In concrete, aggregate mainly plays framework function or interstitial filling. It is a kind of loose granular materials.
In civil engineering, aggregate is mainly used in the following ranges: cement concrete, asphalt concrete, road base, railway base, mortar and so on. The consumption of each year is about 2 billion tons.
Aggregate can provide concrete good stability and more durability than cement stone. It can play decrease function and it can avoid the crack propagation and transport power. This aggregate will reduce water heating up and provide durability function.
In the situation of not affect mixed stand properties, it can add more aggregate into the concrete and reduce concrete’s production costs.
To divide the aggregate materials, there are three methods: depending on the source, depending on the grain size and density.
Depending on aggregate sources, the aggregate can be divided into the following kinds. Natural stone aggregate: it is composed with natural stone materials, such as sand, pebble, and gravels and so on. Artificial aggregate: it is processed through heating processing with expanded shale and expanded vermiculite; the industry by-product includes mineral slag, iron slag and slag powder and so on. The recycled aggregate: it refers to the crushed concrete and crushed clay bricks and so on.
Depending on aggregate grain size, it can be divided into these types. Coarse aggregate refers to the stone particles whose grain size is larger than 4.75mm, such as pebble and gravels and so on. Fine aggregate refers to the stone ore particles whose grain size is less than 4.75mm, such as river sand, mountain sand and sea sand and so on.
Depending on aggregate density, the aggregate can be divided into common aggregate, light aggregate and weight aggregate. The common aggregate has 2500-2700kg/m3 density. The light aggregate has density of 0-1000kg/m3, such as ceramsite, expanded vermiculite, ruined shale, expanded perlite and so on. The weight aggregate has 3500-4000kg/m3 density, such as iron ore and barite and so on.