JPS6221742A - 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 (Field of Industrial Application) The present invention relates to a hydraulic cement composition, and in particular to a cement composition which has been improved to exhibit non-corrosive properties against steel materials and, in addition, remarkable setting and hardening accelerating properties. Regarding the composition.

(Prior Art) Conventionally, various compounds have been used for concrete and hardened mortar. When obtaining such a hardened product, uncured cement is used to increase the rotation rate of the formwork when using formwork for molding, or to increase the curing speed when concrete is hardened at room temperature or low temperature. A hardening accelerator that accelerates the hydration reaction of cement is added to the cement. A wide variety of cement hardening accelerators have been developed, including chlorides, sulfates, thiosulfates, and carbonates of alkaline earth metals such as calcium or alkali metals such as sodium, but these have not been put to practical use. Various problems have been pointed out in this process. For example, calcium chloride exhibits an excellent hardening accelerating effect, and its initial strength increases by as much as 130 to 140% by adding just 1% by weight to cement. Moreover, it has been used in practice for many years because it is inexpensive. This has the disadvantage that it causes rust or corrosion of the steel buried in the concrete as a reinforcing material. In response to solving these problems, Japanese Patent Publication No. 42-22957 was proposed, in which calcium nitrite was proposed as a non-corrosive hardening accelerator. This has been gradually replaced by calcium chloride, but this hardening accelerator has a hardening effect that is not as strong as that of conventional calcium chloride, and therefore cannot be used in construction where strong and quick hardening properties are desired. Therefore, in order to solve the problem of insufficient hardening accelerating performance of calcium nitrite as a non-corrosive hardening accelerator, calcium nitrite and formate were used in combination, rhodanate and thiosulfate were used in combination,
Formate, nitrate.

Although the use of thiocyanate or the like alone has been proposed, none of them have sufficient curing accelerating performance and problems remain in practice. As a practical cement composition, it is sufficient if it has cement hardening acceleration performance to the extent that can be obtained by adding calcium chloride, and can also have non-corrosion performance to the extent that can be obtained by adding calcium nitrite. The reality is that this is difficult to achieve in reality.

(Problems to be Solved by the Invention) This invention enables the hardening of concrete to be accelerated to the same level as conventional calcium chloride, which exhibits an excellent hardening accelerating effect, without rusting or corroding the steel buried in concrete. The aim is to obtain a cement composition.

(Means for Solving the Problems) This invention provides 0.1 to 3.0% by weight of calcium nitrite, 0.005 to 0.1% by weight of amino alcohol, and 0.01 to 3.0% by weight of cement. A cement composition characterized by containing 2.0% by weight of an amidosulfonate or a water-soluble amide compound. Moreover, to show an embodiment of this invention, in this invention, the amino alcohol is
Cement compositions in which the amidosulfonate is triethanolamine, jetanolamine, monoethanolamine or mixtures thereof, and in which the amidosulfonate is a salt of sodium, potassium, calcium, magnesium or a mixture thereof; The amide compounds include acrylamide, acetamide, formamide,
A cement composition that is dimethylformamide or urea.

The cement used in the present invention is a hydraulic cement that hardens by a hydration reaction, such as ordinary Portland cement, early strength Portland cement, moderate heat Portland cement, sulfate-resistant cement, fly ash cement, blast furnace cement, and white cement. be. Calcium nitrite used in this invention may be any ordinary commercially available industrial product as long as it does not affect the hardening of cement or the corrosiveness of reinforcing steel, and may be in the form of powder or aqueous crystal, but for convenience of use, Aqueous crystals are preferred. The amidosulfonate used in this invention has the general formula M (NH2S03)rL
(However, M represents a metal atom, and n represents an integer that matches the valence number of M.) M is sodium and potassium.

Examples include calcium and magnesium, and calcium amidosulfonate is particularly preferred.

Examples include magnesium amidosulfonate.

One or a mixture of two or more of these may also be used. Also, the water-soluble amide compounds used in this invention are acrylamide, acetamide, formamide, dimethylformamide, and urea. Furthermore, the amino alcohol used in this 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 ,
Examples include N-dimethylethanolamine, N,N diethylethanolamine, N-(β-aminoethyl)ethanolamine, N-methylethanolamine, N-methyljetanolamine, and particularly preferred ones include triethanolamine, Diethanolamine, monoethanolamine or a mixture thereof.

The present invention uses calcium nitrite for cement.

Amidosulfonates or water-soluble amide compounds.

Furthermore, it is necessary to add a combination of the three amino alcohol components; adding each of the above components alone or any two of the above components to cement will not provide sufficient hardening accelerating performance. First, it does not provide the same hardening acceleration performance as when calcium chloride is used. The amount of the above three components added is 0.1 of calcium nitrite to cement.
-3.0% by weight, 0.01-2.0% by weight for amidosulfonic acid salts or water-soluble amide compounds, and 0.005-0.1% by weight for amino alcohols. If the amount of calcium nitrite is less than 0.1% by weight, the rust prevention effect will be insufficient, and if it is added in excess of 3.0% by weight, no further increase in rust prevention ability can be expected, and the effect per unit weight On the contrary, the promotion ability decreases.

In addition to the above, amino alcohol is 0% for cement.
．． When added in an amount of 0.005 to 0.1% by weight, the curing accelerating performance can be improved due to their synergistic effect.

If it is less than 0.005% by weight, the curing accelerating performance will not be sufficient, and if it is added in excess of 0.1% by weight, no synergistic effect can be expected.

Further, in the present invention, by adding or adding an amidosulfonate or a water-soluble amide compound to the cement, the curing accelerating performance is further improved, and a cement composition that is free from practical problems can be obtained. The amount added is 0.01 to 2.0% by weight based on cement. If it is less than 0.01% by weight, the curing accelerating performance will not be sufficient, and if it exceeds 2.0% by weight, no further synergistic effect can be expected.

As mentioned above, in the present invention, a significant improvement in hardening acceleration performance can be expected only when predetermined amounts of the three components of calcium nitrite, amino alcohol, amidosulfonate, or water-soluble amide compound are simultaneously added to cement. Therefore, even if any two of these components are added, the curing accelerating performance will not be as good as that of calcium chloride, and will be insufficient from a practical point of view.

The present invention will be further explained below with reference to Examples.

Examples, 1 to 6 and Comparative Examples 1 to 8 Various additives were added to cement in the ratios shown in Table 1, and standard sand was used in accordance with JISR5201 at a water-cement ratio of 6.
5% 1:2 mortar was applied to the specimen size (4X4X16cm).
), and after curing I in water at 20°C, the compressive strength of each material was measured. The results were as shown in Table 1.

From the results of Examples 1 to 6 shown in Table 1, it can be seen that the curing accelerating performance of the composition of the present invention is significantly accelerated by the synergistic effect of the added components. For example, calcium nitrite is 0.625% by weight, calcium amidosulfonate is 0.1% by weight, and triethanolamine is 0.625% by weight based on cement.
In Example 1, in which 01% by weight was added, the compressive strength of the cement mortar improved by 143% after 1 day curing and 130% after 7 days curing, compared to the cement mortar without additive (Comparative Example 1). It can be seen that

Examples 7 to 12 and Comparative Examples 9 to 16 Each additive shown in Table 2 was added to cement in the proportion shown in Table 2, and the concrete composition shown in Table 3 was JISA11.
3g of concrete was mixed and molded into a cylindrical specimen with a diameter of 10G and a height of 20c11. This product was cured in a form at 20℃ for one day.

The 7-day curing and 28-day curing were carried out in water at 20°C. The curing acceleration performance was measured by measuring their compressive strengths. The results are shown in Table 2.

From the results in Table 2, it can be seen that in all Examples (7 to 12), the curing acceleration performance was significantly improved due to the synergistic effect of each additive component. For example, calcium nitrite is 0.25% by weight, calcium amidosulfonate is 0.1% by weight, and triethanolamine is 0.25% by weight based on cement.
In Example 7, in which 01% by weight was added, the compressive strength was 148% after curing for 1 day, and 1% after curing for 7 days, compared to the one without additives.
The improvement was as much as 30%, which shows that curing is significantly accelerated.

(Effects of the Invention) The cement composition of the present invention has significantly enhanced hardening performance by adding and blending calcium nitrite, amidosulfonate or water-soluble amide compound, and a very small amount of amino alcohol to cement. In addition to being effective, it can also have rust-preventing ability almost equivalent to calcium nitrite. Cement paste, mortar, concrete, etc. prepared by using the cement composition of the present invention in a conventional manner can be obtained. Furthermore, chemical admixtures for concrete, such as AE agents, water reducers, AE water reducers.

A high performance water reducing agent or a cement admixture such as fly ash or slag powder can also be added, and the cement composition of the present invention is considered to have great practicality.

Claims (4)

[Claims] (1) 0.1 to 3.0% by weight of calcium nitrite, 0.005 to 0.1% by weight of amino alcohol, and 0.01 to 2.0% by weight of amidosulfonate or A cement composition characterized by containing a water-soluble amide compound. (2) The cement composition according to claim 1, wherein the amino alcohol is triethanolamine, diethanolamine, monoethanolamine, or a mixture thereof. (3) The cement composition according to claim 1, wherein the amidosulfonate is a sodium, potassium, calcium, or magnesium salt or a mixture thereof. (4) The cement composition according to claim 1, wherein the water-soluble amide compound is acrylamide, acetamide, formamide, dimethylformamide, or urea.