Clitheroe
Shap
Horwich, Bolton
Chorley
Horwich, Bolton
Clitheroe
Shap
Horwich, Bolton
Chorley
Horwich, Bolton
In big construction projects, there’s a lot of focus on spec sheets and concrete grades; but the materials going into the mix are just as important. And it all starts with the aggregate.
If the quality of your aggregate isn’t up to scratch, you’re risking strength, durability, and long-term performance. Good aggregate helps concrete do its job properly, and keeps it solid for the long haul.
At Armstrongs, we supply certified, high-grade aggregates straight from our North West quarries. We work with commercial buyers, contractors, and large-scale projects where quality can’t be left to chance.
Aggregate usually makes up 60–80% of the concrete mix by volume, so it’s no surprise that it plays a huge role in how the material behaves.
When the aggregate is poor - whether it’s the wrong grade, too fine, or contaminated, it can cause:
In real-world terms, that means a bigger risk of failures on site, costly repairs, and concrete that doesn’t last as long as it should, especially when it’s exposed to the elements or heavy use.
Whether you’re pouring an industrial slab, precast unit, or reinforced foundation, you need to know the aggregate is up to standard. Here’s what to keep an eye out for:
Too much clay, silt, or organic matter in the mix can weaken the bond between the cement and aggregate. We wash and grade our products so that they meet the mark every time.
Well-graded aggregate helps everything pack tighter together, which means fewer gaps and better strength. Ours meets BS EN 12620 standards for concrete use.
Angular particles give better grip inside the mix, while rounded ones may be easier to work with but won’t offer the same strength. We supply both, depending on your needs.
The stronger the original rock, the stronger the aggregate. Our gritstone and Shap granite are some of the most durable options available in the UK - ideal for demanding concrete pours.
For commercial projects, it’s not just about getting the right type of stone, it’s about proving it meets the spec. That’s where regular testing and compliance come in.
At Armstrongs, our concrete aggregates are tested for:
This ensures our materials meet BS EN 12620 (aggregates for concrete) and other relevant British Standards. We can also supply declarations of performance (DoP) and test certificates on request, ideal for project handover packs or audit trails.
If the concrete’s going to be exposed to harsh weather, chemicals, or heavy traffic, like in highways, coastal areas, or industrial yards; then durability is even more important.
Poor-quality aggregate makes concrete more likely to break down over time, letting water in and weakening the structure. That’s why for anything with a high exposure class, the right aggregate makes a real difference.
We supply materials that can handle it, like our tough granite and gritstone, proven in projects across infrastructure, highways, and civils.
Different jobs demand different mixes and the aggregate you use should reflect that. Choosing the right type can affect everything from finish quality to workability on site.
Some examples:
Our team can help advise on the best blend for your application, including specialist mixes for exposed, sulphate-rich or aggressive environments.
We run our own quarries, including Shap Quarry, Montcliffe Quarry, and Waddington Fell; so we know exactly where our materials come from and how they’re processed.
All our concrete-grade aggregates:
We work closely with batching plants, contractors, and project managers who need reliable delivery, consistent quality, and full confidence in their supply.
On large-scale pours or phased developments, consistency is everything. Variations in moisture, grading or rock type can cause problems with strength, setting time, and finish.
By sourcing your concrete aggregate from a single, trusted supplier like Armstrongs, you benefit from:
We operate multiple quarries but maintain tight quality control and cross-site consistency, so no matter where your delivery comes from, it performs as expected.
We’ve been trusted to supply key materials for major roads, large industrial buildings, energy sites, and everything in between.
If you need granite for strength, gritstone for durability, or a consistent blend of sands and gravels, we’ve got the capability and the capacity to deliver - and to keep you on schedule.
Aggregate isn’t just something to bulk out a mix. It’s a key part of how your concrete performs - and how long it lasts.
If you’re working on a project that demands long-term strength and durability, we’re here to help. Get in touch to talk about your aggregate requirements or learn more about how we operate.
Concrete aggregate is typically made from crushed rock such as granite, limestone, or gritstone. It can also include sand and gravel, depending on the required strength, finish, and application of the concrete.
Low-grade aggregate can lead to weaker concrete, poor compaction, higher water demand, and increased risk of cracking or shrinkage. It also reduces long-term durability, especially in exposed or high-load environments.
Concrete-grade aggregates should be tested for grading, particle shape, water absorption, strength (aggregate crushing value), and cleanliness. All Armstrongs aggregates meet BS EN 12620 standards and undergo regular in-house and third-party testing.
In some applications, recycled aggregates can be used, but their performance varies and they must meet strict quality criteria. For structural or high-strength concrete, primary aggregates are usually preferred to guarantee consistency and durability.
This depends on the application. Common sizes include 10mm and 20mm, but the right grading and mix design are key. Armstrongs can advise on the most suitable option based on your spec and intended use.
Yes. All of our concrete-grade aggregates are fully certified, traceable, and supplied in accordance with BS EN standards. We provide documentation as required for batching plants, civil contractors, and project managers.
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