ASHRAE 160 standard for concrete

[Michael Hurd]

The ASHRAE 160 standard requires the initial moisture content of concrete to be set at two times EMC90 for concrete. This seems excessive to me for concrete that is oriented vertically, whether it is a poured in place concrete wall or architectural precast that is cladding the exterior of a building. Are there any studies that validate 2 x EMC90 for vertical concrete? I can understand the use of this for flat floor/roof slabs that can pond water during construction but not for a vertical application. Also, while running a calculation with 2 x EMC90 for C35 concrete, I receive an error message that indicates that I have exceeded the moisture content that concrete is capable of holding - is this typical? If so, this also leads me to believe that 2 x EMC90 is too extreme. Thoughts?

[Manfred Kehrer]

Hello Michael,
2xEMC90 applies only if your concrete is not sheltered, otherwise it is EMC90. I have not seen any measurements justifying that. If 2x EMC90 exceeds the max. moisture content then just adapt to make it work. Needless to say, we cannot address every single type of concrete when we discuss in SSPC 160. Also I don't think that 2xEMC90 is in general too high for unsheltered on site poured concrete.

The standard also states if you know it better then use your own approach.

Hope this helps,

[Axelarris]

So, how do I determine the ECM90?
I want to model concrete-filled CMU. I don't see CMU or concrete in the North American database.
I am using "concrete screed, mid layer" for the concrete in the core, and "masonry cement mortar - type S" for the mortar joints, but how do I model the CMU face?