JPS59164661A - Efflorescence preventer for cement products - 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 an efflorescence inhibitor for cement products.

Previously, methods for preventing efflorescence in cement products were (1) nearly impossible; The efflorescence occurs when soluble components in the hardened cement precipitate on the surface of the hardened cement when water evaporates as the surface dries. Therefore, conventional solutions include reducing crosstalk water by using water reducing agents, adding inert substances finer than cement particles, filling capillaries, and adding other oils, fats, and synthetic resins. However, even if these methods reduce efflorescence to some extent, no efflorescence inhibitor has been developed that can completely prevent efflorescence in cement products.

The present inventors have discovered an excellent efflorescence inhibitor that does not cause efflorescence even under adverse conditions where efflorescence is extremely likely to occur, and is completely different from conventional efflorescence inhibitors, and has completed the present invention.

Fatty acid esters of sorbitan or their ethylene oxide adducts are well known and are in practical use as cement retarders and air entraining agents. When used as a setting retarder, a product prepared by adding about θ to 4 moles of ethyl(2)lene oxide to 1 mole of fatty acid ester of sorbitan is usually used, and when used as an air entrainment agent, usually ,
A product obtained by adding about 20 moles of ethylene oxide to 1 mole of fatty acid ester of sorbitan is used. As a result of intensive research into compounds that have an excellent efflorescence prevention effect on cement products, the present inventors surprisingly found that ethylene oxide was added at a specific ratio of 5 to 15 moles to 1 mole of sorbitan fatty acid ester. that the compound has good efflorescence prevention effect on cement products;
In addition, a block-shaped coadduct in which 5 to 15 moles of propylene oxide is added and then ethylene oxide is added in a specific ratio has a particularly excellent effect of preventing efflorescence, has little retardation of setting of cement, and has a low air entrainment effect. The present invention was achieved by discovering that there is almost no damage to the material.

That is, the present invention is based on the general formula (1) (3) (wherein R is an alkyl group having 4 to 1 carbon atoms, EO is an ethylene oxide residue, PO is a propylene oxide residue, and (a+b+c) is an alkyl group having 4 to 1 carbon atoms). 15, (d+e+f) is a number from O to 15, and -(PO)-(EO)- indicates that the ethylene oxide residue and propylene oxide residue are random or block-shaped.) This is an anti-efflorescence agent for cement products consisting of a compound that

By incorporating the efflorescence inhibitor of the present invention into the interior and/or surface of a cement product using the method described below, it is possible to prevent the occurrence of efflorescence from the product.

The compound of general formula (1) of the present invention is usually produced by esterifying sorbitol with a fatty acid and then cyclodehydrating it, or adding a predetermined amount to a sorbitan fatty acid ester obtained by esterifying sorbitol with a fatty acid and then cyclodehydrating it, or by esterifying it with a fatty acid and cyclodehydrating it. It can be obtained by adding alkylene oxide. At this time, the fatty acids used in the present invention include those having an alkyl group having 4 to 18 carbon atoms, and specifically include valeric acid, caproic acid, enane (4) acid, caprylic acid, pelargonic acid, These include saturated fatty acids such as capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, and nonadecanoic acid, and unsaturated fatty acids such as undecylic acid, oleic acid, and elaidic acid. It will be done. When a fatty acid having an alkyl group having 3 or less carbon atoms is used, the efflorescence prevention effect is significantly reduced. Further, if a fatty acid having an alkyl group having 19 or more carbon atoms is used, not only the effect of preventing efflorescence is reduced, but also the effect of retarding the setting of cement becomes noticeable, which is not preferable. Most preferred are fatty acids having an alkyl group having 11 to 17 carbon atoms.

In the general formula (1) of the present invention, -(EO)- represents an ethylene oxide residue, and -(PO)- represents a propylene oxide residue. Indicates the number of added moles of ethylene oxide (a
+b+c,) must be within the range of 5 to 15. If (a+b+c) is less than 5, the efflorescence prevention effect will not be significantly reduced, and it will give the cement a significant setting retardation effect, which is preferable5). Furthermore, when (a+b+c) exceeds 15, the efflorescence prevention effect is similarly significantly reduced and the air entrainment property is also significantly increased, which is not preferable.

Most preferred is the case where (a+b+c) is a number within the range of 7 to 12. In addition, the compound of the present invention may be used to which ethylene oxide alone is added, but it is preferable to further co-add propylene oxide in a block or random manner to this compound because it significantly improves the efflorescence prevention effect. It is essential that (d+e+f), which indicates the number of moles of propylene oxide added, is a number within the range of 0 to 15. If this (d + e + f) exceeds 15, not only will the efflorescence prevention effect decrease, but also the defoaming effect will appear, making it difficult to entrain a predetermined amount of air (for example, about 4%) into the concrete, which is undesirable. . Most preferably, (d+e+f) is a number between 5 and 10;
and the ratio of (a+b+c)/(d+e+f) is within the range of 1 to 2. Regarding the addition form of ethylene oxide and propylene oxide, a block coadduct (6) is more preferable than a random coadduct from the viewpoint of preventing efflorescence. The added block-like coadduct has the greatest efflorescence prevention effect and is more preferable. In addition to ethylene oxide and propylene oxide, oxides such as butylene oxide and styrene oxide may also be co-added within the range that does not impair the performance of cement products (usually 50% by weight or less of the total oxyalkylene). Included within the range.

Cement products treated with the above-mentioned efflorescence inhibitor of the present invention include commonly known mortar or concrete structures, secondary cement products, and also cement products treated according to the present invention described below. It also includes.

The cement used here is Portland cement,
Mixed cement, white cement, etc.

Preventing efflorescence of cement) FD products is achieved by including (adding or impregnating) the efflorescence inhibitor of the present invention represented by the above general formula (1) inside or/and on the surface of the cement product. This can be achieved by There are the following methods for incorporating an efflorescence inhibitor into a cement product.

The first method is to add 0.2% by weight or more, preferably 1.0 to 3.0% by weight (internal grinding) of the above-mentioned efflorescence inhibitor to the cement when kneading raw materials for cement products. This is a method for uniformly dispersing the inventive anti-efflorescence agent throughout a cement product.

The second method is to prevent efflorescence according to the present invention by immersing the cement product in the above-mentioned efflorescence inhibitor, applying it with a brush, etc., or spraying it as soon as possible after the cement setting (initial setting) time. This method involves impregnating the surface of cement products with an inhibitor. This second method is preferred over the first method because it achieves the objective with the use of a small amount of anti-efflorescence agent. That is, in the second method, the compound represented by the general formula (1) is usually prepared in an aqueous solution or an aqueous dispersion (concentration is usually 1
This method involves impregnating the cement product with a concentration of 0% to 100% by weight. In this case, the amount of the present anti-corrosion agent to be impregnated into the surface of the cement product is (8) generally 20 g/rd or more, preferably 50 g/rrr or more as a pure content.

Furthermore, as a third method, a method combining the first method and the second method can be carried out, and this method has an even greater effect of preventing efflorescence than the first or second method.

Most efflorescence can be prevented by implementing the first, second, or third method, but if efflorescence occurs slightly due to the passage of time under conditions that are particularly prone to efflorescence, In some cases, it is possible to prevent further progress of efflorescence by repeatedly performing the second method.

As described above, by using the efflorescence inhibitor of the present invention, it is possible to completely prevent efflorescence that precipitates from the surfaces of cement products such as decorative concrete and exposed concrete, and from the joints of tiles and blocks.

The present invention will be explained below with reference to Examples. In addition, in the formulation examples in the examples, parts and % indicate parts by weight (9) and % by weight, respectively.

Example 1 Method ■: Mix 1 part of ordinary Portland cement, 3 parts of sand, and 0.75 parts of water, and further add various efflorescence inhibitors of the present invention shown in Table 1 at a ratio of 1.0 parts to the cement. Add 10%
A cement mortar prismatic body measuring 10 x 40 cm was molded, cured in humid air for 24 hours (20°C, R 90%), and then demolded. 2c in the longitudinal direction of these mortar prisms
The specimens were cut with a width of 1.3 mm to prepare specimens each measuring 1010×10×2.

A 1 cm thick section of the obtained specimen was immersed in water at 7°C, and the entire body was heated at 7°C, R) 150%, and wind speed 0.
．． The degree of efflorescence generation was visually observed after being left in an environmental container at 2 to 0.3 m/sec, and the results shown in Table 1 were obtained.

Method ■: A mixture of 1 part of ordinary Portland cement, 3 parts of sand, and 0.75 parts of water was formed into a cement mortar prism of 10 x 10 x 40 cm, and left to dry in a humid air for 24 hours (20
℃, (10) RH 90%), and then demolded. This mortar prismatic body was cut into 2cIn width in the longitudinal direction, each 1010X10X2
A specimen was prepared.

Next, various efflorescence inhibitors of the present invention shown in Table 1 (50 parts aqueous solution or aqueous dispersion) were applied to the surface of the specimen at a purity of 90 g/n? After coating at a ratio of 1, the degree of efflorescence was visually observed in the same manner as in Method 1, and the results shown in Table 1 were obtained.

Method ■: Mix 1 part of ordinary Portland cement, 3 parts of sand, and 0.75 parts of water, and further add 0.7% of the various efflorescence inhibitors of the present invention shown in Table 1 to the cement. te10
After molding a cement mortar prismatic body of x 10 x 40 cm and curing it in humid air for 24 hours (20°C, RH 90%),
It was demolded. Two parts m of these mortar prisms in the longitudinal direction
It was cut across the width to produce specimens each measuring 1010 x 10 x 2.

To these specimens, 50 g of the various efflorescence inhibitors of the present invention (50 parts aqueous solution or aqueous dispersion) as a pure content was added.
/rd, the degree of efflorescence was visually observed in the same manner as in method (11), and the results shown in Table 1 were obtained.

The degree of efflorescence was also observed for specimens that did not contain any anti-efflorescence agent or were coated with any anti-efflorescence agent, and the results are also shown in Table 1 as a comparative example.

Table 1 (12) In Table 1, ◎ indicates that no efflorescence is observed even after 4 months, ○ indicates that almost no efflorescence is observed even after 4 months, and Δ indicates 4 The mark ``X'' indicates that slight efflorescence was observed after 3 to 4 days.

Further, in Table 1, [0 indicates ethylene oxide, PO indicates propylene oxide, *1) indicates a random adduct, and *2) indicates a block adduct.

Patent applicant: Nippon Cement Co., Ltd. Sanyo Chemical Industries, Ltd. Representative: Patent attorney: Yasuhiro Funakoshi (13)

Claims (1)

[Claims] 1. The following general formula (1) (wherein, R is an alkyl group having 4 to 18 carbon atoms, EO is an ethylene oxide residue, PO is a propylene oxide residue, and (a+b+c) is 5 ~15, (d+e+f) is a number from 0 to 15, -(PO)-(EO)- indicates that the ethylene oxide residue and propylene oxide residue are random or block-like.) An anti-efflorescence agent for cement products consisting of the compound shown above.