Construction aggregate, or simply “aggregate”, is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and road side edge drains. Aggregates are also used as base material under foundations, roads, and railroads. To put it another way, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete.
The American Society for Testing and Materials publishes an exhaustive listing of specifications for various construction aggregate products, which, by their individual design, are suitable for specific construction purposes. These products include specific types of coarse and fine aggregate designed for such uses as additives to asphalt and concrete mixes, as well as other construction uses. State transportation departments further refine aggregate material specifications in order to tailor aggregate use to the needs and available supply in their particular locations.
Sources for these basic materials can be grouped into three main areas: Mining of mineral aggregate deposits, including sand, gravel, and stone; use of waste slag from the manufacture of iron and steel; and recycling of concrete, which is itself chiefly manufactured from mineral aggregates. In addition, there are some (minor) materials that are used as specialty lightweight aggregates: clay, pumice, perlite, and vermiculite.
Shipment / storage
Example of loading aggregate/limestone by port conveyor system
TERMS AND CONDITIONS OF SHIPMENT OF AGGREGATE VIA THE AGGREGATE SHIP LOADING SYSTEM
The following are to be read in conjunction with the Port Rules and Regulations in the Port Ordinance 1982 and the Port Tariff 1995, (both as may be amended from time to time) and for the time being in force.
The Port will perform the following terminal handling services in relation to aggregate for shipments, subject to the further following conditions set out below.
Transportation from the designated stockpile area to the carrying ships hold, by transfer conveyor, of the sizes of aggregates not less than 8 M.M. and not more than 40 M.M. and with a density not less than 1.6 Metric Tons per cubic meter. (Products of smaller grain size and other products may be handled subject to Agreement.)
Stockpile areas will be allocated to different customers. Prospective customers should contact the Port Authority for obtaining the land area, and for the terms & conditions under which such land area will be allocated.
The use of the allocated stockpile, including grading and replenishment is the responsibility of the customer.
Blending on the conveyor is strictly prohibited. On belt sampling is not available. The Port reserves the right to reject any material or grade of material for loading.
The customers should demonstrate and confirm that full amount to be loaded is available for full loading operation prior to the berthing of the vessel.
The Port reserves the right to reject load operations in situations, where in the opinion of the Port, the quantity of material in the stockpile is inadequate to maintain a fair volume throughput in the ship loader.
The vessels that will be accepted for loading aggregates/limestones should have the following configuration.
1. Vessel must be capable of loading at 2,200 m/t per hour.
2. Vessel beam shall be between 18 and 40 meters.
3. Maximum length over hatches 260 meters
4. Maximum Air Draft adjacent hatches and in minimum ballast 17 meters.
5. Maximum departure draft 15 meters.
6. Hatches must be clear of horizontal and vertical dividers. The loading of wing tanks is not acceptable. (Anything outwith the above specifications is subject to Port Acceptance on a case by case basis.)
Building aggregates and sands are also delivered in bulk bags of approx. 1 t. each.
- Moisture damage (seawater)
- Contamination (defilement)