JP3385884B2 - High fluidity cement composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-fluidity cement composition which is suitable as a concrete production material and a self-leveling material and which has a high fluidity and a high strength development property.

[0002]

2. Description of the Related Art In recent years, along with the increase in the number of layers of concrete structures, along with the rationalization of construction methods and labor saving, excellent strength development has been achieved, and compaction work is not required without increasing the unit water volume, and overcrowded bar arrangement is required. The development of a cement composition having excellent fluidity that extends to the details of a mold having a middle portion and a narrow portion is underway. Further, as a cement-based self-leveling material which is required to have self-fluidity, one having higher fluidity is required.

As the cement used for this purpose, Portland cement is mixed with various admixtures such as blast furnace slag, fly ash, and limestone powder, various high-performance AE water reducing agents, cements to which thickeners are added, and cements whose particle size distribution is adjusted. , A cement obtained by spheroidizing cement particles has been proposed.

However, the addition of the admixture not only complicates the quality control, but also deteriorates the durability after curing, making it difficult to obtain high-strength concrete. In addition, in order to manufacture cement with adjusted particle size distribution and cement with spheroidized cement particles, in addition to ordinary cement manufacturing equipment and processes, special equipment and processes for imparting properties are required. However, there is a problem that productivity is remarkably reduced because separation is required.

As one method of overcoming these difficulties, Japanese Patent Laid-Open No. 6-80456 discloses 3CaO.Al.
The clinker of increased 2CaO · SiO ₂ weight while reducing ₂ O ₃ and _{4CaO · Al 2 O 3 · Fe} 2 O 3 solid solution amount,
A fluid hydraulic composition has been proposed in which gypsum containing 50% by weight or more of insoluble anhydrous gypsum is added, and a dispersant is further added. According to the composition proposed here, the above-mentioned drawbacks, in particular, the problems in production are considerably improved, but in terms of characteristics, for example, the flow value is smaller than 240 mm, it is still insufficient, and especially for a longer time. Improvements were needed for the suppression of flow loss in Japan.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a cement composition exhibiting extremely high fluidity.
Another object of the present invention is to provide a high-fluidity cement composition which is further improved than the above-proposed high-fluidity cement composition, and particularly excellent in flow retention.

[0007]

As a result of examining the relationship between the characteristics of the cement composition and the decrease in the flow, the inventors found that the decrease in the flow was due to the mineral composition in the cement, the amount of hemihydrate gypsum, and the Blaine ratio. It has a close relationship with the surface area and the n value, and the cement composition in which these values are adjusted within a specific range has excellent fluidity even when a small amount of a high-performance AE water reducing agent is added. The present invention has been accomplished by finding that the decrease hardly occurs. That is, the present invention provides 13% by weight or less of 4CaO.Al ₂ O ₃
· Fe include ₂ O _3, 5 wt% or less of 3CaO · Al ₂ O _3, balance is composed of clinker and 3-7% gypsum consisting 3CaO · SiO ₂ and 2CaO · SiO _2, hemihydrate gypsum weight Is 37% by weight or more with respect to the total gypsum and 2.5% by weight or less with respect to the entire cement component, the amount of anhydrous gypsum is 35% by weight or less with respect to the total gypsum, and the Blaine specific surface area is 3000 to 4500 cm ^2. High-fluidity cement composition in which a high-performance AE water reducing agent is further added to the cement component of 1 / g. The present invention will be described below.

[0008] In the present _{invention, 4CaO · Al 2 O 3 ·} Fe 2 O 3 and 3CaO · Al ₂ O ₃ contained in the clinker
The amount of is closely related to liquidity. 4CaO ・ Al ₂ O ₃・
When Fe ₂ O ₃ exceeds 13% by weight, 3CaO · A
When l ₂ O ₃ exceeds 5% by weight, the fluidity decreases and the flow loss also increases, so 4CaO · Al ₂ O ₃ · Fe ₂
O ₃ is 13% by weight or less, preferably 8% by weight or less,
3CaO.Al ₂ O ₃ is 5% by weight or less, preferably 4% by weight or less. Also when the 3CaO · SiO ₂ in the remainder components increases, in other words, the less 2CaO · SiO _2, early strength increases but decreases the fluidity, since flow losses also increased, in order to improve the fluidity 2Ca
O.SiO ₂ is 40% by weight or more in the balance, preferably 5
It is desirable to set it to 0 to 70% by weight. 2CaO / SiO
By increasing the content of ₂ , a cement composition having low heat generation and high fluidity can be obtained.

In the present invention, the total amount of gypsum in the cement composition is 3 to 7% by weight. If the total amount of gypsum is less than 3% by weight, the amount of gypsum will be insufficient and the effect of improving the fluidity will not only be reduced, but there will also be problems such as crushing of cement and contraction after hydration. Results in
Liquidity decreases.

The amount of hemihydrate gypsum is also important. In the present invention, the amount of hemihydrate gypsum is 37% by weight or more based on the total gypsum and 2.5% by weight or less based on the entire cement components. As is clear from the results of Examples described below,
By adjusting the amount of hemihydrate gypsum within this range, the flow immediately after kneading was significantly improved.
It is possible to obtain a cement composition having high fluidity of mm or more, almost no flow loss, and no material separation.

When the amount of hemihydrate gypsum in the gypsum is less than 37% by weight, the hydration reaction of 3CaO.Al ₂ O ₃ is fast, the effect of improving the fluidity cannot be expected, and the flow loss becomes large. Further, if the content of hemihydrate gypsum in the cement component exceeds 2.5% by weight, the flow immediately after kneading becomes remarkably small, resulting in high performance AE.
It is not preferable because the required amount of the water reducing agent increases.

[0012] If anhydrous gypsum is included, the flow is improved, but if the amount is too large, not only the flow immediately after kneading becomes rather small, but also the flow loss becomes large. Therefore, in the present invention, the amount of insoluble anhydrous gypsum contained in gypsum is 35% by weight or less.

In the present invention, gypsum exhibits sufficient fluidity even if it is ground at the same time as the clinker, or if it is added by a method in which gypsum powder is mixed with a previously ground clinker. It is preferable because it shows fluidity.

In the cement composition of the present invention, the Blaine specific surface area of the cement component is 3000 to 4500 cm ^2.
/ G, preferably 3800 to 4200 cm ² / g. The lower the Blaine specific surface area, the better the fluidity, but if the Blaine specific surface area is less than 3000 cm ² / g, the viscosity becomes too low to cause material separation.
If it exceeds 500 cm ² / g, the effect of the water-reducing agent will decrease, the dispersibility of cement particles will deteriorate, and the fluidity will decrease.
The above range is preferable.

In the present invention, the cement component n
The value is preferably 1.05 or less. When the n value is small, the filling rate of the cement is improved and the fluidity is improved.
The n value of the cement can be changed by changing the type of crusher, changing the ball diameter of the ball mill, adding a grinding aid,
It can be adjusted by adding a classification step during pulverization.

The amount of the high performance AE water reducing agent added is 0.05 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the cement component. The high-performance AE water-reducing agent reduces the amount of water as its amount increases, improves the dispersion of cement particles, imparts fluidity, and improves the properties after curing, but if the amount is too small, However, the effect as a water-reducing agent cannot be expected, and if it is too large, it does not contribute to the increase in fluidity, but rather causes material separation and deteriorates the properties after curing.

As the high-performance AE water reducing agent, for example, naphthalene type (naphthalene sulfonic acid formalin condensate etc.), melamine type (melamine sulfonic acid formalin condensate etc.), amino sulfonic acid type ( Aromatic amino sulfonic acid polymer etc.), polycarboxylic acid type (polycarboxylic acid ether etc.)
Can be mentioned.

In addition to water, the high-fluidity cement composition of the present invention is a known additive such as a hardening accelerator, a hardening retarder, a shrinkage-reducing agent, a reinforcing bar rust inhibitor, and a special admixture such as an expanding material. Does not cause any problems

[0019]

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in more detail with reference to specific examples. (1) Kneading of mortar This was carried out as follows using the device and equipment described in the method of mechanical kneading of JIS R5201 10.4.3. 800g cement and sand (Soma sand) 1280 in a mortar
g and mixed at low speed with a Hobart mixer for 30 seconds. The Hobart mixer was stopped, and 240 g of water containing a predetermined amount of a high-performance AE water reducing agent [polycarboxylic acid type: manufactured by NM, trade name Rheobirde SP-8S (B)] was added, and the mixture was kneaded at low speed for 2 minutes. Then, the mixer was stopped, and the mortar adhering to the kneading bowl and the paddle was scraped off with a spoon for 20 seconds, and the mortar on the bottom of the kneading bowl was stirred for 2 to 3 times. Then, the mixture was mixed again at low speed for 2 minutes and 40 seconds. The water cement ratio was 0.
3, the sand cement ratio is 1.6.

(2) Measurement of n-value of cement component The Rosin-Rammler formula is used from the measured value of the particle size distribution measured using a laser diffraction type particle size distribution measuring instrument [trade name: SK laser, manufactured by Seishin Enterprise Co., Ltd.] Calculated. still,
The particle size used for the calculation is 6 to 32 μm.

(3) Flow Measurement Immediately after Kneading Using a flow cone specified in JIS R5201 "Cement physical test method", the flow value at 0 stroke was measured. The flow value is preferably a value of 240 mm or more, and when the flow value is less than 240 mm, the fluidity is poor, so that it is necessary to add a large amount of the high-performance AE water reducing agent, which is difficult in terms of workability.

(4) Measurement of flow (flow loss) after 120 minutes The kneaded mortar was wet-sealed, the flow after 120 minutes was measured, and the flow loss was calculated by the following formula. Flow loss (%) = [{(flow immediately after kneading)-(120
Flow after minute)} / (flow immediately after kneading)] × 100 Flow loss exceeding 20% cannot be said to be preferable because predetermined workability cannot be maintained during construction, and flow loss below 20% is not preferable. It was good.

In the following description, 2 in the clinker is used.
CaO ・ SiO ₂ is C ₂ S, 3CaO ・ Al ₂ O ₃ is C
₃ A, describes _{4CaO · Al 2 O 3 · Fe} 2 O 3 for short C ₄ AF respectively. Most of the balance is 3Ca
Since it is O.SiO ₂ , the detailed description of its constituent components is omitted.

Examples 1 to 4 and Comparative Examples 1 and 2 A clinker consisting of 66% C ₂ S, 3% C ₃ A, 12% C ₄ AF and the balance C ₃ S was added to gypsum dihydrate or hemihydrate. After adding 3.0% of the cement component to gypsum, crush it with a small ball mill, taking care not to dehydrate the gypsum, and the brane specific surface area containing only gypsum dihydrate is 3250 cm.
A cement B having a Blaine specific surface area of 3200 cm ² / g containing only ² g of cement A and gypsum hemihydrate gypsum was obtained. These two types of cements A and B were mixed to prepare cements shown in Examples 1 to 4 and Comparative Examples 1 and 2 of Table 1 which do not contain anhydrous gypsum and have different hemihydrate gypsum contents.
A high performance AE water reducing agent is added to this cement 1.8
A mortar was prepared by adding it in a weight percentage, and the flow immediately after kneading and the flow loss after 120 minutes were measured. The results are shown in Table 1.

[0025]

[Table 1]

In Examples 5 and 6 and Comparative Examples 3 and 4, the dihydrate gypsum content or hemihydrate gypsum content was set to 5.
Blaine specific surface area is 3150 cm ² / g in the same manner as in Examples 1 to 4 and Comparative Examples 1 and 2 except that it is 0% by weight, and the cement C containing only dihydrate gypsum as gypsum and the Blaine specific surface area are Cement D containing only hemihydrate gypsum as gypsum at 3100 cm ² / g was obtained. On the other hand, add anhydrous gypsum, and use only anhydrous gypsum as the cement component of 5.0
A cement E having a Blaine specific surface area of 3150 cm ² / g, which was included in a weight percentage, was prepared. These three types of cements C, D and E were mixed to obtain cements having hemihydrate gypsum content and anhydrous gypsum content shown in Examples 5 and 6 and Comparative Examples 3 and 4 of Table 1, and Examples 1 to 4 and The flow characteristics were evaluated by the same method as in Comparative Examples 1 and 2. The results are shown in Table 1.

Example 7 and Comparative Example 5 The amount of gypsum dihydrate or gypsum hemihydrate was 5.0% by weight of cement.
Cement F having a Blaine specific surface area of 4450 cm ² / g and containing only gypsum dihydrate as gypsum, and Blaine specific surface area of 4400 cm ² / g in the same manner as in Examples 1 to 4 and Comparative Examples 1 and 2 except that Cement G containing only hemihydrate gypsum as gypsum was obtained. These two types of cements F and G were mixed to obtain a cement having the amount of hemihydrate gypsum shown in Example 7 and Comparative Example 5 in Table 1. A high-performance AE water reducing agent was added to the cement in an amount of 2.0% by weight of the cement. % To prepare a mortar, and the flow characteristics were evaluated by the same method as in Examples 1 to 4 and Comparative Examples 1 and 2. The results are shown in Table 1.

Example 8 The clinker was changed to 56% C ₂ S, 3% C ₃ A, 12% C ₄ AF and the balance C ₃ S, and the dihydrate gypsum content or hemihydrate gypsum content was used. 5.0% by weight of cement component
In the same manner as in Examples 1 to 4 except that the cement H having a Blaine specific surface area of 3300 cm ² / g and containing only gypsum dihydrate as gypsum, and a Blaine specific surface area of 3250 cm 2.
Cement I containing only hemihydrate gypsum as gypsum at ² / g was obtained. The two cements H and I were mixed to prepare a cement having a hemihydrate gypsum content as shown in Example 8 of Table 1,
The flow characteristics were evaluated in the same manner as in Examples 1 to 4 and Comparative Examples 1 and 2. The results are shown in Table 1.

Example 9 A plaster having a Blaine specific surface area of 3300 cm ² / g was prepared in the same manner as in Examples 1 to 4 except that the ball was crushed by changing the ball diameter of a ball mill to obtain cement having a large n value. A cement J containing only gypsum dihydrate and a cement K containing only hemihydrate gypsum as gypsum with a Blaine specific surface area of 3200 cm ² / g were obtained. These two types of cements J and K were mixed to prepare a cement having a hemihydrate gypsum content shown in Example 9 of Table 1, and treated in the same manner as in Examples 1 to 4 and Comparative Examples 1 and 2. The flow properties were evaluated. The results are shown in Table 1.

As can be seen from the results shown in Table 1, all the cement compositions prepared by the method of the present invention have a flow value immediately after kneading as high as 240 mm or more and a flow loss after 120 minutes as low as 20% or less. It is excellent. In particular, when the n value of the cement component is less than 1.05, the flow value immediately after kneading is as high as 260 mm or more, and the one excellent in characteristics is obtained. On the other hand, in a cement composition having an amount of gypsum hemihydrate outside the range of the present invention, the flow value immediately after kneading is as low as 200 mm or less, and the flow loss after 120 minutes becomes high in some cases. The results in Table 1 also show that even if anhydrous gypsum is not present, a characteristically high value can be obtained if the amount of hemihydrate gypsum is within the range of the present invention, and the flow immediately after kneading due to the presence of some anhydrous gypsum. Although the value is improved, it is also shown that the flow value immediately after kneading decreases if the amount becomes too large.

[0031]

EFFECTS OF THE INVENTION The cement composition according to the present invention has a remarkable effect that it exhibits extremely high fluidity, has a small flow loss, and is not impaired in fluidity during construction work.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-6-80456 (JP, A) JP-A-6-199549 (JP, A) JP-A-7-144941 (JP, A) JP-A-8- 183636 (JP, A) JP 2-80355 (JP, A) JP 61-251545 (JP, A) JP 64-28254 (JP, A) JP 10-512841 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 28/02-28/16 C04B 22/08-22/16 C04B 7/02-7/06 C04B 7/52

Claims (3)

(57) [Claims] 1. A 13 wt% 4CaO · Al ₂ O ₃ · F
include e ₂ O _3, 5 wt% or less of 3CaO · Al ₂ O _3, balance is composed of clinker and 3-7% gypsum consisting 3CaO · SiO ₂ and 2CaO · SiO _2, hemihydrate gypsum weight 37% by weight or more with respect to the total gypsum and 2.5% by weight or less with respect to the entire cement component, the amount of anhydrous gypsum is 35% by weight or less with respect to the total gypsum, and the Blaine specific surface area is 3000 to 4500 cm ² / A high fluidity cement composition in which a high performance AE water reducing agent is further added to the cement component of g. _{2. The} amount of 2CaO.SiO ₂ in the balance is 4 of the balance.
The high fluidity cement composition according to claim 1, which is 0 to 70% by weight. 3. The high fluidity cement composition according to claim 1, wherein the cement component has an n value of 1.05 or less.