Falling apart: America's neglected infrastructure | Emergency Preparedness | Forums

• Roofing: When the roofing of a building fails, this will quickly deteriorate the structure itself. Most roofing isn't able to last more than 20-40 years, and after that you'll have UV breaking down the roofing and water will start to get into the building. Roofing materials today are often TPO or built-up roof, and are oil based.
• Urethane/Silicone Sealant (called caulk by the general public): Buildings now require sealant at all joints in the building, whether it's around brick, windows, or metal flashings. Urethane sealant is good for about 15 years, and silicone for maybe 30 years. After this, you'll start to get water into all these joints. Once water gets in, the structure will begin to deteriorate. It is extremely costly to replace all sealant on an office tower and you need electricity to operate the swing stages to access the sides of buildings. Even on smaller buildings, what are you going to use to protect the joints if sealant isn't available?
• Corrosion resistance of brick anchors: We used to build with mass walls, meaning brick/stone were stacked up and the walls were thick. These walls could hold up without much maintenance, or the maintenance could be done without industrial means. Now, we have very thin walls supported by the skeleton of the building, and all cladding materials are held on with stainless steel or galvanized anchors. Despite what stainless steel sounds like, it corrodes also. If there is continuous exposure to water, as would happen with lack of sealant, these anchors will corrode over time and cladding material will be falling from buildings.
• Depth of carbonation: For the worst case scenario, for concrete structures constructed in the year 2030, in areas where carbonation induced corrosion would be a concern (moderate humidity,higher temperatures), for a dry exposure class, we can expect structures to begin to show a reduction in serviceable lifespan due to climate change of approximately 15–20 years, with signs of damage being apparent within 40–45 years of construction

definition of carbonation from wikipedia:

Carbon dioxide from air can react with the calcium hydroxide in concrete to form calcium carbonate. This process is called carbonatation, which is essentially the reversal of the chemical process of calcination of lime taking place in a cement kiln. Carbonation of concrete is a slow and continuous process progressing from the outer surface inward, but slows down with increasing diffusion depth.

Carbonatation has two effects: it increases mechanical strength of concrete, but it also decreases alkalinity, which is essential for corrosion prevention of the reinforcement steel. Below a pH of 10, the steel's thin layer of surface passivation dissolves and corrosion is promoted. For the latter reason, carbonation is an unwanted process in concrete chemistry. It can be tested by applying phenolphthalein solution, a pH indicator, over a fresh fracture surface, which indicates non-carbonatated and thus alkaline areas with a violet color.

http://en.wikipedia......arbonation

also about corrosion cell in concrete:

Corrosion of steel embedded in concrete is an electrochemical process that involves the formation of an electrical circuit between areas of active corrosion (anodes) and passive areas (cathodes). The formation of corrosion products at the anodes is an expansive process that results in the cracking and eventual spalling of the concrete. In the corrosion process, the concrete acts as an electrolyte allowing the flow of ions from anodes to cathodes.

edit here's a bit on mass wall construction (just means thick walls, opposed to stick walls with insulation+brick veneer: http://www.wbdg.org/.....v_wall.php

• Stainless steel isn't stainless - it just corrodes slower. One big example -- The St. Louis arch is corroding (though it is not structural now).
• HVAC prevents condensation. Once HVAC systems go out, many buildings will become uninhabitable. Most walls today are designed so that based on the interior and exterior temperatures, condensation will not occur inside the wall. However, turn off the HVAC, and you'll start to get condensation on plywood, 2x4s, steel studs, and all the rest. This is extremely common even now with poor construction practices. I've seen entire apartment buildings require total recladding due to rotting 2x4s and plywood inside the wall. This will accelerate at a massive speed once the power goes out. I expect most buildings will need to be abandoned since they can only work with an HVAC system.

edit Here's a good historical overview of how our buildings have gotten more energy inefficient and less durable over time.

edit As for scrapping steel in the future, I'm extremely pessimistic. I think it was Kunstler or Orlov who think we'll be running around with acetylene torches. Good luck making acetylene -- you need an electric arc furnace and specialized torch lines. Having worked with these torches in a factory, I can tell you that you regularly need new parts. The hoses get torn and you need parts to fix these. I'm also curious how you intend to get compressed cylinders of oxygen and gas once industrial society breaks down. This shit didn't exist before they end of the 19th century, and I'd very surprised if these were around in another 100 years. We won't be able to do any scrapping in the future beyond using simple tools like hammers. That means we'll just have to wait for buildings to collapse naturally.

edit Kunstler says skyscrapers are in trouble, but I think he's being very optimistic here. Low-rise buildings that are built with industrial materials will not do much better. How do you plan to maintain roofs like this in the future? Fucking thatch? You'll have to demo this building for scrap very quickly after collapse happens. Not to mention depth of carbonation -- all houses are on foundations and have roofs that have limited lifetimes, and no way to repair them after collapse. Once the roofing goes, your plywood sheathing will rot, and the structure of the house will soon be gone. We're now building with things like TJI joists and OSB sheathing, both of which cannot be exposed to any moisture, or they decay incredibly quickly.

edit damage to buildings is exponential. Something that is cheap to fix this year becomes exponentially more expensive each year. I've seen deferred maintenance that multiplies the cost by 10x by just waiting a few years. Imagine how this will play out w/peak oil.

edit I became somewhat of an expert on marble cladding failures. This was a material we used in the 1960s, and it was a massive mistake. A great example of the failure of this material is the Amoco building in Chicago. They had to replace all of the marble panels. This is a global problem, and the only solution for these buildings is to remove every piece of marble and replace with something else. Take a look up at a marble building in your city -- you're likely to see that the panels are bowing. All it might take is a gust of wind and the panel will fall. The public is totally unaware of this issue.

Here's a list of some of the few buildings I worked on that required total cladding replacement (these are only the biggest ones I worked on):

• Exxon Mobil headquarters in Houston -- total marble replacement -- Exxon is now selling the building
• Dental Branch in Houston -- total removal of marble before demolition
• Jones Hall in Houston -- total marble replacement
• Bank of America Building -- total marble replacement required

edit Many of the biggest failures are huge secrets. Due to litigation and insurance, we're not allowed to talk about it. People have no idea about the potential catastrophes that are all around us. I worked on a building where the 15,000 lb concrete cladding panels were detaching from a building due to failed welds. None of the panels fell, but one panels was totally detached from the building and was only hanging on due to friction. The building was directly adjacent to a commuter train line. If we hadn't performed repairs immediately, a panel easily could have fallen on the train line. I can't say the building, but repairs cost over $5 million, and this is still a secret.

edit Repair materials come from many different chemical companies, but some of the largest are: BASF (Ludwigshafen, Germany), Sika (Baar, Switzerland), Euclid Chemical (USA), GE (USA), and Tnemec (USA). These are global companies, and when there are massive disruptions to the global economy, we are going to lose access to these materials, and we'll have no way of repairing our buildings. The world depends on a constant flow of output from these companies to maintain what we have, and there is no substitute. This is a lot different than say, if you can't drive your car, you can simply walk, or if the industrial food system goes down, we can grow our own food. When collapse happens, everyone will soon realize that buildings are in very serious trouble. We've committed ourselves to an industrial dependent system in building, and there is no way out at this point.