SK44693A3 - An additive to hyudrautic connections and its use - Google Patents

Abstract

Use of condensation products of melamine and glyoxylic acid as additive for hydraulic binders, and building materials produced from these binder mixtures.

Description

The invention relates to the use of condensation products of inelamine and glyoxylic acid as an additive in hydraulic binders to improve the properties of these binders, in particular to maintain fluidity. These include, for example, cement, anhydrite or gypsum, as well as building materials made with these binders. According to the invention, it is possible to maintain the flowability of aqueous suspensions of these binders at the time of their practical use.

BACKGROUND OF THE INVENTION

In high-altitude, deep or road construction, in the production of finished building components in the field of sanitation of buildings and the like, the processing of hydraulic binders such as Portland cement, blast furnace cement, road cement and fly ash cement, anhydrite, gypsum and the like optionally with the addition of other inorganic components such as sand, gravel and various clays and / or organic components such as fibers or dispersions of plastic fibers, resins, and the like. U.S. Pat. 3,537,869 or 4,725,665 to these binders are added polycondensate formaldehyde and naphthalene sulfonic acid salts to improve the processability of the fresh compositions, in particular to maintain their flowability at the previously given water / binder ratio or to increase the strength of the cured material by reducing the used the amount of water, i.e. reducing the water to binder ratio. These substances are referred to as additives which help to maintain fluidity, dispersants or water-reducing agents and usually have the common disadvantage that the flowability of the mixtures cannot be maintained for a sufficiently long time. As the increasing amount of concrete is transported to the construction site in the form of a mixture with water, the loss of workability in a relatively short period of time, often referred to as sudden loss of workability, is a serious problem that needs to be addressed as quickly as possible.

A common emergency solution is to add additives to the transported concrete to maintain fluidity just before use on the construction site. Such a procedure may result in inaccuracies in dosing and inaccuracies of the composition in the material; it is also necessary to use a separate device and process, which also increases the pot life.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an additive for hydraulic binders which, by using it, would be able to maintain the flowability of these materials after mixing with water for a sufficient period of time without strongly retarding subsequent solidification and curing.

SUMMARY OF THE INVENTION

It has now been found that the icondensation products of melamine and glyoxylic acid can alone; or, in combination with known dispersing agents, to prevent the flowability of said materials and hence their workability.

The present invention provides the use of condensation products of melamine and glyoxylic acid or salts thereof as an additive to hydraulic binders. Unexpectedly, it has been found that in this way it is possible to prevent a sudden loss of processability and despite the relatively high content of carboxyl groups, the solidification of the resulting mixture and its curing to a material with high mechanical strength is only slightly retarded.

The condensation products of the invention can be obtained by reacting melamine with glyoxylic acid. Glyoxylic acid (T na can also be used in hydrated form or in the form of salts, in particular alkali metal salts and as a mixture of acid and salts. Preferably from one to 6 moles of glyoxylic acid per mole of melamine is preferred. The reaction is preferably carried out in an aqueous solution, since this solution can then be used directly as an additive to the binder, but the resulting product can also be isolated by distilling off the solvent by precipitation with a solvent in which the condensate does not dissolve or by spray drying to give the product in the form of a powder The reaction proceeds well, for example at 40 to 120 ° C. In this temperature range, the condensation is complete after 10 to 60 minutes. The condensation product according to the invention can be obtained in such a way that 50% the lyoxylic acid is diluted with water and optionally adjusted to pH 5-6 by addition of 50% sodium hydroxide solution. The calculated amount of melamine is then added to achieve the desired ratio of melamine to glyoxylic acid, the solution is heated and stirred until all the melamine is dissolved in the solution. The solution is then further stirred at the above condensation temperature to form a clear low viscosity solution.

The condensation products of the invention can be added directly to the binder mixtures, for example cement, mortar or concrete, in the form of aqueous solutions or in the form of powder. The condensation products are added in an amount of 0.01 to 3, preferably 0.05 to 1% by weight, based on the amount of binder. The products influence the flowability of the material very well, while the increased flowability of the binder is maintained over a period of time of more than 120 minutes. If such extended flowability is not required, a higher strength of the cured building material can be achieved by using a lower water to binder ratio.

The condensation products of the invention can be used alone, but also in combination with known dispersing or flow enhancing agents, such as the condensation products of formaldehyde and naphthalenesulphonic acid salts or condensates of sulphonated melamine and formaldehyde, which materials can be mixed over a wide range conditions. If the proportion of the condensation products according to the invention is increased in such a mixture, the time during which the material remains in the liquid state and hence its workability is increased. In this way, by suitably adjusting the ratio of the amounts of the individual components, the properties of the resulting mixture can be adjusted to suit practical requirements, in particular delaying the sudden loss of processability, the said time between mixing the binder with water and other ingredients to optimal values. Surprisingly, the effect of the mixture of condensates according to the invention and conventional additives on prolonging the flowability of the resulting mixture is higher than the sum of the effects of the individual components. This synergism of effects was not expected. In this way, smaller amounts of the individual components may be used to achieve a comparable flow time effect. This favorable dose-dependency state is advantageous from an economic point of view, but also in this way a significant reduction in the occurrence of undesirable side effects can be achieved, in particular the use of these mixtures does not greatly retard the solidification time of the material as higher amounts of known additives to maintain fluidity of the material.

The invention also provides a method for increasing the flowability of hydraulic binder materials and, optionally, the strength of components made of these materials, the process comprising adding condensation products of melamine and glyoxylic acid or salts thereof to the hydraulic binder.

The invention also relates to a mixture of binder materials comprising hydraulic binders and also condensation products of melamine and glyoxylic acid or salts or water and other conventional additives. The invention also relates to building materials based on an increased flowability hydraulic binder comprising a condensation product of melamine and glyoxylic acid or salts thereof.

The following non-limiting examples illustrate the invention.

DETAILED DESCRIPTION OF THE INVENTION

A. Production of condensation products

Example 1

To a 4-liter four-necked flask having a stirrer, reflux condenser, drip funnel, powder addition funnel and thermometer was charged 1066 g, 7.2 moles of 50% aqueous glyoxylic acid solution (Chemie Linz) and this solution. is diluted by adding 540.6 g of deionized water. Then, with stirring, 576 g (7.2 mol) of 50% sodium hydroxide solution are added such that the pH of the resulting solution is in the range of 5.0 to 5.5 after the addition is complete. During the addition, the temperature of the mixture was maintained at 45-50 ° C by cooling. 302.7 g (2.4 moles) of melamine (Chemistry Linz) are then added and the mixture is allowed to condense for 30 minutes at 95 ° C with stirring, resulting in a clear solution containing 38.2% by weight of Additive A.

Examples 2 to 6

In a manner analogous to that of Example 1, condensation products are prepared which contain different molar ratios of amino to glyoxylic acid, to obtain additives B to F, in addition to 1066 g, 7.2 moles of 50% glyoxylic acid and 576 g. 2 moles of 50% sodium hydroxide solution using the amounts of water and melamine as shown in Table 1 below.

Table 1 inlet melamine molar ratio concentration clade g g moles of melamine and% by weight.

glyoxylic acid

1 A 540.6 302.7 2.40 1 : 3 38.2 2 B 313.5 151.3 1.20 1 : 6 29.5 3 C 358.9 181.6 1.44 1 : 5 35.6 4 D 427.0 227.0 1.80 1 : 4 36.0 5 E 767.6 454.1 3.60 1 : 2 39.1 6 F 994.6 605.4 4.80 1 : 1,5 39.9

B. Use of condensation products

Example 7 • J 450 g of cement (Portland cement PZ 275F), 450 g of fine sand and 900 g of coarse sand are mixed with 234 g of water containing 3.15 g of additive H according to Example 1 (8.25).

J g of the aqueous solution of Example 1) in a mixer according to DIN standard

18555. The content of Additive A was 0.70% by weight, based on; the cement weight amount, the water / cement ratio (V / Z) was / 0.52. Finally, using a vibrating table according to DIN »! The flowability of the resulting material was determined in 18555 and the measurement was repeated every 30 minutes. The results obtained are summarized in Table 2.

i '«« Α ‘* ύ

The solidification retardation was monitored by placing 1000 g of cement in a 2000 ml flask and adding 321 g of water at 20 ° C, in which 7.0 g of additive A, i. 0.70% by weight based on the amount of cement used. After approximately 30 seconds, the mixture was agitated with a stick for a total of 120 seconds and then poured into a 93 mm diameter plastic vessel equipped with a temperature change sensor, the plastic vessel was trapped in a Dewar vessel. Then, the Dewar flask was closed and a temperature curve was recorded. The retardation time is the time by which the maximum temperature curve is shifted relative to the maximum temperature curve for the cementitious mix (Comparative Example V16), in which the same cement ratio is used but the additive according to the invention has not been used. The results are shown in Table 2.

Examples 8 to 15! In a manner similar to Example 7, the flow is monitored. material versus time and retarded setting of the cementitious compositions, where, as shown in Table 2, additive B according to Example 8 is used instead of additive A in Example 8

4, in Example 9, additive E according to Example 5 is used, and in Examples 10 to 15, mixtures of additive A and commercially available additives based on sulfonated melamine-formaldehyde resin (Additive U, Liquiment UPK, and Chemie Linz) are used. Amounts used in% by weight of solid poly? The parts, based on cement amounts and measured values, are summarized in Table 2.

Comparative Examples V16 to V20 i?

<Analogous to Example 7, the spacing was measured; In the comparison example V16, no additive was used and in comparative examples V17 to V20, the following commercially available flow-retention additives were used instead of additive A increasing the flowability of the material (M, X, Y) or solidifying retardant (Z):

M Additive for extending the flowability based on sulphonated melaminefermaldehyde resin, Liquimeint MPK, Chemie Linz,

X Additive for extending flowability based on acrylic acid copolymers, Cormix 2001, Cormix,

Y flow enhancer based on salts of polyacrylic acid, Sokalan PC10, BASF,

Z solidification retardant of gluconate-based material, Dissolvine, AKZO.

The following Table 2 also shows the amounts of these additives in% by weight based on the weight of cement and the measured values.

C. Material strength tests

On cured test specimens prepared from cementitious mortar by the method of Examples 7, 8, 9, V16 and V17, the compressive strength and flexural strength after 2, 7 and 28 days were measured according to DIN 18555. The values obtained in this way are summarized in Table 3.

Table 2

Flowability and setting of cementitious mixtures (V / Z = 0.52, Portland cement PZ 275F) Additive flow in mm (minutes after mixing) Deceleration of ice% by mass ^X θ 30 60 90 120 Solidification h.

7 0.70 A 190 189 187 187 183 3.0 8 0,70 D 186 186 186 184 172 2.5 9 0.70 E 184 183 180 181 173 6.3 10 0,50 A 0.05 M 204 200 187 164 150 7.0 11 0,40 A 0,10 M 195 190 186 160 140 5.0 12 0,30 A 0.15 M 225 216 184 164 141 4.3 13 0.17 A 0.17 M 234 188 172 150 140 3.0 14 0,10 A 0.20 M 229 180 154 143 130 1.0 15 0.05 A 0.20 M 187 156 149 143 128 2.0 VI6 - 163 155 149 145 137 0.0 VI7 0.40 M 182 155 145 137 120 1.5 VI8 0.20 Draw 234 173 158 150 137 4.0 V19 0.20 Y 216 179 166 156 140 10,0 V20 0.20 M 0.10 W 225 193 174 150 139 14.0 x «, Vo solid form substances, relative F in quantity cement.

Table 3

Material strength measured on test specimens made of cement mortar, V / Z = 0.52, Portland cement PZ 275F example additive bending strength and compressive strength

% wt. ^x tension, N / m &lt; + &gt; 2d N / m ^ 2d 7d 28d 7d 28d 7 0,70 M 4.00 6.94 8.58 16.4 36.6 49.2 8 0,70 D 4.68 7.79 9.05 18.5 36.2 51.6 9 0.70 E 3.51 7.08 8.70 14.7 34.3 53.8 VI6 - 4.19 6.06 7.85 20.5 30.5 48,8 VI7 0.40 M 4.65 6.63 8.00 20.4 31.9 47.0

^x In the form of a solid, based on the amount of cement.

Claims (7)

Use of condensation products of melamine and glyoxylic acid or salts thereof as an additive to hydraulic binders. Use of the condensation products according to claim 1, wherein the molar ratio of melamine to glyoxylic acid in the condensation product is 1: 2 to 1: 4. Use of the condensation products according to claim 1 or 2, wherein the condensation product is added to the hydraulic binder in an amount of 0.02 to 1% by weight. based on the amount of binder. Use of the condensation products according to any one of claims 1 to 3 to increase the flowability of the binder and, optionally, to increase the strength of the components manufactured using the binder. 5. Additive to a hydraulic binder, characterized in that the active ingredient is a condensation product of melamine and glyoxylic acid or salts thereof. 6. A process for increasing the flowability of hydraulic binders and, where appropriate, the strength of components made from such binders, characterized in that condensation products of melamine and glyoxylic acid or a salt thereof are added to the hydraulic binders. 7. A binder composition comprising a hydraulic binder and condensation products of melamine and glyoxylic acid or a salt thereof, and optionally water and conventional additives. ΖΎ </// · £ ' 8. A builder material based on a hydraulic binder of increased flowability, characterized in that it contains condensation products of melamine and glyoxylic acid or a salt thereof.