Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Patent
1997-11-14
1999-05-18
Marcantoni, Paul
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
106727, 106822, 106823, C04B24/12
Patent
active
059047640
DESCRIPTION:
BRIEF SUMMARY
The object of the present invention is a novel, cement-based product and the method for producing said novel product.
It is known in the cement industry to add powder products, called fillers, to the cement powder to improve the physical and mechanical cement properties.
These products are defined, under the French standard NF P15-301 and are called "fillers" and are calcareous or siliceous products, or organic particles such as styrene butadiene or polyvinyl acetate type polymers.
Said standard P15-301 further specifies that these fillers may not be present in more than 5% by weight.
The grain sizes of the cement powders being used run from about 1 micron (.mu.) for the finest ones to 160 microns for the coarsest ones.
The mineral fillers are composed of very fine grain sizes from 0.10 to 10 .mu., approximately 10 to 20% being particles less than a micron.
Organic fillers have exceedingly small dimensions down to 20 to 30 nm (20 to 30 thousandths of a micron).
The present invention relates not only to the above mentioned mineral and organic fillers, but also to the ultrafine ones, namely having diameters between 5 and 50 nm.
On the other hand, as will be elucidated below, for products having grain sizes larger than those of the above defined fillers, the critical condition is that their diameter at most be equal to that of the cement particles.
Accordingly in the discussion below, "filler" shall designate powdery, mineral or organic products having diameters ranging from 5 nm for the finest ones to 160 microns for the coarsest ones.
It is further known in the cement industry to improve or to modify the mechanical or rheological properties of a cement slurry or of mortar using so-called "additive" products.
In particular the French patent 90.05688 filed on May 4, 1990 by one of applicants describes a novel product in the form of an additive constituted of a fatty amine salt combined with a surfactant. This additive has the property of improving the casting features of a cement slurry also containing additives.
The expression "cationic additive" designates the products described in the patent 90.05688, that is comprising a fatty amine salt, a surfactant and an antifoaming agent.
The expression "anionic additive" designates a product substantially composed of an anionic polymer such as those conventionally used in the field of (non-surfactant) cement additives.
Research by applicant led to the discovery that by combination with a cationic additive and a filler offers synergy allowing to substantially increase the filler proportion in the cement while nevertheless retaining good mechanical strength.
In the prior art, using the known additives, no more than 20% of filler could be added to the cement because, beyond this proportion, the mechanical and physical properties of cement would be degraded.
On the other hand, in the present invention, by combining a cationic additive and an anionic additive, up to 1,000% filler may be incorporated, that is, 50-fold of the present upper limit.
It was found that up to 50% filler (fine and ultrafine) may be incorporated into a cement without modifying or degrading its physical, mechanical or chemical properties. Beyond the 50% proportion, some properties, in particular the mechanical properties, are degraded, however the influence of the fine and ultrafine particles achieve improved chemical resistance, especially with respect to pollution and corrosive waters.
Be it noted that the proportion of the cationic additive plus anionic additive must be adjusted not in relation to the weight of cement per se but as a function of the sum of cement+fine and ultrafine fillers.
For example,
In general, where the additive consists of a combination of two, namely one a cationic additive and the other an anionic additive, the additive proportion by wt must be between 0.05 and 5%.
The cationic additives are fatty acid salts such as: dioctadecyldimethylammonium (DODA).
The anionic additives may be the following:
It must be noted from the onset that for an expert, such combination of cati
REFERENCES:
patent: 4410367 (1983-10-01), Legrand
Baustoffindustrie Teil B., vol. 19, Jun. 1976, Verlag Bauwesen Berlin De, pp. 6-8, DR Henning O. et al: "Die Wirkung grenzflachenaktiver Zusatzmittel in der Anfangspase der Hydratation von Portlandzementen".
Action of Admixtures on Fondu cemt : Part 1. Lithm & Sodium Salts Compou Damidot et al. Adv. Cem. Research (1996), 8(31) pp. 111-119.
Ciments Francais
Marcantoni Paul
Presta Frank P.
Presta Joseph S.
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