Moist Room Construction ( again!)

[mikeofBelAir]

I am new to the forum, but been in the field since Carter was president.( Oh my!!!) I have been tasked with bringing an existing lab up to certification--both soils and concrete. My experience has been using tanks for moist curing, but I am intrigued with the idea of a moist room. One of the main attractions is the efficiency of space that a room affords. We may be moving to a new location, soon, and space would be a consideration. I have read many of the old threads on moisture room construction, and would appreciate some feedback on the ideas I've outlined below.

Room to be constructed in an existing garage with concrete slab-on-grade and climate-controlled air--both heat an A/C. There would be air space all around the moist room.
Excess water would drain through holes drilled through the floor, and getting to the sump which would pump into the sanitary sewer.
I am considering wood-frame using treated studs and plywood sheathing, and then covering all interior surfaces with a rubber roofing membrane.
If we use misting or fogging nozzles for humidity control, using cold tap water, we can then simply the temperature control to a heater only solution. Is this a correct assumption?
I am considering using hot water baseboards units for the heat, and a thermostat to control the circulation pump. This to avoid electrical issues in the high moisture environment.
Lighting would be via simple fluorescent fixtures installed outside the moist room immediately above clear plexiglass/ acrylic panels--again, avoiding electricity in the moist room.
How can I calculate the number of nozzles, flow rates etc?
We estimate a peak load of 100 4X8 cyls per day

This is all based on no experience with moist room construction, so I really value voices of experience to help me avoid costly mistakes.
Be gentle on the old guy, please.

 

[concretemasonry]

Do not use lightweight wood frame construction. Every time you open and close the door, you lose a lot of heat and change the humidity and need to get back to the desired level. Use concrete block walls for thermal and moisture retention properties. Granted, you may have 2800 cylinders in the room at any one time that provides some additional thermal stability.-

If you feel you need additional uniformity, but some EXP foam on the EXTERIOR will provide that. A self closing door (similar to what is used on walk-in coolers) is commonly used in a lab if you use a 2 wheeled cart to move cylinders in and out.

These are minimum procedures and standards for curing concrete in many concrete block and pipe plants, although many use temperature controlled misting water and temperature monitors in a the curing areas, because they desire a higher or cooler temperature environment.

Keep the cylinders warm and cozy 24/7 !!!

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[concretemasonry]

One additional item (there will be more thoughts coming later from others). Use a recording temperature and humidity system to save for future documentation and certification purposes.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[Ron]

Mike...this has been discussed in the forums before. Do a search.

CM's advice is good. Use concrete masonry as it will help stabilize thermal fluctuations.

For configuration, rectangular rooms are more efficient than square rooms and easier to keep the moisture consistent throughout.

Although CM says to keep the cylinders warm and cozy, you have a tight thermal limit range....73F +/- 3F. Sometimes tough to keep, particularly if your walls are exposed to the exterior.

 

[mikeofBelAir]

Thanks for the replies. I did read previous threads, but most of what I saw was several years old. I know concrete curing technology doesn't change much, but I thought an update would be good.
No outside wall exposure. The temperature around the moist room should be controlled to within a few degrees of 70.
Yes, I will have a recording thermometer/ I found one in the lab, and it works. I just need to calibrate it against a NIST-traceable one ( on my list). One of the advantages to the room over six (6) tanks is that I need only one recording thermometer instead of 6!
Waiting on more responses.......

 

[chicopee]

If a moist room is anything like what we had which was a curing room, we used a direct fired steam generator to heat and release moisture for the curing of our cast concrete products. The room was made of CB's with large doors at both ends. The room size was about 20' wide by 60' long and about 10' high. The walls and ceiling were coated with a moisture resistant epoxy. The steam generator was rated at about 8,000 lbm/hr. Curing duration was overnight. Along both long walls, we had perforated steam pipes. There was no condensate return.

 

[mikeofBelAir]

chicopee,
Wow! What a room.
Not what I am looking for, however.
Maybe I failed to make it clear that my intention is a room for curing test cylinders for compression testing. This is typically a 28 day cure at 73 degrees F +/- 3 degrees.
I forget that there are members from many engineering disciplines here.

 

[concretemasonry]

The saving grace is that a good amount of cylinders provide mass stability for moisture and temperature if the design and handling has some faults.

I never liked the concept of a direct fired steam generator because of the CO2/CO that can cause carbonation in a humid environment that is not representative of normal situations. That system is used in some concrete products to create artificial strength for production purposes and temps higher than 73F, but the purpose of a laboratory chamber to to provide and moisture and temperature in accordance with ASTM, but I don't think the ASTM committees have addressed the vapor chemistry in the specifications for cylinders.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.