DE2437083A1 - NEW ADDITIVES FOR CEMENT - Google Patents

Description

L-1238/74

New additives for cements

The invention relates to new additives for cements; as new products all complex compounds made using the cements and the new invention Additives can be produced, as well as the application methods for the additives according to the invention,

In the French patent 71/46535 of December 24, 1971, new additives for cements "are described, specifically the soluble metasilicates and in particular the metasilicates of the formula Si O ^ H _" Na _" and Si (XHK"; this patent explains that the amounts of metasilicates which can be used according to the invention make up between G, 1 and 10% by weight of the cement; in addition, this patent describes a preferred procedure for carrying out the invention, which is characterized in that the said additive (s) are added to the cement Mixing water of the cement can be added.

Of course, the preferred procedure described in patent 71/46535 for carrying out the invention is in no way to be understood as restrictive and mortar-like mixtures can just as well be produced or the additive (s) can be added to the cement itself, for example during conditioning . ^'He who usable metasilicates namely in waters free medium a very high chemical inertia and can therefore cements and possibly the cement / sand mixtures in the form of a fine powder are beigemsicht whose grain size is comparable with the cements used.

This can be seen, for example, from the following experiment:

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- in a bonnet mixer - as he usually does on construction sites is used for public works, the following substances were mixed in powder form:

- CLK cement 4-50 g

- sand 1350 g

- sodium metasilicate 30 g

Sufficient mixing is achieved when the mixer has been running for about two to three minutes; then the 200 g of water were added to the mixture obtained and the mixture was mixed again for about two minutes.

Samples of standardized size were then cast from the product obtained and tear and tear tests were carried out on these specimens Printing tests carried out according to the usual standard tests.

The results obtained are summarized in the table below, where they are compared with the results. obtained with the same mortar which, however, did not contain sodium metasilicate.

TABLE 1

Age of the examinee (days) 1 7 28

(Control piece 4 52 60 flexural strength (bar))

\ Test item according to

^; of the invention 4-8 76 95

(Control piece 10 200 268 Compressive strength (bar)> _{test item according to}

) of the invention 110 210 300

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This table proves that the use of metasilicate in powder form (as well as the dry mixing of this additive with the components of the mortar) possible and of Interest is. The possible uses and uses of this metasilicate according to the invention are therefore very large.

It has now been established that the same additives (metasilicates) can be used in all types of cement where they have beneficial effects; so you can for example Portland clinker, blast furnace slag, pozzolan cement, be added to the plug dust, the mixtures of these various compounds and the various binders that these various compounds act as Basic products included.

So if the Portland clinker is 0.1-10% metasilicate by weight is added, the time required for setting is markedly reduced and the workability is reduced when applying the cement increases; the same is the case when the same additive is added to the slag cements is added, which consists of mixtures of slag and clinker and / od. Lime exist, or if he is the known Compositions is added that are produced using pozzolana or plug dust.

For example, the setting times (t- and t-) according to the usual ones were compared for different compositions Norms and flow time (with the Lesage meter); the The results obtained are shown in the table below listed:

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TABLE 2

Portland cement

+ 2% Na metasilicate

Slag cement

+ 2% Na metasilicate

t ₁ t ₂ pleating time

2h 5h 15s 20 min.Ih45min 5s

3h 8h

15s

40min. 2hl5min. 4s

However, it has also been found that the metasilicate itself can be an interesting binder and, consequently, as a Such can be used in a mixture with blast furnace slag, pozzolana and plug dust, compounds that Currently only usable when mixed with at least one other hydraulic binder, such as clinker or lime are. Here, too, the amount of metasilicate to be used is compared to the slag or the pozzolan earth or the Airborne dust $ 0.1-10 by weight.

For example, the following mixture was created:

sand I35O G ground slag 450 G Well metasilicate 30th G water 200 G

(In this experiment, the metasilicate can be used indifferently in powder form with prior mixing of the solid or im Mixing water and dissolved constituents are used).

The test specimens obtained from this mixture were subjected to the standardized mechanical bending and compression tests.

- 5th

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The results obtained are shown in the table below listed (where they are compared to a control sample that does not contain metasilicate).

TABLE 3 - -

Age of the examinee (days) 1 7 28 180

(Control piece. 5 8 50 80 Flexural strength (bar) /..

) with addition 30 75 85. 95 ( (2%) . "■. ■" ■ .-

(Control piece 10 27 130 2oO

Compressive strength (bar) I. -.

) with addition 120 460 56O 700

These results prove that the various types of

of

mechanical strength are excellent with the addition of 2% sodium metasilicate mixture; they are virtually identical to the results obtained using a 325 portland cement.

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Claims (4)

PATENT CLAIMS 1 / New additives for "cements", namely the soluble ones Metasilicates, in particular the sodium and potassium ketasilicates, which compared to the cement in a weight-wise manner Ratio of $ 0.1-10 can be used. 2. New additives according to claim 1, characterized in that that they are used together with a "cement" selected from the following substances or compounds: Portland clinker, blast furnace slag, pozzolana, plug dust, the mixtures of these various compounds and the various binders that use these compounds as basic products contain. 3. Procedure for using the new additives according to one of claims 1 and 2, characterized in that said additives with the cement in question be dry mixed and that said mixture is used. 4. Procedure for using the new additives according to One of Claims 1 and 2, characterized in that the said additives are added to the mixing water will. FRENCH STATE, represented by the MINISTRY OF EQUIPMENT AND HOUSING, CENTRAL LABORATORY OF THE ROAD CONSTRUCTION OFFICE. 609807/0908