The forests of gleaming skyscrapers rising from most world urban centers today may be a symbol of modern human technological innovation and ingenuity, but some materials used in their construction are nearly as old as civilization itself. Roman structures built almost entirely from cement and aggregates are still standing two thousand years later. Builders today hope to achieve similar longevity using more environmentally friendly concrete.
The concept of building with a material completely in harmony with nature is primarily a marketing concept, but one with a solid foundation of truth. What most people think of as concrete is made in part from broken and crushed rock called aggregate. The size of these rocks varies according to intended use, and they are mixed into a liquid slurry that is mostly water and portland cement, as well as additives.
Although rock meets the definition of a natural substance, the cement does not. Portland cement was invented during the Industrial Revolution, and is commonly used today in grout, mortar, and other products. Handling it requires caution, and exposure can cause serious burns. It also contains potentially toxic silica and chromium, and production of this material creates additional carbon emissions into the atmosphere.
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.
Production of cement increases the possibility of water pollution, and makes safe disposal of demolished material necessary. Although made mostly from natural rock, the substance does not naturally decompose, but must be broken into smaller chunks using machinery. Once it has deteriorated, it must either be reinforced with fresh material or torn down. Recycling is increasing, and a considerable amount of re-purposed material is used in highway construction.
Similar to many other potentially hazardous industrial processes, a carbon-negative production method is possible, but costly. Developing nations are currently the biggest users, and resist adding additional, built-in expenses to construction. For many companies, using this material intelligently and judiciously is just as important environmentally as improving inherently hazardous cement production methods.
Using concrete manufactured locally eliminates costly and high-emissions transportation, although what constitutes local is still debated. The substance can be an energy-efficient asset by creating a thermal mass, or large solid body that retains both heat or cold, which helps regulate interior temperatures throughout the day. While cities typically are hotter than countryside, aggregate surfaces can reflect sunlight and slightly reduce the heat index.
The best environmental quality of all is long life. When hardened, the substance resists nearly every kind of weather and extreme fluctuation of temperature. It can even be made more earth-tremor resistant. When a building has a long life expectancy, costs even out, and demolition hazards becomes less important. Ever-improving building design and construction methods make this a viable material that can be compatible with nature.
The concept of building with a material completely in harmony with nature is primarily a marketing concept, but one with a solid foundation of truth. What most people think of as concrete is made in part from broken and crushed rock called aggregate. The size of these rocks varies according to intended use, and they are mixed into a liquid slurry that is mostly water and portland cement, as well as additives.
Although rock meets the definition of a natural substance, the cement does not. Portland cement was invented during the Industrial Revolution, and is commonly used today in grout, mortar, and other products. Handling it requires caution, and exposure can cause serious burns. It also contains potentially toxic silica and chromium, and production of this material creates additional carbon emissions into the atmosphere.
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.
Production of cement increases the possibility of water pollution, and makes safe disposal of demolished material necessary. Although made mostly from natural rock, the substance does not naturally decompose, but must be broken into smaller chunks using machinery. Once it has deteriorated, it must either be reinforced with fresh material or torn down. Recycling is increasing, and a considerable amount of re-purposed material is used in highway construction.
Similar to many other potentially hazardous industrial processes, a carbon-negative production method is possible, but costly. Developing nations are currently the biggest users, and resist adding additional, built-in expenses to construction. For many companies, using this material intelligently and judiciously is just as important environmentally as improving inherently hazardous cement production methods.
Using concrete manufactured locally eliminates costly and high-emissions transportation, although what constitutes local is still debated. The substance can be an energy-efficient asset by creating a thermal mass, or large solid body that retains both heat or cold, which helps regulate interior temperatures throughout the day. While cities typically are hotter than countryside, aggregate surfaces can reflect sunlight and slightly reduce the heat index.
The best environmental quality of all is long life. When hardened, the substance resists nearly every kind of weather and extreme fluctuation of temperature. It can even be made more earth-tremor resistant. When a building has a long life expectancy, costs even out, and demolition hazards becomes less important. Ever-improving building design and construction methods make this a viable material that can be compatible with nature.
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