JPH0643265B2 - Quick-setting cement composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fast-setting cement used for civil engineering, construction work, secondary concrete products, solidification of industrial waste, and the like. More specifically, the present invention relates to cement used for emergency repair work, cold district work, rock and ground stabilization work, grout work, secondary concrete product manufacturing, and solidification treatment of various industrial wastes.

[Prior Art] As a quick-hardening cement, conventionally, a clinker containing a large amount of a rapid-hardening component such as calcium fluoroaluminate or calcium aluminate is fired, and gypsum is added to grind it to a Blaine specific surface area of about 5000 to 6000 cm ² / g. It is known how to do it. This method requires special consideration for the raw materials for clinker production and the clinker firing conditions, and its main purpose is to provide rapid hardening in terms of physical properties. It does not have any particular effect on other physical properties such as frost damage.

On the other hand, it is known that the hydration reaction is promoted by finely pulverizing an ordinary Portland cement clinker to have a Blaine specific surface area of 6000 cm ² / g or more. In the above, since the fluidity of the paste, mortar or concrete is remarkably reduced, the amount of water required for obtaining the desired fluidity is considerably increased, and as a result, sufficient strength cannot be obtained. Therefore, the use of such highly finely ground cement, for example, to use for ground injection with an extremely large water cement ratio, or when forcibly kneading at a low water cement ratio, vibration molding, The range of use was limited.

In addition, as a method of accelerating hardening of Portland cement clinker, mixed cement and the like, a method of adding an accelerator such as chloride, aluminate, alkali metal carbonate, sodium silicate or the like is known. Furthermore, there is also known a method of increasing the strength by adding a naphthalene-based, melamine-based, or lignin-based high-performance water reducing agent to reduce the required water amount to some extent.

[Problems to be Solved by the Invention] The main object of the present invention is to prevent deterioration of fluidity, which is a fundamental problem in imparting the effect of high fineness to Portland cement.

That is, it is excellent in a normal water-cement ratio without impairing various advantages that are imparted by high fineness, such as fast hardening, denseness, excellent permeability into gaps, neutralization suppression, and frost damage resistance. Various examinations were made on the conditions for securing liquidity.

[Summary of the Invention] In the present invention, Portland cement having a 3CaO / SiO ₂ content of 45 to 75% by weight, a 3CaO / Al ₂ O ₃ content of 6 to 12% by weight, and a Blaine specific surface area of 8000 cm ² / g or more is used. 0.1 to 1.0 parts by weight of an oxycarboxylic acid or a salt thereof is added to 100 parts by weight of cement obtained by substituting 50% by weight or less of the Portland cement with blast furnace slag or fly ash. It is a hard cement composition.

DETAILED DESCRIPTION OF THE INVENTION The Portland cement clinker used in the fast-setting cement composition of the present invention has a 3CaO.SiO ₂ content of 4.
5 to 75% by weight, 3CaO / Al ₂ O ₃ content is 6 to 12
It is desirable that the content is wt%. The rapid hardening properties which are expected to have a 3CaO.SiO ₂ content of less than 45% by weight and a 3CaO.Al ₂ O ₃ content of less than 6% by weight are not exhibited. In addition, a clinker having a 3CaO.SiO ₂ content of more than 75% by weight is difficult to be baked and the quality thereof is largely changed, so that a stable clinker is hardly obtained. 3Ca
If the O.Al ₂ O ₃ content exceeds 12% by weight, the effect of improving the fluidity by the oxycarboxylic acid or its salt becomes small, and it is not preferable in terms of chemical resistance and drying shrinkage. The other main compound in the clinker is 2CaO ・ S
iO ₂ , 4CaO ・ Al ₂ O ₃・ Fe ₂ O ₃ , CaSO ₄・ 2
H ₂ O and the like.

Blaine specific surface area of these clinker is 8000 cm ² / g or more, preferably 9000 to 13 by a suitable crusher.
It is crushed to 000 cm ² / g. In this case, gypsum may be added to crush it in order to reduce the power required for crushing.
From the viewpoint of physical properties, it is preferable to reduce the amount of gypsum as much as possible. 0.1 to 3.5% by weight is preferable based on SO ₃ in the cement, and a particularly preferable embodiment is 0.3 to 1.5% by weight. Regarding the highly finely ground cement obtained by the above method, depending on the purpose of use, for example, when chemical resistance, solidity, etc. are required, 50 weight parts of blast furnace slag or fly ash having a similar particle size is used. You can substitute up to%. If it exceeds 50% by weight, the initial strength is excessively reduced, which is not preferable.

Next, in order to improve the fluidity, oxycarboxylic acid or a salt thereof is added to the highly finely ground cement, and examples thereof include citric acid, gluconic acid, tartaric acid and salts thereof, and more preferably citric acid. Acids or sodium citrate are effective. The addition amount of oxycarboxylic acid or its salt is the fineness of highly finely ground cement, the amount of gypsum added,
Furthermore, the appropriate value varies depending on the type of oxycarboxylic acid or its salt, the material temperature at the time of kneading, and the amount of blast furnace slag or fly ash, but the range is within the range of highly finely ground cement 10.
It corresponds to 0.1 to 1.0 parts by weight with respect to 0 parts by weight.
If it is less than 0.1 part by weight, sufficient fluidity cannot be obtained, and
If it exceeds 1.0 part by weight, the setting of cement will be significantly delayed and the development of the initial strength may be hindered, which is not preferable. The oxycarboxylic acid or its salt may be premixed before or after the clinker crushing, or may be dissolved in the kneading water at the time of preparing the mortar or concrete, and the same effect can be obtained.

The quick-hardening cement composition of the present invention is used for producing paste, slurry, mortar or concrete, and the water-cement ratio in that case varies depending on the purpose of use and the molding method, but is generally within the range of 30 to 70%. It is in. When dry shrinkage is a problem, it is possible to use a commonly used cement swelling agent or organic shrinkage reducing agent. Next, examples of the present invention will be described.

Examples 1 to 3 and Comparative Examples 1 to 2 Portland cement clinker having a different compound composition was jet milled to have a Blaine specific surface area of 11000 to 1200.
The 0 cm ² / g was ground to a target, to prepare an additive to high pulverized cement dihydrate gypsum Blaine specific surface area of 12500cm ² / g was ground separately as SO ₃ in the cement is 1.3% by weight. To 100 parts by weight of these highly finely ground cement, 0.5 parts by weight of trisodium citrate was added, and JIS
Mortar strength was tested according to R5201. The results are shown in Table 1.

Examples 4-7, Comparative Examples 3~5 3CaO · SiO ₂ 54 wt%, 2CaO · SiO ₂
25% by weight, 3CaO / Al ₂ O ₃ 9% by weight, 4CaO
・ Al ₂ O ₃ · Fe ₂ O ₃ 9% by weight of Portland cement clinker was added with gypsum dihydrate so that SO ₃ in the cement would be 1.3% by weight, and a Blaine specific surface area 6320 with a ball mill or jet mill. 8630, 1092
Crushed to 0,12850 cm ² / g and added trisodium citrate to these cements JIS
Mortar strength was tested according to R5201.

The results are shown in Table 2.

Examples 8-9, Comparative Examples 6-7 Using the Portland cement clinker of Example 4,
SO _{3 in} cement is 0.9, 1.5, 4.0, 6.0
After adding dihydrate gypsum so that the weight ratio becomes 9% to 10500 cm ² / g by a jet mill, 0.35 parts by weight of trisodium citrate is added to 100 parts by weight of these cements. About added J
The mortar strength according to IS R 5201 was tested.

The results are shown in Table 3.

[Effects of the Invention] As in the present invention, by finely pulverizing Portland cement clinker, functions such as fast hardening, solidity, adhesiveness, excellent penetration into gaps, neutralization suppression, and freeze resistance However, for this purpose, improvement of fluidity caused by high pulverization is a prerequisite.

The present invention relates to 3CaO · SiO ₂ , 3CaO in cement.
-Al ₂ O ₃ amount is limited, more preferably, gypsum added amount is limited as much as possible, and finely ground to a fineness of 8000 cm ² / g or more, and an appropriate amount of oxycarboxylic acid or salt thereof. , Preferably by adding citric acid or a salt thereof, to provide a paste, slurry, mortar or concrete with excellent fluidity in a normal water-cement ratio, without compromising the advantages as described above due to high fine grinding. ing.

That is, the present invention is a fast-setting cement composition that can not be reached under the above-mentioned one condition, and exhibits an excellent effect that is first achieved by the combined effect of all conditions, civil engineering, construction work, It can be effectively used for solidification of secondary concrete products and industrial waste.

Claims (4)

[Claims] 1. A 3CaO · SiO ₂ content of 45 to 75 wt%, 3CaO · Al ₂ O ₃ content of 6-12 wt% the balance being mainly _{2CaO · SiO 2, 4CaO · Al} 2 O 3 · Fe 2
A fast-setting cement composition comprising O ₃ and 0.1 to 1.0 part by weight of an oxycarboxylic acid or a salt thereof with respect to 100 parts by weight of Portland cement having a Blaine specific surface area of 8000 cm ² / g or more. 2. The quick-setting cement composition according to claim 1, wherein SO ₃ in the semetone is 0.3 to 1.5% by weight. 3. 50% by weight of Portland cement
The rapid hardening cement composition according to claim (1), wherein the following is replaced with blast furnace slag or fly ash having a Blaine specific surface area of 8000 cm ² / g or more. 4. The fast-curing cement composition according to claim 1, wherein the oxycarboxylic acid or its salt is citric acid or its salt.