DE2811295A1 - MATERIAL CONTAINING ETTRINGIT - Google Patents

Description

The above materials were placed in a pressure vessel and air was passed through the slurry at a temperature of 80 ^° C. and an air pressure of 2 kg / cm ² . After about 7 hours the reaction product was filtered off and dried in a desiccator.

X-ray diffraction analyzes showed that the product is an ettringite of very high purity. 6 shows a photomicrograph of an ettringite obtained by means of a scanning electron microscope (50O magnification). This ettringite shows beautiful needle-shaped crystals with an aspect ratio of 30 to 50. Ettringite could not be obtained ^{under the conditions of this example, but at an oxidation temperature of less than 0 ° C.} At a temperature below 7O ⁰ C, the time required for synthesis has been extended. And at one temperature. above 100 ⁰ C ettringite could not be obtained. 7 is a photomicrograph of plaster whisker obtained by means of a scanning electron microscope (50X magnification) for comparison purposes. These are needle-shaped crystals with an aspect ratio approximately equal to that of ettringite.

Example 6

Following the procedure of Example 1, but with the addition of 0.1 g of nickel sulfate (NiSO ₄ -7H 4 O), an ettringite which was almost identical to that of Example 5 was obtained. The time required for the synthesis was two hours instead of the 7 hours in Example 5. The same effect of decreasing the reaction time was observed when the metal salt was not nickel sulfate but a salt such as iron sulfate or aluminum sulfate. When the amount of the metal salt was less than 0.1% by weight based on the raw materials of the synthesis process, the effect of shortening the reaction time was small. If the amount was more than 1.0% by weight,

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809838/0903

the reaction product tended to discolour. In example 7
cases are described in which calcium sulfate, which after
Examples 5 and 6 was used, in part by plaster of paris
had been replaced. The alumina cement has been replaced by other aluminous materials.

Example 7

By replacing the aluminum-containing cement of the approaches
Examples 1 and 2 by aluminum-containing materials given in Table 2, and according to the procedure described above, an ettringite of the same quality as in Examples 1 and 2 was obtained. In those cases where
If lime was mixed with the aluminum-containing material before the reaction and the mixture was pulverized before the reaction, the reaction proceeded faster.

Table 2

39 CaO Al 2 ° 3 SiO 2 Other
Components Powder from high
furnace slag 11 , 45 14th , 05 31, 05 MgO 4, Combustion product
of sludge from the
Paper industry 1 , 29 42 , 88 15, 81 Mn 8, Waste product of
Aluminum indus trie , 12 55 , 80 2, 28 SO ₄ 6, r3 rO4 , 81

Annotation:

The table above shows the chemical composition of

aluminum-containing materials used.

809838/0903

Claims (1)

OIPL.-ING. H. FINK PATENTANWALT · D 7300 ESSLINGEN NEAR STUTTGART - HINDENBURGSTRASSE Polentgnwolt FINK - D 7300 Esslingen (Nedcor), Hlndenburgstrasse 44 P 6454 March 15, 1978 Minoru TANAKA, 1-1-9 Matsugaecho, Kitaku, Kobe, Japan Genzo HASHIZUME, 2-13-4 Tanakacho, Higashinadaku, Kobe, Japan Hiroshi MATSUI, 2-9 6 Edayoshi, Tarumiku, Kobe, Japan Satoru NAKAGAWA, 2-37-3 Shirakawadai, Sumaku, Kobe, Japan Claim Composite material based on ettringite, characterized in that it is acicular Crystals of the high aspect ratio ettringite are mixed with a matrix material containing at least one of the contains the following materials a) base materials for paper production, b) resins, c) plaster of paris, d) cement, e) fibrous materials for reinforcement and f) lightweight aggregates. 8 0 9 8 3 8/0903 ORIGINAL _ 9 -