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Moments in time

Houston skyline 

I am heading to Houston today, where I will meet up with a Brazilian university delegation and go to Rice University. After that, we go Louisiana and then Washington. This is a follow-up to our successful visit in February, but this one will be aimed more at the graduate student part of the Science w/o Borders program. On this visit, we are talking emphasizing oil & gas and biosciences.  I look forward to learning something new. 

I missed the first couple days of the program because I had to stay in Brasília for the presidential election.  My colleagues did all the important organizing work, but I add some value by being around and lending my ostensible authority to decisions.  We need somebody around to do that and/or take the blame if things do not work out as they should.  A lot of leadership is intangible.  When it is working well, it doesn’t seem to matter; when it stops working, everything just seems to fall apart.


But now I am on track. The usual Delta flight to Atlanta is getting routine.  I have traveled this year more than any time before.  I have become a gold member.  This is good, since I can choose better seats, but it still sucks. Travel gives time for reflection. Airports are semi-familiar. 

I decided to write a kind of stream of consciousness in my little notebook to give myself a shot of the day.  I transcribed them below. No big insights.

Indigo Hotel 

Coming into Houston. From the window it looks very flat and sprawling.  Flight attendant says that we are in the Central Time zone.  It makes me recall my mother. She died forty years ago, but is not forgotten. Strange that this reference would provoke a recall, however.  Central time is 4 hour different from Brazil.  Will be some jet-lag.

Off the plane easily.  Stopped at Dunkin Donuts for food and coffee I don’t need.  I am early and luggage will take a while to arrive.  It seems odd speaking English to clerks.  Not sure English is their first language anyway, but Portuguese would not work.

Passing adverts for MD Anderson Cancer Center.  Reminds me again of Ma, when I see on about a woman cured of leukemia.  When you are thinking about something, you notice connections.

Signed up for Super Shuttle.  At $24 is it much cheaper than the taxis. My travel budget will be cut and it is always a good idea to save money for Uncle Sam anyway.  Fifteen minute wait, they say. No worries. I still have the Dunkin Donuts coffee to finish.  I like it more than Starbucks, but I drink little coffee in general.
Reading “Concrete Planet” book about cement, probably the most ubiquitous manmade material around.  Concrete reinforced with rebar is doomed. The rebar rusts, expanding and causing concrete to crack and crumble.  This gives us hope that many of those horrible “modern” buildings built in the 1960s will turn to dust, but not such a good thing talking about bridges etc.  Romans used concrete better than we do.  Their structures don’t have rebar and have lasted thousands of years.  Rebar seemed a good idea at the time.

Go on the shuttle with two guys going to MD Anderson. Guy next to me is a biochemist/biophysicist now semi-retired.  Used to work at  Baylor, now at the University of Texas in Brownsville. Studies proteins and is interested in dengue.  I told him re our Brazilian mission and gave him my card.  He was very interested in getting Brazilian students and researchers. Don’t know how much he will pay attention, however. He was going to MD Anderson for a serious operation.

Both guys got out. Talking to the driver. He has been in Houston for ten years and loves it. Says that people who live in Houston love it, but visitors don't.  It is not pedestrian friendly and its hard to know where things are unless you live her.  Told me that the many rich Mexicans are moving to an area called “the Woodlands” and building big mansions. They are fleeing the violence and kidnappings of their own country.

He said he used to work at one of the country clubs in the area. Said that the rich people were often odd and told a story about a woman who could not get her car started. When he check, he found she had just run out of gas.  Somebody had always done that for her. I joked that she was so rich that she could just get a new car when the old one ran out of gas.  He didn’t get the joke and told me that they did indeed fill up the tank.   

My pictures show Houston from the CVS, a sundial at the Gallery and my hotel. 

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Saw cuts and rebar have nothing to do with each other. Rebar prenvets failure from weight being applied to the top of the slab. Concrete is only strong in compression, meaning a crushing force. It is very weak in tension, meaning a pulling force. When a load is applied to the slab, the top is under compression while the bottom is under tension. When the bottom fails from tension, the crack spreads upwards to the top. This happens when the ground under the slab settles, leaving a void. Rebar is meant to prevent the crack from continuing to the top of the slab, creating two separate pieces. Wire mesh does the same thing. That's why reinforcing should always be in the bottom 1/3 of the slab, not near the top. It's like bending a piece of wood; it always starts to break on the convex side, not the concave side. Saw cuts are used to prevent surface cracks. They are not structural, they just don't look good. These happen because the concrete creates heat through a chemical process. The heat rises to the top, drying the surface more quickly than the interior. The differing rates of dehydration and cooling create tension, making cracks. Saw cuts create weak points in the slab, which will release the tension first. They are meant to hide the cracks that would normally look jagged in the bottom of the straight line. Filling the saw cuts with caulking won't affect how the relief cuts perform, but it will keep debris out of them. For a 10 25 pad, you could probably get away without the cuts. I build factories for a living, and supervise the concrete finishers. We usually cut the slab into 12 6" x 12 6" squares, but that would only mean one joint in your case. I can't speak for a stamped finish, though. This should settle the question of relief cuts vs. rebar, though. They do two different jobs.BTW, all concrete needs rebar, wire mesh, or fiberglass mesh. Plain concrete without any reinforcing will break into pieces under its own weight. Fiberglass mesh is added to the concrete at the plant.

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