Application situation and trend of concrete aggregates

The aggregate size of concrete consists of coarse and fine aggregate; by formation is divided into natural and artificial aggregate of aggregate. Aimed primarily at aggregate grains in the sandstone standard levels (grading, fineness modulus), clay content and other indicators are provided, does not meet technical requirements, is not qualified.

At present, the concrete industry, especially ready-mixed concrete used fine aggregate, and often does not meet the requirements of these standards. Major nonconformity is the fraction of fine aggregate and clay content. Investigate its reasons has such points: quality River sand excavation out or ban mining; grain level aspects, natural fine aggregate due to its natural property, cannot always reached standard requirements; artificial fine aggregate is is because some processing equipment process behind, led products cannot completely reached standard requirements; containing mud volume aspects, main reasons is through washing reduced containing mud volume of method, increased aggregate production enterprise of cost, then increased concrete production enterprise of procurement cost, in water resources lack of area washing is not reality of. In addition, the negative pressure to the powder wet natural river sand to remove clay powder of artificial fine aggregate creates a lot of powder processing and stacking issues. Therefore, for use by both unintentionally reduced the mining standards, exceed fine aggregate large amounts of mud is applied to the concrete.

The so-called "unacceptable" popular aggregate was able to, which is the most fundamental reason: access to so-called qualified aggregate less and less, even in some areas, no access to qualified aggregates.

Aggregate standard specification in the grain level index of provides, main is consider has concrete as a non-are quality composite, gap rate should as low, to projections out of ideal standard value, or according to yiqian a period common of, and can large gets to of, and and can get lower gap rate of natural sand aggregate for template design of; and containing mud volume index of determine, more is for on strength and durability aspects of consider. But these targets, not all areas of natural aggregates can be reached directly. Also, not all areas are suitable for processing into aggregates of limestone ore, quartz and other mineral resources.

As resources become more scarce, geographical protection of mineral resources in many areas, restrict or even prohibit the exploitation of natural sand and mine, take more stringent control measures of saving water. It can be said that the so-called qualifying aggregate, less and less, the concrete industry will have to plan ahead, face an increasing deterioration of aggregates. In the future, concerning the so-called "unqualified" aggregates, it is may not be a problem that is not allowed, but the problem of how to use.