CS240258B1 - Binding agent on base of silicates with increased initial strength - Google Patents

Abstract

According to the invention, the binder base comprises of silicates ground cement clinker by specific surface area of 450 to 900 m2 / kg, mixing % water, 0.2 to 3 wt. a plasticizer, e.g. a water-soluble lignin derivative, 0.1 up to 3% by weight. alkali hydroxide or % silicates and 1 to 6 wt. calcium sulfate, all related to the weight of the ground cement clinker.

Description

The invention relates to a silicate-based binder with increased initial strength.

Portland cement, which is the most widely used hydraulic binder, achieves strength after hardening, allowing many applications for more than 24 hours. The research work carried out in a number of countries is therefore aiming to increase the strength after setting and to shorten the start of the setting of Portland cement.

Numerous processes have been proposed to increase the solidity after solidification, such as increasing the fineness of grinding, reducing the water coefficient by adding surfactants.

An important group of hydraulic binders are cements with altered phase and chemical composition. E.g. Uchikawa and Kasai in U.S. Pat. No. 3,919,384 have proposed to supplement the Portland cement clinker composition with a calcium fluoroaluminate mineral. This mineral causes rapid solidification and rapid strength development.

The special cement produced with this addition under the name “Onoda Jet” achieves high initial strengths. The “Onoda Jet” mortar sets after 10 to 15 minutes and reaches the compressive strength after 2 hours

7.5 MPa, after 3 hours 9.8 MPa, after 6 hours 14.16 MPa, after 24 hours 21.7 MPa and after 28 days 46 MPa.

A further modification of the clinker chemical composition may be an increase in the aluminate content, possibly an increase in the mineral content of C12A7 (Murray) and (Brown in US 4,012,264 J. Increasing of initial strengths can also be achieved with cement containing a certain proportion of his work by N. Fokuda in Bull Chem. Soc. Japan 34, 138 (1961).

Another way to increase solidification after solidification is to eliminate gypsum from the mixture with ground cement clinker (without changing the chemical and phase composition) and replace it with another control system, as described by Škvár et al. In "Portland Gypsum Cement Free" - Silicates 25, 251 (1981), Kolar et al. author's certificate 198 053 and Škvárou and others in MS. certificate.

These cements can be generally described as a system: ground cement clinker with a specific surface area of 200 to 3,000 m ² / kg - a plasticizer (eg a lignin derivative) - an alkali carbonate or bicarbonate. These systems, which do not contain gypsum, allow the preparation of cement pastes with an unusually low water coefficient and achieve high short-term and long-term strengths after solidification.

Experimental work carried out in the study of the influence of calcium sulfate on the ground clinker - lignin sulphonate - alkali carbonate or bicarbonate system shows some dependencies:

(a) The presence of calcium sulphate (in the form of gypsum CaSCU. 2 H2O, or α - or β - CaSO 2/2 H2O (hereinafter referred to as PH) in the ground clinker - lignin sulphonate - alkali carbonate system is not desirable;

As a result of this effect, it is often not possible to prepare slurries with a low water coefficient, talk as possible in this system in the absence of calcium sulfate. The presence of calcium sulfate also often causes a slow increase in initial strength. These facts are consistent with the data published in the literature. For example I. Jawed, WA Klemm and J. Skalný in J. Amer. Ceram. Soc. 82, 461 (1979), who studied the Portland cement system (specific surface area 505 m ² / kg) - sodium ligninsulfonate - Na 2 CO 3 found, at a water coefficient greater than 0.28, a strong liquefying effect of the simultaneous presence of ligninsulfonate and carbonate.

This effect was stronger in the presence of lignin sulphonate and carbonate than in the presence of lignin sulphonate alone. However, it was not possible in this system to slurry with a low water coefficient. Similarly, P. Thormainn (Betonwerk u. Fertigtell No. 10, 621 (1980), who studied the Portland cement class 550 system (specific surface area 530 m ² per kilogram) - sodium lignin sulphonate - Na 2 CO 3, did not find the possibility of preparing free-flowing slurries in this system. at low water coefficient.

By eliminating gypsum from this mixture, this free flowability could be achieved. According to his results, the initial strengths (1-day in the vast majority of experiments with Portland cement class 550 - sodium lignin sulphonate - Na2CO3 were very low. This disadvantage of ground clinker - gypsum - lignin sulphonate - alkali carbonate was eliminated by increasing C3A content in show the research work carried out in PLR.

Modified Portland cements made on the basis of these works include: ground Portland cement clinker with higher CsA content (cement surface area 500 to 600 m ² / ikg), sulphite leachates and alkali carbonates. These cements are characterized by a high increase in initial strength (compressive strength after 1 hour 3 to 5 MPa, after 2 hours 8 to 12 MPa, after 4 hours 20 to 28 MPa and after 28 days 55 to 60 MPa).

bj The presence of calcium sulphate (gypsum, PH) in the ground clinker - lignin sulphonate - NaHC3 system results in poor processability at low water coefficients and a relatively slow increase in initial strengths 1 when ground, high surface area clinker is used.

High strength can only be achieved after a certain period of time. By optimizing the composition of the system: ground Portland cement clinker (specific surface area 440 to 600 m ² / kg) - - lignin sulphonate (0.75 to 1.26% by weight) - - NaHCOs (1.5 to 2.5% by weight) reached Wills (US 4,019,918) delaying the onset of rigidity 240253 forces the concrete to reach high strengths after 24 hours while adding 1.5 to 4% w / w. calcium sulfate. However, even in this optimized system it was not possible to prepare low water coefficient materials.

A strong liquefying effect of another possible combination, lignin sulphonate-alkali hydroxide, has been described by Lea (US 2,684,720), which found a cementation process using a Portland cement (conventional fineness of grinding) sodium lignin sulphonate-alkaline hydroxide mixture.

However, the strengths achieved in this system after a few hours and on the first day after solidification are very low. Novotny and others in MS. No. 208-038 discloses a gypsum-free ground blend - lignin sulphonate - an alkali hydroxide which, upon setting, immediately reaches a compressive strength of 1 to MPa.

Disadvantages of the prior art for achieving short-term strengths and maintaining good processability at low water coefficients have been solved by the present invention. The disadvantage of the existing solutions is primarily the need to change the chemical and phase composition of the clinkers.

It is an object of the invention to provide a binder of increased initial strength, which does not require a change in the chemical composition of the clinker. The binder according to the invention comprises a ground cement block having a specific surface of 450 to 900 m ² / kg, mixing water, 0.2 to 3% by weight. % of a plasticizer, e.g. a water-soluble lignin derivative, 0.1 to 3 wt. % alkali hydroxide or silicate and 1 to 6 wt. calcium sulfate, preferably in the form of α-PH, all based on the weight of the ground ceraentary clinker.

Such gypsum, O-PH and anhydrous calcium sulfate (anhydrite III) may be used.

The ratio of mixing water to ground cement clinker is preferably at least 0.19.

This binder is workable even at very low water coefficients (0.20-0.25) while maintaining a free-flowing consistency of the slurries. The liquefaction effect is based on the synergistic effect of the simultaneous presence of ligninsulfonate and an alkali hydroxide effect of the simultaneous presence of ligninsulfonate and an alkali hydroxide, respectively. silicate.

The synergistic effect of this combination is not eliminated by the presence of calcium sulphate, as in the case of the ligninsulfonate-alkali carbonate system. bicarbonate, when after adding gypsum to the system ground clinker - lignin sulphonate - carbonate, theological properties change rapidly (the loose liquid slurry turns into a solid paste). The resistance of the ligninsulfonate-alkali hydroxide system to calcium sulfate is probably due to the fact that the resulting calcium hydroxide (from calcium sulfate and NaOH) has a higher solubility than calcium carbonate. This results in a higher stability of the ligninsulfonate-alkali carbonate complex relative to the ligninsulfonate-alkali carbonate complex.

The presence of calcium sulphate in the lignin sulphonate-alkali hydroxide system causes the start of slurry solidification to be delayed, where the addition of or-PH is particularly pronounced. The retarding effect of the ligninsulfonate-alkaline hydroxide-α-PH system is higher than that of the ligninsulfonate-alkaline hydroxide-gypsum system. The concentration of calcium sulfate (especially α-PH) in this mixture is optimally lower than that of Portland cement.

Additives, i.e. calcium sulfate, resp. the lignin derivative may be added to the ground clinker in the preparation of the binder prior to its use or the clinker may be milled with calcium sulfate and the lignin derivative. Both cases are possible. The hydroxide must be added to the mixing water.

The advantage of the described system is to achieve high strengths in a very short time after setting (minutes) and to maintain free flowability of the slurries even at low water coefficient.

The achievement of high short-term strengths is made possible by the higher specific surface of the ground clinker. By combining four parameters, ie grinding fineness, lignin sulphonate content (or other plasticizer), alkaline hydroxide (or silicate) and calcium sulphate (in various modifications), it is possible to change the properties of this binder. The combination of ground clinker with a specific surface area greater than 450 m ² / kg, lignin sulphonate, alkaline hydroxide and calcium sulphate has not been described in the literature.

The invention can be used in special applications, for example in applications where a rapid increase in strength is required or solidification at low temperatures.

The following examples illustrate the present invention without limiting it.

The following abbreviations are used in the examples:

NaLig ... sodium ligninsulfonate or-PH resp. β-ΡΗ ... and- respectively. β-CaSO4.1 / 2 HzO

In assessing theological properties of the mash, an empirical scale was used according to the visual assessment:

workability

O - unprocessable, dry - slurry flows only at 50 Hz vibration - slurry flows only when tapping on mixing bowl - slurry flows out of mixing bowl due to gravity - slurry is free flowing - slurry is free flowing with low viscosity

The percentages in the examples are always based on the weight of the ground cement clinker.

All compressive strength data refers to the set strength (for example, the strength value in the 10 min column indicates the compressive strength measured 10 minutes after set).

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Example 3

Cement porridge

Cement The boundary is 740 m ² / kg, mash with the same visual workability

additives volume changes (% of original length) 1 hour 3 hours 20 hrs Five days 7 days 28 days 0.5% NaOH + 1% NaLig + 2% α-PH 0 * +0.06 +0.05 +0.05 +0.10 0.5% NaOH + 1% NaLig · + 4% α-PH +0,11 * +0.22 +0.27 +0.23 +0.28 0.5% NaOH + 1% NaLig + 4% + PH +0.06 * +0.12 +0.17 +0.14 +0.17 0.5% NaOH + 1% NaLig * +0.04 +0.10 * + 0.08 +0.08 + 4 ° / o gypsum 0.5% Na 2 O SiO 3 + 1% NaLig + 4 O / o α-PH —0.03 * · +0.07 +0.12 +0.13 1% NaCl + 1% NaLig + 2% α-PH * +0.05 +0.04 * +0,00 +0.08 0.5 o / o NaOH + 1% NaLig control —0.19 * -0.17 * -0.07 —0.08 AO 198,053 1 θ / o NaHCO3 + 1% NaLig + 2 o / o α-PH control experiment according to * * +0.04 * +0.05 -0.01 USP 4,019,918 Waterplug, control spec. c. Thoro (USA) —0.04 ... * —0.07 —0.04 —0.03 —0.03 additives microhardness (Vickers method) 1 hour 3 hours 20 hrs Five days 7 days 28 days

0.5 o / o NaOH + 1% NaLig + 2% α-PH 2,8 3,9 * 34.4 57.4 56.2 0.5 o / o NaOH + 1% NaLig + 4% α-PH 2.7 32.4 49.1 56.2 , 63.8 0.5% NaOH + 1% NaLig + 4% + PH immeasurable 20.9 44.3 50.0 53.8 0.5 o / o NaOH + 1% NaLig + 4% gypsum * 3.7 10.2 * 55.3 51.7 0.5% NazSiOs + 1% NaLig + 4% a-PH ' 2.5 8.7 * 42.6 56.3 1 o / o NaCO2 + 1% NaLig + 2 o / o α-PH immeasurable 29.5 * 54.7 56.8 0.5% NaOH + 1% NaLig control AO 198,053 immeasurable 27, ϋ * 46.9 50.1 1 o / o NaHCOs + 1% NaLig immeasurable to 24 h * 44.1 44.9

+ 2% a-PH control experiment according to USP 4,019,918

Waterplug, control experiment not measurable spec. c. Thoro [United States]

5.8

11.2 15.1 13.8

After solidification, the prepared slurries were stored in an environment of saturated water vapor at + 20 ° C. The + sign for volume change values indicates expansion, the - shrinkage sign, * not measured ·

Example 4

Cement porridge

cement additives w beginning solidification processed- vatelnost compressive strength (MPa) 1 Hour 24 Hour

Border 1% NaLig 2% NaHCO 3 0.26 90 min 1 0.4 0.5 360m ² / kg 3% α-PH 1% NaLig + 1.5% NaHCO 3 0.26 240 min 1 1.0 : i, 8 3% α-PH 1% NaLig + 0.2% NaOH 3% α-PH 0.26 70 min 1 1.0 2.2 1% NaLig + 0.4% NaOH 0.26 300 min 5 1.0 2.1 2% α-PH 1% NaLig + 0.3% NaOH 0.26 120 min 5 1.0 2,0 2% α-PH 1% NaLig + 0.2% NaOH 5% gypsum 0.26 60 min 4 1.0 2,0 control test according to US 2 6:84 700 20 min PC 400 0.6% NaLig + 0.4% NaOH 0.25 end 3 Malomerice control experiment according to solidification US 2,684,700 (Lea) after 4 hours PC 400 0.1% NaOH + 0.5% NaLig 0.25 60 min 3 Lochkov control test according to end US 2,684,700 (Lea) solidification

after

5.5 hours

Example 5 Cement slurries

cement additives w beginning solidification processed- vatelnost

Boundary 400 m ² / kg 1% NaLig + 1% NazCOs 5% gypsum 0.27 10 to 15 minutes 2 > 1% NaLig + 1% NazCOs 2% gypsum 0.27 30 min 3 1% NaLig + 1.5% NaHCO 3 3% α-PH 0.25 90 min 2 ' 1% NaLig + 1% NazCOs 2% α-PH 0.26 20 min 2 1% NaLig + 0.2% NaOH 3% α-PH 0.25 300 min 5 Example 6 1% NaLig + 0.2% NaOH 2% gypsum 0.25 5 min 2 Cement porridge cement additives. , w beginning solidification processed- vatelnost Wet 450 m ² / kg 1% oxidized calcium lignosulfonate + 0.3% NaOH + 2% α-PH 0.25 150 min 4 to 5 0.2% NaLig + 0.7% sodium ferric polyphenolate - | - 0.3% NaOH + + 2% α-PH 0.25 30 min 4 1.2% NaLig + 0.3% NaOH 2% β-ΡΗ 0.25 120 min 4 1.2% NaLig + 0.75% NiaHCO3 + 2% α-PH 0.26 45 min 2 0.5% NaLig + 0.2% NaOH 4-1% α-PH 0.25 40 min 4

248258

Example 7

......... ·· ...............

The clinker from the Mokrá cement plant was in the presence of 2 wt. Sodium ligninsulfonate ground cement with a specific surface area of 680 meters ² / kg. A foundry molding compound was prepared from this cement (the ratio of cement to foundry sand was 1: TO by weight). 4% and - - CaSO 3 were added to the cement. H 2 O 2 and 0.5% NaOH, water content - water: cement ratio was 0.4. This mixture

1U reached 0.5 MPa after 30 minutes from solidification, after 60 minutes 0.58 MPa, after 2 hours 0/68 MPa and after 24 hours 2.28 MPa.

After comparison, a control experiment according to AO 195 022 was carried out with the same cement, where 1% of Na 2 CO 3 was added instead of calcium sulfate and NaOH. Compressive strengths were 60% lower after 60 minutes and 50% lower after 24 hours than in the present invention.

Claims (2)

Subject CLAIMS 1. An increased initial strength silicate binder comprising ground cement clinker having a specific surface area of 450 to 900 meters ² / kg, mixing water, 0.2 to 3% / wt. % of a plasticizer, e.g. a water-soluble lignin derivative, 0.1 to 3 wt. % alkali hydroxide or silicate, characterized in that it contains 1 to 6 wt. sulfate INVENTION calcium, all based on the weight of ground, cernentary clinker. 2. The binder of claim 1, wherein the calcium sulfate is an alpha modification of CaSO3. V 2 H 2 O, preferably in a content of 2 to 4% by weight, based on the weight of the milled ceinenter clinker.