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Construction materials and sustainable development
Published in Natalia Yakovleva, Edmund Nickless, Routledge Handbook of the Extractive Industries and Sustainable Development, 2022
Patrick Junior, Daniel M. Franks
Aggregate is a broad category of granular mineral particles mainly used in construction (Wang, 2016), corresponding to particular grain sizes (Craig & Loughnan, 1964). Aggregates are used as ingredients in cement and concrete production, asphalt mixtures, ballast, and fill materials for road bases and formation. Aggregates are also used for industrial purposes, such as sandblasting and, to a lesser extent, in the hydraulic fracturing process of oil and gas extraction. The American Society of Testing Materials (ASTM) defines aggregates as granular materials, such as sand, gravel, crushed stone, or iron blast-furnace slag, used with cementing medium to form hydraulic-cement or mortar (ASTM, 2012). Aggregates may be categorised into natural (sand, gravel, and crushed stone), manufactured (recycled concrete), and artificial (slag). Natural aggregates are those that are obtained from mineral sources through mechanical processing only.
Numerical investigations of discrete crack propagation in Montevideo splitting test using cohesive elements and real concrete micro-structure
Published in Günther Meschke, Bernhard Pichler, Jan G. Rots, Computational Modelling of Concrete and Concrete Structures, 2022
B. Kondys, J. Bobiński, I. Marzec
The concrete mix consisted of cement CEM II/A-LL 42.5R, flying ash, aggregate and water (Table 1). Aggregate was divided into three main fractions i.e. sand with maximum grain size equal 2 mm, gravel with the grain size in the range of 2 mm and 8 mm and gravel with the maximum grain size equal 16 mm.
Aggregates
Published in A. Bahurudeen, P.V.P. Moorthi, Testing of Construction Materials, 2020
Aggregates form 70–80% of the total volume of concrete, along with binders, i.e. cementitious materials. Aggregates can be either obtained naturally or produced by different crushing methods. The necessity for understanding the properties of aggregates arises since any changes brought about by the inherent properties of the aggregates can affect the integrity of the structure, which can be fatal in nature due to lack of durability and required strength. This necessitates the essentiality to know about the aggregates’ origins, their production methods, the influence of different aggregate types and their characteristics in fresh and hardened properties of concrete. In general, aggregates can be classified into different heads, as shown in Figure 3.1.
Unconfined compressive strength prediction of recycled cement-treated base mixes using soft computing techniques
Published in Road Materials and Pavement Design, 2023
Rishi Singh Chhabra, Rajesh Mahadeva, G. D. Ransinchung R.N.
Moreover, there is presently an environmental worry over natural resource shortage and a rising trend to lessen this impact (Namutebi et al., 2011; Ullah et al., 2021). Reclaimed asphalt pavement material (RAPM) as a natural resource replacement can reduce natural resource extraction and save the environment. When compared to natural aggregates, reclaimed asphalt pavement material has a significantly different composition and properties, making it difficult to anticipate the performance of the material-based cement-treated base (CTB) and its mix design proportions (Chhabra et al., 2021). The use of RAPM in the preparation of CTB mixes for the construction of recycled cement-treated base (RCTB), and other pavement layers is a method of recycling this material. Such a massive amount of waste, if not properly managed, will lead to environmental degradation (Dal Ben & Jenkins, 2014; Zaumanis et al., 2018). At the same time, natural aggregates for the construction of new pavements are already in short supply in India (Adresi et al., 2019; Debbarma et al., 2020). Natural aggregate mining, such as crushed rock and river sand, substantially affects the environment (Namutebi et al., 2011). Consequently, the construction sector is trying to figure out ways to use RAPM in pavement construction to ensure long-term sustainability (Adresi et al., 2019; Chhabra et al., 2021; Singh et al., 2019; Ullah et al., 2021).
Performance evaluation of dispersed basalt fiber on strength of lightweight expanded clay concrete
Published in Cogent Engineering, 2022
Paschal Chimeremeze Chiadighikaobi, Dafe Aniekan Emiri, Mohamed Ibrahim Abu Mahadi, Kebba Camara, Foud Adnan Noman Abdullah Al-shaibani, Majeed M. Haidar, Lina Abass Saad
The concrete mix design procedures recommended for the development of BF Lightweight EC Aggregate concrete (Figure 3) completely varies from normal or the widely known aggregate concrete mix design. Most of the mixtures found in the papers reviewed were based on the fixation of either the aggregate content or paste volume of the concrete, irrespective of the aggregate characteristics and the strength requirements. It is a generally known fact that, the concrete mixture design has accentuated not only the strength properties, but also the durability of concrete. The porous feature of LWA causes the reduction in its capacity and reduces the free water from the paste matrix, based on this, it is crucial to include some admixtures that reduce the porosity in concrete. Hence, it requires stone flour (Stone flour), adding some percentages of BF to the concrete mixture which will help in reducing the pores and at the same time serve as a reinforcement to the concrete (Jian-jun & Zhi-ming, 2016) also, adding large amount of cement paste to achieve appropriate workability and strength (Kvande, 2001). This may affect the durability requirement for the structural concretes. Some of the key parameters that are considered for mix design of any concretes are water cement ratio, cement content, and aggregate content. In addition, proper combination of aggregate grading facilitates appropriate aggregate packing within the concrete matrix, which will reduce the cement content and enable superior properties of the hardened concrete.
Machine learning techniques for estimation of Los Angeles abrasion value of rock aggregates
Published in European Journal of Environmental and Civil Engineering, 2022
Mojtaba Asadi, Abbasali TaghaviGhalesari, Saurav Kumar
Aggregates are widely used for engineering applications such as concrete production, road construction projects, drainage and filtration, railway track ballast, and ground improvement. They comprise 75 to 80% by volume of Portland cement concrete, and 93 to 100% by volume of asphalt mixes and base courses (Ugur, Demirdag, & Yavuz, 2010). The suitability of aggregates for use in a given type of construction is of great importance due to their key role as the main load carrying component of unbound and bound mixtures. They must be clean, stiff, durable and resistant to deterioration and abrasion, and uniform in quality. The physical, mechanical and chemical properties of materials that are used for a given construction type should be assessed to determine the suitability of aggregates since they are susceptible to deterioration in processing, transporting and construction. Owing to increase in construction and a concomitant decrease in aggregate resources, the demand for crushed stone aggregates has substantially increased. Although there has been a tendency toward using recycled crushed aggregates in past decade, almost 52% of aggregates for construction projects come from crushed stones and 42% of them are from natural resources (Waltham, 2009).