DD232035A1 - HYDRAULIC LIMESTONE AND MAGNESIA-CONTAINING BINDING MATERIAL - Google Patents

Abstract

The invention relates to a hydraulic lime- and magnesia-containing binding building material which, despite other starting materials for its production compared to known hydraulic bindings at least the same uses as these. The aim of the invention is the utilization of dolomite, dolomite limestone u. ae. m. for producing hydraulic binding materials with approximately the same properties in comparison to known hydraulic binding materials. The object of the invention is a hydraulic magnesia-containing binder which does not tend to Magnesiatreib and is easy to produce. According to the invention, the object is achieved by a hydraulic bonding agent which consists of a finely ground mixture of 20 to 70% by mass at low temperatures of calcined dolomite, dolomite-containing limestone or the like. m. and 30 ... 80% by weight of possibly pretreated pozzolans such as calcined clay, fly ash, metallurgical slag.

Description

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Title of the invention

Hydraulic lime and magnesia binding building material

Field of application of the invention

The invention relates to a hydraulic lime- and magnesia-containing binding building material which, despite other starting materials, can be used in construction in at least the same fields of application as known hydraulic binding building materials in comparison with known hydraulic binding building materials.

Characteristic of the known technical solutions

It is known that dolomite or dolomite limestone as a component for the production of hydraulic binding materials, such. B Portland cement can not be used, or can only be used in small amounts, since the resulting high MgΟΙ 5 content of the binders leads to so-called magnesia rubbing in concretes made from these binders. Magnesia rubbing can occur if the MgO content of the Portland cement exceeds 5 %. is.

Furthermore, attempts are known to produce magnesia-containing Portland cements with MgO contents of more than 5 % .

Thus, it has been found that Portland cements with MgO contents of more than 5 % are not prone to magnesia rubbing, if it is possible to produce the periclase responsible for the magnesia shoot in small crystals and uniformly distributed in the clinker. Practically, this method has found no use the control of Periklaswachstums and the achievement of a uniform distribution procedurally

hardly controllable and difficult to detect ·

It is also known that for hydraulic binders based on pozzolanic base component as Portland: ementen, quicklime o.ä.m. MgO, which was made exclusively from magnesite, can be used · This binding construction material (magnesia Hydraulit) has found no spread, because its production is energy-intensive, costly raw material processing (Peinmahlung) intimate mixing of the components (ζ · Β · by suspending the Components with subsequent drying) uam required.

As a result of d6r listed disadvantages, it is not possible at present, the existing dolomite in large quantities, dolomitic limestones u.a. To use starting materials as raw materials for the production of hydraulic binders in larger quantities

Object of the invention

The invention aims to use the previously largely unexploited Dolomite, dolomitic limestones and similar Ausgangsma- materials to a significant extent as a starting material for the production of hydraulic bindings, which are at least equivalent to the comparable known bindings in the main parameters,

Explanation of the essence of the invention

The object of the invention is to develop a hydraulic binding material with MgO contents of more than 5 % on the basis of dolomites, dolomite-containing limestones or similar starting materials which, when further processed into concretes, show no magnesia rubbing which is easily controlled in terms of process engineering - and can be produced and largely dispensed with energy-intensive, complex process steps and in its Haaptparametern comparable binding materials is at least equivalent

According to the invention the object is achieved in that the hy-

Draulic binding material of a finely ground mixture Residue on the 90 μm sieve <10 % - of 20 - 70% by mass of calcined dolomite, dolomite-containing limestone or similar starting materials and 30 ... 80% by weight of possibly pretreated pozzolans, such as ζ · Β , fired clay, plug pockets, metallurgical slag, consists of

The firing temperatures of the dolomite, dolomitic limestone or similar starting materials are preferably between 900 · ..1000 ⁰ C, since the oxides of MgO and CaO are present in this manner in reactive form and it during solidification so that the formation of Ca and Mg silicate and aluminate hydrates comes. Brucite formation and the resulting driv- ing phenomena in concrete production are avoided •

When using fired clay, the firing temperature between 650 to 85O ⁰ C ... are, in use of metallurgical slags or ashes plug as pozzolanic component, they must be dried to a Peuchtigkeitsgehalt below 2% ·

The resulting hydraulic bonding agent has an MgO content between 8 and 25 % and uses dolomite, dolomite-containing limestone or other starting materials to a great extent. The production of the binder is technically simple to implement and takes place in comparison with Portland cement with significantly lower energy consumption Concretes made with the binder according to the invention prove to be equivalent to concretes made from comparable binders, they have additional special resistance against aggressive media, especially sulphates.

embodiment

The binder according to the invention is to be explained in more detail on an exemplary embodiment. It is a mixture of

40% by mass of calcined dolomite (internal temperature 95O ⁰ C)

60% by weight of calcined clay (firing temperature 75O ⁰ G) and ground until the residue on the 90 μm sieve is < 10%. The starting materials have the following composition

on:

100

SiO ₂

^2W 3

Al ₂ O

Pe ₂ O ₃

CaO

Dolomite mass% Sound mass' 0.05 63,40 0.03 19.10 0.02 6.50 30.84 1.40 21.20 0.60 44.96 8.00

105

Ignition loss at 100O ⁰ C

The hydraulic binding material obtained in this way has the following chemical composition (mass%):

MgO 15.80

CaO 23.32

SiO ₂ 41.38

Al ₂ O ₃ 12,48

2 3 4, & 3

To determine the quality of the binding material obtained, samples were prepared in the form of prisms with the dimensions 10 × 10 × 60 mm and 40 × 40 × 160 mm. The samples consisted of sand concrete of the composition 1: 3 (Bin & ebaustoff 1 Prüfsand) to mass. To prepare the concrete, water was taken in an amount of 40 % based on the weight of the binder.

The concrete samples showed after one year of storage in water, seawater or residual seawater as well as in other sulphate

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did not sing any signs of corrosion ·

The test results are given in the following table:

Age of the samples (Ta & e) 3 7 28 365

Compressive strength (MPa) 12 17 20,6 30,2

Bending tensile strength (MPa) 1.4 2.1 2.7 3.6

Solidification time (Vicat test) according to TGL 10573:

Beginning 180 min end 480 min

Room stability (according to TGL 10573 and according to ASTM C 151 to 153) Length change in water storage after 28 days: 0.07%

in a cooking experiment: 0.06 %

Autoclave treatment: 1.12 %

Claims (3)

invention claim 1 · Hydraulic lime and magnesia binder, characterized in that it consists of a finely ground mixture - residue on the 90 "sieve <10 % - of 20-70% by mass of calcined dolomite, dolomitic limestone or similar starting materials and 30% .80 mass% optionally pretreated pozzolans, such as. Burnt clay, fly ash, metallurgical slag. 2. Hydraulic lime and magnesia-containing binding material according to item 1, characterized in that the firing temperature of dolomite, dolomite-containing limestone or similar starting materials should be 900 ... 1000 ° 0, 3 · Hydraulic lime and magnesiahaltiger binding building material according to pt 1-2, characterized in that when using fired clay as Puzzolankomponente whose firing temperature at 650 ... 850 ⁰ G, when using fly ash or metallic slags as pozzolanic component whose moisture content is less than 2 should be % .