Aggregate properties are important when they are to be used as Portland Cement Concrete (“PCC”). These properties are essential because the aggregate represents 70% to 85% by weight of PCC. The workability, strength, durability, and performance of these construction materials are influenced greatly by the aggregate’s characteristics.
Although some variation in aggregate properties is expected, characteristics that are considered when selecting concrete aggregate include:
- grading or size classification
- particle shape and surface texture
- abrasion resistance
- unit weights and voids
- absorption and surface moisture
The combined aggregate gradation used in a concrete mix usually is obtained by blending two or more aggregate sizes. Aggregates are divided into two distinct categories – fine and coarse. Fine aggregates generally consist of natural or manufactured sand, with most particles passing through a 3/8-inch (9.5-mm) sieve. Coarse aggregates are any particles greater than 0.19 inch (4.75 mm), but generally range between 3/8 and 1.5 inches (9.5 mm to 37.5 mm) in diameter. Gravels constitute the majority of coarse aggregate used in concrete with crushed stone making up most of the remainder.
Concrete aggregates can be broadly classified as natural or manufactured, both with respect to source and to the method of preparation. Natural sands and gravels are the product of weathering and the action of wind and/or water, while manufactured fine aggregate and crushed stone are produced by crushing larger aggregate. Once processed, these aggregates are handled and stored in a way that minimizes segregation or degradation, and prevents contamination.
All of the Concrete aggregates produced at our facilities are monitored through our continuous quality control program, which include daily, weekly, and annual testing. This testing is performed by our in-house testing facilities, independent laboratories, and finally by Governmental Agencies such as CalTrans. If you need any test data, please contact sales at the location in which you are interested.