When it comes to construction, concrete and aggregate are two of the most important materials used. But what is the difference between them? Are they the same? In this article, we'll explore the differences between concrete and aggregate, and how they are used in construction. The aggregate is a collection of inert granular material comprising up to 60% to 80% of a typical concrete mix. There are many different types of aggregates that are commonly found in concrete, such as sand, gravel, and crushed stone.
Cement also looks similar to aggregate because it contains sand, one of the most commonly used aggregates. Cement is slightly thicker than aggregate because it is finely ground rock, usually limestone or shale. Although the terms cement and concrete are often used interchangeably, cement is actually an ingredient in concrete. Concrete is basically a mixture of aggregates and paste.
Aggregates are sand and gravel or crushed stone; paste is water and portland cement. Concrete grows stronger as it ages. Portland cement is not a trade name, but rather the generic term for the type of cement used in virtually all concrete, just as stainless steel is a type of steel and sterling silver is a type of silver. Cement makes up 10 to 15 percent of the concrete mix, by volume.
Through a process called hydration, cement and water harden and bind aggregates together into a rock-like mass. This hardening process continues for years, meaning concrete grows stronger as it ages. A mixture with an excess of cement paste will be easy to place and will produce a smooth surface; however, the resulting concrete is more likely to crack and be uneconomical. One benefit of concrete is that production only emits greenhouse gases when mixed with water, but these emissions generally stop after it solidifies.
It is made by mixing materials with water and aggregates, which are the most common elements on Earth, so no specific or difficult processes are required to manufacture concrete. Due to the variety of mixes of different colors and textures available, exposed aggregate concrete is very versatile and can be combined with all types of exterior and landscaping designs. To produce good quality, durable concrete containing a portion of recycled concrete aggregate, test concrete mixes and close control of the properties of old recycled concrete are often required, with mix adjustments made as needed. The absorption and surface moisture of aggregates are simple but critically important aspects of producing concrete that consistently achieves the specified or desired strength. Recycled concrete is created by breaking, removing and crushing existing concrete to a preferred size.
Note that removing sand from a mix transforms conventional concrete into a fineless mix, also known as permeable concrete (see Permeable Concrete Pavements). If there is a deficiency in a locally available fine aggregate, concrete may benefit from the addition of air entrainment, additional cement, or a supplemental cementitious material (SCM) to address these deficiencies. In addition to Portland cement, concrete may contain other cementitious materials including fly ash, a waste by-product of power plants that burn coal; ground slag, a by-product of iron and steel manufacturing; and silica fume, a waste by-product of silicon or ferrosilicon metal manufacturing. In addition, aggregates must be clean and free of any matter that may affect the quality of the concrete.
This is a summary of the most important factors to consider when selecting and dosing concrete aggregate. Cement does not have much strength on its own; however, when mixed with water and aggregates, it becomes concrete and gains greater strength. Both gravel and crushed stone are generally acceptable for manufacturing quality concrete (Photo), although gravel is generally preferred for exposed aggregate. The use of non-potable water or water of unknown purity jeopardizes the quality and workability of concrete. In conclusion, while both cement and aggregate are important components in making quality concrete mixes for construction projects, they are not interchangeable terms. Cement is an ingredient in making concrete while aggregate refers to inert granular material used in making up part of the mix.
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