Measurement of Aggregate Selection for Clients

Gravels constitute the majority of coarse aggregate used in concrete with crushed stone making up most of the remainder. Clients can also order the specific aggregates grading they require. Grading refers to the particle-size of aggregates. Aggregate grading greatly affects cement and water requirements, workability, pumpability, and durability of concrete.

Suppliers of aggregates acquire gravel and sand that are dug or dredged from a pit, river, lake, or seabed. Crushed aggregate is produced by crushing quarry rock, boulders, cobbles, or large-size gravel. Recycled concrete is a viable source of aggregate. Suppliers can work with clients by retailing aggregates or even providing a steady supply direct to a construction site. They can adjust the aggregate processing that consists of crushing, screening, and washing the aggregate to obtain proper cleanliness and gradation required by the client. After processing, suppliers can even store the aggregates in a way that minimizes segregation and degradation and prevents contamination and then delivers it to clients in specific intervals suitable for the construction schedule.

Particle shape and surface texture influence the properties of freshly mixed concrete more than the properties of hardened concrete. Rough-textured, angular, and elongated particles require more water to produce workable concrete than smooth, rounded compact aggregate. Consequently, the cement content must also be increased to maintain the water-cement ratio. Generally, flat and elongated particles are avoided or are limited to about 15 percent by weight of the total aggregate. Unit-weight measures the volume that graded aggregate and the voids between them will occupy in concrete. The void content between particles crushed by professional with the best quality and the most competitive prices affects the amount of cement paste required for the mix. Angular aggregate increases the void content. Larger sizes of well-graded aggregate and improved grading decrease the void content. Absorption and surface moisture of aggregate are measured when selecting aggregate because the internal structure of aggregate is made up of solid material and voids that may or may not contain water. The amount of water in the concrete mixture must be adjusted to include the moisture conditions of the aggregate. Abrasion and skid resistance of an aggregate are essential when the aggregate is to be used in concrete constantly subject to abrasion as in heavy-duty floors or pavements which often using machines to obtain the final products. Different minerals in the aggregate wear and polish at different rates. Harder aggregate can be selected in highly abrasive conditions to minimize wear.