The Complete Guide to Construction Aggregates

At Armstrongs, we supply a wide range of aggregate materials to the construction industry for a range of different applications, direct from our own quarries.Construction aggregates play an important role in building and infrastructure projects, offering essential support and strength to various structures. In this guide, we will explore the different types of construction aggregates, their uses, and the benefits they offer.

What is Construction Aggregate?

Construction aggregate is a broad category of coarse- to medium-grained particulate material used in construction. It includes materials such as sand, gravel, crushed stone, slag, and recycled concrete. Aggregates are used in various construction applications, from residential buildings to major infrastructure projects, providing foundational strength and stability.

Types of Construction Aggregate

Natural Aggregates

Natural aggregates are sourced from natural deposits and are commonly used in construction projects. These include:

• Sand: Fine aggregate used in concrete and mortar, providing bulk, strength, and stability.
• Gravel: Coarse aggregate typically used in concrete mixes, road construction, and drainage systems.
• Crushed Stone: Made from crushed natural rock, it is used in construction, road bases, and as a binding material.

Recycled Aggregates

Recycled aggregates are produced from recycled materials such as demolished concrete, asphalt, and other construction debris. Examples include:

• Recycled Concrete: Created by crushing old concrete and used for road base, backfill, and new concrete mixes.
• Recycled Asphalt: Made by reprocessing used asphalt and commonly used in road construction and repair.

Using recycled aggregates offers several benefits, including reducing waste sent to landfills, conserving natural resources, and often providing cost savings. They are an eco-friendly alternative to natural aggregates, contributing to sustainable construction practices.

Manufactured Aggregates

Manufactured aggregates are produced through industrial processes. Examples include:

• Slag: A byproduct of steel production, slag is used in road construction, concrete, and as a soil amendment.
• Expanded Clay: Lightweight aggregate made from heating clay, used in lightweight concrete, insulation, and hydroponics.

Manufactured aggregates are designed to meet specific engineering standards and offer unique properties, such as improved strength and durability.

Natural Aggregate at Armstrongs

Natural aggregates are valued for their strength, versatility, and availability. At Armstrongs, we provide natural aggregates from our 5 quarries across the North West and Cumbria including Shap, Brinscall, Montcliffe, Pilkington 1 & 2 and Waddington Fell. 

The Extraction Process

The first step in the process of creating natural aggregate is identifying the perfect place to blast for the required stone. Once the right place in the quarry has been found, holes are drilled to the depth that is needed, depending on the amount of aggregate required. The holes are then filled with explosives, which allow us to release the stone we need for making the aggregate. Then it’s time for the blast! Once everyone has evacuated to a safe distance, we give the all clear and an almighty rumble is sent through the quarry as the rock is blasted.Usually, this produces large pieces of stone that would otherwise be used for projects that require cut stone, such as buildings. However, for aggregate, we collect the large pieces and bash them using an excavator with a pecker tip.We then put the smaller broken down pieces of stone into the crusher machine, which does exactly what it says on the tin! The stone is crushed down to various sizes which is sorted into categories.Using an excavator and a truck, the pile of smaller aggregate is then transported to the screener, which will wash and sort the piles.

The Screening And Washing Process

The screener is a large vibrating box which consists of a number of various sized screens and meshes. This will separate the different sized aggregates like a sieve until they are all separated and washed.  These sieves will separate the different sizes of aggregates and create t piles which will vary in sizes. During this screening process, the aggregate is washed to remove any unwanted materials such as clay, silt and dirt which may be present. We do this so that there is no drying effect or impurities in the future which could lead to cracking.The various sized aggregates can be used for different functions. At Armstrongs, we produce a range of aggregate sizes from 2mm and 10mm all the way to 75mm and the gabion sized aggregate 150mm.

What is Aggregate Used for in Construction?

Structural Uses

Aggregates help with the structural integrity of concrete and asphalt, two of the most commonly used materials in construction. In concrete production, aggregates act as a filler material that provides bulk, strength, and stability to the mix.The combination of aggregates with cement and water creates a robust material capable of withstanding significant loads and environmental stresses. Similarly, in asphalt production, aggregates are mixed with bitumen to create a durable and flexible material suitable for road surfaces.The importance of aggregates extends to foundation construction, where they are used to create a stable base for buildings and infrastructure. Aggregates help distribute the weight of the structure evenly and provide necessary drainage, preventing water accumulation that could undermine the foundation.

Coastal Protection

Another example of aggregates and their uses are gabion baskets, which is a large aggregate inside a metal mesh basket. These gabion baskets create a sturdy structure which is perfect for coastal management.For this, we use a 150mm sized aggregate. Gabions are used in garden purposes and also civil engineering projects as well. 

Train Track Aggregate

Have you ever noticed the stone which is laid between and around the tracks which trains run on? Large and rough aggregate is used to hold down the cross tie pieces of wood between the tracks, so that they do not separate. This also helps to absorb the vibrations from the trains themselves.

Decorative Uses

Beyond their structural and coastal applications, aggregates are also used for decorative purposes in landscaping and construction. Decorative aggregates, such as coloured stones, pebbles, and gravel, are employed to enhance the aesthetic appeal of outdoor spaces. They are commonly used in pathways, garden beds, and as ground cover to create visually pleasing and low-maintenance landscapes.In decorative concrete, aggregates can be exposed to create unique textures and patterns. This technique, known as exposed aggregate concrete, is popular for driveways, patios, and walkways. It combines the functionality of concrete with the natural beauty of aggregates, offering both aesthetic and functional benefits.Here’s a table to demonstrate different aggregate sizes and their example uses:

Aggregate Product	Application example
0-2mm Sand, dry or washed	Mortar and Render
0-4mm Sand, dry or washed	M Grade sand, Concrete production, Block Pavers, Flags
10mm	Suitable for pathways and drives, concrete production. Pipe bedding
20mm	Suitable for pathways and drives, concrete production. Pipe Bedding
10-5mm
20-5mm
40mm	Sub Base and Type B drainage material
75mm	Sub base and Type B drainage material
150mm	Clean 6g Gabion material for civil engineering projects
40mm crusher run	Combination of crushed rock and stone dust creates a low void sub base material
75mm crusher run	Backfill, trench fill sub base
6F2	A recycled material used as bulk fill or cap and lay material. Good for Piling Mats
6F5	A recycled material used as bulk fill or cap and lay material
MOT Type 1	Granular sub base material, good load bearing properties
Rip Rap	Used for shoreline, bridge abutments, pilings
Dimensional Stone	Can be trimmed or cut to any shape or size.
Rock Armour	Sea/River defences, Stabilisation projects

Properties of Construction Aggregates

Physical Properties

The physical properties of construction aggregates, such as size, shape, texture, and grading, significantly influence their performance in concrete and asphalt applications.

• Size: Aggregates are classified by size, ranging from fine particles like sand to coarse aggregates like gravel and crushed stone. The size affects the workability and strength of the concrete mix.
• Shape: The shape of aggregates can be angular, rounded, or irregular. Angular aggregates interlock better and provide higher strength, while rounded aggregates improve workability.
• Texture: The surface texture of aggregates impacts the bonding between the aggregate and the cement paste in concrete. Rough-textured aggregates provide better bonding and strength.
• Grading: Proper grading of aggregates ensures a well-distributed particle size, which enhances the density and strength of the mix.

These physical properties are crucial in determining the quality and performance of construction materials. 

Mechanical Properties

The mechanical properties of construction aggregates, including strength, durability, and abrasion resistance, are essential for their performance in different construction applications.

• Strength: Aggregates must have sufficient strength to withstand the loads and stresses imposed on them in concrete and asphalt applications. High-strength aggregates contribute to the overall strength of the structure.
• Durability: Durability refers to the ability of aggregates to resist weathering, chemical attack, and freeze-thaw cycles. Durable aggregates ensure the longevity and stability of the construction material.
• Abrasion Resistance: Aggregates used in surfaces subjected to wear and tear, such as roads and pavements, must have high abrasion resistance to maintain their integrity and appearance over time.

Understanding and selecting aggregates with the appropriate mechanical properties is vital for the success of construction projects.

Sustainable Aggregate Practices at Armstrongs

Sustainability is a core value at Armstrongs. We prioritise recycling and the reuse of materials to minimise environmental impact. Any excess stone from blasts carried out to produce large stone for building projects is turned into aggregates.  

Armstrongs is FORS Accredited 

As part of our ongoing efforts to continually improve our working practice we are delighted to announce that Armstrongs Aggregates LTD is now FORS accredited.The Fleet Operator Recognition Scheme (FORS) is a voluntary accreditation scheme for fleet operators which aims to raise the level of quality within fleet operations.Achieving our FORS accreditation demonstrates our long term commitment to our customers, staff and the industry; as an industry pace setter and a leader in fleet transport best practice.Instilling a mindset of continual improvement, joining an elite group of operators that boast exemplary levels of safety, efficiency and environmental awareness.

Aggregates FAQs 

What is construction aggregate?

Construction aggregate is a broad category of coarse- to medium-grained particulate material used in construction, including sand, gravel, crushed stone, slag, and recycled concrete. These materials are essential components in creating concrete, asphalt, and other construction materials.

What types of aggregate are used in construction?

There are three main types of aggregates used in construction: natural aggregates (such as sand, gravel, and crushed stone), recycled aggregates (such as recycled concrete and asphalt), and manufactured aggregates (such as slag and expanded clay). Each type serves specific purposes based on its properties and the requirements of the construction project.

How are construction aggregates produced?

Construction aggregates are produced through a series of processes, starting with the extraction of raw materials from quarries. These materials are then crushed, screened, and washed to achieve the desired size and quality. Armstrongs employs state-of-the-art machinery and strict quality control measures to ensure that our aggregates meet industry standards.

What is aggregate used for in construction?

Aggregates are used in various construction applications, including as a key component in concrete and asphalt production, as a base material for roads and foundations, and in decorative applications such as landscaping and pathways. They provide essential structural support, durability, and stability to construction projects.

How does Armstrongs ensure the quality of its aggregates?

Armstrongs ensures the quality of its aggregates through rigorous quality control processes at every stage of production. From quarrying and extraction to processing and final inspection, we adhere to strict standards to ensure consistency and performance. Our commitment to quality is reflected in the high satisfaction of our customers.

Where can I buy construction aggregates?

You can purchase construction aggregates directly from Armstrongs. We offer a wide range of high-quality aggregates to meet various project needs. Our knowledgeable team is available to assist you in selecting the right materials and providing technical support. Contact us for more information and to place your order.

How can I choose the right aggregate for my project?

Choosing the right aggregate for your project involves considering factors such as the project's specific requirements, the properties of the aggregate, environmental conditions, and sustainability. Armstrongs' team of experts can help you assess these factors and recommend the most suitable aggregates for your needs.