Appeal No. 2006-2413 Page 4
Application No. 10/250,412
mixing a predominantly positively-charged polyelectrolyte with Portland cement
to form a dry mix; and
combining the dry mix with water and a predominantly negatively-charged
polyelectrolyte in a compressed gas spraying apparatus to form the aqueous
cementitious mixture.
Thus, claim 27 is directed to a composition comprising four ingredients: Portland
cement, water, and two polyelectrolytes: a “predominantly negatively-charged
polyelectrolyte comprising a negatively-charged repeat unit” and “predominantly
positively-charged polyelectrolyte comprising a positively-charged repeat unit.” The
specification states that “[t]he polyelectrolytes of the present invention are water soluble
polymers which comprise a repeat unit that is positively or negatively charged.” Page 4,
lines 29-30. This definition is consistent with the art-recognized meaning of
“polyelectrolyte.” See Hawley’s Condensed Chemical Dictionary 893 (14th ed. 2001) (a
polyelectrolyte is a “high-polymer substance, either natural (protein, gum arabic) or
synthetic (polyethyleneimine, polyacrylic acid salts), containing ionic constituents; may
be either cationic or anionic”). Thus, one of skill in the art would have recognized that a
“polyelectrolyte” is a polymeric substance having more than one ionic group.
The plain meaning of a “repeat unit” in a polymer is a chemical structure that is
repeated (present in at least two copies) in the polymer. The claimed composition
comprises a polymer having an overall negative charge and including a repeat unit
having a negative charge and a second polymer having an overall positive charge and
including a repeat unit having a positive charge. The claim also requires a Portland
cement to water ratio of about 1:3 to about 3:5.
Claim 54 is directed to a process of preparing an aqueous cementitious mixture
having an increased viscosity. The final mixture contains water and Portland cement,
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