JP2001039748A - High-early-strength cement admixture and concrete and concrete product containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture showing good workability and high early strength and to produce concrete and a concrete product containing the admixture. SOLUTION: The high-early-strength cement admixture consists of a clinker composition containing one or more kinds of 3CaO.SiO2-2CaO.SiO2-CaOa gap material, 3CaO.SiO2-CaO- a gap material, 2CaO.SiO2-CaO- a gap material and CaO- a gap material as the main mineral composition and containing 50 to 92 wt.% of CaO crystal, or it consists of a mixture pulverized material of the clinker composition and quicklime and gypsum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength cement admixture, concrete containing the same, and concrete products. More specifically, the present invention relates to an early-strength cement admixture that imparts good workability and early-strength to concrete, and concrete and concrete products using the early-strength cement admixture.

[0002]

2. Description of the Related Art Conventionally, for example, to produce a concrete product in a short time, steam curing is used as follows. That is, fine aggregates and / or coarse aggregates, water, admixtures such as water reducing agents and fluidizing agents, and admixtures such as silica fume are added to cement and mixed, and the kneaded concrete is poured into a mold. And shaping while giving vibration with a vibrator or the like. Next, this was transferred to a steam curing tank or placed in an appropriate place, covered with canvas, left to cure for 1 to 5 hours, and then steam was fed in.
The temperature is raised to 60 to 80 ° C. at a rate of temperature increase of 60 ° C./hour, and this temperature is maintained for 2 to 3 hours. After that, the supply of steam is stopped to allow the water to cool naturally, and the mold is removed to obtain a concrete product.

[0003] However, this conventional method still requires a long time from molding to demolding of the concrete, and usually, the production cycle in one mold is about one cycle per day. Also, the time required for curing and demolding of centrifugally formed concrete products such as fume pipes and concrete piles is substantially the same as that of ordinary concrete products, except that the molding method is different. The production amount per unit is about once a day. Therefore, it has been strongly desired to improve the productivity by increasing the rotational efficiency of the formwork in order to reduce the cost.

[0004] In order to improve the production efficiency, a cement composition is used in which a predetermined amount of lithium, aluminum, gallium, thallium sulfate or a double sulfate containing these metals is added to cement. A method of curing at a high temperature is described in JP-A-60-21839. According to this method, steam curing is performed directly without pre-curing, and rapid high-temperature curing at a heating rate of 40 ° C./hour or more and a curing temperature of 80 ° C. or more can be performed. It is said that it is possible to enhance the character.

[0005] It is said that the pre-curing is not required in this method because ettringite is generated early by the action of the above-mentioned sulfate or double sulfate. However, in this method, the generation of ettringite is too short. , It was difficult to obtain the desired workability. Therefore, in order to actually produce a concrete product or the like using the cement composition, concrete to which a sulfate or a double sulfate is not added is first kneaded in advance, and the kneaded material is transported to a place where the formwork is installed, and the formwork of the formwork is formed. It must be transferred to another mixer installed nearby, where sulfates and double sulfates are added and kneaded again before pouring or pouring into the mold within a short time. Such a transfer operation to a mixer significantly impairs productivity, and it is very difficult to put this mixer to practical use in this type of operation that produces the largest production. In this case, if the amount of sulfate or double sulfate is reduced, the hydration reaction can be delayed to a certain extent.However, the hardening of the concrete is delayed, so that the mold cannot be removed in a short time and the productivity can be increased. Disappears. Incidentally, the above problem is not limited to concrete, but is also true of mortar.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional cement or concrete, and has good workability until the completion of the concrete casting. It is an object of the present invention to provide an early-strength cement admixture which hardens early to obtain high-strength concrete, a cement composition containing the same, and a concrete or concrete product thereof.

[0007]

That is, the present invention provides:
(1) The main mineral composition is 3CaO.SiO ₂ -2CaO.
SiO ₂ —CaO—interstitial material, 3CaO · SiO ₂ —Ca
O- gap material comprises one or more 2CaO · SiO ₂ -CaO- gap material and CaO- gap material, and CaO crystals containing 50 to 92 wt% clinker composition with ground mixture of gypsum, Alternatively, the present invention relates to an early-strength cement admixture comprising a mixed and pulverized product of the clinker composition, quicklime and gypsum.

[0008] The cement admixture of the present invention is preferably (2) a cement admixture comprising the above-mentioned mixture and pulverized mixture of the clinker composition and gypsum, wherein 5 to 50 parts by weight of gypsum is added to 100 parts by weight of the clinker composition. Are mixed.

The cement admixture of the present invention preferably comprises (3) a cement admixture comprising the above-mentioned clinker composition, a mixture of quicklime and gypsum, and a total of 100 parts by weight of the clinker composition and quicklime. The clinker composition is 20 parts by weight or more, and 5 to 50 parts by weight of gypsum is mixed with 100 parts by weight of the total of the clinker composition and quicklime.

The present invention also relates to (4) 100 parts by weight of Portland cement or mixed cement, the above (1),
(3) The early-strength cement admixture described in (2) or (3)
The present invention relates to an early-strength cement composition characterized by mixing parts by weight.

The present invention further relates to the following concrete and concrete products comprising the above cement composition. (5) An aggregate and water or an admixture for aggregate, water, and concrete are added to the early-strength cement composition according to claim 4.
Concrete characterized by mixing and kneading (material). (6) The concrete of (5) is poured into a mold, cured in the air, cured, demolded, and left standing in the air or cured in water. Concrete products. (7) The concrete of the above (5) is poured into a mold and immediately put into a steam curing tank or a steam is cured by feeding a steam with a cover provided, and 50 to 50 hours in 30 to 1 hour.
After raising the temperature to ~ 85 ° C, the supply of steam is stopped, and the concrete is released after the strength of the concrete reaches the demolding strength. Thereafter, the concrete is left in the air or cured underwater to produce. Concrete products.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. The clinker composition used in the early-strength cement admixture of the present invention has a main mineral composition of (a) 3Ca
O · SiO ₂ -2CaO · SiO ₂ -CaO-interstitial material,
(B) 3CaO · SiO ₂ -CaO- gap material, (c) 2CaO
· SiO ₂ -CaO- gap material, and (d) CaO-containing one or more gaps material, and a CaO crystal 5
It is characterized by containing 0 to 92% by weight.
That is, the clinker composition contains at least CaO crystals and interstitial materials as main mineral compositions,
CaO.SiO ₂ ) and / or belite (2CaO.
A clinker composition which may or may not contain SiO ₂ ), wherein the content of CaO crystals is 50 to 92% by weight.

The interstitial material is similar to a mineral that fills a space between alite and belite in the cement clinker mineral, and specifically, for example, 2CaO.Fe ₂ O ₃
Calcium aluminate mineral such as 3CaO.Al ₂ O ₃ or 6CaO.A
_{l 2 O 3 · Fe 2 O} 3, 4CaO · Al 2 O 3 · Fe 2 O 3, 6C
calcium etc. _{aO · 2Al 2 O 3 · Fe} 2 O 3 alumino a ferrite minerals.

By containing at least CaO crystals and the interstitial material as the main mineral composition, CaO plays a role of promoting heat generation during hydration and the hydration product thereof to promote hardening of the cement. Acts as a flux on CaO and plays a role in suppressing the rate of hydration of CaO, and the coexistence of both has an effect of promoting cement hardening without significantly impairing workability.

The content of CaO crystals contained in the clinker composition is suitably from 50 to 92% by weight. If the content is less than 50%, the desired early strength cannot be obtained, while
If the content exceeds 92%, the amount of the interstitial material is relatively reduced, and it is also difficult to obtain desired properties.

The clinker composition is alite (3CaO.Si)
O ₂ ) and belite (2CaO · SiO ₂ ) may or may not be contained. Those containing these greatly suppress the hydration rate of CaO, and these hydrates contribute to the strength development of cement.

The above clinker composition is prepared by mixing calcareous raw materials, clay raw materials, silica stone, slag, gypsum and the like so as to have the above-mentioned composition to prepare a raw material mixture, and the raw material mixture is heated to 1300 to 1600 ° C. using a rotary kiln or the like. It is manufactured by baking and firing sufficiently until the desired clinker mineral composition is obtained at the temperature.

When the clinker composition is fired, a mineralizer (flux) can be added to the raw materials to improve the production efficiency. As the mineralizer, those generally used when firing cement-based compounds can be used. Specifically, CaSO ₄ , CaF ₂ , Fe ₂ O, Mg
A compound containing O, Al ₂ O _3, etc., for example, gypsum, fluorite, serpentine or the like may be added to the raw material in an amount of about 10% by weight or less, followed by firing.

The cement admixture of the present invention comprises (a) a mixed and pulverized product of the above clinker composition and gypsum, or
(B) A mixture of the above clinker composition, quicklime and gypsum.

Mixing the clinker composition with gypsum has the effect of increasing the initial strength of the concrete (demolding strength during simple steam curing). The effect of this gypsum is that when quicklime is blended, the activity of the quicklime is high (that is, the calcining degree is low and 4-N hydrochloric acid consumption is large)
Is more remarkable. Since such an effect of gypsum or quicklime can be obtained, it is not necessary to use an alkaline hardening accelerator, and therefore, the long-term elongation of concrete strength is good and the long-term durability of concrete is excellent.

As the gypsum to be mixed with the cement admixture of the present invention, commercially available general gypsum can be used.
Gypsum is classified into anhydrous gypsum, gypsum hemihydrate and gypsum dihydrate according to its crystal form, and any gypsum can be used in the present invention. Preferably, anhydrous gypsum is used.

The amount of gypsum in the cement admixture of the present invention is as follows: (a) When the cement admixture is a two-component system of a clinker composition and gypsum, 5 to 50 gypsum per 100 parts by weight of the clinker composition The part is appropriate. When the (b) cement admixture is a ternary system of a clinker composition, quicklime and gypsum, the total amount of the clinker composition and quicklime is 1
5 to 50 parts by weight of gypsum is suitable for 00 parts by weight.

When the amount of the gypsum is less than the lower limit of the above-mentioned amount, the effect of adding the gypsum is scarcely exerted and the early strength is not exhibited. By the way, as shown in the test data described later, those without gypsum have a simple steam curing strength of demolding in 4 hours from water injection of less than 8 N / mm ² . On the other hand, if the amount of gypsum exceeds 50 parts by weight, there is a concern that strength may be reduced due to expansion cracking of mortar or concrete.

The cement admixture of the present invention is not limited to a two-component mixture comprising the clinker composition and gypsum, but also includes a three-component mixture obtained by mixing quick lime with the clinker composition and gypsum. The clinker composition and quick lime are heat sources. By adding quick lime, the calorific value of the entire cement admixture is increased, and the strength development is improved as compared to when the clinker composition is used alone. In addition, by using the clinker composition and quick lime together, it is possible to obtain an admixture capable of producing concrete or mortar that maintains fresh properties even when a wide range of quick lime from hard-burned quick lime is used. Further, the calorific value per unit amount of the cement admixture can be controlled by using quick lime ranging from hard-burned quick lime to soft-burned quick lime. The calorific value of concrete causing early strength development depends on the type of cement used, casting volume, unit cement amount, etc., but the cement admixture of the present invention has a clinker composition-quick lime-gypsum mixing ratio. Since the amount of heat generated per unit amount of the cement admixture can be controlled by adjusting, it can be applied to concrete mixing according to various situations.

As quicklime added to the admixture of the present invention, commercially available quicklime can be used. Quick lime is classified into extremely soft-burned quick lime, soft-burned quick lime, hard-burned quick lime, and extremely hard-burned quick lime according to the degree of calcining, and its evaluation method is generally a coarse-grain titration test using 4N-hydrochloric acid of the Japan Lime Association. Is used. According to this coarse-grain titration test method, the classification of quicklime is indicated by the total amount of 4N-hydrochloric acid used in the titration, the extremely soft-burnt quicklime is 800 ml or more, the soft-burnt quicklime is 800 to 650 ml, and the medium-burnt quicklime is 650 to 30 ml.
0 ml, hard burnt lime is 300-130 ml, and extremely hard burnt lime is 130 ml or less.

The degree of calcination of quicklime shown by the above test method has a great influence on the workability of concrete containing the quicklime. That is, when the mixing ratio to the clinker composition is the same, the higher the value of the rough titration test with 4N-hydrochloric acid (the lower the degree of firing), the greater the time-dependent change of the slump. May come.

However, this tendency can be controlled by adjusting the mixing ratio to the clinker composition. That is, when the ratio of the clinker composition is large, 4
Even if using quick lime having a high coarse-grain titration test value (low firing degree) with N-hydrochloric acid, there is no decrease in workability,
When the proportion of the clinker composition is low, use of quicklime having a low coarse-grain titration test value (high calcination degree) with 4N-hydrochloric acid can suppress a decrease in workability. In addition,
Generally, in order to produce concrete with good workability, the coarse particle titration test value with 4N-hydrochloric acid is 650 ml.
Hereafter, it is preferable to use quicklime of preferably 400 ml or less (medium baking degree or less).

In the cement admixture of the present invention, the content of quicklime is 400 parts by weight based on 100 parts by weight of the clinker composition.
It is suitable that the amount is less than 80 parts by weight, that is, less than 80% by weight in the total amount of the clinker composition and the quicklime. If the content of quicklime is less than this, the effect is not obtained, and if it is more than this, the workability of the concrete is extremely reduced and the expansion is undesirably excessive. As described above, the amount of gypsum may be 5 to 50 parts by weight based on 100 parts by weight of the total amount of the clinker composition and quick lime.

The cement admixture of the present invention comprises the above-mentioned mixture of the clinker composition, quicklime and gypsum, which may be individually pulverized and then mixed, or mixed and pulverized. Good. For the pulverization, a pulverizer usually used for pulverizing cement, such as a ball mill or a roll mill, can be used. In general, as the particle size of the pulverized product increases, the greater the degree of fineness, the sooner the cement strength develops and the higher the hydration ripening tends to be. This fineness is equivalent to or higher than that of Portland cement or mixed cement used by mixing the cement, and the specific surface area of the brane is 3,000 to 60.
00cm is the well at ² / g, equivalent specific surface area (Blaine), for example 4000~5000cm about ² / g are preferred.

The high-strength cement composition of the present invention comprises Portland cement or mixed cement and the above cement admixture. The appropriate amount of these additives is 3 to 30 parts by weight of the cement admixture per 100 parts by weight of Portland cement or mixed cement. If this amount is less than 3 parts by weight, the desired early strength of the present invention cannot be obtained. On the other hand, if the mixing ratio of the cement admixture exceeds 30 parts by weight, the expansion becomes excessive and the concrete may be broken, which is not preferable.

The portland cement includes ordinary portland cement, fast-strength portland cement, white portland cement and the like. The mixed cement is blast furnace cement, fly ash, silica cement, or the like.

The concrete of the present invention is obtained by adding an aggregate (fine aggregate and / or coarse aggregate) and water to the above-mentioned early-strength cement composition as a raw material. And kneaded with an admixture (material) for use.
The compounding amounts of these aggregates, water and admixture (material) may be within the compounding amounts of ordinary concrete. The type of aggregate and admixture (material) may be any as long as it is used for ordinary concrete.

An example of the concrete manufacturing process will be described below. (1) The concrete is poured into a mold, cured in the air, cured, and then removed from the mold, and left in the air or cured in water. (2) The concrete is poured into a mold and immediately put into a steam curing tank, or steam curing is performed by feeding steam with a cover provided, and 50 to 50 hours in 30 minutes to 1 hour.
After the temperature is raised to 85 ° C., the supply of steam is stopped, and after the strength of the concrete reaches 10 MPa or more, the steam curing is terminated. After the mold is released, the concrete is left in the air or cured in water.

The cement admixture of the present invention may be a water reducing agent such as a naphthalene-based high-performance water reducing agent, an admixture generally used in the field of cement concrete, a melamine-based, lignin-based, polycarboxylic acid-based water reducing agent, It can be used together with an agent, an AE agent and the like. It is also possible to use admixtures such as blast furnace slag, limestone fine powder, fly ash, and silica fume.

Further, when the cement admixture of the present invention is used together with a cement hardening accelerator, a more remarkable effect is exhibited. That is, when the admixture of the present invention and the cement hardening accelerator are used in combination, a higher synergistic effect is exhibited than when each is added alone, and the hardening of the concrete is remarkably quicker. Specifically, for example, steam curing A high strength with a compressive strength of 10 MPa or more for the next two to three hours is obtained. Therefore, the concrete product can be removed in a short time, and the production efficiency can be improved.

As the cement hardening promoting substance, an inorganic substance or an organic substance can be used. Examples of the inorganic substance-based cement hardening accelerator include alkali metal salts, alkaline earth metal salts, and trivalent metal salts. Specific examples include sulfites, sulfates, carbonates, rhodanes, thiosulfates, and formates. Examples thereof include sodium sulfate, potassium sulfate, aluminum sulfate, ferrous sulfate, and ferrous sulfate.
Iron, magnesium nitrate, calcium nitrate, calcium nitrite, sodium carbonate and the like can be used. Examples of the organic substance-based cement hardening accelerator include triethanolamine and glycerin. These one
Species or two or more can be used. Further, among these cement hardening accelerators, sodium sulfate, potassium sulfate, aluminum sulfate, iron sulfate, and triethanolamine are preferable, and sodium sulfate is particularly preferable.

The cement hardening accelerator is added in an amount of not more than 10% by weight, preferably 0.05 to 5% by weight in terms of anhydride, based on Portland cement or mixed cement.
More preferably, the content is 0.1 to 2% by weight. In addition, even if it is added in excess of 10% by weight, the effect of the addition is small, and there is a possibility that the long-term strength of the concrete is rather lowered.

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 [Preparation of clinker composition] Limestone, silica stone, clay, iron raw material, and anhydrous gypsum were blended in the ratio shown in Table 1, and a raw material mixture was prepared so as to have a composition shown in Table 2. This raw material is roasted in a rotary kiln at 13
Clinker is manufactured by baking at 00 to 1600 ° C. and a residence time of 60 to 120 minutes.
The mixture was pulverized with a pot mill until it reached about 0 cm ² / g. The degree of baking was measured by 4N hydrochloric acid consumption according to the Japan Lime Society standard test method. As shown in Table 2, the obtained clinker compositions (Nos. 1 to 10) contained alite (3CaO.SiO ₂ ).
And belite (2CaO.SiO ₂ ) together with CaO and interstitial material.

[0039]

[Table 1]

[0040]

[Table 2]

Example 2 [Preparation of cement admixture] The clinker composition of Example 1 (Table 2) and the quicklime and gypsum of the types shown in Tables 3 and 4 were used to produce a cement admixture of Table 5. . Table 5 shows the types and amounts of the clinker composition, quicklime and gypsum used in the cement admixture. The kind of clinker in Table 5 is indicated by the symbol in Table 2.

As quicklime, three types shown in Table 3 were used. Further, three types of gypsum shown in Table 4 were used. The quicker the calcined lime, that is, the lower the consumption of 4N-hydrochloric acid, the higher the energy unit price and the higher the cost. Also,
Sources are limited due to the need for special manufacturing methods. For this reason, quicklime currently marketed has an activity (4N
Most of the lime is high (consumption of hydrochloric acid). An economically advantageous quick lime is quick lime with a consumption of 4N-hydrochloric acid of 300 ml or more. The cement admixture of the present invention can maintain the workability of fresh concrete satisfactorily even when using quicklime with a consumption of 4N-hydrochloric acid of 300 ml or more.

[0043]

[Table 3]

[0044]

[Table 4]

Example 3 [Preparation of Mortar] Using the cement admixture (80 g) prepared in Example 2, commercially available ordinary Portland cement (1000 g) was mixed with sand (19 g).
10 g), water (380 g) and a water reducing agent (10 g) to prepare a mortar. In addition, the cement admixture does not contain quicklime and gypsum, that is, the clinker composition alone (No.B1 to No.B10), does not contain gypsum (No.B11 to No.B11).
No. B16) is shown as a comparative example. In addition, the above admixture is not blended with ordinary Portland cement (ordinary Portland cement: 1000 g, sand: 2000 g, water: 380 g,
Water reducing agent: 10 g) is shown as a comparative example (No. B17). The water reducing agent used was a commercially available naphthalene-based high-performance water reducing agent. The clinker composition, quicklime and gypsum, which are components of the admixture, were thoroughly mixed and pulverized in advance to prepare a cement admixture. This cement admixture was added to the cement, mixed well, and kneaded. First, cement, a cement admixture, and sand were put in a kneading bowl, and the kneading machine was started to knead the mixture for 15 seconds. Water was added for the next 15 seconds, and then kneaded for 60 seconds. Next, kneading was stopped for 20 seconds to scrape off, kneading was started again, and kneading was continued for 120 seconds to obtain mortar.

Table 5 shows the flow values of the obtained mortar immediately after kneading. As shown in Table 5, the mortar containing the cement admixture according to the present invention has a flow value of 118 to
It was 250 mm and sufficient workability was secured. On the other hand, the flow values of Comparative Example No. B13 and Comparative Example No. B14 were as low as 116 mm and 106 mm, respectively, showing extreme stiffness immediately after kneading, and it was difficult to mold the kneaded mortar.

The prepared mortar was subjected to standard curing and steam curing, and the strength was measured. In addition, each strength test was performed as follows. In any case, the measurement of compressive strength is a standard
(JIS-R-5201). The results are summarized in Table 5. (A) Strength test by standard curing: Mortar is used in formwork (4cm × 4c)
mx 16 cm), capping was performed about 2 hours after casting, cured in a moist empty box at 20 ° C, demolded 20 hours after the start of kneading of the mortar, and measured for compressive strength. (B) Strength test by steam curing: Mortar is used for mold (4cm × 4c)
(m × 16 cm), cured for about 30 minutes before (capping during this time), and then subjected to steam curing. The temperature of this steam curing was raised to 60 ° C. for 1 hour, and the temperature was maintained at 60 ° C. for 1 hour and then released. 4 hours after the start of kneading of the cooled mortar, the mold was released and immediately measured for compressive strength.

[0048] As shown in Table 5, those using cement admixture of the present invention has a standard aging at 25 N / mm ² or more, a 8N / mm ² or more compression strength in steam curing. On the other hand, the comparative examples (No.B1 to B10) using the cement admixture of the clinker composition alone without blending quicklime and gypsum all have a somewhat large flow value, but are compressed in both steam curing and simple curing. The strength has dropped significantly. in this way,
In the case of using the cement admixture of the present invention, the early strength is clearly increased as compared with the comparative example (No.B-17) using only ordinary cement, and the comparative example using no gypsum (No.
B1 to No. B16) clearly show that the early strength is increased.

[0049]

[Table 5]

[0050]

[Table 6]

[0051]

[Table 7]

[0052]

[Table 8]

[0053]

[Table 9]

Example 4 [Effect of quicklime] A cement admixture was prepared using quicklime having different firing degrees shown in Table 3. The composition of this admixture is shown in Table 6. Using this admixture, a mortar was prepared in the same manner as in Example 1, and its compressive strength after standard curing and steam curing was measured. The results are summarized in Table 6. In Table 6,
No.11-1, No.11-2, No.11-3 are No.8-20, No.8-21, No.
Same as 8-22. As shown in Table 6, all the samples using the cement admixture of the present invention had a standard curing of 25 N / mm ^2.
As described above, it has been found that it has a compressive strength of 8 N / mm ² or more in steam curing and is not affected by the degree of calcining of quicklime.

[0055]

[Table 10]

Example 5 [Effect of gypsum] A cement admixture was prepared using gypsum having different forms shown in Table 4. Table 7 shows the composition of this admixture. Using this admixture, a mortar was prepared in the same manner as in Example 1, and its compressive strength after standard curing and steam curing was measured. The results are summarized in Table 7. As shown in Table 7, those using cement admixture of the present invention is 25 N / mm ² or more in a standard curing, has a 8N / mm ² or more compression strength in steam curing, it may not be affected by the type of gypsum I understand.

[0057]

[Table 11]

Example 6 [Preparation of concrete] Using the cement admixture (No. 1-5, No. 8-21) prepared in Example 2, ordinary Portland cement, fine aggregate and coarse aggregate, water, And the concrete which mix | blended the admixture in the ratio shown in Table 8 was prepared. After kneading this concrete,
Poured into a copper mold (diameter 10cm x height 20cm), immediately put into steam curing tank and fed steam, heated to 60 ° C in 1 hour, then stopped sending steam and allowed to cool did. 4 after water injection
After taking out from the steam curing tank at time, the mold was removed from the mold, and immediately thereafter, the pressing strength was measured. After demolding, leave at room temperature for 7 days.
After 14 days, the compressive strength was measured. The result is shown in FIG.
As shown in FIG. Furthermore, after kneading and mixing these concretes, they were poured into a copper mold (diameter 10 cm x height 20 cm) and left in a moist air chamber at 20 ° C without steam curing.
Compressive strength was measured after 1, 7 and 14 days. The results are shown in FIGS. As shown in Figs. 1 and 2 for admixture No. 1-5 and Figs. 3 and 4 for admixture No. 8-21, in each case, the admixture was higher than that without admixture (No. 30). In the case where the material was added, the rise of the initial strength (4 hours) was large, and the compressive strength was improved in proportion to the amount of the admixture. This tendency is the same for the compressive strength after 1 to 14 days.

[0059]

[Table 12]

Example 7 [Production of concrete product] Concrete materials having the composition shown in Table 9 were kneaded with a mixer to produce concrete having a slump of 10 cm and an air volume of 2.5%. This concrete was filled into a box-shaped reinforced concrete product form shown in FIG. 5, and after compaction with a rod-shaped piper, the top surface was immediately covered with a canvas, and steam was fed between the form and the canvas. After the temperature was raised to ° C, the supply of steam was stopped. After 4 hours of water, the canvas was removed and the mold was removed, lifted by a crane using a hook attached in advance, and moved to the yard. No abnormality was found in the concrete product through the removal and transportation. Further, a mold (diameter 10 cm × height 20 cm) was molded using the same concrete as above, and the compressive strength of the test specimen obtained by steam curing the molded article under the same conditions as the above concrete product was measured for 4 hours and 1 day. However, each one
It was 6.5 MPa and 33.9 MPa.

[0061]

[Table 13]

[0062]

According to the cement composition of the present invention, it is possible to obtain sufficient fluidity to secure a sufficient construction time in molding a concrete product or construction of a ready-mixed concrete, and at the same time to obtain a necessary scalpel at an early stage. Can be expressed to accelerate demolding. In particular, in the production of concrete products, it is possible to express the shipping strength early without performing steam curing, and to remove the mold in a short time with a small amount of steam curing. The benefits are great. In particular, since the cement admixture of the present invention has an expansion function, it can be applied to concrete products that require shrinkage compensation or concrete products that are expected to have a chemical prestress effect, such as box culparts and fume tube production. It is extremely useful to

[Brief description of the drawings]

FIG. 1 shows the results of a simple steam curing test of Example 6 (Admixture No.
Graph showing 1-5).

FIG. 2 Results of air curing test of Example 6 (Admixture No. 1-5)
A graph showing.

FIG. 3 shows the results of a simple steam curing test of Example 6 (Admixture No.
A graph showing 8-21).

FIG. 4 shows the results of an air curing test of Example 6 (Admixture No. 8-2).
Graph showing 1).

FIG. 5 is an external perspective view showing a mold of Example 7.

Continuing from the front page (72) Inventor Masaki Takimoto 2-4-2 Daisaku, Sakura-shi, Chiba Pref. Inside the Sakura Research Center of Cement Co., Ltd. (72) Inventor Koichi Soeda 2-4-2 Daisaku, Sakura-shi, Chiba Pref. Pacific Cement Stock 4G012 MA00 MB01 MB23 PA04 PB03 PB06 PB11 PB25 PC03 PD03 PE05

Claims (7)

[Claims] The main mineral composition is 3CaO.SiO ₂ -2.
CaO.SiO ₂ -CaO-interstitial material, 3CaO.SiO ₂
-CaO- gap material, one 2CaO · SiO ₂ -CaO- gap material and CaO- interstitial material or comprises two or more, and CaO crystals containing 50 to 92 wt% clinker composition with ground mixture of gypsum Or an early-strength cement admixture comprising a mixed and pulverized product of the clinker composition and quicklime and gypsum. 2. A cement admixture comprising a mixed and pulverized product of the above clinker composition and gypsum, wherein the clinker composition 10
The early-strength cement admixture according to claim 1, wherein 5 to 50 parts by weight of gypsum is mixed with 0 part by weight. 3. A cement admixture comprising a mixed and pulverized mixture of the clinker composition, quicklime and gypsum, wherein the clinker composition is at least 20 parts by weight based on a total of 100 parts by weight of the clinker composition and quicklime. 2. The early-strength cement admixture according to claim 1, wherein 5 to 50 parts by weight of gypsum is mixed with 100 parts by weight of lime and quick lime in total. 4. An early-strength cement obtained by mixing 3 to 30 parts by weight of the early-strength cement admixture according to claim 1, 2 or 3 with 100 parts by weight of Portland cement or mixed cement. Composition. 5. A kneaded mixture of the early-strength cement composition according to claim 4 and aggregates and water or a mixture of aggregates, water and a concrete admixture (material). Concrete. 6. The method according to claim 5, wherein the concrete according to claim 5 is poured into a mold, cured in the air, cured, demolded, and left in the air or cured in water. Concrete products. 7. The concrete of claim 5 is poured into a formwork and immediately put in a steam curing tank or a steam is cured by feeding steam with a cover provided, and the temperature is reduced to 50 to 85 ° C. in 30 to 1 hour. A concrete product produced by stopping the supply of steam after raising the temperature, removing the concrete after the strength of the concrete reaches the demolding strength, and then leaving it in the air or curing it in water.