CS251966B1 - Plasticizing additive for cement composites - Google Patents

Abstract

The subject of the solution is the adjustment of the composition of classic plasticizing additives based on ligninsulfone salts or other surface-active substances used for the production of cement composites, which removes, or at least severely limits, their aeration effect. The removal of the aerating effect of classic plasticizing additives is achieved by adding 0.5 to 30 parts by weight of an effective defoaming component to 100 parts by weight of a watery classic plasticizing additive, while silicone emulsion with defoaming effects, amyl alcohol, octyl alcohol, or other alcohol with a medium number of carbon atoms in the molecule can be used as a defoaming component; or their derivatives — with any admixture of an emulsifier. According to the solution, plasticizing additives do not cause uncontrolled aeration of cement composites when they are used, which is the cause of a decrease in their bulk density and, as a rule, a decrease in their strength. Their use is suitable in the construction industry for the production of all concretes where higher aeration is not desirable, especially for the production of ready-mixed concrete, for the production of concrete for demanding building structures, as well as for the production of concrete building components.

Description

251966

BACKGROUND OF THE INVENTION The present invention relates to a plasticizing additive of docement composites without aeration effects.

Conventional plasticizing agents for cement mortars and concretes, based on lignosulfone salts as well as other surfactants, generally exhibit a significant aeration capacity in the black composite compositions, as well as the large plasticization efficiency. As a result of their action, a large number of small air voids - similar to those of typical aeration additives - are produced in the fresh cement composite blend. The formed air voids contribute to the plasticizing effect of the additive, but at the same time cause a reduction in bulk density and subsequent Significant reduction in cement composite strength. The total volume of air cavities formed in the cement composite is dependent upon its overall composition, method of preparation, and the amount and dose of the plasticizer used. A particularly high increase in air volume in the composite mixture - by up to a few percent by volume - occurs when the mixing process is overloaded with the mixture. for ready-mixed concrete, transported instead of from a central concrete plant in concrete mixers. The undesirable aeration efficiency of the predominantly majority of the plasticizing additives makes it impossible to use them efficiently for the production of tones and other cementitious composites, whereby their higher aeration and the associated drop in strength are permissible due to their desired parameters and purpose.

The aforementioned drawback of conventional plasticizing additives removes the plasticizing agent for cementitious composites according to the invention, which consists of a solution containing, in addition to 100 parts by weight of an anhydrous plasticizer, based on ligninsulfonic salts or other conventional plasticizing agent. 5 to 30 parts by weight of a supplementary antifoam component which significantly limits the formation of air tubules in the composite composition and thereby elimine its aeration efficiency. In so doing, the antifoam component of the additive may be a silicone emulsion with a de-foaming action, amyl alcohol, octyl alcohol, and other alcohol with a medium number of carbon atoms in the molecule, or derivatives thereof, with optional emulsifier.

By correcting the composition of the plasticizer additive, a new type of plasticizing agent is obtained which, in principle, is similar to, or only slightly less than, that of the original classical plasticizer used to produce it, but which in fresh composite blends of up to approx. 5 ° / oz of cement, does not show aeration effects. Composite compositions made with the present invention in conventional dosages generally exhibit a lower air content and a higher bulk density than the corresponding non-additive composite compositions - with the same water coefficient. Thus, these composites do not reduce their strength due to their uncontrollable aeration and possible use of the plasticizing effect of the additive to reduce the batch water in the composite, allowing for a marked increase in its strength. The plasticizing agent according to the invention can therefore also be used in the production of ready-mixed concrete and the production of all concrete and other cement-based composites requiring high plasticity, but in which an increased aeration degree is desired.

Examples of the modification of the composition of the classical plasticizing additive according to the invention include: Example no. 1

Plasticizer No. 1 according to the invention - prepared by adding to the solution containing 100 parts by weight of sodium lignosulphonate (e.g. 3 parts by weight of a silicone e-emulsion Lukosan A 311 in the form of a conventional plasticizer Sj) and blending the mixture Example No. 2

Plasticizer No. 2 according to the invention - prepared by adding to the solution containing 100 parts by weight of sodium lignosulfonate 6 parts by weight of amyl alcohol with an emulsifier and homogenising the mixture. Example 3

The plasticizing additive No. 3 according to the invention - prepared by adding 5 parts by weight of a silicone emulsion Lukosan A 311 to a solution containing 100 parts by weight of synthetic polyphenolic tannins (e.g. in the classical additive Ralentol 25) A significant reduction in the aeration performance of the treated additives is shown in the comparative test results given in Table 1. The aeration efficiency of the ingredients was determined in mortars made using a constant Portland cement of anormous sand with a weight ratio of 1: 3 and while maintaining a constant aqueous coefficient of 0.50, the compared additives were added to the mortars at a rate of 0.20.5 and 1.0% by weight of the cement, and all mortars were produced in a constant manner.

Claims (3)

SUBJECT INVENTION CLAIMS 1. A plasticizing additive for cementitious composites, characterized in that it comprises a solution comprising 100 parts by weight of an anhydrous ligninsulfone salt plasticizing additive and 0.5 to 30 parts by weight of a defoaming silicone emulsion. 2. A plasticizing additive according to claim 1, characterized in that it contains the same amount of amyl alcohol, octyl alcohol or another medium-carbon alcohol or derivative thereof, optionally with an emulsifier, instead of a silicone defoamer. 3. Plasticizing additive according to claim 1, characterized in that it contains 100 parts by weight of synthetic polyphenolic tannins or other surfactants or mixtures thereof with ligninsulfone salts which, in themselves, have significant aeration efficiency.