Far from being just a humble by-product of quarrying, limestone aggregate is a remarkably versatile material. It’s also very much in demand for civil, commercial and residential uses. Here we explore why limestone aggregate is so popular and where it can be used.
Limestone blocks have been used in building since ancient times – perhaps most notably in the construction of the Great Sphinx and pyramids in Ancient Egypt over 4,000 years ago. And the Romans used local limestone aggregate to build solid foundations for nearly 2,000 miles of roads throughout Britain during their four centuries of occupation (43-410 AD).
Over the centuries, the flexibility of limestone aggregate has been gradually uncovered. Today it is indispensable in many applications, including…
Probably the most widely used worldwide construction material, concrete is made from a mixture of cement, sand, and water. Adding a coarse aggregate (often made from crushed limestone) builds in extra strength to the finished concrete.
Limestone aggregate is commonly used in roadbuilding, where a strong, robust base is needed to withstand the weight of traffic. Limestone aggregate creates a strong, durable foundation on which to lay the tarmac or asphalt. You’ll also often see limestone aggregates used in channels at the roadside (or on the central reservation) to help with run-off drainage.
Driveways and paths
Limestone aggregate makes an ideal alternative to gravel for robust surfacing on driveways, footpaths, cycle paths and car parks. Known for being strong and long-lasting, limestone aggregate also drains really well – and it’s much cheaper to source and lay than other non-porous surfaces like tarmac, asphalt or concrete.
Limestone aggregate is often chosen as the ballast used to support the rails in railway construction. As with roadbuilding, limestone aggregate is popular with track layers due to its strength, durability and excellent drainage-promoting qualities.
Underground pipe bedding
With underground pipes, limestone aggregates are often used as a bedding layer for the pipes. As it doesn’t expand or contract, the limestone aggregate protects and insulates the pipe from any soil movement caused by temperature changes, moisture or external factors such as traffic passing above.
Whether it’s laying half a dozen slabs for a garden shed base, or hundreds of paving stones in a public square, the secret to a robust, level finish is laying a level of hardcore between the slabs and the earth. Limestone aggregate is ideal for this – keeping the slabs level whilst guarding against settlement cracks and providing good drainage.
Limestone aggregates are often added to the exposed surface of felt roofing. This is not only because they look more attractive than bare felt, but also because the weight of the crushed limestone anchors the roofing felt in high winds and provides protection from direct exposure of the felt to the sun and rain.
Originating from sedimentary rock, limestone aggregate (or crushed limestone) is very rich in nutrients which can enrich the soil and boost the growth of flowers, plants, grass and crops. Crushed limestone also serves to regulate the pH level of soil by neutralising acidity or alkalinity. It is regularly used in farming, but also in domestic gardens, where it can also provide excellent ground cover on flowerbeds and rockeries.
Crushed limestone is also used as an agent to refine the metal in smelting. During the heating process, the limestone attracts any impurities, making them much easier to remove.
Limestone aggregate – making the most of limestone quarrying
Whilst most limestone quarries exist primarily to extract limestone blocks for use in construction, flooring and other interior/exterior stone, it is great to know that their key by-product – limestone aggregate – doesn’t go to waste!