Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
1998-12-14
2001-08-07
Dawson, Robert (Department: 1712)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S719000, C106S724000, C106S727000, C106S764000, C524S004000
Reexamination Certificate
active
06270567
ABSTRACT:
This invention relates to surface appearance-improving agents for mouldings of cementitious materials.
“Mouldings” in this case include concrete which has been cast in place or cementitious compositions which have been placed in a form or a mould. Such compositions include cement paste, mortar, grout and concrete.
For all such mouldings, good surface appearance is a requirement. It is especially important for concrete which is cast in place and which is to remain exposed without further surface treatment. When casting is taking place, the concrete is generally consolidated by means of a vibrator. The result of this consolidation is often marks on the surface.
Attempts have been made to solve this problem by means of admixtures, for example, silicone- or fatty acid ester-based antifoaming agents, or polyethylene oxide adducts of polypropylene glycol. Although these materials decrease the number of consolidation marks, they often result in the appearance of fewer, larger marks. In addition, they can remove completely minute foam marks which do not mar appearance but which contribute to freeze-thaw resistance and therefore have a deleterious effect on the durability of the concrete.
For mouldings cast in a factory, it is possible to use a very fluid concrete. However, foam marks are relatively easily made in such a concrete, and their removal necessitates more work.
It has now been found that these problems can be substantially and sometimes completely overcome by the use of a particular admixture. The invention therefore provides a method of improving the surface appearance of a moulding of a hardened cementitious material by treating the cementitious material prior to hardening with an admixture which comprises a polyalkylene oxide compound selected from the group consisting of
(a) a polypropylene oxide adduct of a polyethylene glycol; and
(b) a polypropylene oxide adduct of an ethylene diamine polyethylene oxide adduct
said compound being polyethylene glycol or ethylene diamine polyethylene oxide adduct with polypropylene oxide chains attached to all terminal groups thereof.
By “treating” is meant either mixing the admixture into the cementitious material at mixing stage, or applying it to the surface of an already moulded, but not yet hardened, cementitious composition. The mixing is preferred.
It is possible and permissible to use both types of polyalkylene oxide compound in a single cementitious material. It is also possible to use more than one type of each.
The polyalkylene oxide compounds hereinabove described are either polyethylene glycol or polyethylene glycol-ethylene diamine adducts on all terminal groups of which have been grafted chains of propylene oxide units. Thus, the polyalkylene oxide compounds of type (a) will have two polypropylene oxide chains per molecule and those of type (b) will have four per molecule. These polyalkylene oxide compounds have an average molecular weight (weight-average) of from 2,000-10,000, preferably 2,500-7,500 as measured by gel permeation chromatography with sodium polystyrene sulphonate as standard.
It is preferred that there should be from 3-50 moles ethylene oxide per mole of polyalkylene oxide compound, and that the weight ratio of ethylene oxide to propylene oxide should be from 5:95-40:60. The ratio may be selected, depending on the solubility in water desired and the amount of air entrainment of a given cementitious composition.
When the polyalkylene oxide compound is mixed into the cement composition, it should be present to the extent of from 0.001-5% by weight solids on cement. Preferably, it is present to the extent of from 0.01-0.5% by weight.
There may also be added to the admixture a water-reducing agent, for example, lignosulfonic acid salts, oxycarboxylic acid salts, polyalkylsulfonic acid salts, polycarboxylic acid salts, condensate salts of napthalenesulfonic acid and formalin, condensate salts of melaminesulfonic acid and formalin, aminosulfonic acid salts and polysaccharide derivatives.
The oxycarboxylic acid salts hereinabove described may include glucoronic acid, citric acid and glucaric acid salts. The polycarboxylic acid salts may include a copolymer of arylether and maleic acid half ester, and the salts thereof, a copolymer of styrene and maleic acid half ester, and the salts thereof, a copolymer of (meth)acrylic acid salt and (meth)acrylate, and the salts thereof. The polysaccharide derivatives may include saccharide alcohol, sulfurated polysaccharide and the like.
The amount of the water-reducing agent used is preferably 0.01-5 wt. % solids by weight on cement.
The admixture for use in the process of the present invention may contain other art-recognised materials in art-recognised quantities to perform their normal functions. Such materials include, but are not restricted to, aeration control agents, shrinkage reducing agents, accelerators, retarders, foaming agents, anti-foaming agents and thickeners.
The invention additionally provides a surface appearance improvement admixture for cementitious compositions, comprising a polyalkylene oxide compound selected from the group consisting of
(a) a polypropylene oxide adduct of a polyethylene glycol; and
(b) a polypropylene oxide adduct of an ethylene diamine polyethylene oxide adduct
REFERENCES:
patent: 4209336 (1980-06-01), Previte
patent: 5258072 (1993-11-01), Gopalkirshnan et al.
patent: 10251050 (1998-09-01), None
Copy of GB Patent Office Search Report for GB 9828269.2 dated Mar. 25, 1999.
Matsuo Shigemi
Udagawa Yasumasa
Yaguchi Minoru
Aylward D.
Dawson Robert
Fish & Richardson P.C.
MBT Holding AG
LandOfFree
Surface appearance-improving agent does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surface appearance-improving agent, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface appearance-improving agent will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513378