JP4677261B2 - Method for producing hardened cement - Google Patents

Description

  The present invention relates to a method for producing a hardened cement body that can rapidly harden due to a hydration reaction of cement and produce a hardened cement body even when a substance that inhibits or delays the hardening of the cement is mixed. .

  Generally, when manufacturing hardened cement mainly composed of cement, aggregates, and wood reinforcing materials such as pulp, wood chips, and wood wool, some of these ingredients in wood reinforcing materials inhibit the hardening of cement. In addition, since a hardening inhibiting component that causes a delay is included, the strength of the cement cured body using the same may be reduced.

  Various substances are known as substances that inhibit curing. Examples thereof include inorganic substances such as fluoride, phosphate, and borate, and organic substances such as oxycarboxylic acids, ketocarboxylic acids, sugar alcohols, and sugars. It is done.

  Therefore, in order to suppress such hardening inhibition of cement, conventionally, a wood reinforcing material is treated with acid or alkali, etc., and the hardening inhibiting components of cement are eluted and washed. Or a method of adding a curing accelerator, a method of adding an adsorbent such as calcium silicate hydrate, or the like has been implemented or proposed.

  The method for elution and washing of the cement hardening inhibiting component is described in, for example, the prior art of Patent Document 1 below, but this method sufficiently suppresses cement hardening inhibition even if such treatment is applied. However, there is a problem that a large amount of drainage is generated during processing.

Japanese Patent Publication No. 7-102984

  In addition, as a method of coating with fast-curing cement or the like, there is a method as described in Patent Document 2 below, but first there is a step of coating a wood reinforcing material, and then the process proceeds to a main kneading step. Since the procedure is complicated, the work becomes complicated, and the fast-curing materials are difficult to control the working time, which makes it difficult to manage the process.

JP-A-6-87737

  Furthermore, in the method of adding a curing accelerator, chloride, sulfate, nitrate, nitrite, formate, acetate, and the like are used as the curing accelerator. For example, Patent Document 1 discloses that calcium chloride or the like is used as a hardening accelerator instead of the above-described cleaning method.

  These are intended to suppress the hardening inhibition by completing the hardening of the cement before the hardening inhibiting component elutes from the wood reinforcing material. Then, it may not be cured within a desired time. Also, depending on the manufacturing process, there is a risk that the hardening accelerator is concentrated in the recycle liquid, etc., and it becomes difficult to control the pot life, and there is a risk of rusting when, for example, chloride is used. It is not necessarily an effective measure.

  Furthermore, a technique of using calcium silicate hydrate having a large specific surface area value as an adsorbent for a curing inhibitor is the most useful method for removing a curing inhibitor that causes a problem due to an adsorption action. However, due to the properties of calcium silicate hydrate, it has a porous structure and is bulky, and moisture is absorbed into the interior simultaneously with the curing inhibitor, so that handling such as kneading and molding has been a problem depending on the amount added. For this reason, if the water content of the kneaded material is increased, the cured body itself becomes rough, causing a problem of strength reduction.

  The present invention can solve such problems. The method using the conventional cleaning means, the method using the means for coating the wood reinforcement, the method using the hardening accelerator, and the calcium silicate hydrate It is an object of the present invention to provide a method for producing cement hardening that can be easily performed for suppressing the inhibition of hardening without various problems such as a method of using as an adsorbent.

The present invention has been made to solve such problems, and the invention according to claim 1 is a substance containing a curing inhibitor component containing a curing inhibitor component that inhibits hardening of cement (excluding the admixture for concrete). ) Is used as a raw material together with cement, in which a part or all of the cement is previously pulverized with a wet pulverizer and hydrated to form calcium silicate hydrate on the cement surface. A slurry is manufactured, and then the curing inhibiting component-containing substance is added to the finely divided and hydrated cement slurry, and a curing inhibiting component eluted from the curing inhibiting component-containing substance is formed on the cement surface. It is characterized by producing a hardened cement body while suppressing the inhibition of cement hardening by adsorbing on the surface of the calcium silicate hydrate .

The invention according to claim 2, Te manufacturing method odor cement body according to claim 1 wherein the hardness-inhibiting component-containing material, characterized pulp, wood chips, that is wood reinforcement wood wool or the like.

  In the present invention, as described above, a part or all of cement is pulverized and hydrated with a wet pulverizer to produce a slurry, and then the pulverized and hydrated cement slurry inhibits cement hardening. A cured cemented body while suppressing curing inhibition of cement by adding a curing inhibiting component-containing substance containing a curing inhibiting component and adsorbing the curing inhibiting component eluted from the curing inhibiting component-containing substance to the surface of the slurry Therefore, a part of or the whole of the cement as described above is preliminarily pulverized with a wet pulverizer, and the conventional method using a cleaning means is coated with a wood reinforcing material. Without causing various problems such as a method using a means, a method using a hardening accelerator, and a method using calcium silicate hydrate as an adsorbent. There is an effect that it is possible to suppress the inhibition.

  In particular, the finely divided slurry obtained by wet grinding the cement is finer than the raw material cement, so the surface area is large, and the surface of the finely divided slurry comes into contact with water to hydrate calcium silicate. The generation of substances is promoted to form a film of the calcium silicate hydrate, whereby there is an effect that the curing-inhibiting component-containing substance can be suitably adsorbed.

  The embodiment of the hardened cement body of the present invention will be described more specifically. First, a part or all of the cement as a raw material of the hardened cement body is pulverized with a wet pulverizer until a predetermined particle size is obtained. “Part of cement” means that a part of the prepared cement is wet-ground and then a curing-inhibiting component-containing substance is added as described below, and the remainder is added without setting the curing-inhibiting ingredient-containing substance. Means that. Further, “all the cement” means that all of the prepared cement is wet-pulverized and then the curing-inhibiting component-containing substance is added.

  The particle size of the cement having a predetermined particle size is not particularly limited, but is preferably 1 to 10 μm. If the thickness exceeds 10 μm, the action of forming a calcium silicate hydrate film due to the contact of the surface of the micronized slurry with water is slightly less likely to occur, and the effect of adsorbing the curing-inhibiting component-containing substance is slightly reduced. is there. On the other hand, it is uneconomical to pulverize until it becomes less than 1 μm.

  A general wet pulverizer can be used as the pulverizer. For example, a tower mill, a medium stirring mill, an attritor, a ball mill, or the like can be used.

Further, the water / cement ratio in the wet pulverization step may be within a range where the wet pulverization can be efficiently performed, and is preferably within a range of 0.3 to 1.5. If it is less than 0.3, the viscosity increases, so efficient pulverization is difficult, and if it exceeds 1.5, the solid content concentration becomes dilute, resulting in poor pulverization efficiency and economical disadvantage. is there.
The water / cement ratio in the wet pulverization step is as described above, but the amount of water used in the production of the hardened cement body may be less than that in wet pulverization. In such a case, water may be separated by a stationary sedimentation method or the like after wet pulverization.

  Moreover, it is also possible to promote hydration by using warm water in this wet pulverization step, or by heating and keeping warm.

  Furthermore, in this wet pulverization step, the slurry state can be maintained while stirring so as not to consolidate until the cement slurry has a predetermined amount of hydrate.

  Next, a curing inhibitor component-containing substance is added to the finely pulverized and hydrated cement slurry obtained by wet pulverization as described above. Here, the hardening-inhibiting component-containing substance is, for example, a wood reinforcing material such as pulp, wood chips, and wood wool. For example, in the case of pulp, newsprint can be crushed and used.

The fine particle slurry obtained by wet pulverizing cement is finer than the raw material cement, and therefore has a large surface area, and its surface is formed by calcium silicate hydrate formed by contact with water. Yes. Such calcium silicate hydrate has a porous structure, and adsorbs various organic compounds, which are hardening-inhibiting components, contained in the wood reinforcing material on the surface and pores of the calcium silicate hydrate. It is.

  According to such a method for producing a hardened cement body, since a thin film of calcium silicate hydrate is formed on the surface of the cement as compared with a method of adding an adsorbent such as calcium silicate hydrate particles, it is hardened. The contact area with the inhibitor becomes more efficient, and even when compared with the case where the same amount of calcium silicate hydrate is added, the ability to adsorb and remove the cure inhibitor is excellent. Therefore, the total amount of calcium silicate hydrate can be reduced, and the handling can be prevented from being lowered due to moisture absorption.

  The film thickness of the calcium silicate hydrate becomes thicker as the slurry retention time in water is longer and the pulverization temperature is higher, and the total amount of hydrate is higher as the degree of pulverization is higher and the retention time in water is longer. The higher the number, the more.

  In addition, the unhydrated component remaining inside can be expected to have the same curing performance as cement normally used as a hardener, but the contact area with water is larger than that of cement before the micronization treatment. Further, the hydration reaction can be expected to be promoted, and the advantage that an inexpensive cement with lower activity can be used is also provided.

  Therefore, by controlling factors such as the above grinding energy, grinding temperature, water retention time, etc., a finely divided cement slurry can be produced and blended with any degree of fineness, hydrate film, and amount of hydrate adjusted. By substituting a part or all of the cement, it is possible to produce a hardened cement body having the same physical properties as a conventional hardened cement body without adding an adsorbent or an accelerator.

   In addition, the kind of cement used for a cement hardened body does not ask | require, What is necessary is just to use the cement generally used. It is also possible to mix blast furnace slag fine powder or fly ash.

  Examples of the present invention will be described below.

Example 1
First, a pulverizing pot of a vibration mill (Chuo Kako Co., Ltd., MB-0 type) was filled with high chromium spheres having a diameter of 2 mm as a medium in a bulk volume of 80%, and the pot and medium were heated to 80 ° C. with a dryer. 1000 g of early strong Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.) and 700 g of hot water at 80 ° C. were added to the pot, sealed and pulverized for 2 minutes. After grinding, the medium was removed with a sieve to obtain a cement slurry.

The water content of the cement slurry and the amount of crystallization water in the solid content were measured by the following method.
(1) Measurement of moisture content As a result of measuring about 2 g of the slurry with an infrared moisture meter (ML-50, manufactured by A & D), the moisture content was 38.8%.

(2) Measurement of the amount of water of crystallization After adding 50 g of acetone to about 20 g of the above slurry and stirring, the process of suction filtration using 5C filter paper was repeated 3 times to remove the adhering water, and then with a vacuum drier 48 After drying for a period of time, about 2 g of the dried product was precisely weighed in a magnetic crucible, and the loss on ignition at 1000 ° C. was measured with an electric furnace. The loss on ignition was 3.8%.

  Next, blast furnace slag, fly ash, pulp as a wood reinforcing material, and kneaded water were added to the cement slurry obtained as described above to produce a cured cement. The blending ratio is as follows.

Cement slurry: 340.0 g (unreacted cement content: 200 g,
Moisture: 131.9 g,
Reactant amount: 8.1 g)
Blast furnace slag (Nagoya Esmento Co., Ltd.): 292.0g
Fly ash (Techno Chubu Co., Ltd.): 145.0g
Pulp (newspaper crushed material): 19.8 g
Kneaded water (tap water): 280.6g

  The process will be specifically described. First, the cement slurry, pulp and kneaded water obtained as described above were put into a pulverizer and defibrated for 4 minutes. Next, the defibrated pulp was put into a plastic container, slag and fly ash were added, and kneaded for 2 minutes with a hand mixer. Next, this kneaded material was formed into a simple mold having a diameter of 50 × 100 mm and steam-cured at 85 ° C. for 5 hours. Then, it stood to cool for 1 hour and the cement hardening body was obtained.

(Comparative example)
The following cement composition was prepared as a comparative example.
Normal Portland cement (Sumitomo Osaka Cement Co., Ltd.): 195g
Slag (Nagoya Esment): 292g
Fly ash (Techno Chubu Co., Ltd.): 145.0g
Pulp (newspaper crushed material): 19.8 g
Kneaded water (tap water): 412.5 g

  A hardened cement body was produced from the cement composition having such a composition in the same manner as in Example 1.

(Test Example 1)
The compressive strength of the cured cement thus obtained was measured. The results are shown in Table 1.

  As apparent from Table 1, the compressive strength of the hardened cement body of Example 1 was much higher than the compressive strength of the hardened cement body of the comparative example.

(Test Example 2)
From the compositions of Example 1 and Comparative Example above, the viscosity of the slurry kneaded with the pulp removed was measured with a rotating cylindrical viscometer (using a Viscotester VT-03F1 rotor manufactured by Rion). The results are shown in Table 2.

  As is clear from Table 2, the viscosity of the composition of Example 1 (excluding pulp) was substantially equivalent to the viscosity of the composition of Comparative Example (excluding pulp).

Claims (2)

In a method for producing a hardened cement body using a hardening-inhibiting component-containing substance (excluding a concrete admixture) containing a hardening-inhibiting component that inhibits hardening of cement as a raw material, a part or all of the cement is wet-ground in advance A slurry in which calcium silicate hydrate is formed on the surface of the cement is manufactured by pulverizing and hydrating with a machine, and then the curing inhibitor component-containing substance is added to the micronized and hydrated cement slurry. A hardened cement body is produced while inhibiting the hardening of the cement by adding and adsorbing the hardening inhibiting component eluted from the substance containing the hardening inhibiting component to the calcium silicate hydrate formed on the surface of the cement. A method for producing a hardened cement body. Method for producing a curing inhibition component-containing material, pulp, wood chips, cement hardened body of claim 1 wherein the wood reinforcement wood wool or the like.