Aggregate is the word used to describe sand, rocks, gravel, crushed stone and shale that are used in construction.
Aggregate is used virtually everywhere – in all buildings and infrastructure, including homes, roads, schools and hospitals. Without aggregate, we could not build these essential parts of our modern world.
Here is everything you ever wanted to know about ... AGGREGATE!
FAST FACTS!
Aggregate is the most-mined material in the world.
People have used sand and stone for foundations for thousands of years but it was the Romans who refined the production and use of aggregate when they used it to build their vast network of roads and aqueducts. The invention of concrete created an immediate, permanent demand for construction aggregates. Today, everything built with concrete contains aggregate, including homes, roads, schools and hospitals.
It takes a lot of rock to build a road! In fact, it takes 18,000 tons of rock aggregate to build one kilometre of road. That’s enough to fill four Olympic-sized swimming pools.
Each person uses 10 to 15 tonnes of aggregate each year. That’s one tandem truckload per Nova Scotian. For example, building a single family requires about 160 tonnes of gravel (about 11 truckloads). Building a school or hospital requires about 15,000 tonnes of aggregate.
We need to extract 10-15 million tonnes of new aggregate each year to build and maintain Nova Scotia’s infrastructure.
Aggregate quarries and pits only use about 0.11% of Nova Scotia’s landmass. That is a tiny amount of land compared to the huge contribution aggregates make to our lives.
Aggregate makes up about 80% of concrete and about 94% of asphalt.
Point Pleasant Park, one of Nova Scotia’s most beautiful natural spaces, contains over 50 former quarries that provided stone to build forts and walls in the park. For example, slate from the Quarry Pond was used to help build the Prince of Wales Tower, which is the oldest Martello tower in North America.
Ever notice that some roads and highways are red? The color is determined by the aggregate used to build them. Most roads are black or grey because most rock aggregate is black or grey. Rock from quarries like this one in Kemptown, Nova Scotia, gives roads a reddish color..
Building one kilometre of two-way highway requires about 18,000 tonnes of aggregates.
Disney World was built on Nova Scotia rock. Aggregate from Nova Scotia was used as fill at Disney World in Orlando, Florida, and to help make the highways that bring millions of people to Orlando each year. Nova Scotia’s easy access to shipping by sea, and close proximity to the United States, makes us an important supplier to the US construction industry.
Asphalt and concrete are recyclable. When paving crews dig up old roads and highways, they often save the asphalt so it can be crushed, mixed with other aggregate and used again as aggregate in new pavement. This reduces our environmental impact by diverting waste from landfill and reducing the amount of quarrying we need to do for new aggregate.
Hourglasses, or sand clocks, measure time by the descent of sand from one glass bulb to another. According to the Guinness Book of World Records, the first hourglass was invented by a French monk called Liutprand in the 8th century AD. Hourglasses first appeared in European ship inventories from the 14th century. The hourglass was ideal for ocean travel because the bobbing waves didn’t affect its accuracy.
Building one kilometre of two-way highway requires about 18,000 tonnes of aggregates.
USES
HOW AGGREGATE IS USED
Aggregate is used in virtually all infrastructure including homes, roads, schools and hospitals. It is the main component in both concrete and asphalt, which all modern heavy construction relies on as their key building ingredients. Aggregate makes up about 80% of concrete and about 94% of asphalt.
Aggregate provides solid, safe foundations for things like playing fields, trains, pipelines, water lines and sewer systems.
Rocks are used for erosion control and slope protection, dams and protecting shorelines and navigation channels.
Aggregate helps clean the air, too, in flue gas desulfurization of smokestacks and reduction of sulfur dioxide using limestone.
It is also used in water filtration, sewage control, wastewater control and drinking water purification.
Stone, sand and gravel go into the production of household products such as cleansers, cosmetics, toothpaste and chewing gum. They are involved in the manufacture of everyday products like paper, glass, medicines, and fertilizer.
An important use of aggregate in Nova Scotia is erosion control. Rock placed on the shore or in breakwaters absorbs the energy of incoming waves and reduces erosion along shorelines. Nova Scotia quarries help protect the environment this way.
The infographic below illustrates the many ways aggregates contribute to your home:
Aggregate extraction in Nova Scotia goes back centuries with early European settlers taking sand and gravel from coastal areas.
For example, many of the islands in Mahone Bay were known for their excellent beach sand deposits and a flourishing trade developed between Mahone Bay and Halifax, where the sand was used in concrete for many early structures such as the Halifax shipyard which opened in 1889.
Downtown Halifax under construction. Aggregate is used in virtually all infrastructure. (Photo credit: The Chronicle Herald)
Due to environmental concerns with this historical practice, sand and gravel extraction switched to in-land sites in the 1900s. As good sand and gravel deposits became harder to find, the industry increasingly focussed on quarrying bedrock. (A pit is a site where sand and gravel is loose and can simply be dug up, and a quarry is a site where blasting is required to extract the stone.) According to the Government of Nova Scotia, quarried stone represented only 13% of total aggregate production in 1970 and grew to 45% in 1990. The trend toward bedrock quarries has continued since.
Today, most quarries and pits in Nova Scotia are established to provide aggregate for local road and highway construction. Aggregate is usually used relatively close to where it is extracted to improve the local public road system and make it safer for residents.
It is important in construction and paving to have access to aggregate as close as possible to the construction site. This reduces costs and makes projects more efficient. The farther a quarry is from the construction site, the more trucks are needed to transport it and the more expensive the paving project is for taxpayers. Trucking longer distances also harms the environment by increasing fuel consumption and generating more emissions.
About two-thirds of Nova Scotia’s mining and quarrying industry is aggregate production, most of which is used in the province for construction, such as building homes, roads, schools and hospitals. Most of the companies that extract aggregate are local paving and construction companies, generally multi-generation, family-owned, rural businesses that are pillars of their communities. They provide thousands of jobs, mostly in rural areas, and contribute hundreds of millions of dollars to the province’s economy each year.
Nova Scotia also exports aggregate to jurisdictions that do not have good quality aggregate of their own. Places like Prince Edward Island, Florida and the Caribbean, for example, have wonderful sand or soil but do not have rock aggregate like Nova Scotia does. In fact, Disney World was build on Nova Scotia rock. Aggregate from Nova Scotia was used as fill at DisneyWorld in Orlando, Florida, and to help make the highways that bring millions of people to Orlando each year. Nova Scotia’s easy access to shipping by sea, and close proximity to the United States, makes us an important supplier to the US construction industry.
According to the Government of Nova scotia, aggregate quarries and pits only use about 0.11% of Nova Scotia’s landmass. That is a tiny amount of land compared to the huge contribution aggregates make to our lives.
The Quarry Pond, one of over 50 former quarries in Point Pleasant Park.
AGGREGATE AND THE ENVIRONMENT
The mining and quarrying industry is stringently regulated by the provincial government. Everything from environmental considerations to dust, noise and blasting activities are closely controlled by the province. The province’s regulatory regime helps ensure that Nova Scotians enjoy the full benefits of the materials we take from the ground, and that the industry operates in a safe, sustainable, responsible fashion.
Companies are required to do ongoing monitoring of various aspects of their operations, and to submit regular reports to the government, to ensure they are compliant with all rules and regulations. The provincial government does regular inspections and strictly enforces all rules.
It is also important to understand that the companies themselves are committed to being good stewards of the environment. After all, companies are made up of people who have families and usually live in the communities in which they operate. They too want to leave a better world to our children. They use best practices and ever-improving technology to increase safety and efficiency, and reduce their impact on the environment.
Aggregate is used to help protect the environment in a number of important ways, including landscaping, erosion control, drinking water filtration systems, and wastewater and sewage control.
Asphalt and concrete are recyclable. When paving crews dig up old roads and highways, they often save the asphalt so it can be crushed, mixed with other aggregate and used again as aggregate in new pavement. This reduces our environmental impact by diverting waste from landfill and reducing the amount of quarrying we need to do for new aggregate.
Reclaimed quarry in Shubie Park, Dartmouth.
UNDER 4-HECTARE QUARRIES
A lot of Nova Scotia’s quarries are smaller than four hectares. To keep construction costs down, companies establish a lot of small quarries widely dispersed throughout the province, especially in areas where construction projects are planned. This is the only economic way to build and maintain our roads and highways, and to keep our infrastructure safe for Nova Scotians.
Under-4-hectare quarries are usually used infrequently for short periods when a company gets a local construction contract. These quarries can go years without being operational and often operate for only a month or two when they are used.
Four hectares is a very small industrial site, i.e. 200 metres x 200 metres. To put that in perspective, the world record for sprinting 200 metres is just over 19 seconds!
Quarries that are smaller than four hectares are held to the same environmental and safety standards as any other quarry – i.e. the buffers are the same; the noise, dust and water management rules are the same; and the reclamation requirements are the same. They go through the same Industrial Approval (IA) process that larger quarries do, and it is the IA that rigorously addresses these operational and environmental issues, not environmental assessments as is sometimes suggested.
The only difference is that quarries under four hectares are considered by the government to be lower risk for the environment so they do not require an environmental assessment. They are simply too small to have the sort of impacts that are addressed through an environmental assessment and the IA process is the more effective and appropriate way of regulating them. Regardless, quarries smaller than four hectares are regulated just as stringently as any other quarry.
Merv Sullivan Park, (aka “The Pit”) in Halifax, a former gravel pit.
