Construction aggregate is a broad class of coarse to medium grained particulate material employed in construction, which also includes sand, gravel, crushed stone, slag, recycled concrete and geo artificial aggregates. Aggregates are one of the most well-mined materials within the world. Aggregates are composed of materials such as concrete and asphalt concrete.
- DEFINITION OF AGGREGATE
- TYPES OF AGGREGATE
- CONSTRUCTION AGGREGATE PRICE
- DENSITY OF AGGREGATE
- USES OF AGGREGATE
DEFINITION OF AGGREGATE
Aggregate is associate with the nursing aggregation of non-metallic minerals obtained in particulate kind and may be processed and used for civil and route engineering construction.
Aggregates are principally classified into 2 categories:
• Fine mixture
• Coarse mixture
TYPES OF AGGREGATE
Fine aggregate and coarse aggregate are two main types of aggregate:
Fine Aggregate
• Definition: Fine aggregates are tiny size filler materials used in construction
• Size of Particles: Fine aggregates range in size from 4.75 mm to 0.075 mm
• Materials: The materials which are used as fine aggregate in concrete are sand, surki, Stone Screenings, burnt clays, cinders, etc
• Sources: Watercourse sand, machine sand, crushed stone sand, crushed gravel sand are the most important sources of a fine aggregate
• Surface Area: Fine aggregates are having a higher surface area
• Function in Concrete: The voids between the concrete are usually filled up by fine aggregate
• Uses: Fine aggregates are utilized in mortar, plaster, concrete, filling of road pavement layers, etc
Coarse Aggregate
• Definition: Coarse aggregates are filling materials used in construction that are larger in size
• Size of Particles: Coarse aggregates are having size up to 4.75 mm
• Materials: Brick chips (broken bricks), stone chips (broken stones), gravels, pebbles, clinkers, cinders, etc. are some of the materials which are used as coarse aggregate
• Sources: Dolomite aggregates, crushed gravel or stone, natural disintegration of rock are some of the most common sources of coarse aggregate
• Surface Area: Coarse aggregates are having a smaller surface area compared to fine aggregates
• Function in Concrete: Coarse aggregates acts as inert filler material for concrete
• Uses: Coarse aggregates are principally employed in concrete, railway track ballast etc
CONSTRUCTION AGGREGATE PRICE
Construction Aggregates Price | No of Products (%) |
Rs 180-300 | 10% |
Rs 300-490 | 29% |
Rs 490-820 | 49% |
Rs 820-1350 | 11% |
DENSITY OF AGGREGATE
Bulk and Relative density
i. Bulk Density:
The bulk density is the mass of an aggregate that is required to fill a container of a given unit volume.
Bulk Density = Mass/volume
Key Features:
• If the given volume is unity then, Bulk Density= Mass
• Unit – kg/m3 or lb/ft3
• In the above definition, the volume consists of both the aggregates and the voids which are between the aggregates
• The approximate bulk density is between 1200-1750 kg/m3
ii. Relative Density:
The density (specific gravity) of aggregate is defined as the ratio of the mass of aggregate and mass of an equal volume of water
Relative Density = weight of the Aggregate/weight of an equal volume of water
Key Features:
• Most of the aggregate particles are having a density within the range 2.4-2.9 with a corresponding particle (mass) density of 2400-2900 kg/m3
• The relative density of an aggregate can be found on an oven-dry basis or a saturated surface dry (SSD) basis
USES OF AGGREGATE
A) Uses of Aggregate in Concrete
• Increases the degree of concrete, so reduces the price. Aggregates account for 60-75% of the degree of concrete and 79-85% weight of PCC
• To give a rigid structure
• To cut back the shrinkage and cracking
• Concrete mixture is employed in several structures and substructures e.g. completely different components of a Building, bridges,foundations
• The smaller the aggregate size the bigger is its area and also the additional binding material (cement) is going to be needed, leading to a better price
• The bigger the aggregate size the larger are going to be the voids, leading to wastage of binding material (cement)
B) Uses of Aggregates in Roads
• Stabilized treatment of building materials (blends of cement, fly ash, slag, lime)
• Stabilized with hydrocarbon materials (bitumen or tar)
• Stabilized with alternative materials (resins, fibers, geosynthetics, etc.)
• Recycled mixture
C) Uses of aggregate in Railway Ballast
• An absolutely loaded train weighs thousands of tons. To avoid injury to the rails, ground, and other close structures, a really robust aggregate is required to support this high weight
• Railway ballast usually consists of a tricky stone (crushed), like granite, with a bigger diameter varied between 30mm to 50mm. Particles finer than this diameter in higher proportion can cut back its drainage properties
• Some of the other uses are fills, backfills, drainage, and filtration applications
SUMMARY
Aggregate is employed in buildings and constructions, is additionally a fabric used for combining with cement, bitumen, lime, gypsum, or alternative adhesive to make concrete or mortar. The combination results to give volume, stability, resistance to wear or erosion, and alternative desired physical properties to the finished product.