Construction aggregates are highly versatile building materials that are used widely across different project types. They are leveraged for non-reinforced work, foundation works, retaining walls, preparing concrete, etc. and are available in a wide range of dimensions. They can occupy close to 60-80% of a concrete mix, giving it compressive strength and bulking.
Buyers can find the right type of aggregate based on their specific requirement, by analysing the different types available and their associated properties. They should focus on key points of consideration when buying construction aggregates, namely size, application, type, prices, and its key properties.
It is important to start with the right type of construction aggregates required (size, dimension, composition), followed by what properties are required from the aggregates (grading, durability, abrasion, etc.).
Types of construction aggregates
There are largely two distinct types of construction aggregates, differentiated by their size, manufacturing processes, and use-cases.
Coarse aggregates: Coarse aggregates can be termed as irregular broken stone or rounded gravel that cannot pass through a 4.75 mm opening sieve. They can be as large as 60-80 mm in size and are obtained through stone quarries or via crusher machines.
Fine gravel: 4 mm – 8 mm
Medium gravel: 8 mm – 16mm
Coarse gravel: 16 mm – 64mm
Fine aggregates: Fine aggregates consist of natural sand or crushed stone in many cases and can pass through a 4.75 mm sieve and retain on 0.15 mm sieve. They include crusher dust, fine sand, manufactured sand, etc.
Coarse sand: 2.0 mm – 0.5 mm
Medium sand: 0.5 mm – 0.25 mm
Fine sand: 0.25 mm – 0.06 mm
Buyers should also focus on the right shape of construction aggregates when making a procurement decision.
Rounded aggregates: Rounded aggregates are defined by attrition and can offer better workability on-site. They need lesser water-cement ratio, and do not have strong interlocking and bond-strength, which is why they may not be considered for high-strength concrete.
Angular aggregates: Angular aggregates have well-define edges, formed by crushing rocks at-scale. They offer lesser workability and greater compressive strength (10-20% in many cases), while forming stronger aggregate-mortar bond.
Irregular aggregates: Irregular aggregates are formed in sand pits and gravel, giving lesser workability but higher bond strength when compared to rounded aggregates. Buyers can also opt for flaky, elongated, and mixed aggregates based on the project requirements.
Key Properties and Use-Cases
Coarse aggregates are larger sized materials that offer lesser surface area, but greater strength, hardness, and durability. They can be procured in different shapes, based on their core benefits, and used for a wide range of applications. Coarse aggregates are used extensively for preparation of ready-mix concrete, which is why it is important to select the right type for your project.
Fine aggregates are widely used for preparing mortar for masonry work, flooring, plastering, concrete work, etc. They have a higher surface area and can seamlessly fill voids between coarse aggregates for greater volume and dimensional stability. Fine aggregates also increase the workability of a project, by filling gaps that may have otherwise been left by coarse aggregates.
Buyers should focus on the essential properties they need from aggregates and opt for the right type, size, and shape, for their construction requirements. It is also important to know the types of tests needed to be performed to gauge quality.
Important Considerations During Procurement
Buyers should perform price discovery and supplier research using online marketplace portals and gain transparent pricing on best options. The right procurement platform is just as important as the right type and size of aggregates acquired. All fine and coarse aggregates should comply with IS 383:2016 standards for consistency and quality.
Payment terms, logistics & handling, additional charges, and unloading terms should also be reviewed when larger quantities of construction aggregates are being ordered. Different aggregates must be stored separately, while avoiding moisture to build up within the bags.
Construction aggregates are some of the most versatile materials in the construction industry, required for a range of applications across projects. Buyers need to assess the right aggregates for their specific requirement, by analysing their features, dimensions, and specifications. BuildSupply, a real estate and construction focused procurement platform, offers several ranges in coarse and fine construction aggregates, with transparent pricing, clear seller terms, end-to-end tracking, and easy RFQ management system.