December 29, 2008

Blast Resistant Wall Paper and Enhanced Civil Defense

This a follow up to prior article about re-inventing civil defense using and one on improving blast resistance of buildings.

The U.S. Army has developed a new blast-protection adhesive tape called X-Flex. This X-FLEX tape would be used to coat the interior sides of exterior walls in order to absorb the shock of a blast, protecting the occupants from flying concrete and metal turned into projectiles. Of course, such a material could also be used to protect civilians. (xflex system website)

X-flex being applied like wall paper

The Engineer Research and Development Center (ERDC) is also developing a $10-million modular protective system that it claims in a promotional video is made from material "10 times stronger than concrete." The system would allow soldiers to construct temporary structures or reinforce existing ones with walls consisting of a double layer of armored panels held together by a collapsible frame.

There has been progress on research for making buildings hurricane resistant using fiber board based on jute trees and plastic and another project using glass fiber to make stronger wall boards.

The hurricane resistant board could even be used on low cost housing in North America and even Bangladesh.

If the six-month project is a success, the technology could also be used in the U.S. "Uddin said that while this next phase of his fiber-composite research is taking place overseas, the technology, if it proves viable, will have tangible benefits for the coastal regions of United States, including parts of Alabama. 'The potential payoff of this program could be the rapid insertion of the tree-fiber technology into the rebuilding and future construction of homes in the Gulf Coast states, especially in flood and storm prone areas like Mobile and New Orleans,' Uddin said."

Recently there was a simulated test in which the equivalent of a 15-foot piece of wood traveling at 130 miles per hour hit the less than 6-inch-thick SIP. The object barely made a dent on impact."

A blast-wave overpressure of 5 pounds per square inch, which is associated with winds around 150 miles per hour, is enough to destroy wood-frame buildings and cause severe damage to brick apartment buildings. However, with simple and cheap construction improvements and retrofits it is possible to enable all wood-frame buildings to survive 5 PSI. Further construction improvements can increase the survivability of buildings and the people inside them.

There is an article that overviews the general concepts around re-inventing civil defense

Hurriquake nails add $15 to the price of a home and make a house 50% more resistant to a hurricane or strong winds (or over pressures from a nuke).

UPDATE: The nails fit in a modern nail gun

The Hurriquake nails have been widely available since 2006. They were only available in the Gulf region. Bostich, the manufacturer, added new production lines to meet nationwide demand. The nails are used in tens of thousands of homes since 2006.

The Hurriquake nail is widely available on and other hardware suppliers

The bottom section of the HurriQuake nail is circled with angled barbs that resist pulling out in wind gusts up to 170 mph. This "ring shank" stops halway up to leave the middle of the nail, which endures the most punishment during an earthquake, at its maximum thickness and strength. The blade-like facets of the nail's twisted-top -- the spiral shank -- keeps planks from wobbling, which weakens a joint. The
HurriQuake's head is also 25 percent larger than average to better resist counter-sinking and pulling through.

For purposes of very rough estimation, it is sometimes assumed that the radius of 5 pounds per square inch overpressure defines the circle for which the number of survivors inside would equal the number of fatalities outside, taking into account all the listed effects other than fallout. This would mean that the total number of early fatalities, other than from fallout, would be estimated as the population density multiplied by the area of this circle.

If every building could survive 5PSI then there would be no building failures for category 5 hurricanes or less and potentially no deaths outside the 5PSI radius of a nuclear blast for anyone inside a building. This would reduce the casualties from a nuclear bomb by half or more.

There is a new method of handling wood fibers so that cellulose fibres are undamaged. The mechanical tests shows undamaged cellulose paper has a tensile strength of 214 megapascals, making it stronger than cast iron (130 MPa) and almost as strong as structural steel (250 MPa). This would be a cheap way to increase the strength of construction material and further reduce the fatal blast radius. If cellustic fiber provided inexpensive reinforcement up to 20PSI, then the fatal blast radius for those inside buildings could be reduced to 35%. This would be five times lower fatal area or only 20% of the casualties.

As the technology becomes available and affordable continue to increase higher levels of robustness.

Level 1: Hurriquake nails and other cheap adjustments that are widely available now and in use for some new construction. Expect to get to 2-5 PSI and up to 10-15 resistant houses. Also need treatments for improved fire resistance. 50-70% casualty reduction.

Level 2: Use cellustic fiber that is almost up to the strength of steel (nanopaper made from wood), more steel framed construction, better concrete or carbon fiber, or graphene reinforcement. Stronger windows, doors OR monolithic domes for some new construction. Resistant PSI 10-25+. 60-85% casualty reduction. Add anti-radiation damage drugs (see the bottom of this article on new carbon nanotube based drugs that are 5000 times more effective.) Total 85-92% casualty reduction.

Level 3: Better materials (more advanced carbon nanotube, graphene reinforcement with hydrogen impregnated for radiation shielding) and designs. PSI 25-100+. 85-98% casualty reduction. Need anti-radiation gene therapy and anti-radiation drugs as the radiation casualties would be dominant.

Level 4: Molecular nanotechnology. PSI 1000+.
Integration of radiation to electricity systems Integrate room temperature superconductors for strong magnetic shielding. Rapid evacuation from utlity fog systems. Metamaterials that guide earthquakes shocks and other waves around buildings. 99.9%+ casualty reduction.

Buildings already provide substantial radiation shielding.

Shelter in Place: Shielding by Buildings

Buildings provide considerable protection from fallout.

- A brick building provides better protection than does a brick veneer building, which is better than that of a frame building.
- Multiple stories increase protection as well.
- The interior of a one-story building reduces exposure by 50 percent.
- A level below ground reduces exposure by 90 percent.
- Additional levels provide more shielding and increase the overall effectiveness above and below ground.
- The five-story building illustration, below, shows that the middle floors provide better shielding than the ground floor because fallout that covers the ground emits gamma radiation along with that on the exterior surfaces of the building.
- Moving to a higher floor in the building increases the distance from the ground source but, at some point, increases exposure from the source on the rooftop.
- The best option is to move to the center of the building away from the exterior walls (and below ground, if possible) or to a middle floor above ground.
- Note how the position in the building and surroundings affect the percentage by which exposure is reduced in various locations.

A new drug tested on mice and monkeys provides protection from radiation exposure.

Gene therapy has been shown to increase radiation survival from 50% to 80%

Dosage is translated to casualties on a linear scale which measures the probability of the victim dying of radiation sickness. At 250 REM, the number of deaths is assumed to be effectively zero; note that small children, the elderly, and those with existing medical problems could conceivably die at this dosage. 250 REM is sufficient to give most people mild to moderate radiation sickness. At 600 REM, death is assumed to be virtually certain, especially with the probable scarcity of medical care in the wake of an attack. Massive attacks on a small area such as a missile base can produce 600+ REM fallout up to several hundred miles away.

Medical management (treating the injured) is important to reduce fatalities. So it makes sense to harden medical facilities to 100 PSI or higher. Other facilities to harden are power generation.

Monolithic domes are inherently strong and with better concrete can achieve 100PSI resistance.

Advancing technology means that weapons are getting more and more powerful and eventually more nations and groups will have access to nuclear weapons or more powerful weapons. It would foolish to assume that we must safely walk a tight rope without a safety net. A moderate increase in building costs will mean more survivable buildings that will save lives from severe weapons and warfare.

When carbon nanotubes are cheap after 2015 or so, then it will easy to increase buildings to 100-4000PSI strength while maintain most of the aesthetic look.

Nuclear weapons effects

Strengthen buildings and be able to shift the reduced fatalities over to the higher PSI level distances.

Having an intact structure will save more people from the blast and reduce the radiation that they are exposed to. Both immediate radiation and fallout.

By reducing the fatal radius for nuclear weapons means it would take 4 times, 20 times or more nuclear bombs to threaten the same percentage of the population.

Wikipedia's entry on bunkers

Product literature and code compliance for Hurriquake nails

The Hurriquake nails help against earthquakes too

On Page 265 of applications for Carbon Nanotubes

functionalized with additional hydrogen species, the composite materials could serve as radiation protection from secondary radiation events. Imparting nanotubes into the midplane or on the surface could serve as radiation protection or as protection against lightning strikes.

Discussion of materials for shielding against ionizing radiation. The more hydrogen in the materials the better the shielding.

Lithium hydride is a popular shield material for nuclear power reactors, but is generally not useful for other functions. The graphite nanofiber materials heavily impregnated with hydrogen or any composite thereof may well represent a viable multifunctional component in future space structures. In this case study of
the graphite nanofiber, hydrogen content is ~ 68% wt while in laboratory in single-walled carbon nanotubes (SWNT) hydrogen storage has been achieved ~ 10% wt.

Revolutionary methods of radiation shielding

(1) Active (electromagnetic) shield concepts:
• Electric fields.
• Magnetic fields (attached coils).
• Magnetic fields (deployed large-diameter coils or shields bearing magnets).
• Plasma methods (expand magnetic field, produce electric field).
Common elements:
• Many previous studies of physics for most; some studies of engineering.
• Requires space power to develop fields; requires superconducting magnets.
• To shield against GCRs one must have either very high fields or very extended fields.
• ∫ L BXdl
> 1,000 G km or V > 10**10 V.
Proposed figures of merit/discriminators:
• ∫ L BXdl
> 1,000 G km or V > 10**10 V.
• Smallest stored energies in field.
• Minimized effects of fields on crew and equipment (<2,000 G).
• Perceived practicality.
• Hazards.

(3) Novel materials concepts:
• Quasi-crystal H absorbers.
• Palladium, alloys as H absorbers.
• Carbon nano-material absorbers.
• Solid H.
• Metal hydrides.
• Borated CH2 and other compounds.
Common elements:
• Mass shielding.
• Goal is lowest average atomic mass achievable (polyethylene, CH2 is current “standard”).
• Dual use would modify the lowest average atomic mass rule.
• Neutron absorption.
• Structural or other use.
• Volumetric considerations.
Proposed figures of merit/discriminators:
• Average atomic mass number.
• Mass fraction of H.
• Dual use as construction material, neutron absorber, fuel, etc.
• Perceived practicality (fabrication, mechanical properties).
• Hazards

There is currently a 9 month study that started Jan 2008 to see if a new drug that is 5000 times more effective at preventing radiation injury in mice will work on humans.

The drug is based on single-walled carbon nanotubes, hollow cylinders of pure carbon that are about as wide as a strand of DNA. To form NTH, Rice scientists coat nanotubes with two common food preservatives -- the antioxidant compounds butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) -- and derivatives of those compounds.

"The same properties that make BHA and BHT good food preservatives, namely their ability to scavenge free radicals, also make them good candidates for mitigating the biological affects that are induced through the initial ionizing radiation event," Tour said.

Affordable (for wide deployment) and better radiation shielding and far more effective drugs could greatly reduce the deaths from ionizing and fallout radiation.

1987 Nuclear war survival skills book (300+ pages) by Kresson H Kearny

Some interesting tidbits. The overpressure from the Nagasaki air blast peaked at 65 PSI for buildings on the ground.

A lot of the protection was based on crude materials like lumber and dirt. By looking to upgrade the survivability of our regular houses and office buildings now and in the future, we need materials that people are happy to live and work in. Graphene with hydrogen impregnation reinforcing polymers could provide protection with thinner material, so that it would not look like we are living in bunkers even when 4-6 inch thick wall might be reducing radiation by 16 times or more.

Very high strength concrete mixtures (greater than 10,000 psi) have been around for decades.

Typical concrete mixes have about 4,000 psi. Reinforced concrete structures, depending on the type of concrete mix and steel employed, can support 300 to 500 times their combined weight and behave, according to general mechanics, as a single structural entity.

A team from the University of Tehran, competing in a contest sponsored by the American Concrete Institute, demonstrated several blocks of concretes with abnormally high compressive strengths between 50,000 and 60,000 PSI at 28 days. The blocks appeared to use an aggregate of steel fibres and quartz – a mineral with a compressive strength of 160,000 PSI, much higher than typical high-strength aggregates such as granite (15,000-20,000 PSI).

iCrete, which is now in common use in New York and is being used for Freedom tower, has a PSI strength over 14000 PSI.

Polymer concrete is concrete which uses polymers to bind the aggregate. Polymer concrete can gain a lot of strength in a short amount of time. For example, a polymer mix may reach 5000 psi in only four hours. Polymer concrete is generally more expensive than conventional concretes. (May be used in regular wood and steel formwork)

A monolithic dome made from 4000 PSI concrete would be able to easily survive 300mph winds which would put 1094 PSI pressure on a 100 foot diameter, 35 foot high dome. The shell is allowed 2,394 psi. The safety margin is actual three to four times.
Using iCrete a monolithic dome then the shell dome of that size could take 8379 PSI which is winds up to 900-1000 mph [overpressure PSI of about 50]. Using superconcrete with steel fibres and quartz the dome shell could take around 32000 PSI, which is winds up to 18000 mph or around 100 PSI overpressure.

Peak overpressure Maximum Wind Speed
50 psi 934 mph
20 psi 502 mph
10 psi 294 mph
5 psi 163 mph
2 psi 70 mph

Note that any higher construction costs are offset by lower maintenance costs and lower insurance for individuals and society. Monolithic domes can apply for home insurance discounts because of lower risks for fires and damage.

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