Nov 27

Concrete Homes – Built to last!

Concrete Homes

Courtesy of Buildipedia.com

With an ever growing population in a constant need for new housing options, a planet that seems to want to shake us of her back with record floods, earthquakes, hurricanes, tornadoes and wild fires, building stronger home as well as conserving non-renewable resources is becoming an absolute imperative. As a result, old and new ideas emerge, and in the field of construction, concrete homes is making a headway.

WHAT ARE CONCRETE HOMES

In addition to pouring the usual concrete slab as the foundation and a driveway, concrete homes replace stick framing with concrete walls that are made with forms. The idea to replace wood structures is by no mean new, adobe homes are some of the oldest dwellings still standing that used rammed earth in lieu of wood. But they require substantial man power and time. Concrete homes on the other hand can be built in very little time with a small crew for about the same price as regular stick framed homes.

NEW DISCOVERY?

Not really! In 1908, while looking for an affordable and durable housing solution, Thomas Edison invented a concrete forming system for homes and patented it! The whole process would take 4 days to erect the mold structure, then pouring the concrete in 6-hour increments, completing the entire project in less than 2 weeks!  In 1937, Frank Lloyd Wright built its famous Fallingwater home in concrete showcasing its strength and ability to create unique shapes that beautiful blend with the surrounding natural setting.

concrete home using insulated concrete forms, ICFs

Setting up insulated concrete forms. Courtesy of saipreethiprecastbuilder.com

HOW CONCRETE HOMES ARE BUILT

To replace the wood structure, insulated concrete forms (ICF) are used. Once the forms are stacked up to form the wall, they are braced on the outside, a moving scaffolding is used to pour the concrete poured into the walls. Some insulated concrete forms incorporate expanded polistyrene (EPS) for greater insulation (R-60). The next day, the walls are set and framing of the interior walls can start and the scaffolding can be moved to the next house. This process could save up to 2 days of work per house!
Watch how a 250 square foot studio home is built in less that 3 hours in this short video.

WHY BUILD A CONCRETE HOME

Concrete homes are tornado and hurricane proof

Concrete home left standing after Katrina.      Courtesy of Conradscastles.com

Ask any long-time home owner what features would an ideal house have and the following is mentioned:
– Moisture, mildew and mold protection
– Termite resistant
– Provide better insulation at the same price
– Eliminate cold spots
– Provide even temperature through day and night.
– Protection against wild fires in drought prone regions (concrete is naturally fireproof)
– Withstand high winds (in hurricane prone regions)
– Meet seismic building code requirements (up to zone 4)
– Better sound proofing
Unbelievable but true, concrete homes address every feature in this list without adding extra cost for each problem.

GREEN BUILDING

Concrete homes are considered green because they recycle cementitious materials like fly ash, slag cement, silica fume that would otherwise be dumped into landfills.

For builders and home owners looking to green their homes, concrete homes completely eliminate the need for volatile preservatives found in the various glues that make up particle wood panels.

With over 9 states in the US experiencing exceptional to abnormally dry weather in 2015, the need for better insulated homes is paramount. When cooling and heating bills in Southern California can be as high as $600-800 a month for a 2,800-square-foot home, the possibility of saving up to 50% of your energy is a huge plus.

DESIGN BENEFITS

Left in its original grey color , concrete can be experienced as masculine, a bit cold and dull, but the use of concrete finishes can transform this material into warm and stunning surfaces that can be combined with wood, glass and other materials.
Concrete homes also offer a greater flexibility in terms of design. Curved walls can easily be incorporated and cheaper to build. They can be very simple and have been transformed into magnificent designs by architects around the world leveraging the surrounding landscape and terrain. Concrete can accommodate very unique modern futuristic designs and angles and can even be used to build monolythic domes.

ISSUES WITH CONCRETE HOMES

Placing concrete in the walls can be challenging and blow-outs can occur. But a experienced operator can take all the necessary precautions to avoid them.

Concrete homes used to cost 3-5% more than standard stick-framed buildings but with a 30-45% energy savings and up to 20% insurance discounts, the monthly operating costs of a concrete homeowner is equal and often even less than regular homes. So cost is no longer an issue when building a concrete home!

MARKET ADOPTION

In a market that constantly sees ups and downs, concrete homes represents a real business opportunity for concrete operators and pumping companies to stand out. Accurate placement of walls requires expertise and know-how. As in all well-established industries, new ideas can be threatening but the benefits of concrete homes so far outweighs the small learning curve builders have to go through to familiarize themselves with ICFs, pouring techniques etc.

More and more environmentally conscious consumers are doing their research and asking for concrete homes that offer energy-efficient solutions, that are much more durable and less toxic. They will only hire contractors that have experience and can do the work. So while most builders may shy away from new techniques and rather do what they know best, there is a growing new market that is waiting to be grabbed.

What size market are we talking? About 14% of the single family homes built in 2002, that’s about 171,000 homes were concrete homes, according to Jim Nicholl, PCA residential promotion manager. So with increasing unpredictable harsh weather patterns we are seeing all over the world and certainly in the US, the need and future for safer and more sustainable concrete homes is real and promising.

If you are looking for great deals on used concrete pumps or aerial lifts,
call United Equipment Sales at: (503)283-2105.

REFERENCE MATERIAL

http://concretehomesmagazine.com/

http://www.cement.org/think-harder-concrete-/homes/building-systems

S.M.L.

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Nov 13

Fly Ash Concrete

Fly ash in concrete

FROM GREY TO GREENISH …

If you consider yourself a green person, you may think using fly ash, a by-product of burning coal, in your concrete mix rather sacro-saint! After all, coal plants are some of the biggest polluters and CO2 emitters.  In recent decades, in an attempt to minimize its environmental impact, the EPA forced coal-powered plants to trap particulate matter before it is released in the smokestacks, to properly capture and dispose coal ash, a.k.a. as fly ash, the residue found after smokestacks are cleaned. Disposal of fly ash is usually done by mixing it with water and placing it into open impoundments (that could be damaged by storms), storage ponds or buried in landfills that have been known to occasionally breach or leak as in the case of the December 2008 collapse at the Tennessee Valley Authority’s Kingston Fossil Plant, releasing 5.4 million cubic yards of coal fly ash into the Emory River! So how much are we reusing? Approximately 43-45% of all fly ash is being recycled today.

Electrical PoleWith 50% of all electricity in the US being generated by coal plants, one couldn’t begin to imagine the huge amount of fly ash produced by coal-powered plants daily. Capturing it and reusing it in a safe way would in fact prevent the inevitable spread of some of the heavy metals  it contains (depending on the coal bed makeup: arsenic, lead, chromium, mercury, dioxins etc.) in the atmosphere we breathe, the water we drink… So when the first attempts at substituting fly ash to Portland cement resulted in a concrete with greater strength and durability, what was once a worrisome problem looked like it could be turned into a solution for the environment and the construction industry. Recycling fly ash into concrete would not only reduce CO2 emissions but also neutralize the harmful effects of the known carcinogens it contains and the need to mine for new raw materials. Also called geopolymer concrete, this “green” concrete is cheaper to produce and is being widely adopted for all types of concrete applications.

2 TYPES OF FLY ASH
There are 2 classes and both can be used as a replacement for Portland cement or hydrated lime. They act as a filler providing contact points between larger aggregate particles in asphalt concrete mixes.

Class F: is made from burning anthracite and/or bituminous coal
Class C: is made from lignite or subbituminous coal

BENEFITS OF USING FLY ASH IN CONCRETE

Earth-Friendly-IconECO FRIENDLY?
The process of making cement is quite energy-intensive and could account for 5-8% of greenhouse gas emissions around the world. Factor in steady population growth and the number will continue to increase unless a massive adoption of greener alternatives happens. Fly ash concrete is one of them because of its abundant availability, cheap cost and the fact that it could reduce as much as 90% of CO2 emissions when considering the end to end process.

Green builders can gain points towards their LEED goals (Leadership in Energy and Environmental Design) if they can replace at least 40% of Portland cement with it. Bricks that are made with fly ash can even store CO2 from the atmosphere.

ALL AROUND BETTER CONCRETE
Fly ash is known to improve concrete’s workability, pumpability, chemical resistance, finish, strength, and durability. Fly ash particles are similar in size with Portland cement and as a result requires less water during the mixing stage. This means better surface finish, sharper edges in precast concrete. Its fine particles reduce bleeding and segregation and improve overall workability. This is especially helpful in extending working time in hot weather.

DECREASED PERMEABILITY:
Fly ash produces a concrete that is less porous than Portland cement. The pozzolanic effect of fly ash creates a denser product due to smaller pore sizes. It also reduces bleed channels and permeability in concrete.

Widely used in road projects, fly ash increases the stiffness of the asphalt, improving rutting resistance and mix durability.

EXAMPLES OF FLY ASH REUSE

In addition to replacing Portland cement, fly ash is being used in the following areas and the list keeps expanding:

  • Road construction: ideal self-compacting backfill material (as a replacement for compacted earth) for backfill, embankments, road sub base construction, mineral filler in asphaltic concrete, as a loose application on roads for ice control, in highway sound barriers…
  • Agriculture: fertilizer, soil amendment and stabilization.
  • Aggregate material substitute: for brick production replacing clay.
  • Dam construction: in roller compacted concrete dams.
  • Waste management: waste solidification and stabilization, conversion of sewage sludge into organic fertilizer or bio fuel.
  • Roofing material: tiles, granules.
  • Marine: pilings, artificial reefs
  • Binding agent: paints, undercoating.
    And much more

IN CONCLUSION

Only time will tell whether or not small amounts of heavy metals could leak from the concrete over time and if this new found durability is truly long lasting. Recent spills have prompted environmental groups to call for tougher regulations, so whether or not the EPA decide to classify it as hazardous  material remains to be seen. But until then and until coal powered plants are being phased out for greener alternatives, and the huge reserves of fly ash remains an environmental issue, the safe use of fly ash in concrete makes sense and should continue. 

United Equipment Sales

Sources:
Marc Boyer: How fly ash concrete works
Fly Ash on Wikipedia
Fly ash products
Fly ash suppliers