the military applications. During this period, the fighter planes were the most advanced instruments of war. The lightweight yet strong materials were in high demand. Further, applications like housing of electronic radar equipment require nonmetallic materials. Hence, the glass fiber-reinforced plastics (GFRPs) were first used in these applications. Phenolic resins were used as the matrix material. The first use of composite laminates can be seen in the Havilland Mosquito Bomber of the British Royal Air Force. The composites exist in day-to-day life applications as well. The most common existence is in the form of concrete. Concrete is a composite made from gravel, sand, and cement. Further, when it is used along with steel to form structural components in construction, it forms one further form of composite. The other material is wood, which is a composite made from cellulose and lignin. The advanced forms of wood composites can be plywoods. These can be particle-bonded composites or a mixture of wooden planks/blocks with some binding agent. Nowadays, these are widely used to make furniture and as construction materials.
Concrete Technology
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Once it is placed and compacted, the concrete must be cured before it is finished to make sure that it does not dry too quickly. As the cement solidifies, the concrete shrinks. To minimize this problem, concrete must be kept damp during the initial days it requires to set and harden.
Life cycle environmental impact considerations for structural concrete in transportation infrastructure
Published in John Harvey, Imad L. Al-Qadi, Hasan Ozer, Gerardo Flintsch, Pavement, Roadway, and Bridge Life Cycle Assessment 2020, 2020
Coupled with this growing material consumption to meet societal demand, there have been notable environmental impacts from the production of concrete and its constituents. Among the most discussed impacts are the high greenhouse gas (GHG) emissions from the production of cement. Conventional cement is composed of finely ground clinker, a kilned and quenched material, and mineral admixtures. The production of clinker requires high temperature heating, at ~1400°C, and results in calcination of limestone (the conversion of CaCO3 → CaO + CO2) to form a reactive material. The high levels of cement production and the GHG emissions from both energy-derived and process-derived (i.e., those from calcination) sources contribute to concrete being responsible for over 8% of anthropogenic GHG emissions (Miller et al., 2016a). As a result of both the energy resources used in the cement kilns and the raw materials in the kilns, there has also been growing concern related to air pollutant production from cement manufacture, such as SOX emissions (USEPA, 2016a). Additionally, the production of particulate matter (PM) has been noted for almost every stage of raw material acquisition through concrete production (USEPA, 1994, USEPA, 1995, USEPA, 2006). Much of the PM emissions from energy resources and cement manufacture have controls to reduce the amount of particulates that enter that atmosphere; however, fugitive emissions from sources such as handling, leakages, and transportation can still contribute notable PM emissions.
LGBM-based modeling scenarios to compressive strength of recycled aggregate concrete with SHAP analysis
Published in Mechanics of Advanced Materials and Structures, 2023
Bin Xi, Enming Li, Yewuhalashet Fissha, Jian Zhou, Pablo Segarra
The construction industry is a significant contributor to global greenhouse gas emissions. Notably, concrete production, one of the most commonly utilized building materials worldwide, generates billions of cubic meters annually. Nonetheless, the manufacture of concrete necessitates substantial amounts of natural resources such as aggregates, water, and cement, raising concerns about its environmental impact in terms of carbon emissions and depletion of natural resources [1, 2]. To mitigate these concerns, Recycled Aggregate Concrete (RAC) has been proposed as a sustainable solution, whereby recycled construction and demolition materials are utilized as aggregates [3–8]. In recent years, the use of RAC has gained momentum due to its several advantages over conventional concrete, including lower environmental impact, production costs, and increased sustainability. Additionally, the incorporation of recycled aggregates into concrete presents a potential solution to waste disposal challenges, as it reduces the quantity of waste sent to landfills [9, 10].
Development and challenges in finite element modelling of post-installed anchors in concrete
Published in Structure and Infrastructure Engineering, 2023
Chandani Chandra Neupane, Jessey Lee, Tilak Pokharel, Hing-Ho Tsang, Emad Gad
There is limited research considering dynamic loading as compared to static loading which might be due to the complexity associated with modelling and analysis. Further, behaviour of post-installed anchors subjected to extreme loading conditions (e.g., seismic load, wind load etc.) have not been studied using FEA as per author’s knowledge. Concrete is weak in tension, so it is invariably prone to cracking due to external loading or thermal constraints. Whenever a crack forms in the concrete, there is a high probability of crack being formed at the location of anchors (Eligehausen, Mallee, et al., 2006). Figure 8a illustrates changes in stress distribution in uncracked and cracked concrete. As compared to uncracked concrete, the change in stress distribution contributes to different failure mode and substantial reduction in anchor capacity (Eligehausen & Balogh, 1995; Yoon, Kim, & Kim, 2001).
Effect of multiwalled carbon nanotubes on compressive behavior of concrete at elevated temperature for mass concreting
Published in European Journal of Environmental and Civil Engineering, 2023
Kashan Nisar, Muhammad Shahid Siddique, Muhammad Rizwan, Syed Hassan Farooq, Muhammad Usman, Asad Hanif
Concrete is a building material composed of cement, fine aggregates (sand), and coarse aggregates mixed with water. Due to its great strength, durability, and raw material availability, it is one of the most often used construction materials (Khaliq & Kodur, 2013). Portland cement is one of the most common synthetic substances used in concrete production. It is the most utilized man-made commodity on the earth (Lothenbach et al., 2011). The world’s population has expanded recently, so the need for high-rise structures utilizing high-strength concrete is significantly increased (Choe et al., 2015). High-strength concrete is becoming popular due to its excellent mechanical qualities, including compressive and tensile strength (Shah et al., 2019). It is also more resistant to chemical assaults when compared to normal-strength concrete (NSC) (Shannag & Shaia, 2003). Furthermore, because of its dense microstructure, high-strength concrete has low permeability (Tobbala et al., 2022).