Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
2001-05-03
2003-11-18
Marcantoni, Paul (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S730000, C106S804000, C106S823000
Reexamination Certificate
active
06648964
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to admixtures for mineral binders based on hydrogenated disaccharide(s). It also relates to admixture-containing mineral binders and to a process for the preparation thereof.
BACKGROUND OF THE INVENTION
The term “mineral binder” means primarily any hydraulic binder and more particularly any composition, notably any mineral powder, capable of forming with water a paste which sets and hardens gradually, even away from the air. Conventionally, at ambient temperature, a hydraulic binder starts to form such a paste with water within a period of about a few minutes to less than 48 hours, generally between about 30 minutes and 24 hours.
This definition applies to the following, this list being in no way restrictive:
cements, and particularly those belonging to the group comprising cements of the artificial Portland type, cements of the blended Portland type, blastfurnace slag cements, Portland blastfurnace cement 85, Portland pulverized fuel ash cements, and ground cements for more particular uses of the type including slag cement containing lime, masonry cement, natural cement, supersulfated cement, rapid-hardening cement, quick-setting and rapid-hardening cement, cement for work in water with low or high sulfate contents,
natural or artificial hydraulic limes,
mixtures such as mortars, slurries, coatings and concretes based on cement and/or lime, water and/or aggregates of all particle sizes (sands, gravels, crushed stones . . . ) and particularly those belonging to the group comprising ready-mixed dry industrial mortars, site-mixed mortars, pre-batched dry industrial mortars, ready-mixed mortars, grouting compounds, injection mortars, slurries and injection slurries, reinforced and unreinforced concretes, ready-mixed concretes, flowing concretes, heavy concretes, lightweight concretes, lightweight insulating concretes, cellular concretes, fiber concretes, prestressed concretes and fair-faced concretes.
This definition also includes the raw materials used in the production of cements such as pozzolanas, clinkers, slags, calcareous fillers and silica fume.
The term “mineral binder” also means non-hydraulic binders, particularly materials based on calcium sulfate, gypsum and/or lime.
Mineral binders are materials which are very widely used, particularly in the building industry, for producing the various parts of structures such as the framework, floor, shell and roof, and also in public works, particularly for the production of bridges, tunnels, dams, roads and other works such as, for example, offshore structures or nuclear power stations.
Depending on the final use of these materials and also depending on the conditions under which they will be used, it is sometimes necessary to add admixtures to the mineral binders. Said admixtures modify, by improving them, the properties of the mineral binders to which they are added in small proportions, generally at most equal to 5% by weight of the mineral binder. Examples of admixtures include grinding agents or grinding auxiliaries, plasticizers, water-reducing plasticizers, superplasticizers, set and hardening accelerators, retarders, air entraining agents, waterproofing compounds and curing agents. These admixtures make it possible, for example, to modify the workability, setting, hardening, strength, durability and/or certain other properties of the hydraulic binder.
Numerous water-reducing plasticizer products or superplasticizers are already in use. Examples include:
molasses derived from sugar beet and sugar cane, which are relatively inexpensive products capable of fermenting and with limited effectiveness;
raw lignosulfonates derived from the paper industry which are relatively inexpensive but have the disadvantage of causing foaming of the mortars or concretes, thus reducing their strength at 28 days;
sugars derived from starch which are good water-reducing plasticizers but strong retarders;
oxidized sugars such as gluconates and oxidized starch hydrolysates which are very good water-reducing plasticizers, retarders and which also make it possible to improve the strength at 28 days as described in French patent FR 2 387 194 and in GB 1 508 761;
sulfonated condensates of naphthalene formaldehyde and sulfonated condensates of melamine formaldehyde which are very good plasticizers, weak retarders but which do not improve the strength at 28 days and are rather unacceptable environmentally;
polyacrylates which are superplasticizers, weak retarders but which bring about little or no improvement in the strength at 28 days;
polyols such as hydrogenated sugars such as sorbitol and hydrogenated starch hydrolysates which, as described in patent FR 2 726 550, are water-reducing plasticizers but which have a markedly weaker retarding effect than oxidized sugars whilst improving the strength at 28 days, as follows from American patent U.S. Pat. No. 4,073,658; hydrogenated sugar syrups are also described as grinding agents, such as oxidized glucose syrups, according to patent EP 0 695 557;
copolymers of styrene and maleic anhydride which are both superplasticizers and grinding agents as follows from patent FR 2 744 714.
At present, for the preparation of cements, the trend is to use products that are less expensive than clinker. However, clinker confers good strength at 28 days. There is a need, therefore, for an admixture capable of correcting the strength at 28 days of cements containing little or no clinker.
Moreover, with regard to mortars, slurries and concretes, industry is seeking plasticizers and water-reducing agents or superplasticizers which are ecologically acceptable and which at the same time confer very good plasticity with little retardation, an early strength i.e. at between 8 and 24 hours, sufficient to allow rapid dismantling of the formwork, and improved strength at 28 days, if possible.
There is a need, therefore, for an ecologically acceptable admixture which makes it possible to obtain a good compromise between retardation, plasticity, early mechanical strength and mechanical strength at 28 days.
Within the scope of the present invention, the term plasticity of the mineral binder means the ability to obtain a Theological state in which the mineral binder is workable, pourable or pumpable.
The plasticity is measured according to the standardized method CEN 196-01 by which the spreading of a given volume of mineral binder over a vibrating table is measured in mm.
The initial set and final set are measured on a mineral binder by means of an automatic setometer with the brand name “ACMEL”.
Within the scope of the invention, the early mechanical strength is measured on a specimen of mineral binder according to the standard CEN 196-01 mentioned above, 17 or 24 hours after the production of said specimen.
For applications in the building sector, this early mechanical strength must generally be more than 5 MPa to allow dismantling of formwork.
Moreover, the strength at 28 days of mineral binders is also measured according to the above-mentioned standard CEN 196-01.
After numerous searches, the Applicants discovered, to their merit, that of all the polyols, only the compositions containing at least 40% by weight of hydrogenated disaccharide made it possible to obtain a good compromise between retardation, plasticity, early mechanical strength and mechanical strength at 28 days. In particular, the Applicants observed, surprisingly and unexpectedly, that the higher the molecular weight of the polyols, the greater their retarding properties, and the lower their molecular weight the greater their tendency to give rise to false sets.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention relates, therefore, to an admixture for mineral binders comprising a polyol composition containing at least 40% by weight, preferably at least 55% by weight and even more preferably at least 65% by weight of hydrogenated disaccharide, this percentage being expressed with respect to the dry weight of all the polyols contained in said composition.
The term “hydrogenated disaccharide” within the mea
Graux Jean-Pierre
Mentink Leon
Robert Clement
Marcantoni Paul
Roquette Freres
Sturm & Fix LLP
LandOfFree
Admixtures for mineral binders based on hydrogenated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Admixtures for mineral binders based on hydrogenated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Admixtures for mineral binders based on hydrogenated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3184653