|
Concrete is Produced Locally from Abundant Natural Resources
The primary ingredients of concrete--crushed stone or gravel, sand and water-- account for approximately 90% of the volume of the mixture and are plentiful in most locations. Cement, which accounts for most of the rest of the mixture, is usually produced and available regionally as well.
As the one building material that is always produced in proximity to its use in buildings and infrastructure, ready mixed concrete greatly reduces the environmental impact of material transport by minimizing fuel requirements, energy consumption and emissions for transportation and handling. In addition, as a made-to-order material, concrete construction results in less building waste.
Concrete can be made with reclaimed industrial materials that would otherwise burden landfills Recycled materials in concrete reduce CO2 emissions Like any manufacturing process, the production of cement used in concrete results in the creation of greenhouse gases, including CO2. The U.S. cement industry has reduced CO2 emissions by 30% since 1972 and now accounts for approximately 1.5% of U.S. emissions, well below other sources such as heating and cooling homes and buildings (33%), truck and auto use (27%) and industrial operations (19%). The CO2 embodied in concrete as a finished building product is a very small quantity considering that cement accounts for a small proportion of the finished product.
The concrete industry also uses industrial waste byproducts such as fly ash (from coal combustion) and blast furnace slag (created in iron manufacture) to constitute a portion of the cement used in producing concrete. Use of such byproducts in concrete prevents 15 million metric tons a year of these waste materials from entering landfills. Utilizing these "supplemental cementitious materials" as a replacement for cement improves the strength and durability of concrete and also further reduces the CO2 embodied in concrete by as much as 70%, with typical values ranging from 15% to 40%.
Finally, when a concrete structure has served its purpose, it can be crushed for use as aggregate in new concrete or as fill or base materials for roads, sidewalks and concrete slabs. Even the reinforcing steel in concrete (which often is made from recycled materials) can be recycled and reused.
At the end of a concrete building or pavement’s usable life,concrete can be recycled
Pervious concrete percolates stormwater into soil, recharging aquifers and preventing polluted runoff from overwhelming streams and lakes Pervious concrete is made with little or no sand, producing a strong and durable pavement with voids that allow rain water to pass through. Pervious concrete pavements reduce or eliminate runoff and support pollution mitigation by capturing the first flush of rainfall and allowing it to percolate into the ground. Soil chemistry and biology can then "treat" the polluted water naturally. Pervious pavements reduce runoff that would otherwise burden streams with warm, polluted water and instead help replenish aquifers. This approach also reduces or eliminates the need for stormwater detention ponds with corresponding energy reductions and cost savings for the developer as well as the opportunity to make use of that otherwise unproductive land.
Pervious concrete pavement systems are recognized as a valuable stormwater management tool under the requirements of the EPA Storm Water Phase II Final Rule. These regulations provide programs and practices to help control the amount of contaminants in waterways. Pervious concrete is a well-understood engineered product, with tested characteristics for compressive, tensile, flexural strength and freeze-thaw durability. Additional information regarding pervious concrete's applications, engineering properties, environmental benefits, structural and hydrological design characteristics, mix designs and construction techniques can be found at PerviousPavement.org
Concrete’s thermal mass reduces temperature swings in buildings and conserves energy |