Compositions: coating or plastic – Coating or plastic compositions – Metal-depositing composition or substrate-sensitizing...
Patent
1980-06-16
1983-01-04
Poer, James
Compositions: coating or plastic
Coating or plastic compositions
Metal-depositing composition or substrate-sensitizing...
106314, C04B 735
Patent
active
043670946
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention is concerned with the use of a lignin sulfonate product obtained by special treatment of lignin and containing more than 0.2 mols of carboxyl groups and more than 0.1 mols of sulfon groups per phenyl propane unit as an agent for preventing deterioration in the slump properties of mortar concrete and the method for using the same.
BACKGROUND OF THE INVENTION
Mortar concrete is subjected to a hydration reaction upon addition of water thereto and its consistency drops with the lapse of time. Such a lowering of consistency gives rise to some trouble in placing or compacting of concrete, although the degree of such a lowering may be depending upon the kinds of cements, aggregates or admixtures, the mixing conditions and the post-treatment conditions.
Recently wide acceptance of air-entraining agents or cement dispersants plays an important role in improvements in the various physical properties of mortar cement. However, such air-entraining agents and/or cement dispersants have little or no affect on the prevention of a lowering of consistency with the lapse of time and rather have a tendency to promote it.
Among the cement dispersants a so-called high-powered dispersant which excels especially in the dispersing effect and may be used in considerable amounts with causing any adverse influence such as delays in setting or excess entrainment of air is being widely used for the production of mortar concrete demanded to be of high strength, inter alia, secondary products at a factory. It is noted, however, that the addition of such a high-powered dispersant, for instance a high condensation product of naphthalene sulfonate and formaldehyde, a co-condensation product of naphthalene sulfonate and lignin sulfonate formaldehyde or sulfonate product of a melamine formaldehyde condensation product to mortar concrete results in a marked lowering of consistency with the lapse of time as compared with that having no admixture.
This lowering of consistency with the lapse of time presents many problems including: be transported; which are caused by changes in consistency due to changes in the preservation time at a placing region; and clogging or jamming of piping;
In order to solve these problems such various methods as mentioned below have heretofore been proposed or actually carried out; however, no satisfactory results are still obtained.
Among these methods, there is a method for obtaining a somewhat large increase in consistency at the time of mixing by increasing the amount of water added per unit, thereby compensating for a lowering of consistency during the preservation of concrete. In this method, however, the water to cement ratio increases with decreases in strength and durability. In addition, there is a fear that segregation or clogging of a pump may be caused. Since the centrifugal molding permits an given amount of water to be squeezed out the concrete, the addition of an increased amount of water seemingly gives rise to no difficulties, but a considerably degree of segregation possibly takes place, thus leading to losses of strength.
In order to avoid this defect, an additional step of increasing the weight of cement per unit in proportion to increases in the quantity of water per unit may be provided; although this step is useful for the prevention of a lowering of strength, however, it results in not only an economical disadvantage but also a great degree of shrinkage and hence cracking of the cured mortar cement.
In a word, the aforesaid method for adjusting the consistency of the concrete upon mixing to above a given value by increasing the amount of water per unit offers no satisfactory solution for reducing an essential lowering of consistency with the lapse of time.
On the other hand, another conventional method which is old but frequently used in recent years is a so-called "delayed addition process for cement dispersants". More specifically, this process involves the addition of a cement dispersant, which must substantially be added at the starting poi
REFERENCES:
patent: 3375873 (1968-04-01), Mitchell
patent: 3476740 (1969-11-01), Markham et al.
patent: 3578651 (1971-05-01), Ludwig
patent: 3841887 (1974-10-01), Falkehag et al.
patent: 4047567 (1977-09-01), Childs et al.
patent: 4065318 (1977-12-01), Detroit et al.
patent: 4181652 (1980-01-01), Detroit
patent: 4219471 (1980-08-01), Detroit
Ramachandran, V. S., Zement-Kalk-Gips, vol. 31, No. 4, Apr. 1978, pp. 206-210.
Fujimaru Yukio
Fujioka Shigenobu
Sugiwaki Toshihiro
Ueoka Keiji
Poer James
Sanyo-Kokusaku Pulp Co., Ltd.
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