JPS61141649A - Cement composition - 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 [Industrial Application Field] The present invention relates to improvements in the performance of hydraulic cement compositions, particularly cement compositions that exhibit significant setting and hardening accelerating properties as well as non-corrosion to copper materials. Regarding.

[Conventional technology]

Conventionally, hardened concrete products obtained by kneading and mixing various formulations have been widely used. At that time, in order to increase the rotation rate of the formwork in the method of forming into the formwork,
Alternatively, in the case of construction in which concrete is hardened at room temperature or low temperature, in order to adjust the hardening speed of concrete, a substance that promotes the water use reaction of cement is added to unhardened cement. Substances that can promote this water-use reaction are called cement hardening accelerators, such as:
A wide variety of chlorides, sulfates, thiosulfates, carbonates, etc. of alkaline earth metals such as calcium or alkali metals such as sodium have already been developed, but there are only a few that are practical P+, and the representative ones are chlorides. Calcium. Calcium chloride exhibits an excellent hardening accelerating effect; for example, adding 1% by weight to cement can improve the initial strength of cement by as much as 130 to 140 inches, and it has been used in practice for many years because it is available at a low price. However, it has been pointed out that steel materials used as reinforcing materials in concrete rust or corrode due to added cyclized calcium (1), and it is desired to provide an alternative hardening accelerator.

Since calcium nitrite was proposed as a non-corrosive hardening accelerator in Japanese Patent Publication No. 42-22957, it has gradually replaced calcium chloride and is gradually being put into practical use. Therefore, it is difficult to put it into practical use in construction where strong and quick hardening properties are desired.

JP-A-51-67325 proposes the combined use of calcium nitrite and calcium formate in order to make full use of the non-corrosive properties of calcium nitrite while compensating for its lack of hardening acceleration performance. The problem is that calcium formate has a low water solubility of about 10%, making it impossible to obtain a practical high-concentration hardening accelerator aqueous solution, and calcium chloride does not have strong hardening accelerating performance, nor is it inexpensive. It is said that

U.S. Pat. No. 3,782,991 discloses amino alcohols or compositions of amino alcohols and sodium silicate as setting accelerators;
It does not exhibit sufficient curing accelerating action. Furthermore, West German Patent No. 2,611,419 proposes the use of a composition containing Toshi, a calcium formate main component, and a small amount of calcium thiocyanate as a hardening accelerator, but calcium thiocyanate is Since calcium formate is corrosive, it is difficult to prepare a highly concentrated aqueous solution as described above, and its curing accelerating performance is not strong either, so this composition is also not satisfactory and has poor practical use.

In this way, it is recognized that it is sufficient for a practical cement composition to have both the hardening acceleration performance obtained by adding calcium chloride and the non-corrosion performance obtained by adding calcium nitrite. However, such additives are still unknown and their provision is desired.

[Problem that the invention seeks to solve]

It is therefore an object of the present invention to provide a cement composition improved by an additive that combines non-corrosion performance, such as that provided by calcium nitrite, and hardening performance, such as that provided by calcium chloride. .

[Means for solving problems]

The cement composition which is the object of the present invention is composed of cement 1ci
1,0.1 to 3.0] it% of calcium nitrite and thiocyanate in an amount of 10 to 200% by weight relative to the calcium nitrite in the cement composition; Furthermore, 0.00 for cement
It is obtained by adding 5 to 0.06 weight amount of amino alcohol.

The cement used in the present invention is ordinary Portland cement or early strength Portland cement.

Moderate heat Portland cement, sulfate resistant cement, fly ash cement, blast furnace cement.

Covered with hydraulic cement that hardens through water use reactions.

Calcium nitrite used in the present invention may be an ordinary commercially available industrial product that does not affect the hardening of cement or the corrosivity of reinforcing steel, and may be in the form of powder or aqueous crystal, but from the convenience of use. Aqueous crystals are preferred. The thiocyanate used in the present invention is represented by the general formula M(SCN)n (where M represents a metal atom by an integer equal to n minus the valence number of M), and is also known as Rodin field.

It is a compound called rhodanide, rhodanate or thiocyanide. Examples of M include sodium, potassium, magnesium, calcium, and the like. Examples of preferable thiocyanates used in the present invention include sodium thiocyanate, calcium thiocyanate, and the like. These thiocyanates can also be used in combination. The amino alcohol used in the present invention is a water-soluble organic compound having a structure in which the hydrogen atom of the amine is substituted with an alkanol group, and examples thereof include monoethanolamine, jetanolamine, triethanolamine, N , N-dimethylethanolamine, N.

N-diethylethanolamine, N(β-aminoethyl)ethanolamine, N-methylethanolamine, N
-Methylgetanolamine, etc., and particularly preferable ones include triethanolamine, jetanolamine, monoethanolamine, etc., and these can also be used in combination.

[Effect]

Calcium nitrite gold 0.1 to 3.0 to cement
When thiocyanate is added in an amount of 10 to 200% by weight based on this calcium nitrite, or a combination of these and an amino alcohol in an amount of 0.005 to 0.066% by weight based on the cement is added to the cement. Due to the synergistic action of these components, the anticorrosive ability and hardening accelerating ability of the resulting cement composition are significantly improved. Therefore, the additive consisting of the sum of the above-mentioned added components has, in terms of performance per unit weight, a rust-preventing ability almost equivalent to that of calcium nitrite and a hardening accelerating ability almost equivalent to that of calcium chloride.

The amount of calcium nitrite added to the cement is 0.
If it is less than 1% by weight, the rust prevention ability is insufficient, and even if it is increased to 3.0% by weight or more, no increase in the rust prevention ability is observed, and the ability to accelerate hardening per unit weight as an additive is rather reduced. . If the amount of thiocyanate added in combination with calcium nitrite is less than 10% by weight relative to calcium nitrite, a synergistic effect on hardening acceleration performance cannot be obtained, and
If it is more than 200 degrees, the rust prevention ability will decrease, which is not preferable.

A particularly preferred ratio is 20 to 1 to calcium nitrite.
00% by weight. Furthermore, when aminoalcohol gold is used in addition to the above components, 0.0
By adding about 0.05 to 0.06% by weight, more favorable synergistic effects can be obtained in terms of paper-making and curing acceleration performance.

〔Example〕

Example 1 A 1% aqueous solution of the compositional additives listed in Table 1 was prepared using sodium thiocyanate, calcium thiocyanate, and calcium nitrite, and a steel material was immersed in this and the natural electrode potential was completely measured. The antirust ability of the above aqueous solution was tested. The measurement method is based on the method of JISA 6205, using a silver-copper chloride electrode, using a saturated aqueous solution of calcium hydroxide instead of pure water, and measuring the natural electrode potential over the course of the immersion time of the steel material. Ta. All measurement results are shown in Table 1.

The results in Table 1 are sodium thiocyanate.

Additives used in combination with calcium thiocyanate and calcium nitrite in an amount of 300% by weight or more relative to calcium nitrite all increase the potential toward the base and cause corrosion of steel, but nitrite Calcium alone and additives containing less than 100% by weight of thiocyanate relative to calcium nitrite (Experiment M 4.5.8.9) all increased the potential toward the higher side, and were different from the potential of calcium nitrite. It is almost equivalent to gold, indicating that it has anti-corrosion ability.

Examples 2 to 7 and Comparative Examples 1 to 5 To compare the setting acceleration performance of the composition of the present invention with conventional calcium chloride, thiocyanate, etc., various additives were added to cement in the ratios shown in Table 2, and JIS -Prepare mortar according to R5201 and test AST for accelerating performance
The test was carried out by measuring the total resistance value when the blocker was penetrated to a depth of over an inch in accordance with the method of M-C403-63T. All results are shown in Table 2.

In the same table, TEA represents triethanolamine.

The results of the examples in Table 2 show that the synergistic effect of the added components significantly improves the setting promotion performance.

Examples 8 to 13 and Comparative Examples 6 to 10 Various additives gold were added to cement at the ratios listed in Table 3.
Standard gold dust water cement ratio 65 according to JISR5201
% of 1:2 mortar total specimen dimensions (4 x 4 x 16
cm ), and after curing in water at 20° C., the compressive strength of each material was measured to perform a hardening acceleration capacity test.

The results are shown in Table 3. TEA was obtained by adding 1 weight of calcium pressing stone to 1 degree cement containing all triethanolamine (Comparative Example 7), or the compressive strength of cement mortar after curing for 1 day, or the one without calcium nitrite (Comparative Example 7). 8), and even after 7 days of curing, it is still 1% of that of the additive-free product.
The effect of promoting hardening is about 10-1, but the effect of promoting hardening is not large, whereas calcium nitrite total 0 and 8
The compressive strength of Example 101 Kyoto cement mortar containing 0.4% by weight of calcium thiocyanate and 0.030% of triethanolamine i after curing for 1 day compared to that without additives 1481.1 after curing for 7 days
It has improved to 32 inches, which is a surprising effect of accelerating hardening.

〔Effect of the invention〕

The corrosion-preventing effect of calcium nitrite is generally explained as, for example, that calcium nitrite prevents the destruction of a passive film existing on the surface of silver material in alkaline concrete.

Although the cement composition of the present invention contains thiocyanate, which causes corrosion, at 100 weight tts relative to calcium nitrite, the above-mentioned corrosion prevention effect is not lost and is almost equivalent to the case where calcium nitrite is added alone. It is amazing that water has anti-rust ability.

It is also surprising that although the amount of amino alcohol added in combination with calcium nitrite and thiocyanate is extremely small, the curing accelerating performance of cement compositions containing these kings is significantly enhanced. It is an effect.

From the cement composition of the present invention, cement paste, mortar, concrete, etc. can be obtained by conventional blending, and in addition, conventional cement additives such as EVA, sulfonated melamine formaldehyde condensate salt, sulfonated naphthalene formaldehyde condensate salt, lignin can be used. Sodium sulfonate,
Oxycarboxylic acid salt, water reducing agent such as polyol hakama combination, AE
Ordinary cement admixtures such as fly ash and slag powder can also be added, greatly increasing the practicality and improving effect of the cement composition of the present invention.

Claims (5)

[Claims] (1) Calcium nitrite in an amount of 0.1 to 3.0% by weight based on cement and 10 to 200% in weight based on the calcium nitrite.
A cement composition characterized in that it contains % by weight of thiocyanate. (2) The cement composition according to claim 1, wherein the thiocyanate is a sodium, potassium, calcium or magnesium thiocyanate or a mixture thereof. (3) Calcium nitrite in an amount of 0.1 to 3.0% by weight and amino alcohol in an amount of 0.005 to 0.06% by weight relative to the cement, and 10 to 200% by weight relative to the above calcium nitrite.
A cement composition characterized in that it contains % by weight of thiocyanate. (4) The cement composition according to claim 3, wherein the amino alcohol is triethanolamine, diethanolamine, monoethanolamine, or a mixture thereof. (5) The cement composition according to claim 3 or 4, wherein the thiocyanate is a sodium, potassium, calcium or magnesium thiocyanate or a mixture thereof.