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Saturday, September 28, 2013

Updating - September 28, 2013

Our construction project is moving along although there was a disturbing occurrence this week. When they arrived for work on Thursday morning, the construction managers discovered that there had been a break-in, and thousands of dollars worth of tools were taken.  The Honolulu Police Department as well as the military police are investigating, and it is our hope that they will be able to recover these tools.

Meanwhile, work continues on the project.  Workers poured concrete again this week, and there is a pad for the custodians' room, and all of the stem walls for the administration building appear to be done.  If you've never seen this huge machine pouring concrete, it is amazing!  I cannot imagine how that thick concrete can go from the truck, and up that distance, until it comes down to be poured into the foundations.

These photos show the custodians' room prior to and after the cement pour.

Here's how the administration building is progressing.  I wonder why they smooth out part of the cement but not most of it.  (Look closely at the photo on the right.)


Finally, work resumes on digging trenches for the underground wires including new electrical lines for our new buildings.  This is the area in front of F-building.


Wednesday, September 18, 2013

Clarifications on Earlier Posts :-)

As you may be aware, all of this construction is totally new to me!  I am learning so much by observing and asking questions, but I have not done any research or learned the proper vocabulary (yet).  So I wanted to share an email I received from Bob Purdie who is the Department's project manager for our construction project.  Thanks, Bob, for sharing all this information!  I'll try to be more accurate in the future :-)

Here's the information from Bob:

Couple of items of interest.  We are not pouring cement.  We are placing concrete.

Cement is the "glue" in the concrete composed of sand (fine aggregates), aggregates (coarse aggregates), water (hydrator) and the cement ("portland cement").

What turns the "wet" concrete into the dry hardened stone is the hydrolysis of the water and cement into a gel.

That is why the mix truck spins the concrete before placement to be sure all the hydrating cement is evenly and completely covering each and every particle of concrete aggregate.

The concrete hydrolysis is exothermic- that is it produces heat in changing state from its solid to the gel.  If you were to feel the forms an hour or so after placement you would find them uncomfortably warm to the touch.

Some of the reinforcing you show in your photos is actually "temperature" steel that counteracts the heat of hydration in the concrete and adds to the overall strength of the structure by controlling first the expansion and then contraction of the concrete mass.

After initial "set" of the concrete the gel continues to strengthen in its cure.  Curing requires added moisture to complete all hydrolysis of the cement gel, hence we spray a water loss barrier on the concrete surface, or we spray water directly on a slab to assist in the "cure".

The normal cure period is 21 days to achieve the design strength of the concrete but in reality because excess cement is added to the mix, your cure goes on forever, getting better and better with age.

The "finish" of the concrete is created by "floating" a portion of the cement gel to the surface by working the hardening concrete by trowel or other mechanical means.  The concrete "finisher" (an important concrete craftsman) creates the desired end texture to the surface of the concrete- be it rough or coarse for a stem wall, or fine for an even walking surface.  The finisher will "broom" the surficial cement gel to create a pleasing non-slip permanent surface for safe traction and sheet water flow.

So did Brenda also give you the answer for the "blue tape"?  There are 3 purposes for the tape.  First it is a warning to those who dig- that an important utility is below, so 'BEWARE".

Second, the tape is an aluminium conductor which allows for conductive and radio frequency "toning"- electronic location.  Conductive toning is done with a conductive transmitter and receiver that creates a "tone" from the foil when over the pipe.  Good toning tools can also calculate the depth of the tape, which at times is a help.

And third, because the tape is "blue" it signifies the material in the pipe is not "hazardous" and is "water".  There is an agreed standard for underground utilities used by the Garrison and standard in the utility industry.  Red is for DANGEROUS materials- electricity, explosive or radioactive utilities; yellow is for HAZARDOUS utilities such as piped gas; orange is for telephone or fiber optic cables; green is for sewer or potentially less biohazard waste;  blue is water, potable, fire, non-potable; purple is reclaimed (R-1 or R-2) water- non potable.

Also shown in the photo is a pressure valve and end connection for adding and removing water and air from the pipeline to test it (or disinfect it if it were potable).  The blue pipe extents in contact with the soil to provide a testing temporary thrust block so the gasketed pipe lines won't separate when under hydrostatic test.

Friday, September 13, 2013

Update - September 12, 2013

It's been a few days since I updated this blog and shared about our project.  Construction is going well; in fact, they are ahead-of-schedule right now.  The custodial room will be the first to be completed; right now, they are preparing to pour cement for the slab in a couple of weeks.  Today, the boom and the cement truck were at the school bright and early to pour cement for part of the administration building footings. We thank the students, parents, and staff for your continued patience during this project!

Here are some updates as well as a question; I would love to have some of our students venture a guess to this question!

The administration building as it looked yesterday 
. . . and today, after pouring 50 yards of cement. 

And now, here's a photo and a question.  (Thank you to Brenda Lowrey for pointing this out to me and suggesting the question for my blog.)

Why do they have foil (notice the shiny blue with words on it) on this pipe?  I would love to have our students find out the answer to this question and post it in the "Comment" section.