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.