CS221232B1 - Admixture ammeliorating the workability of plasters and concrete mixtures - Google Patents

Description

(54) Additive improving the workability of mortars and concrete mixtures

The invention relates to the formulation of a novel additive improving the workability of mortars and concrete mixtures.

The invention solves the technical problem of improving the efficacy of lignosulfonic acid salt additives by adding an imidazolidone derivative.

An additive is characterized in that its active ingredient consists of:

up to 99.8 parts by weight of lignosulfonic acid salts;

0.2 to 10 parts by weight of 1,3-dimethylol, 4,5-dihydroxyimidazolidone.

The invention relates to an additive improving the processability of mortars and concrete mixtures.

According to the principle of action, the active ingredient of plasticizing ingredients produced t. No. Can be divided into the following groups:

(a) surfactant-based preparations;

(b) preparations with no appreciable effect on the surface tension of water.

The active ingredient of the surfactant-based additives consists mainly of salts of lignosulfonic acid and of naphthalene derivatives. Formulations on this basis account for a substantial proportion of the overall commercial range of surfactant-based ingredients. The advantage of these formulations is their relatively high liquefaction efficiency and low cost. Particularly in the case of additives based on the salt of lignosulfonic acid, sulphite leaches, which are a by-product in the production of cellulose, are preferably used as raw materials.

The disadvantage of these preparations is that they cause a relatively intense formation of air pores and thus an overall significant increase in volume.

Water Compressive strength coefficient after 28 days

0 0.775 2 - 1 lM ^! Bye 0.3% sodium lignosulfonate 0.7: 25 25 MPá weight of cement. . 0.3% lignosulfonate mixture 0,712 27.5 MPa

sodium and an imidazolidone derivative

This effect has been verified on multiple mixes with varying doses of cement, water and aggregate.

The additive can be successfully used in mortars and air in concrete mixtures above the permissible limit. As a result, the strengths of mortars and concrete samples tend to decrease as the aeration of the mixtures increases.

This disadvantage is greatly reduced for the additive according to the invention, the active ingredient of which is composed of 95 to 99.8 parts of lignosulfonic acid salt and 0.2 to 10 parts by weight of 1,3-dimethylitylol, 4,5-dihydroxyimidazoilidone.

The addition of an imidazolidone derivative increases the surface tension of aqueous solutions of lignosulfonic acid salts, thereby also limiting the formation of a micro foam which causes the mixture to aerate. In addition, it positively affects the formation of a solid cement binder structure. This multifunctional effect will favorably increase the strength of the samples compared to the strength of the same samples containing only the lignosulfonic acid salt alone.

From the following example treatment with sodium lignosulfonate and mixture 95 _; % of sodium lignosulfonate and 5% by weight of the imidazolidone derivative results in a higher technical effect of the additive according to the invention on the properties of a 4 X 4 X 16 cm sample made of river sand with a maximum grain size of 8 mm with SPC 325 Stupava cement. kg. m ^{-3 of the} mixture.

concrete mixtures with cement binder, as well as plasticizing and slightly aerating additives for lime and cement plasters.

Claims (1)

Subject An additive improving the workability of mortars and concrete mixtures characterized in that it consists of 90 to 99.8 parts by weight of lignosulfonic acid salt OF THE INVENTION 0.2 to 10 parts by weight of 1,3-dimethylol, 4,5-dihydroxyimidazolidone.