What is concrete and aggregate?

Concrete aggregates are composed of geological materials such as gravel, sand and crushed rock. The particle size determines whether it is a coarse-grained aggregate (e.g., gravel) or a fine aggregate (e.g., the resulting concrete can be used in its natural state or crushed, according to its use and application. Email address required Invalid email address Invalid email address ACI Resource Center Southern California Midwest The page may have been updated, moved or deleted. Also be sure to check your spelling.

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Aggregates are the most basic material used in construction. They provide the basis for roads, bridges and buildings, while constituting more than 90% of an asphalt pavement and up to 80% of a concrete mix. On average, 38,000 tons of aggregates are needed to build a mile of lane of an interstate highway. Building an average house requires 400 tons of aggregate, while the average size of a school or hospital requires 15,000 tons.

The aggregate provides much of the strength, thermal and elastic properties of concrete, as well as dimensional and volumetric stability. Leveling limits and maximum aggregate size are specified because these properties affect the amount of aggregate used, as well as cement and water requirements, workability, pumpability, and concrete durability. Well-graded aggregate is best, however, aggregates rated at maximum density can give concrete a rough texture. And to go even further, changes in the size, weight, moisture content and gradation of each aggregate can also alter the characteristics of concrete.

Meanwhile, of the nearly 1 billion tons of sand and gravel produced, 24% was used in road construction, 12% in asphalt and 44% in concrete. Recycled concrete is a viable source of aggregate and has been successfully used in granular subbases, soil cement and new concrete. Excess sanding is also used when pumping concrete to allow better flow, as well as when swaging concrete to allow finer details. The aggregate is a collection of inert granular material comprising up to 60% to 80% of a typical concrete mix.

Aggregates greatly influence freshly mixed and hardened concrete properties, mix ratios and economy. When used with a binding medium, such as water, cement, and asphalt, they are used to form composite materials, such as asphalt concrete and Portland cement concrete. The aggregate is also very important for the strength, thermal and elastic properties of concrete, dimensional stability and volume stability. The term concrete aggregates encompasses a variety of products, but they are generally summarized as stone and sand, in coarse-grained and fine grades.

A variety of materials are used as aggregates in concrete, and each affects the quality of the concrete in a number of ways.

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