PL102452B1 - A METHOD OF PLASTICIZING CONCRETES - Google Patents

Description

The subject of the invention is a method of plasticizing concretes, including prestressed concretes, among others.

Hitherto known methods of plasticizing concrete, consisting in the use of plasticizing agents such as abietates, products based on sulfite liquors with added mineral salts products, products based on sulfonated aryl sulfone resins or alkylarylsulfone resins and other macromolecular compounds caused corrosion due to the content of mineral salts, especially chlorides, added together with the above-mentioned products to concrete mixtures for the purpose of regulating setting time and therefore could not be used for prestressed concretes.

In addition, they caused, inter alia, aeration of the concrete mix, which in turn influenced reduction of concrete strength, delayed the setting of cement, lowered the initial strength of concrete, and in the case of double overdosing, they caused the mixture to deteriorate (it stopped binding cement). Known So far, attempts to apply resins based on melamine and formaldehyde to concrete mixes have resulted in this extending the setting time of the cement. A characteristic feature of these resins was the high molecular weight, expressed as the viscosity of their 20% aqueous solutions, ranging from 10 to 412 cP at 20 ° C.

These disadvantages limited the scope of application of the above-mentioned measures, and even in many cases prevented their use in the production of prefabricated elements.

It was unexpectedly found that it is possible to achieve plasticization of concretes, including prestressed concretes, without the risk of corrosion, while avoiding the disadvantages described above - by adding to concrete mixtures as a plasticizing agent, a low-molecular melamine-formaldehyde resin with a viscosity of 20% an aqueous solution of less n / 5 cP at 20 ° C in the amount of 0.1-3% in relation to the cement weight.

The method according to the invention can be applied to concretes intended for all types prefabricated, reinforced and prestressed elements, as well as for monolithic concrete.

The method according to the invention by improving the workability while maintaining the other required concrete properties, enables reduction of cement consumption. Affects the elevation, especially when machining2 102 452 the initial thermal strength of concrete in relation to the actual cement content in the concrete at which does not change the setting time of the cement, which allows to shorten the production time of precast elements all.

Example. For concrete mix with a cement-water ratio of 2.4 and a consistency of 32 sec., concentrated on the VeBe apparatus, 2% in relation to the weight of the cement, low-molecular resin melamine-formaldehyde with a viscosity of 1.5-3.5 cps and mixed completely.

The concrete mix prepared in this way changed the consistency for 8 seconds, i.e. from wet to almost half-liquid. The action of the additive did not change the setting time of the cement, increasing the initial strength concrete in compression in relation to concrete without plasticizer according to the invention, after 3 days by 20%, and after 7 days by 30%, with the concrete not changing the air entrainment.

Claims (1)

1. Patent claim A method of plasticizing concretes intended for all types of prefabricated, reinforced and prestressed elements, as well as for monolithic concretes, characterized in that a low-molecular melamine-formaldehyde resin is added to the concrete mix as a plasticizing agent. of which a 20% aqueous solution at 20 ° C has a viscosity of less than 5 cP in an amount of 0.1 to 3% based on the weight of the cement. Wash. Typographer. UP PRL, circulation 120 + 13 Price PLN 45