Sustainability

Why Concrete Can Be Considered Environmentally Unfriendly

There’s no mystery as to why concrete is envi­ron­men­tal­ly unfriend­ly. In fact, gaining insight into that question is fairly simple. Let’s start the dis­cus­sion on how concrete is made.

Concrete is of the earth”. We extract the elements that go into making concrete out of rock and earth. The next step after col­lect­ing the rock is to grind it into a powder. So far, so good. In the most elemental sense, powdered cement is green”. In its powdered form, cement is also biodegrad­able. Its envi­ron­men­tal­ly friendly ways go downhill from there.

We make concrete by mixing cement material with sand or fly ash and gravel, limestone or granite, and enough water to allow the material to set”, thereby binding it together. We make cement for that recipe by fusing together limestone and clay, sub­ject­ing them to great heat, and then grinding the com­bi­na­tion into a powder.

Why concrete is not envi­ron­men­tal­ly friendly. In general, it is not the ingre­di­ents, so much as the processes we use to make concrete that fail the sus­tain­abil­i­ty test.

  • Quarrying for the sand and other aggregate materials like limestone or granite can destroy and pollute the mine area.
  • To make cement takes a lot of energy and water.
  • There’s a lot of waste in the mixing process. The concrete hardens quickly and if there’s not enough time to lay it down before it hardens, builders just throw it away.
  • Concrete is known for its high carbon emissions into the atmos­phere, which con­tributes to green­house gases. This occurs in the process of making cement when the clay burns at high tem­per­a­tures and the limestone burns to create the high tem­per­a­tures. Big carbon footprint here.

But what would we do without concrete? Concrete is the most common building material in the world. We use it for our building footers and our basement walls and floors. We build our homes on slabs made of concrete. We use concrete to finish our driveways. We create sidewalks and stairs and porches around our home from concrete. We wouldn’t have our built-in pools without this versatile building material. We use concrete for the mortar that holds our brick fire­places and brick walls together, and for our patios and even benches to sit on. Is there anything to replace concrete in a sus­tain­able way? The answer is yes.

Three Advances in Concrete

Pervious Concrete. One envi­ron­men­tal­ly friendly product that replaces tra­di­tion­al concrete as a paving substance is pervious concrete.

Tra­di­tion­al concrete is envi­ron­men­tal­ly unfriend­ly with respect to the health of our water supply. As concrete covers more of our ground, less rainwater soaks into the soil. Tra­di­tion­al concrete is imper­vi­ous to water and so the water just runs off the paved surfaces. This creates lots of problems, the most notable soil erosion, flash flooding, depleted water table resources, and pollution from our oil-soaked and deicing-chemical-filled roadways.

More and more busi­ness­es and local­i­ties have switched to pervious concrete. Pervious concrete is a porous material that helps hold stormwa­ter runoff so that it per­co­lates into the ground and refills the water table. So instead of gushing down your driveway to the street gutters and sewers, your porous driveway, sidewalks, patio and pool areas snag the rainwater and hold it in tiny voids until it slowly seeps into the ground like nature intended.

CO2 Absorbing Concrete. A British man­u­fac­tur­er called Novacem claims that it has developed a new kind of concrete that absorbs large amounts of carbon dioxide during the hardening process instead of emitting carbon gases. Novacem claims its product can absorb .6 tonnes of CO2 compared to tra­di­tion­al concrete which emits .4 tonnes of CO2.

The product is still in trial stages but would sig­nif­i­cant­ly impact the building market if it were available for builders to use and designers to require.

Composite Cement. The Bautex wall system is based on a composite material that combines EPS foam beads with cement to provide an improved method of con­struct­ing walls. The Bautex wall system provides the storm resistant strength, fireproof prop­er­ties and ease of con­struc­tion of tra­di­tion­al concrete walls. It also provides insu­lalt­ing, sound absorbing, weight saving, moisture resis­tance of foam.

The use of foam in the composite also reduces the amount of cement required to provide a more envi­ron­men­tal­ly friendly solution. The result is a high per­for­mance wall system that saves energy, is faster to install, has less chance of instal­la­tion errors and is more envi­ron­men­tal­ly friendly.

To talk more about this, or anything else, please contact us. We look forward to sharing our ideas with you.