Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
1993-07-15
2001-05-29
Marcantoni, Paul (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S725000, C106S728000, C106S823000
Reexamination Certificate
active
06238474
ABSTRACT:
The invention concerns a quick-setting, hydraulic binding agent containing calcium silicate cements, in particular Portland cement, reactive calcium aluminates, in particular high alumina cement, (commonly referred to as aluminous cement) as well as, if required, known additives and/or admixtures within the meaning of the definition according to DIN 1045 and DIN 4226.
Among the additives and added substances are, for example, agents to improve processibility, pore-forming materials, condensers, bond improvers, pigments, sealing compounds and the like. Admixtures for concrete or mortar mixtures made from the quick-setting hydraulic binding agent of the invention can, for example, be stone powder, trass, flue ashes, silica dust and the like.
Numerous compositions are known which contain high alumina cement and Portland cement and which are used as quick-setting mixtures.
The following should be elaborated upon with respect to the prior art:
For example, U.S. Pat. No. 4,012,264 discloses that a cement can be produced which sets and hardens very quickly by mixing Portland cement and high alumina cement, if required, by using various accelerators; in addition, a calcium aluminate and Portland cement composition is described which contains retarders and/or accelerators.
Plaster of Paris or anhydrite gypsum have also already been added to high alumina cement to obtain more solid forms and castings; see e.g. T. D. Robson, High Alumina Cements and Concretes, John Wiley & Sons, N.Y., 1962; it is noted on pages 126-127 of this reference that lithium salts are suitable as accelerators for high alumina cement.
However, it was found that compositions which contain high alumina cement, gypsum and lithium salts as accelerators by themselves show an excessive shrinkage and wet expansion when in a hardened state.
A quick-setting binder mixture is known from European Patent No. 0 228 595 which contains Portland cement clinkers, reactive calcium aluminates and/or high alumina cement, reactive calcium sulfate, an organic setting retarder as well as alkali carbonate.
In this binder mixture, a very steep setting characteristic results after the pot time, with very high early consistencies and high final consistencies.
The disadvantage of this binding agent is in the strict or limited requirements with respect to the choice of primary materials. That is, pulverized Portland cement clinkers are used with the addition of a limited amount of calcium sulfate as a main component instead of commercial Portland cement.
European Patent No. 0 211 362 describes a mixture for producing quick-setting mortar which contains binding agents as well as conventional admixtures and additives. A quick-setting mortar can be produced from this dry mortar mixture by adding mixing water. Said quick-setting mortar is suitable for crack-free filling of breaks in old concrete and for crack-free coating of coarse patches.
European Patent No. 0 211 365 discloses a quick-setting cement which contains reactive calcium silicates and reactive aluminates and which sets very quickly with high early consistency, yet relatively slight final consistency.
In addition, European Patent No. 0 213 390 describes a mortar mixture which contains reactive calcium silicates, reactive aluminates, calcium hydroxide, hydrated calcium sulfate, calcium sulfate anhydrite-II and an organic setting retarder, in addition to the conventional admixtures and additives, whereby an increase in the amount of reactive aluminates results in an improvement in the early and final consistency, a step, however, which leads to a considerable increase in the cost of materials.
Having regard to the content of reactive calcium aluminates or high alumina cement in quick-setting binder mixtures of the present type, the noted patents show that portions of at least 5% by volume, usually considerably higher portions of a model-type high alumina cement with 50% Al
2
O
3
content, are considered to be indispensable in the trade. While developing the quick-setting binding agent of the invention, it was surprisingly found that a decrease in the content of high alumina cement below this value leads to a clear improvement in the development of compressive strength while only slightly reducing the early consistency.
It is now the object of the present invention to produce a quick-setting, hydraulic binding agent by selecting a specific formularization of the composition which does not have the disadvantages of the above-described, quick-setting binding agents of the prior art while attaining advantages.
This object is solved in a quick-setting, hydraulic binding agent of the above-noted type thereby that the binding agent of the invention is characterized by a content of:
a) 0.1 to 2.0% by volume of an organic and/or inorganic accelerator for hydrating the calcium silicates,
b) 0.10 to 2.00% by volume of an organic and/or inorganic setting retarder inhibiting the hydration of the calcium silicates, if required, having a liquefying effect,
c) 0.01 to 0.05% by volume of an organic and/or inorganic setting accelerator for hydrated calcium aluminates, and
d) 0.01 to 0.20% by volume of an inhibitor with respect to formation of the hydrated calcium aluminum sulfates.
The quick-setting binding agent of the invention is, for example, characterized by the special advantage that it has, when using the smallest possible portions of high alumina cement on the one hand, and commercial Portland cement on the other hand, it has both high early consistency and a high increase in consistency which is typical for Portland cement.
Additional advantages are noted in the following:
The base for the primary materials for producing the quick-setting binding agent of the invention is significantly broader as the demands on the Portland cement and high alumina cement used, which go beyond the usual extent, are not made.
By using calcium silicate cements, in particular Portland cement of various consistency classes, the compressive strength of the quick-setting binding agent of the invention to be attained can be adjusted appropriately to the respective application.
By considerably reducing the content of high alumina cement in the quick-setting binding agent of the invention, a significant decrease in the cost of materials is attained.
While, as experience has shown, conventional quick-setting cements of the Portland cement/high alumina cement-type experience, on contact with air, a clear increase in the setting time already within a few hours after being mixed with water, the quick-setting binding agent of the invention shows a remarkable insensitiveness with respect to this point. As a result of low material and ambient temperatures, the setting time of the quick-setting binding agent of the invention is extended only slightly.
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patent: 3664854 (1972-05-01), Kokuta
patent: 3689294 (1972-09-01), Braunauer
patent: 3748158 (1973-07-01), Braniski et al.
patent: 3772045 (1973-11-01), Haldas et al.
patent: 4012264 (1977-03-01), Murray et al.
patent: 4131578 (1978-12-01), Crinkelmeyer et al.
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patent: 5328507 (1994-07-01), Crocker
patent: 87102228 (1987-11-01), None
patent: 254246 (1988-01-01), None
patent: 2024379 (1991-10-01), None
patent: 0073220 (1978-06-01), None
Structure and Performance of Cements,(1983) Barnes pp. 376-377, and p. 429.
Heidelberger Zement AG
Marcantoni Paul
Staas & Halsey , LLP
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