JPH09142910A - Cement composition and method for controlling hardening time of cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain such a cement compsn. that the hardening time of the cement can be easily controlled and a cement mortar having good fluidity and mortar strength can be prepared. SOLUTION: The feature of this cement compsn. is that a water-soluble cellulose ether having an effect to delay hardening of a cement and xylose having an effect to promote hardening of a cement are compounded in a cement. The hardening time of a cement is controlled by changing the mixing ratio of a water-soluble cellulose ether which has an effect to delay hardening of a cement and xylose having an effect to promote hardening of a cement in the cement compsn.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a building mortar,
The present invention relates to a cement composition used for concrete and these secondary products, and a method for adjusting the setting time of cement.

[0002]

2. Description of the Related Art Cement is a material that has a strength that does not lose its shape even if water is added again, by setting and hardening when cement is added after mixing a necessary amount of water and then left to stand. Therefore, it is exclusively used as a main material for cement mortar and concrete.

Regarding the setting and hardening time, JIS (Japanese Industrial Standard) R5201 (Portland cement),
In R5211 (blast furnace cement), R5212 (silica cement), and R5213 (fly ash cement), the initial setting time is 45-60 minutes or more and the closing time is 10 hours or less. Is often changed by the time of cement production.

Therefore, in the preparation of cement mortar or concrete to be actually used for construction, when it is necessary to adjust the setting time within a certain range, a setting accelerator or a retarder is used as an admixture. It is being used.

Saccharose, dextrin lignin sulfonate, oxycarboxylate, aminocarboxylate and the like are known as setting retarders, and as a promoter, chlorine compounds such as calcium chloride, nitrite and thiol are known as accelerators. Inorganic salts such as sulfates and thiocyanates, amines such as triethanolamine, Ca salts of organic acids such as formic acid, acetic acid and acrylic acid are known.

[0006]

However, such a curing retarder or accelerator may change the fluidity of the mortar or concrete prepared by the addition, or the fluidity of the mortar or concrete may change drastically during construction. May cause inconvenience.

Further, depending on the kind of the admixture, it is necessary to add several% or more to the cement in order to adjust the setting time, which may be a cost disadvantage.

The present inventors have conducted extensive studies in view of such problems, and as a result, a cement characterized in that a water-soluble cellulose ether having a cement retarding action and xylose having a cement promoting action are blended in the cement. The present inventors have completed the present invention by finding new findings that the composition can adjust the setting time of cement.

[0009]

That is, the present invention provides a cement composition characterized in that a water-soluble cellulose ether having a cement retarding action and xylose having a cement promoting action are blended in the cement. It is provided.

Further, the present invention is characterized in that a water-soluble cellulose ether having a cement retarding action and xylose having a cement promoting action are blended in a cement composition in various mixing ratios to cure the cement. It provides a method of adjusting the time.

The present invention will be described in detail below. The water-soluble cellulose ether having a cement retarding effect used in the present invention includes, for example, water-soluble alkyl cellulose and hydroxy such as methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. Alkyl alkyl celluloses are mentioned.

These water-soluble cellulose ethers are used by being mixed with cement and dissolved by adding water, and have the effect of adsorbing to the cement particles to delay the hardening time of the cement and reducing the friction between the cement particles. , Has the effect of improving the fluidity of the prepared cement mortar and concrete and making it stable.

The above water-soluble cellulose ethers are obtained by impregnating caustic soda alkali into a pulp using industrially refined pulp as a cellulose raw material, and then adding alkyl halides such as methyl chloride and alkylene oxides such as propylene oxide to cellulose. It is manufactured by subjecting the product to an ether substitution reaction and purifying and pulverizing.

On the other hand, xylose used in the present invention, which has a hardening promoting effect on cement, is a kind of saccharide and is a pentasaccharide which is academically α-D-(+)-xylose. It is produced by the decomposition of hemicellulose contained in many plants.

As a specific example of the production method, the remaining cottonseed shell (called “Halbran”) obtained by removing the fibrous linter portion from cottonseed is decomposed with an acid to obtain a sugar solution, and the sugar solution is There is known a method in which white xylose needle crystals are obtained by washing, deliquoring, desalting, removing impurities as much as possible, and then cooling.

It is generally known that sugars such as xylose delay the hardening time of cement when added to cement. For example, in sugar such as sucrose, only about 0.1% of the cement is added. The setting and hardening time of cement may be delayed by about 300 to 400 minutes.

Surprisingly, the inventors of the present invention studied xylose, and when xylose was added to the cement in an amount of 0.1 to 0.2% and water was mixed to form a paste, the cement was formed in a very short time. Was set and hardened, and it was found to be useful as a setting accelerator for cement.

The above-mentioned water-soluble cellulose ethers have the function of maintaining the necessary fluidity and water retention and stabilizing their performance when added to cement and used as mortar or concrete. The larger the amount, the longer the setting and hardening time of cement.

On the other hand, xylose has a coagulation-accelerating action, and when it is added together with this cellulose ether, the hardening time of the cement can be adjusted without inhibiting the fluidity of the cellulose ether and the stabilizing effect of imparting water retention.

In the cement composition and the method for adjusting the setting time of the cement of the present invention, the blending amounts of the water-soluble cellulose ether and xylose are not particularly limited, but it is meaningless to add more than necessary in terms of cost, When it is desired to accelerate the setting hardening time in the range of 10 hours to 0 hours with respect to the setting hardening time of cement at room temperature (10 to 30 ° C.), cellulose ether 0.01 to 1.0% by weight / xylose 0. It is preferable to add it to the cement in the range of 05 to 2.0% by weight, and conversely, if it is desired to delay the setting time in the range of 0 to 10 hours, 0.1 to 2.0% by weight of cellulose ether. % / Xylose
It is preferable to add 0.01 to 0.05% by weight to cement.

In addition, in the present invention, if the fluidity of the mortar prepared by addition is not changed, in addition to the water-soluble cellulose ether and xylose which are the essential components of the present invention, other setting retarders and accelerators are used. There is no problem even if an agent is added.

The present invention delays the hardening of the material in the extrusion molding device when mixing the aggregate and the reinforcing fiber with cement and manufacturing a molded product having a constant cross section by a vacuum extrusion molding device, or It can also be applied for the purpose of accelerating the curing time.

[0023]

EXAMPLES Hereinafter, specific examples of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Cement mortar was prepared by using the cement mortar composition having the composition shown in "Table 1" according to the method specified in JIS R-5201 (physical test method for cement), and evaluated by the following method. The results are also shown in "Table 1".

[Evaluation Method] "Table flow" was measured according to JIS R-5201. The table flow value is preferably around 160 cm in view of fluidity, and it is preferable that the addition of the admixture does not change with time. "Table 1" shows how much the table flow changed 30 minutes after the preparation of the mortar by the amount of change in the flow value.

"Condensation acceleration delay time" JIS R-520
An intermediate time measurement between the setting onset time and the setting time was measured according to 1. The difference between the measured value and the value of the mortar to which the admixture was not added was represented by-when the setting and curing time was short, and by + when it was long.

"Mortar Strength" The bending strength measured after the mortar prepared according to JIS R-5201 was cured at room temperature in a 28-day mold is shown.

[0028]

[Table 1] 1) Nippon Cement Co., Ltd. ordinary portland cement 2) Mikawa Silica No. 6 3) Shin-Etsu Chemical Co., Ltd. hydroxypropylmethylcellulose 90SH-4000 4) Okamura Oil Co., Ltd. 5) Wako Pure Chemicals Reagent 1st grade 6) Fujisawa Pharmaceutical Co., Ltd. Palic T manufactured by Co., Ltd.

From "Table 1", the cement composition of the present invention containing water-soluble cellulose ether and xylose is
It can be seen that the setting time of the cement can be easily adjusted by changing the mixing ratio, and the cement mortar having good fluidity and mortar strength can be adjusted.

[0030]

According to the present invention, by setting water-soluble cellulose ether and xylose in the cement by changing the mixing ratio, the setting time of the cement can be easily adjusted, and the cement having good fluidity and mortar strength can be easily obtained. Can be manufactured.

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Claims (2)

[Claims] 1. A cement composition comprising a cement and a water-soluble cellulose ether having a cement retarding action and xylose having a cement promoting action. 2. A setting time of a cement is prepared by adding a water-soluble cellulose ether having a hardening retarding effect to the cement and xylose having a hardening promoting effect to the cement composition at different mixing ratios. Method.