There are many advantages to renewing existing concrete surfaces, compared to ripping out the old concrete and re-pouring anew. We talked here about the structural perils of demo-ing residential and commercial pool decks, and that you have a big appetite for risk to do it. Could you even imagine the headache of changing out a worn concrete slab that was built on-top of a commercial parking garage, or that of a cracked walkways in front of a retail stores?
(The time needed for the installation, limited access, noise, dust levels and costs associated with such an adventure make it for many prohibitive.)
Besides these practical hurdles of pouring new concrete, have you ever considered the impact your decision can have on your CO2 footprint?
We did the math, and it doesn’t look pretty when you are a fan of new concrete!
Concrete is a very common building product (in fact it is THE most commonly used building product in the world). Concrete is very strong, but it is also very heavy. Per cubic foot, concrete adds a staggering 150 pounds to the scale.
A key component of any concrete mix is cement, which produces a very high amount of CO2 in manufacturing. Carbon dioxide (CO2) is one of the greenhouse gases that contribute to the warming of the Earth's atmosphere. It is estimated that 180 kg of carbon dioxide emitted during the production of one tonne of concrete. The result is an incredible 1 tonne of CO2 per 200 square feet of new concrete pour, or 6 tonnes of CO2 for an average 1,200 sft pool deck!
Compare this to the average CO2 footprint of a US resident with 16 tonnes CO2, or the CO2 output of a round-trip New York - LA - New York with 1.8 tonnes CO2, or the annual CO2 emissions of an average car at 4.6 tonnes CO2.
So, a simple decision to pour (or not to pour) 1,200 square feet of new concrete on a pool deck can dramatically increase (or decrease) your annual CO2 footprint, not even considering the CO2 emissions caused by a bunch of large trucks hauling away your old concrete. The impact of decisions around commercial properties, such as apartment swimming pools, retail store fronts, etc usually have an even greater impact due to their size!
Here are the details of our calculations for a residential pool deck of 1,200 sft:
150 lbs/cft at 4” slab thickness = 50 lbs/sft
50 lbs/sft * 1,200 sft = 60,000 lbs
180 kg / 2,000 lbs * 60,000 lbs = 5.4 tonnes CO2 emissions
A commercial slab outside of a retail area, total size 15,000 sft, 4” thick: 67.5 tonnes CO2. Equals CO2 emissions of 14 cars for one year
A pool deck in an multi-family apartment complex, total size 6,000 sft: 27 tonnes CO2. Equals carbon dioxide CO2 emissions of 30 single-passenger flights on United Airlines New York - LA - New York
But, what if you want to replace your old concrete with pavers? Would pavers have a lower CO2 impact than a new concrete slab? Sorry, no such luck. Most pavers are made from concrete, or concrete-like materials that use a large amount of cement, too. Usually, these pavers are molded and colored in a factory to give them the unique look and feel that you may love. However, it's safe to assume that the carbon dioxide footprint of a concrete paver is very similar to that of concrete.
Now you know. If you care about your own, your family’s or your company’s impact on CO2 carbon dioxide emissions, you can make a difference by researching how to renew your existing concrete so you don’t have to pour new or install pavers!