JPS6011256A - Cement additive - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement additive, and more particularly, to an additive for cement, which improves the dispersibility of cement particles in cement mixtures (cement paste, mortar, and concrete), and improves the fluidity of cement mixtures. The present invention also relates to an additive for cement that prevents the fluidity from decreasing over time and improves workability.

In cement mixtures such as cement paste, mortar, and concrete, the cohesive force of cement particles is strong, so that a cement mixture with good workability cannot be obtained with the unit amount of water required for hardening the cement. Therefore, in order to improve the workability of cement mixtures, it is necessary to increase the unit amount of water. However, increasing the unit amount of water causes a decrease in strength, so in order to obtain the same strength, it is necessary to increase the unit amount of cement. However, when the unit amount of cement is increased, the curing calorific value increases, which causes the problem that cracks are more likely to occur. Furthermore, after mixing the various materials, cement mixtures are often transported to the pouring site using mixer trucks, etc., but the time required for transportation varies depending on the distance of transportation and the degree of traffic congestion. Cheap. For this reason, at the pouring site, the fluidity of the cement mixture varies, making it difficult to obtain consistent workability. Furthermore, when pumping a cement mixture using a pump, if the pumping is interrupted for some reason and then restarted, the fluidity of the cement mixture in the piping has decreased, so the pumping pressure after restarting is There were problems such as having to raise the pipe or partially blocking the pipe.

As mentioned above, the simplest means to improve the fluidity of a concrete mixture is to increase the amount of water mixed, but increasing the amount of water causes cracks and spalling after construction. Therefore, there is a need for an additive that has a water-reducing effect, improves the dispersibility of cement particles, provides suitable fluidity, and is capable of sustaining the fluidity.

Conventionally, a formalin condensate of sodium naphthalene sulfonate has been known as such an additive. but,
Although this product can impart fluidity to a cement mixture, it cannot maintain that fluidity for a long period of time, so it does not fully satisfy the above requirements.

The object of the present invention is to provide a cement additive that eliminates this problem.

The present invention is a cement additive comprising a saponified styrene-maleic acid copolymer.

The saponified product of the styrene-maleic acid copolymer used in the present invention has the following general formula (wherein, An integer of ~5, n is 4
~10 integer. ), for example, styrene-
It can be obtained by saponifying a maleic acid copolymer with sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, or the like. The styrene-maleic acid copolymer may be either a random copolymer or a block copolymer, and has a number average molecular weight of 1000 to 9000, preferably 1500 to 2.
000 is used.

The saponified product of the styrene-maleic acid copolymer of the present invention thus obtained can be used in a cement paste such as cemented water; a mortar as a mixture of cement, sand and water; It is added to cement mixtures such as concrete, and the appropriate amount is 0.05 to 5% by weight, preferably 0.1 to 3% by weight, based on the solid content of the cement. The blending ratio of cement additives is 0.05 parts I! If it is less than 7%, it cannot be expected to sufficiently improve the dispersibility of cement particles, reduce water, and impart fluidity to the cement mixture. On the other hand, if it exceeds 5% by weight, the cement will be extremely dispersed and a so-called separation phenomenon will occur, making it impossible to obtain the desired strength. Furthermore, when concrete that has separated is pumped and poured, pipes often become clogged.

Incidentally, if necessary, auxiliary components can be added as appropriate to the above-mentioned cement mixture containing the cement additive of the present invention.

By adding the cement additive of the present invention, it is possible to improve the dispersibility of cement particles in a cement mixture, provide suitable fluidity, and extend the duration of the fluidity, which is useful for construction. Improves workability.

Furthermore, this cement additive has a water-reducing effect, and it is possible to obtain mortar and concrete that have sufficient strength without causing cracks or cracks. Therefore, the cement additive of the present invention is extremely useful in fields such as civil engineering and architecture, as well as in fields dealing with secondary concrete products.

Next, examples of the present invention will be shown.

Production Example 1 Styrene-maleic acid copolymer (number average molecular weight 1600
, manufactured by AROo 0hemica1, [5uA-1
oooJ) 100? was dispersed in 100 ml of water. A 10% aqueous sodium hydroxide solution was added to the mixture under stirring at a temperature of 80 to 90°C to adjust the pH to 8 to 9.

Next, the resulting aqueous solution was filtered to remove unreacted styrene.
The maleic acid copolymer was separated by filtration to obtain a saponified product 90f of styrene-maleic acid copolymer.

Production Example 2 In Production Example 1, the styrene-maleic acid copolymer had number average molecules ffi 1700, Al100 Ch
A saponified product of styrene-maleic acid copolymer 80p was obtained in the same manner as in Production Example 1 except that [SM Mu-2000J 100p manufactured by emica1 was used.

Production Example 3 In Production Example 1, the styrene-maleic acid copolymer had a number average molecular ii 1900, AROOChemi
A saponified product of styrene-maleic acid copolymer 70? was obtained in the same manner as in Production Example 1 except that ``SMA-5000J 100f'' manufactured by ca1 was used.

Examples 1 to 6 and Comparative Examples 1 to 2 Predetermined amounts of each of cement, sand, and water were placed in a forced stirring type mortar mixer with a capacity of 10 mm, and stirred for 2 minutes. Thereafter, predetermined additives were added and stirred for an additional 30 seconds to prepare a mortar composition. About this composition J-K8152
A 70-test according to 01 was conducted. The results are shown in Table 1 along with the experimental conditions. In addition, changes over time in the fluidity of the composition were investigated. The results are shown in Figure 1.

・1-・Ordinary Portland cement (manufactured by Tokuyama Soda Co., Ltd.) ・2・Standard sand from Toyoura ・3・Additional amount is weight% of cement (solid content equivalent) ・4・40% aqueous solution (manufactured by Idemitsu Petrochemical Co., Ltd., xPa-1o o o)・5...Using a 40% by weight aqueous solution・6...Value when 15 minutes have passed after preparing the mortar composition

[Brief explanation of the drawing]

FIG. 1 is a graph showing the change in flow value of a mortar composition over time. In the figure, A indicates Example 1. B is Example 2.0 is Example 5. D shows the results of Comparative Example 1.1 and Comparative Example 2. Patent applicant: Idemitsu Petrochemical Co., Ltd., 2. -1 - Time n

Claims (2)

[Claims] (1) A cement additive consisting of a kephide of a styrene-maleic acid copolymer. (2) The cement additive according to claim 1, wherein the styrene-maleic acid copolymer has a number average molecular weight of 1,000 to 9,000.