Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
2002-07-26
2004-11-02
Marcantoni, Paul (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S730000, C106S804000, C106S819000, C568S861000, C568S863000
Reexamination Certificate
active
06811604
ABSTRACT:
The subject matter of the present invention is additives for mineral binders, based on a composition containing at least one product of internal dehydration of a hydrogenated sugar. The subject matter is also mineral binders with additives and the use of said additives or said compositions for the preparation of mineral binders.
By “mineral binder” is meant, in the sense of the present invention, any hydraulic binder, especially any mineral powder, capable of forming with water a paste, setting and hardening progressively even when sheltered from air. Usually, at ambient temperature, a mineral binder begins to form with water such a paste in a time span of roughly several minutes to less than 48 hours, generally between roughly 30 minutes and 24 hours. This definition is applied, amongst other things, to cements, to natural or artificial hydraulic limes, but also to mixtures, pasty or hardened, such as mortars, grouts, coatings and concretes, based on crushed cement and/or limes, water and/or aggregates (sands, gravels, pebbles . . . ), and finally to the raw materials going into the manufacture of cements such as pozzolanic cement, clinker cement, slag cement, calcareous fillers and silica fumes. By “mineral binder” is meant also any non-hydraulic binder based on calcium sulphate, gypsum and/or lime.
Depending on their final usages and conditions of use, it is sometimes necessary to add to mineral binders additives such as grinding agents or crushing aids, accelerators for setting and/or hardening, retarders of setting, plasticisers, water-reducing agents/plasticisers, superplasticisers and thickeners. These additives make it possible, for example, to modify the fluidity, pumpability, handling, setting, hardening, strength, durability and/or certain other properties of the mineral binder.
Numerous sugars and derivatives are already used in the preparation of additives for mineral binders, including:
molasses, which are inexpensive products, used as plasticisers;
sugars, which are very good plasticising water-reducing agents but strongly delay setting;
oxidised sugars, very good plasticising water-reducing agents, retarding agents for setting and which also make it possible to improve strength at 28 days as described in the patents FR 2 387 194 and GB 1 508 761;
hydrogenated sugars, which are plasticisers/water-reducing agents as described in the patent FR 2 726.550, but which are lesser retarding agents than the oxidised sugars whilst improving strength at 28 days, as results from the American patent U.S. Pat. No. 4,073,658;
hydrogenated or oxidised sugar syrups which are also described as grinding agents, according to patent EP 0 696 557;
esters of higher fatty acids and of polyols such as sorbitan trioleate which are agents for controlling the capacity for absorbing water and agents for improving the resistance to water and the adherence of cement compositions in the hardened state as described in the Japanese patent JP 59121143. These esters of higher fatty acids appear, moreover, to be retarders of setting and/or hardening.
Currently, for the preparation of cements, the tendency is to use products which are less expensive than clinker and/or to reduce the use of the latter. However, clinker provides good strength at 28 days. There exists therefore a need for an additive making it possible to correct the strength at 28 days of cements which do not contain clinker or contain little clinker.
Moreover, as regards mortars, grouts and concretes, the industry is searching for new accelerators of setting and/or hardening.
The setting and/or hardening accelerators conventionally used up till present are, on the one hand chlorinated products such as for example calcium chloride, and on the other hand non-chlorinated products, strongly acid or basic, such as for example respectively formic or sulphuric acids, their salts, lime, soda or products deriving therefrom (sodium metasilicates or aluminates).
Such accelerators are currently used particularly during the preparation of mineral binders intended to be used at low temperatures, i.e. at temperatures lower than roughly 15° C., or during the realisation in the factory of prefabricated articles.
However, the chlorinated products have the major drawbacks of being corrosive vis-à-vis enclosures for preparing the binders and the metal reinforcements utilised within the concretes used in civil engineering or the construction of buildings and of being a source of chlorine, a product known to be harmful to the environment.
For their part, the strongly acid or basic products present the drawbacks of being corrosive vis-à-vis metals and aggressive vis-à-vis the skin and the eyes and of not always making it possible to obtain sufficiently improved strengths when fresh and/or at 28 days.
Neutral and non-chlorinated products are sometimes used as accelerators of setting and/or hardening, such as lithium carbonate for example. However this compound has the drawback of being expensive in relation to the above-mentioned products.
Moreover, it has the tendency to reduce significantly the plasticity of the mineral binders and to be weakly effective at low temperatures.
There exists therefore a need to be able to have available an additive for mineral binders which, simultaneously:
is ecological, inoffensive during its use and non-corrosive vis-à-vis metals,
is an accelerator of setting and/or hardening and makes it possible consequently to obtain improved strengths when fresh, sufficient to make possible rapid dismantling of formwork and this as much at ordinary temperatures as at low temperatures,
confers a correct plasticity, if possible improved, to the mineral binders when they are used, and
then confers to these binders mechanical properties at 28 days which are correct and if possible improved.
Within the framework of the present invention, what is meant by plasticity of the mineral binder is the capacity to obtain a Theological state in which the mineral binder can be handled, poured or pumped. The plasticity is measured according to the standardised method CEN 196-01, by which one measures in mm the spread of a given volume of mineral binder on a shock table.
The start and end of setting are measured with the aid of an automatic “prisomètre” with the trademark “ACMEL”.
The mechanical strength when fresh is measured on specimens of mineral binder according to the standard CEN 196-01, quoted above, and this 17 or 24 hours after the manufacture of the specimens. This mechanical strength when fresh should, in general be greater than 5 Mpa to permit dismantling of the formwork. Moreover, the strength over time of the mineral binders (for example at 3 or 28 days) is also measured according to the above-quoted standard CEN 196-01.
The applicant company has had the merit of finding, after extensive research, that an additive meeting the above-quoted requirements of current technology could consist in a particular composition containing a selected sugar derivative.
In a more precise manner, the subject matter of the present invention is a new additive for mineral binders characterised in that it comprises a composition containing at least one product of internal dehydration of a hydrogenated sugar. In a surprising and unexpected manner, such dehydration products behave in a totally different manner from the hydrogenated sugars from which they are derived and which are known as being retarding agents as recalled above.
By “product of internal dehydration” is meant any product resulting, in any manner whatsoever, in one or several stages, from the removal of one or more molecules of water at the level of the original internal structure of a hydrogenated sugar and any compound containing, as a result especially of possible (poly)condensation phenomena, such a product. What is also meant is any compound resulting from the chemical modification and for example from the etherification of such a product or its esterification by a non-fatty chain. Such compounds can consist especially of acetylated, ethylated, methylated, propylated, butylated, ethylenated,
Graux Jean-Pierre
Mentink Leon
Marcantoni Paul
Roquette Freres
Sturm & Fix LLP
LandOfFree
Additives for mineral binders, based on a product of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Additives for mineral binders, based on a product of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Additives for mineral binders, based on a product of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3363636