Those old building structures may look like penny scraps but can equate to big dollars!
A worksite can produce a large quantity of waste that can be turned into treasure. In the midst of the mangled steel beams, plastic and roofing sheets, are chunks of concrete, concrete products, brick and mortar that are known as demolition waste aggregates. Great replacements for natural pebbles and stones, demolition waste aggregates can be reincorporated into the mix with new cement for the manufacture of new concrete, once done right.
Waste aggregates are most often taken from old structures and the excavation of roads. These recycled waste products are usually reused on construction sites in foundations and road bases.
How is it recycled?
Construction rubble from the demolition of old buildings is covered with a mortar that must be removed before it can be used as aggregates. This rubble is also usually mixed with many other waste materials. Often this separation process must be done at another facility that also grinds the product down to the size that is required for the new job. A typical construction and demolition waste aggregate is said to have 65-70% of major coarse as well as fine aggregates, with 30-35% of cement paste.
How do recycled aggregates equate to big dollars?
- Reducing the cost of purchasing new construction aggregates.
Construction waste can save lots of money for everyone involved. Trevor Manning, Managing Director of Garbage Master Ltd. in Barbados, gave some insight into the transportation process.
“If you are transferring materials from a quarry, the total cost will include the transportation cost based on the distance and the cost of the materials by weight or cubic metre. If you are moving rubble mixed with other items from a demolition site to a landfill, it would cost less to the contractor because the truckers will be charged by the load.” Money is saved up front.
- Reducing mining of new materials, reducing environmental footprint.
Depending on the use of the land space, some property owners do not need newly mined rocks to fill spaces but are more than happy to reuse waste to put behind retainer walls and for general backfilling. Recycled aggregates will cost less than from a quarry.
3. Reducing the quantity of waste to the landfill.
“If you dig up a pavement or tear down a concrete structure in the Caribbean, quite often your transportation costs of that material will be lowered because someone will pass by and remember they have a hole in their property to fill. They would be willing to remove it from the site for you because the material is free. However, even if you have to transport it, the distance may not be too far from the demolition site, which could be a bonus,” Manning continued.
That is a significant saving, but all pennies aren’t saved, however! Demolition aggregate recycling for reuse up to standards1 does have its costs and labour. There are costs to recycle the materials which include the transportation of the waste to a cement plant which then has to sort further, if not done at the source site. It then has to be broken down into smaller pieces with additional costs being incurred due to the use of equipment and electricity.
Although not “big business” in the Caribbean as yet, this option for reuse of demolition waste material is a viable commercial consideration. In the meantime, don’t be afraid to ask for that old rubble at that nearby work site. A penny saved may be dollars earned.
For more ways to save on building, why not read our Bamboo in Construction feature?