Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Patent
1998-09-22
2000-05-16
Green, Anthony
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
106696, 106808, 106809, 106823, C04B 2420, C04B 2432, C04B 2802
Patent
active
06063183&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a superfluidifying composition for cement mixes containing a superfluidifying additive combined with an antifoam additive.
It is known in the art the use of additives to improve the quality of the concrete, to facilitate its use and to reduce the relative laying costs. The categories of additives of widespread use are represented by accelerators and driers, retarders, by fluidifying and superfluidifying agents and by air-entraining agents.
The superfluidifying agents have a fundamental importance as they allow to improve the concrete workability keeping constant the water/cement ratio or alternately to reduce such a ratio without penalizing the workability of the material.
In the first applicative form the superfluidifying agents allow to prepare fluid concretes reducing the laying and casting compaction costs; in such a case, the resistance and durability characteristics of the material remain practically unaltered. In the second one, the superfluidifying agents allow to increase the mechanical resistances decreasing the mixing water amount and leaving unaltered the cement dosage.
PRIOR ART
The superfluidifying agents are generally classified in four groups, that is the condensates sulfonate melamine- formaldehyde (SMF), the condensates naphthalenesulfonate-formaldehyde (NSF), the modified lignosulfonates (MLS) and a last one including sulfonic acids esters, carbohydrates esters, etc.
In addition to the traditional kind superfluidifying additives mentioned above, in the last years alternative compounds have been studied which beside having good fluidization properties of the cement mixes are characterized by an easier and cheaper preparation process, such as the "Fuel Oil Cracking Sulfonated" (FOKS), which are cheaper products in particular than the NSF.
The FOKS preparation and their use as superfluidifying additives for cement mixes is described in the European Patent Application EP 341,791.
The cement compositions according to EP 341,791 added with alcohol type antifoam agents show compressive strength values comprised between 392 and 488 Kg/cm.sup.2 after 28 days setting.
According to JP 6019044 polyoxyethylene and polyoxypropylene block copolymer is used as foam-extinguishing agent to prepare a cellulose based composition, that has a levelling efficacy for cement paste and mortar.
U.S. Pat. No. 5,466,289 discloses ultra-high strengh hydraulic cement compositions comprising specific vinyl copolymers as dispersion agent and an antifoam agent, which includes preferably polyoxyethylene and polyoxypropylene block copolymers.
In particular the FOKS is an (alkaline, alkaline-earth or ammonium, preferably sodium) salt of the sulfonated and oxidised product resulting from the reaction between sulphuric anhydride and fuel oils deriving from the steam cracking of oil products.
In the present text, FOKS and the preparation process thereof are as defined in patent application EP 341,791, or in the corresponding U.S. Pat. No. 5,221,344, or in UK application GB 2,159,536, which are herein incorporated by reference, but they may be also obtained according to a slightly modified procedure, as hereinafter described in the present application.
Fuel oils deriving from steam cracking correspond in particular to the residual hydrocarbon fraction in the production of ethylene and other lower hydrocarbons by pyrolysis of naphtha and gas oil.
Such hydrocarbon fraction has a high aromatic compounds content, and at least 50% by weight of such aromatic compounds are represented by aromatic compounds having polycyclic or bicyclic condensed rings in accordance with the ASTM D 3239-91 standards. The FOKS, according to what has been reported in the Patent EP 341 791, are employable as superfluidifying agents in concretes, optionally in the presence of siliconic kind antifoam agents or of alcohols or fatty acids derivatives, in amounts to 10% by weight with respect to the FOKS. The Patent Application WO-A-91/03536 describes antifoam additives for detergents consisting of mi
REFERENCES:
patent: 4964014 (1990-10-01), Jeschke et al.
patent: 5221344 (1993-06-01), Prevedello et al.
patent: 5466289 (1995-11-01), Yonezawa et al.
Cassar Luigi
Goisis Marco
Green Anthony
Italcementi S.p.A.
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