The astonishingly beautiful skylines increasingly gracing cities around the world are a testimony to human ingenuity and creativity, but the basic material used to finish them is not a product of the digital age. Roman construction using mixtures of cement and aggregate still stands proudly in some European cities after two thousand years. Modern builders aim for the same durability using environmentally friendly concrete.
The idea that an industrial construction material can be more in sync with the natural world is primarily a marketing strategy, but the premise is not entirely inaccurate. The substance people recognize as concrete generally is made of small bits of rock called aggregate, which vary in size and content. It is mixed by machine with a liquid paste made of water and portland cement, and can be strengthened using rebar.
Rock is by definition natural, but the cement slurry is not. Portland cement was invented during the Industrial Revolution, and is also used today in mortar, grout, and other products. For humans it is physically harmful, and skin contact can result in burns. It contains toxic chromium and silica, and the manufacturing process cannot be considered ecologically friendly because of high carbon discharges.
Not only is excess carbon dioxide released, but certain kinds of chemicals are routinely added to bolster plasticity and improve other characteristics. Called admixtures, they shorten the setting and drying period, increase flexibility when cured, and use less water overall. Because they are necessary for modern construction methods, added chemicals include polymerics to increase tensile strength, plasticizers, setretarders, and aerators.
Cement production can also result in water pollution, and proper disposal methods are important and necessary to protect the environment. Even though they are made of rock, aggregates do not naturally break down, and need to be pre-processed by machine before dispersion. When it does deteriorate, construction must be reinforced with strong, new material, or else pulled down. Recycling is gaining ground, and demolished, crushed aggregate is commonly used in highway improvement.
As is the case with many useful industrial applications, achieving a carbon-negative method of manufacturing is possible, but very expensive. The heaviest users of this building material are developing nations, who can least afford additional built-in costs. For many builders, making the best and most intelligent use of this material is as important environmentally as upgrading the manufacturing process.
Using only locally produced material reduces the need for long-distance transportation, and cuts emissions. Finished surfaces can actually help control building temperatures by forming a thermal mass, which is a large, solid body that better retains cold and heat, releasing them slowly over time. Cities today experience higher temperatures than surrounding areas, and this substance reflects a measurable amount of sunlight back into space.
Longevity remains the greatest environmental benefit. Properly hardened material resists weathering and cracking, and can even be made more resistant to seismic shock. A structure designed to last decades may be initially more costly, but those expenses even out, making repairs and ultimately demolition more financially manageable. Improved cement production processes and advanced building design methods are helping to improve negative public opinion.
The idea that an industrial construction material can be more in sync with the natural world is primarily a marketing strategy, but the premise is not entirely inaccurate. The substance people recognize as concrete generally is made of small bits of rock called aggregate, which vary in size and content. It is mixed by machine with a liquid paste made of water and portland cement, and can be strengthened using rebar.
Rock is by definition natural, but the cement slurry is not. Portland cement was invented during the Industrial Revolution, and is also used today in mortar, grout, and other products. For humans it is physically harmful, and skin contact can result in burns. It contains toxic chromium and silica, and the manufacturing process cannot be considered ecologically friendly because of high carbon discharges.
Not only is excess carbon dioxide released, but certain kinds of chemicals are routinely added to bolster plasticity and improve other characteristics. Called admixtures, they shorten the setting and drying period, increase flexibility when cured, and use less water overall. Because they are necessary for modern construction methods, added chemicals include polymerics to increase tensile strength, plasticizers, setretarders, and aerators.
Cement production can also result in water pollution, and proper disposal methods are important and necessary to protect the environment. Even though they are made of rock, aggregates do not naturally break down, and need to be pre-processed by machine before dispersion. When it does deteriorate, construction must be reinforced with strong, new material, or else pulled down. Recycling is gaining ground, and demolished, crushed aggregate is commonly used in highway improvement.
As is the case with many useful industrial applications, achieving a carbon-negative method of manufacturing is possible, but very expensive. The heaviest users of this building material are developing nations, who can least afford additional built-in costs. For many builders, making the best and most intelligent use of this material is as important environmentally as upgrading the manufacturing process.
Using only locally produced material reduces the need for long-distance transportation, and cuts emissions. Finished surfaces can actually help control building temperatures by forming a thermal mass, which is a large, solid body that better retains cold and heat, releasing them slowly over time. Cities today experience higher temperatures than surrounding areas, and this substance reflects a measurable amount of sunlight back into space.
Longevity remains the greatest environmental benefit. Properly hardened material resists weathering and cracking, and can even be made more resistant to seismic shock. A structure designed to last decades may be initially more costly, but those expenses even out, making repairs and ultimately demolition more financially manageable. Improved cement production processes and advanced building design methods are helping to improve negative public opinion.
No comments:
Post a Comment