Page 5 - 2017-04-CFR Volume 103 Gypsum Yes or No - April 2017

Gypsum concrete can be processed at the jobsite
using mixing and pumping machines up to 30,000
sq. ft. per 8-hour shift. Concrete contractors add fine
aggregate (sand) at the jobsite and use controlled
measuring techniques for both the sand and water.
This results in predictable high quality poured under-
layments. These contractors use equipment that can
pump product almost 1,000 feet from the mixer/
pump to the jobsite and the same equipment can
pump vertically about 30 stories high. Gypsum con-
crete can be formulated to be “self-drying” where
there is virtually no “free water aka water of conven-
ience” resulting in a high strength mass that can be
covered by non-breathable flooring products in a
matter of hours. Combined with sound attenuation
products, gypsum concrete results in installations
that achieve and exceed current building code re-
quirements. Gypsum concrete can also be used to
flatten, smooth or otherwise correct concrete surfac-
es and it follows the same requirements/restrictions
as PC or CAC SLU’s with respect to RH content in
the host concrete. Think Shonox Worst Subfloor
Contest.

Generally speaking, gypsum concrete is installed at
a significantly lower cost than PC/CAC-based SLU’s
at the same or higher physical properties such as
compressive strength, tensile strength etc. and have
unique characteristics such as slight expansion upon
set (eliminates shrink cracks) as well as provides
safety characteristics due to the chemically bound
water. Properly formulated gypsum concrete can be
used as a wear surface and can be polished.

5 Commercial Flooring Report April 2017