ITRM930363A1 - COMPOSITION AND PROCEDURE TO PREVENT THE EVAPORATION FOR CONCRETE MORTAR AND CONCRETE. - Google Patents

Description

The present invention relates to one

new-composition-capable-of-preventing-evaporation and-its-use-for-cement-mortars-and-concrete

Water-can-evaporate-from-mortar-or-concrete. time-enough-for-the-taking. Two ways of overcoming this inconvenience have been established by the

adding moisture to the concrete surface and applying a barrier layer. The protection from drying-should begin -if possible, immediately -after the concrete or mortar has been put in place, since? cracks due to shrinkage can quickly form in the concrete that you do not? still solidified, in particular when there is-exposure-to-the-breath of winds. The danger of drying? particularly large if the temperature of the concrete? pi ?; higher than that of the surrounding air (for example:. in winter). So the concrete surface must-be-kept-moist-a-for- a- peri odo-up- a-7-gi or nied-even-p i? -Per-cements-c he-do-set-in

a particularly slow-manner. The-fact-of-keeping

the-concrete-wet for-long-periods-of-temp or-?

a-need-in-particular-when-it-must-satisfy-certain-special-requirements, for- example -low-shrinkage-impermeability -to-water, resistance-to-environments- saline- and-freezing, resistance-to-abrasives-etc.

Up to now various methods have been employed for the subsequent treatment of concrete and these have various advantages and disadvantages, examples being constituted by the rear treatment with direct water supply; the back treatment with covers that are kept-moist; sheet metal roofing and agents; to be placed after the treatment and capable of forming films. A variety? of subsequent treatments for the formation of film commonly known as "hardening compounds for concrete"? already? known. Such compounds are often based; on solutions in organic solvent or on dispersions;

aqueous materials such as paraffin waxes and are generally applied by spraying to obtain a coating of sufficient thickness. - slightly moist. however for-this moment-gi? - a lot of water - evaporated The rapid evaporation of the solvent or de-emulsification of the emulsion produces a dense film which covers the surface of the concrete but does not ? absorbed by this and prevents to a large extent (depending on the hardening efficiency index) it prevents the evaporation of water from the concrete. The "Curing Eficiency Index", a measure of the capacity? of a material to prevent the loss of water by evaporation,? defined in the British Mini stry of Public Building and Works General Specification ?? tion No. 201, Appendix B. Protective hair eventually fails as a result of atmospheric influences, weather and mechanical influences. Mechanical damage to the pelicle must be avoided for at least the first 7 days.

Can the films after treatment which do not suffer the wear and tear of atmospheric agents (do not spoil) or which undergo this action only very slowly, can damage or prevent the adhesion of gypsum, flooring finishes? tions, coatings, adhesives, paints etc. and must-be-applied-late. On the other hand, organic-solvents-which-are-unacceptable-from-the-point

from-environmental-view- such as-for-example-benzene-aromatic-hydrocarbons- and-chlorinated-hydrocarbons-must-be-avoided-as-possible-and-yes- should-be-used-forming-agents-of- films which exhibit rapid biological degradation in aqueous systems. Various aqueous emulsions have been shown to be particularly favorable as regards their ratio. cost-efficiency. However, these have the disadvantage of deteriorating particularly slowly on concrete surfaces which are not exposed to sunlight or other atmospheric influences and consequently damage the adhesion of subsequent materials applied such as plaster, finishes for flooring, paint coatings, etc.

Is that why? the-purpose-of-the-present-invention is to-develop paraffin emulsions which begin to age -after only a short period of time (longer than 7 days thus breaking the film and accelerating wear by atmospheric action of the paraffin-part.

Now ? It has been found that paraffin emulsions - which-also-contain-natural-or-synthetic-hydrocarbon-resins - do not

evaporation.

The present invention therefore? provides a compound-hardener and-for-cement-compositions? consisting of a mixture of at least one aqueous paraffinic emulsion and at least one natural or synthetic hydrocarbon resin.

The term "paraffin-mulsion" means an aqueous emulsion of a higher-alkane having a melting point above the ambient temperature which, upon drying of the emulsion, does not form a film in the sense-of-a-paint

of reference). The emulsion can? be stabilized by any convenient means but? it is preferable to use an emulsified paraffin mixture; anionically (melting point of 45-51 ° C) with particle sizes less than 2 microns. Examples of; such paraffin emulsions are Mobilcer 55 or Examples - natural and synthetic hydrocarbon resins suitable for use in the present invention are tall oil resins, rosin, Escorez "trademark), synthetic resins of the type ??, 1000 produced from Esso, "Petrosi l" resins (trademark

or the Necires resins produced by various companies? as well as their blends. The active materials are thermoplastic polymers having a molecular weight lower than 2000 which form dense films starting from; from solutions in organic solvents (see also; Rompp, IX edition, volume 3, page 2291). A material

The emulsions having lower solids content can necessarily be sprayed several times in order to reach the quantity. request is to be applied (consumption of 80-250 g / m.)

Like the components consisting of paraffin and hydrocarbon resin, synthetic or natural - also other constituents, which are already? known as evaporation preventing agents may also be present. Those which can be used are constituted by emulsions of synthetic polymers; based on various chemical compounds, such as di-polyvinyl acetates, styrene-butadiene resins, styrene-acrylates, various acrylate copolymers or Example-Comparison-1-A? agent of? impediment? of evaporation based on rosin and white spirit at 25% solid density? of- coverage 180g / m2 efficiency-index- according to the Austrian-guidelines RVS 11. 064: 95.9%

Example of? comparison 2

Paraffin emulsion "Mobilcer, registered trademark 55 produced by Mobill anio-nic and non-ionogenic, 20% of solids coating density g / m efficiency indexes when applied immediately after application-of the surface-of -concrete 24.2.%; when applied-two-hours-after-the-surface-laying of concrete: 86.9% This value exceeds the minimum requirement of 85%.

Comparison example 3

Paraffin emulsion (UBATOL, trademark - registered FPG -860? Produced? By? Cray Example-comparison 4

A-resin-emulsion - KW (SACOCEL)

di-f embrica deposited-309 produced by the company? XX) anionic, at 30% solids, density? coverage 100 g / m Efficiency index - when applied immediately after concrete installation 14.9% Efficiency index when applied two hours after concreting 8.53%.

With the results of these comparative examples kept in mind, it should be expected that, when using mixtures of paraffin emulsions and resin ion emulsions [hydrocarbon, can be used. a reduction of the relatively good efficiency index of the paraffin emulsion takes place. However ? surprisingly it was shown that there? a significant improvement. For a quoso water system,? also particularly surprising is the fact that the efficiency index can? be increased; Example 2

Paraffin emulsion as in example of comparison 3 with hydrocarbon resin as in example, comparison 4, mixture ratio and content of solids as in example 1, density? of coverage 100 g / m. The efficiency index when applied immediately after the concrete was put in place was 46.40%. The efficiency index when the emulsion was applied two hours after having half in place the concrete was 87.20%.

Example 4 50 parts of water are mixed with 38.88 parts of an emulsion of parajff.ine (commercially available as MULREX (registered trademark) 62 produced by MOBIL) and 11.12 parts of emulsion of hydrocarbon resin of comparative example 4 (the emulsion being commercially available as SACOCELL

. The efficiency index obtained was 86.82?. In comparison, a mixture consisting of 50% water and 50% MULREX, 62 provides an efficiency index of 81.83%.

Claims (1)

4 Aqueous paraffinic emulsions according to any one of the preceding claims characterized by the fact that they contain paraffin and hydrocarbon resins which in a contribution from 95/5 to 30/70 on the basis of the dry substance. 5 Aqueous paraffin-emulsions second? any-one of the -previous claims-, characterized by-the-fact of having a content -of? solids - (paraffin or wax- and hydrocarbon resin respectively) -variable-from 10-to-60% by-weight-and preferably-variable-from-15-to-40% by weight 6. Use of - paraffin-water-emulsions 8. Process according to claim 7 wherein the application of the emulsion is carried out from one hour to 3 hours after having applied the cementitious composition. 9. Process according to any one of claims 6 to 8 wherein the cementitious composition? consisting of concrete or cement mortar. 10. Process according to any one of claims 6 to 9 wherein the quantity? of emulsion? of 80 g / m up to 250 g / m on the basis of the surface of the cementitious material - to which the emulsion is applied. 11. Cement surface to which? an aqueous emulsion according to claims 1 to 5 was applied. 12. Surface-cement ice-to-what -? - was applied-an aqueous-emulsion-according to-any-one of-claims-from-1 to 5-at-a-density-of-80-g / m2 up to 250g / m2.