Concrete is a friend of the environment in all stages of its life span, from raw material production to demolition, making it a natural choice for sustainable home construction.
With the green revolution fully underway, the question of concrete as a sustainable construction substance has to arise sooner or later. Should architects and engineers now consider alternatives in order to comply with the global demand for low-impact building materials? Science, historical data and common sense all say no. Just the opposite is true. Concrete’s inherent nature passively promotes substantial energy conservation. Add in the developing innovations, and it actively contributes to the removal of environmental pollutants, making it sustainable—and quite desirable—for environmentally-friendly construction.
ABUNDANT AND RENEWABLE
The primary component of the cement that binds the aggregate to
form concrete is limestone, one of the most common and abundant
minerals on earth. Because limestone, calcium carbonate, is formed
from the remains of marine life, new deposits continue to form in
the oceans. However, since surface deposits cover vast areas above
sea level, ocean mining may never come into play for manufacturing
concrete. Like limestone, the other constituents of cement and
concrete are found in massive quantities around the world.
A NO-WASTE OPTION
Building with concrete can rightfully be touted as 3-D printing
writ large. Unlike materials that come in bulk and must be cut to
size (with much waste), building with pourable and moldable
concrete requires only enough to fill the forms according to the
pre-established design. Leftover product, if any, usually goes back
to the plant and becomes large, semi-regular blocks. Said blocks
can be used to shore up eroding hillsides, among other purposes.
Very little concrete ever goes to waste.
RECYCLED ADDITIONS AND ITSELF RECYCLABLE
Not only can old concrete be reduced and recycled into new as the
aggregate component, it can be broken up and used in place of whole
rocks. As rip rap, blocks of old concrete serve along waterways to
prevent erosion and along shorelines to quell waves. Often, it is
reused as new road base. For some design purposes, industrial slag
and fly ash from power plants are desirable additions and so help
recycle those elements that would otherwise be handled as waste.
Moreover, biowaste technology will enable more plants to burn trash
to fire the cement kilns, keeping it from feeding the
landfills.
ALMOST AGELESS
Tour any old European city and the ancient ruins therein, and
anyone can see that concrete endures as a building material. Unlike
wood, that rots and burns, and metal that rusts, concrete
structures save on future replacements and never add toxic
particles to the air from combustion.
ENERGY EFFICIENT
As a thermal massor, meaning it absorbs heat, heavy-framed
buildings (concrete walls and roofs) hold the interior the heat in
winter and absorb the exterior heat in the summer. This barrier
between outside extremes and interior comfort reduces operational
HVAC energy usage by an estimated 29 percent, maybe more under
ideal conditions. Furthermore, impervious concrete stops thermal
transfer, unlike most other building materials. As an added bonus,
it does not off-gas, as do petroleum products and
chemically-treated woods, helping prevent “sick building”
conditions.
SO COOL
As a light-colored surface, uncoated concrete reflects sunlight
back to space and thereby exempts itself from the urban heat island
effect.
INNOVATIONS TOWARD CLEAN CITIES
One very exciting concrete product from Italy is photocatalytic
concrete. This special, patented concrete can eliminate smog by up
to 80 percent depending on atmospheric conditions. Smog, consisting
of nitrogen and sulfur oxides combined with volatile organic
compounds or hydrocarbons, is attracted to the photocatalytic
concrete. Once attached, it becomes oxidized and neutralized by the
UV radiation of the sun. Rain and snowmelt then washes the
resulting harmless salts away, leaving a clean, white surface. This
concrete proves great for roads, roofs and exterior walls,
especially in highly polluted cities. It toils away each day to
actively scrub the air. The developers estimate that if only 15% of
urban roadways and buildings were constructed with photocatalytic
concrete, up to 50% of the ambient pollution would cease to exist.
Their product even eliminates some bacteria, fungi and odors.
WATER PRESERVATION
Pervious, porous, concrete, which is actually a fairly old
technology, allows water to percolate through it rather than run
off to water channels. Not only does pervious concrete allow for
the precipitation over cities covered in roofs and paved roadways
to soak back into the ground and refill the aquifers, such
retention-in-place of the water curbs damages from stormwater
runoff. Pervious concrete is plenty strong enough to be used for
parking lots and curbside lanes to capture the runoff from the
existing pavement.
Some may be concerned that the production of concrete adds too much carbon and carbon dioxide to the atmosphere for it to be considered sustainable. From mining, milling, cooking the cement and transportation, one can’t argue that concrete has some impact on the environment. However, no industrial building material, be it lumber, metal, natural stone or a sturdy petroleum-based product, can come into existence without similar carbon costs. Of all extant construction materials, though, the ecological benefits of building with concrete places it very high on the totem pole for ultimate sustainability.
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