Sustainable Building Techniques
HISTORY
It turns out that fly-ash, a by product of coal burning energy plants, has a high content of Pozzolan...
more later in the article.
The Pantheon in Rome (+/- 2158 years old) one of the first major structures constructed with a monolithic concrete dome.
More on cement types, including Possuolana or Pozzolan Cement
An interesting fact is that concrete cures by slowly incorporating CO2 from the atmosphere.
Creating concrete will require machines, therefore additional CO2 emission will be created.
However, few know that the amount of CO2 to create concrete can be offset by the CO2 consumption the concrete needs to cure.
HISTORICAL DATA ON SPEED OF CONSTRUCTION OF CONCRETE STRUCTURES
|
Monument
|
Dome
Diameter |
Date |
Time |
Material
|
|
Pantheon
Rome |
43.30 m. |
118-125 AD |
7 years |
concrete |
|
Ste-Sophia
Istanbul |
32.60 m. |
532-537 AD |
5 years |
concrete |
|
St-Peter
Rome |
42 m. |
1400-1564 AD |
50 years |
stone |
|
Cathedral
Florence |
42.20m. |
1420-1434 AD |
14 years |
tiles concrete |
|
St-Paul
London |
30.80 m. |
1675-1710 AD |
35 years |
stone |
|
Pantheon
Paris |
21 m. |
1755-1792 AD |
37 years |
stone |
It is very interesting to see that with the arrival of the dark Middle Ages the knowledge of concrete construction disappeared, only to reappear in construction in the late 19th Century with the ground breaking work of Pierre Jeanerette and Le Corbusier.
In the early 20th Century we see the emergence of steel re-enforced concrete, now used globally as a key building material in civil and home building.
Concrete in its cured form, has no toxic side effects. The problem is in the 'wash out water' of trucks that deliver the concrete and tools to shape the concrete. After delivery and shaping of the concrete these tools and trucks must be washed out so no concrete 'cakes' on them.
This wash-out water is extremely caustic, in essence can be compared to 'Drano' used in the United States to clean out clogged drains. It kills wildlife, plants and especially fish rapidly if released in the water streams. The USA has currently no measures intact to prevent this pollution.
However, a simple measure to remediate this is available. By attaching a rolling wash out water 'catch' basin to the concrete truck, this caustic side product can actually be reused at the concrete mixing facility to efficiently and inexpensively produce new batches of concrete.
How to deal with toxic concrete wash-out problems and making money in concrete production
With the Global Warming issue it is easy to get confused.
We now know that we seem to be doing something wrong, yet exactly what we are doing wrong seems to be a bit vague.
We as humans, and our machines that give us comfort, create CO2.
Plants on the other hand love CO2, they like to covert it to O2, which we need and as a by product plants create carbon related things like wood, fibers, oils, etc.
All Carbon based products that we like to use can be organically recycled, provided they are not mixed with man-made products.
Man-made products can be recycled as well, as long as they are designed properly.
The Roman Empire basically ran out of wood for construction before 0 AD. It resorted to stone building and invented concrete building.
Mid Europe ran out of wood and forests in the 14th Century, which was its main construction method. It was replaced with a high CO2 producing process where local clay is heated to produce bricks. In the 20th Century concrete replaced bricks as its key building material.
Northern Europe with its vast forests and low population could, to this day, maintain a sustainable wood building method.
Asia ran out of wood in the 10th century. Both China and India resorted quickly to the high CO2 producing ' brick method', currently are on the verge of applying new eco concrete composite building systems to accommodate their anticipated building growth .
Russia, with its massive forests, and once considered the O2 lung of Europe, rapidly depleted its wood resources and resorted to massive concrete buildings in the Soviet era to accommodate its population.
Africa, with slow growth, mainly exports its wood to other parts of the world.
South America, with the Amazon Forest , and considered to be the largest O2 lung and wood reserve in the world, does not use much wood to construct. It mainly builds with brick and concrete. It uses its wood resources to gain capital through exports.
North America, considered to be the second largest O2 lung in the world, has been rapidly depleting its wood resources with 75% of its construction methods still remaining wood based. Its dependence on wood construction and its need to push wood buildings beyond their normal life span, has led North America to infuse its wood building products with many toxins to expand its life time, and to kill vermin that normally will break down the organic material. New emerging market forces in North America are demanding change in this practice.
In the United States the green building revolution is changing the way wood is treated and borax treatment of wood is gaining ground.
Projections are that the urban centers of the world are currently growing by the size of 8 Manhattans per year.
Most of this urban growth is located outside of the United States
Dubai
Chongquin
The explosion of urban living and the global awareness of global warming creates a revolution in green building materials and energy techniques worldwide.
One rapidly developing construction method is based on cement composites, often with foamed plastic cores. Foamed concrete blocks are often used in non-bearing separation walls.
New foam based panels (SIP's) are entering the building process. These building panels are often foam with plywood on both sides, making them impossible to recycle ( see below). Others are foam with cementitious skins, which are better for recycling.
SCIP buildings are the newest development in green cement building systems. These buildings have a foam core and a monolithic cementitious skin, which allows for new fractal engineering techniques developed for carbon fiber airplanes, like Boeing's Dreamliner.
The advantage of the monolithic, thin concrete skin is that all parts of the structure add up to each other, multiplying the overall strength. Another advantage is that 60% of the building's structure is air, upping its strength-weight ratio.
Styropor as green building material.
The Cradle to Cradle principles are brilliantly described by William McDonough in this book
ORGANIC RECYCLABLE BUILDING MATERIALS
Wood, Paper, Bamboo, Straw bales
NON-ORGANIC RECYCLABLE BUILDING MATERIALS
Stone, Concrete, Metals, Plastics, Glass, Earth.
THE LAND FILL PROBLEM
A wood framed house with vinyl siding is hard to recycle and generally ends up in landfill. A wood framed house with a stucco finish is better, although the non-organic matter would first need to rot for the non-organic matter to be recyclable.
A wood house is easiest to recycle, provided that the wood is not treated with toxins to preserve its life.
Urban Structures made completely out of NON-ORGANIC building materials are the easiest to recycle. In interior applications, one has the option to use, a fully organic bio-degradable product (couch - wood, fibers, fabrics) or manmade interior applications ( glass, aluminum, ceramics, etc.) allowing for an abundance of expressions.
The reformatting of plastics into new usable forms can be easily accomplished.
By recycling plastics properly, the energy used to melt and reshape the plastics, are minimal and can be accomplished with sustainable solar and wind technologies.
The key to recycling plastics is to identify and label the type of plastics.
There are broadly 6 types of plastics that if recycled properly, by coding them, can be re-formed endlessly
NEW CEMENT TYPES
New replacements for Portland cement are being developed. Some of these geo polymers can interact with local dirt to create concrete.
Fly ash, a by-product of coal fired electrical plants, has a high level of Pozzolan, which makes it possible to use fly ash as concrete.