JPH06183802A - Setting regulator for quick-setting cement - Google Patents

Abstract

PURPOSE:To provide a setting regulator for quick-setting cement to be mainly used in the civil engineering/construction industry, esp. intended to regulate the setting retarding effect for quick-setting cement combined with a setting retarder. CONSTITUTION:The objective setting regulator containing, as the active comprising (A) quick-setting cement, (B) a setting retarder and (C) the above-mentioned setting regulator are provided. The hydrotalcite which functions as a setting regulator, has such an effect as to be capable of regulating the setting time for quick-setting cement, esp. setting retarder-contg. one.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a setting modifier for rapid hardening cement, which is mainly used in the fields of civil engineering and construction, and more particularly,
The present invention relates to a setting modifier for a rapid hardening cement, which is intended to control the setting delaying effect of a hardening cement with a setting retarder.

[0002]

2. Description of the Related Art Conventionally, setting accelerators and setting retarders have been used to control the setting time of cement.

[0003] In particular, rapid hardening cements such as alumina cements and rapid hardening cements to which cement hardening agents such as calcium aluminate have been added require the use of a setting retarder in combination, and can be obtained depending on the amount of the setting retarder added. The current situation is to adjust the pot life.

However, in the production of these rapid hardening cements, usually, a set retarder is often mixed in advance to prepare a cement composition, and depending on the storage period,
There was a problem that the pot life initially set was greatly exceeded.

As a method of adjusting the pot life to the initially set pot life, there have been methods such as adding a large amount of newly produced rapid hardening cement and adding a setting accelerator.

[0006] However, these methods have problems in terms of economy, time and labor.

Further, the addition of the coagulation accelerator has a problem that it may have negative factors such as abnormal coagulation and abnormal expansion.

The present inventor has found that the above problems can be solved by using a specific material as a result of various investigations in order to solve the above problems, which are excellent in economic efficiency and do not cause negative factors. The present invention has been completed.

[0009]

Means for Solving the Problems That is, the present invention is a setting agent for a rapid hardening cement containing hydrotalcite as an active ingredient, which comprises a rapid hardening cement, a setting retarder and a setting agent. It is a thing.

The present invention will be described in detail below.

The hydrotalcite according to the present invention is a complex basic salt of divalent and trivalent metals and has the general formula [M _1-X ²⁺
Is a generic term for ^{_{M X 3+ (OH) 2]}} X + [A X / N N- · mH 2 O] X- complex non-stoichiometric compound represented. Here, M is a divalent or trivalent cation, A is a monovalent or divalent anion, and N is 1.
Alternatively, 2 and X are 0 <X ≦ 0.33.

Further, as M ²⁺ , Mg ²⁺ , Mn ²⁺ , Fe ²⁺ , C
o ²⁺ , Ni ²⁺ , Cu ²⁺ , and divalent metals such as Zn ²⁺ , M
^Examples of ³⁺ include trivalent metals such as Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Co ³⁺ and In ³⁺ .

Furthermore, as A ^{N-is, OH -, F -, Cl} -, B
Examples thereof include monovalent or divalent anions such as r ⁻ , NO ₃ ⁻ , CO ₃ ²⁻ , and SO ₄ ²⁻ . ^{Among, OH -, F -, Br} -, NO 3 -, CO 3
^2, and SO ₄ ^2- are ^{preferred, OH -, F -, Br} -, NO 3 -, and S
O ₄ ²⁻ is more preferable.

The presence of impurities as hydrotalcite is not particularly limited, and either crystalline or amorphous can be used, but crystalline is preferably used.

The particle size of hydrotalcite is 0.1 to 100 μm.
m is preferred. If it is less than 0.1 μm, the amount of kneading water will increase, which may adversely affect the physical properties such as strength.
If it exceeds 0 μm, the surface area is reduced, and the condensation control performance may be insufficient.

The amount of hydrotalcite used is cement.
With respect to 100 parts by weight, 0.1 to 10 parts by weight is preferable, 0.5 to
2 parts by weight is more preferred. If the amount is less than 0.1 part by weight, the setting control performance becomes insufficient, and if the amount exceeds 10 parts by weight, the amount of kneading water increases, which may adversely affect the strength development.

The quick-hardening cement according to the present invention is a cement having a quick-hardening property, such as a mixture of cement and a cement quick-hardening material or alumina cement.

Here, as the cement, normal, early strength,
Various portland cements such as super early strength, moderate heat, and sulfate resistance, blast furnace slag,
Examples include various mixed cements mixed with fly ash or silica.

The cement rapid-hardening material is a material that is mixed with cement to impart rapid-hardening properties, and examples thereof include inorganic salts such as sodium carbonate, sodium silicate, sodium aluminate, and calcium chloride, and alumina cement, Calcium aluminate, a mixture of calcium aluminate and gypsum, or the like, which has an effect of promoting the setting of cement, can be used, and it is preferable to use a material containing calcium aluminates as a main component.

The amount of cement hardened material used is 100% cement.
The amount is preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, most preferably 15 to 35 parts by weight, based on parts by weight. If it is less than 5 parts by weight, the rapid hardening property is insufficient, and if it exceeds 50 parts by weight, long-term durability may be problematic.

The setting retarder according to the present invention is an admixture which controls the hydration reaction of cement and delays the setting time and initial hydration rate of concrete.

Specifically, organic acids such as citric acid, tartaric acid, gluconic acid, succinic acid and maleic acid or salts thereof, alkali carbonates, phosphoric acids or salts thereof, boric acid, alkali borate, silicofluoride. , Starch, sugar, alcohols and the like, and mixtures thereof.

The amount of the set retarder used is 10
0.05 to 3 parts by weight is preferable with respect to 0 parts by weight, and 0.1 to 1
More preferably parts by weight. If it is less than 0.05 parts by weight, the effect of retarding the setting is difficult to obtain, and if it exceeds 3 parts by weight, the strength development tends to be deteriorated.

Further, in the present invention, aggregates such as silica sand, natural sand, and gravel, setting accelerators such as sodium aluminate, fibrous substances such as glass fibers, carbon fibers, and steel fibers, high molecular polymers Emulsion or latex,
AE agents, water reducing agents, AE water reducing agents, superplasticizers, rust preventives, inseparable admixtures in water such as methyl cellulose, thickeners, waterproofing agents such as sodium silicate, foaming agents, foaming agents, antifreezing agents, and Among the alkaline substances such as calcium hydroxide and the like, one kind or two or more kinds can be used in combination as long as the object of the present invention is not substantially impaired.

Although the action of the hydrotalcite according to the present invention to control the setting time of the rapid hardening cement is not clear, it is believed that the effect of the setting retarder is controlled by the acid adsorbing ability of hydrotalcite. .

[0026]

EXAMPLES The present invention will now be described in more detail with reference to examples.

Example 1 100 parts by weight of cement, 25 parts by weight of cement rapid hardening material, 1 part by weight of set retarder, 100 parts by weight of sand, and 40 parts by weight of water were added to Table 1.
A mortar was prepared by kneading and mixing at 5 ° C. using the composition of For kneading, a small mortar mixer of tabletop universal mixer MH-100 manufactured by Maruhishi Kagaku Kikai Seisakusho was used, and after mixing the cement, low speed 30 seconds and high speed 90 seconds. Using this mortar, setting time and compressive strength were measured.

The setting time was measured by using a continuous temperature recorder, and the time increased by 1 ° C. was regarded as the setting time and the time increased by 4 ° C. was regarded as the curing time. Also, the measurement of compressive strength is 4
A mortar specimen of × 4 × 16 cm was prepared, and the compressive strength on the first day of its age was measured. The results are also shown in Table 1.

<Material used> Cement: Denka Chemical Industry Co., Ltd. trade name “Denka Early Strength Cement” Cement rapid hardening material: Calcium aluminate, 12CaO · 7Al ₂
O ₃ setting retarder: sodium citrate, commercial product Sand: Toyoura standard sand water: tap water Hydrotalcite: Kyowa Chemical Industry Co., Ltd. product name “KW-100
0 "to 0.1N- nitrate 24 hour immersion treated Mg-Al-NO ₃ system,
Average particle size 45μm or less

[0030]

[Table 1]

Example 2 The procedure of Example 1 was repeated, except that the mixture was kneaded at 20 ° C.
The results are shown in Table 2.

[0032]

[Table 2]

[0033]

EFFECTS OF THE INVENTION The hydrotalcite of the present invention functions as a setting regulator, and can improve the setting time of rapid hardening cement, in particular,
The effect of being able to control the setting time of the rapid hardening cement containing a setting retarder is exhibited.

Claims (2)

[Claims] 1. A setting regulator for rapid hardening cement containing hydrotalcite as an active ingredient. 2. A cement composition comprising a rapid hardening cement, a setting retarder, and the rapid hardening cement setting regulator according to claim 1.