JP2000185956A - Dustproof cement composition with improved strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dustproof cement composition hardly causing dust, and capable of providing a concrete and mortar with an improved strength formed out of the composition. SOLUTION: This dustproof cement composition contains 0.01-0.1 pts.wt. polytetrafluoroethylene to be made fibril, and 0.1-5.0 pts.wt. one or more additives selected from the group of a lignosulfonic acid salt, an oxycarboxylic acid salt, a polycarboxylic acid salt, a naphthalenesulfonic acid salt, a melamine resin sulfonic acid salt, and a melamine-condensed product based on 100 pts.wt. cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust-proof cement composition which has been subjected to a dust-proof treatment for preventing powder particles of cement during transportation or storage from scattering into the air.

[0002]

2. Description of the Related Art In order to prevent powder particles of cement during transportation or storage from scattering into the air and causing various adverse effects, conventionally, fibrillating polytetrafluoroethylene (hereinafter referred to as polytetrafluoroethylene) has been used for cement. Dust-proof cements have been developed which have been treated to fibrillate PTFE by adding fluoroethylene (referred to as PTFE) and mixing under compression and shear.

[0003] As a technique for producing such dustproof cement, there is one disclosed in Japanese Patent Publication No. 5-24872. By fibrillating into fibrillable PTFE contained in cement using the technique disclosed in this publication, powder particles of cement are captured by a random network of ultrafine PTFE fibrils in submicron units. Therefore, it is possible to obtain a dust-proof cement composition in which the cement powder particles do not fly into the air.

Further, fibrillating PTFE is mixed with a powdery substance, and the mixture is subjected to compression and shearing at a temperature of 20 ° C. to 200 ° C. to fibrillate the PTFE to generate dust of the powdery substance. A technique for suppressing the above is disclosed in Japanese Patent Publication No. 52-32877.

[0005] However, concrete and mortar formed from dustproof cement manufactured based on the technology disclosed in Japanese Patent Publication No. 5-24872 or Japanese Patent Publication No. 52-32877 have a high dustproof treatment. Assuming that the strength of concrete or mortar formed using cement not to be applied is 100, it is about 85 to 95, and it has been desired to improve the strength.

[0006] The present inventors have pursued the cause of the decrease in the strength of concrete and mortar produced from the dust-proofed cement, and as a result, many bubbles are generated in the concrete and mortar due to the effect of the PTFE dust-proofing agent. , And found to be a cause of lowering the strength.

[Problems to be solved by the invention]

An object of the present invention is to provide a dust-proof cement composition which hardly generates dust and has improved strength of concrete and mortar formed therefrom.

[0008]

That is, the dust-proofing cement composition of the present invention comprises 0.01 to 0.1 parts by weight of a fibrillating polytetrafluoroethylene per 100 parts by weight of cement, lignin sulfonate and oxycarboxylate. , A polycarboxylate, a naphthalene sulfonate, a melamine resin sulfonate, and one to two or more additives selected from the group consisting of a melanin condensate.

Examples of cement include mixed cements such as Portland cement, blast furnace cement, fly ash cement, silica cement, porazon cement, and filler cement, as well as alumina cement, geothermal cement, oil well cement, ultra-hard cement, colloid cement, and expansion cement. Cement such as cement can be used.

[0010] Fibrillable PTFE is disclosed in US Pat.
No. 59750, which is manufactured by emulsion polymerization of tetrafluoroethylene, and has the property of easily fibrillating by applying compression and shearing action. The PTF
E forms include powders and emulsions, both of which are P
It can be used in the composition of the present invention as a TFE dustproofing agent.

The additives used in the present invention include lignin sulfonate, oxycarboxylate, polycarboxylate,
Naphthalene sulfonate, melamine resin sulfonate,
One or more mixtures selected from the group consisting of melanin condensates, many of which are used in admixture with cement as water reducers or fluidizers.

When the amount of PTFE is less than 0.01 part by weight, sufficient dustproof performance cannot be obtained when the amount is less than 0.01 part by weight, and when the amount is more than 0.1 part by weight, excessive aggregate And dispersibility deteriorates. On the other hand, if the content of the additive is less than 0.1 part by weight, sufficient strength improvement cannot be obtained. If the content is more than 5.0 parts by weight, the hydration of the cement is inhibited and the setting time is prolonged. There is.

The dust-proof cement treated with PTFE has a low bulk specific gravity containing a large amount of air as compared with the conventional cement, but concrete and mortar formed from the dust-proof cement also have a low strength including many pores. Becomes
On the other hand, when the above-mentioned additive is added to the cement which has been dust-proofed with PTFE, the additive changes the pores into fine ones, thereby increasing the fluidity of concrete and mortar. The dustproof cement composition of the present invention can form concrete and mortar with a low water cement ratio, and has strength equal to or higher than that of conventional cement.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

In the Portland cement manufacturing process, the clinker that has been calcined is quenched by air, and after adding additives such as gypsum, it is pulverized by a finishing mill, and the particle size is adjusted to obtain cement. Since the cement discharged from the mill has a residual heat of about 100 to 120 ° C., fibrillating PTFE is added to the cement.
The aqueous emulsion is added, mixed and stirred to give compression and shear action to fibrillate the PTFE, dust-proof the cement, and then, when forming concrete or mortar from the dust-proof cement, add the additives. It is advisable to mix to form the dustproof cement composition of the present invention. PT
Preferably, the FE is largely fibrillated.

When preparing the composition of the present invention, PTFE
When the emulsion is diluted with water and used, mixing with the cement is facilitated. When the temperature of the cement is maintained at about 90 ° C. by using a heating device or a heat retaining device, fibrillation of PTFE is facilitated and efficiency is improved. Can well prevent dust from cement. The dustproof cement composition of the present invention can be produced by mixing an additive with the above dustproof cement.

In order to maintain the temperature of the cement at about 90 ° C., a substance (for example, quicklime or lightly burned dolomite) which generates heat of reaction due to the hydration reaction and water are mixed and stirred. A method of increasing the temperature may be employed.

The mixing and agitation operations for compressing and shearing are carried out using a forced kneading mixer, but the suitability of the mixer varies depending on the type of cement, the amount of the fibrillating PTFE aqueous emulsion added, the heating method, the amount of water added, and the like. So
Based on preliminary test results, it is desirable to select an appropriate mixer from among a bread mixer, a twin-screw bag mill mixer, a roller mixer, and the like. This was performed using a mold mixer.

In the case of the roller type mixer, the cement can efficiently receive a combined action such as a compressing action, a shearing action and a rolling action between the roller and the bottom of the kneading tank. It is suitable for the dust-proof treatment of cement to be reduced as much as possible.

[0020]

Example 1 The content of additives to cement was 0.1
%; And the content of PTFE is 0.0; 0.01;
0.03; 0.05; 0.08; 0.10; 0.12;
With respect to the eight types of dust-proofing cement compositions which were changed to 0.15% by weight, the dust-proofing performance, the handling properties and the comprehensive evaluation were performed. Table 1 shows the results. In the same table, the dustproof performance was measured using a digital dust meter and the amount of dust generated was 50 cpm.
Less than ◎, 50 to 150 cpm is represented by 、, more than 150 cpm is represented by ×, and the handling property is very good in handling at the time of transportation or use, ◎, good is represented by 、, conventional level is represented by 、, overall evaluation is very high Excellent is indicated by ◎, excellent is indicated by 、, and the conventional level is indicated by △. The additive used was lignin sulfonic acid as a main component.

[0021]

[Table 1]

As shown in Table 1, the amount of PTFE added was 0.1%.
When the amount is less than 01% by weight, sufficient dustproof performance cannot be obtained, and when the amount is more than 0.1% by weight, cement is excessively agglomerated and dispersibility is deteriorated, so that handling property is deteriorated.

[0023]

Example 2 The content of PTFE was 0.0
3% by weight, and the content of additives is 0.0; 0.1;
Six kinds of dust-proof cement compositions were prepared in which the composition was changed to 0.5; 1.0; 3.0; 5.0% by weight. In addition, what used the polycarboxylate as a main component was used for the additive.

A mortar was kneaded using the six types of dust-proof cement compositions and a cement that had not been dust-proofed (raw cement), and the flow value was measured. In the case of raw cement, the mixing ratio of mortar is 1 for water, aggregate, and cement.
1.1: 66.7: 22.2, and in the case of a dustproof cement composition, the ratio of aggregate to cement is 66.7: 22.2, and the amount of water is blended so as to have the same flow value as the original cement. did. In addition, as a test material, 40 mm × 40 mm × 16
A rectangular parallelepiped of 0 mm was prepared, and the compressive strength was measured. Table 2 shows the composition table, and FIG. 1 shows the test results of the compressive strength.

[0025]

[Table 2]

As shown in FIG.
% Mortar formed from dust-proof cement at all ages has lower compressive strength than mortar formed from raw cement, whereas those with additives increase the amount added As the water-reducing agent is added in an amount of 1.0% by weight or more, the compressive strength becomes equal to or higher than that of the mortar formed from the raw cement. Further, as can be seen from Table 2, the fluidity is improved with an increase in the additive, so that the water-cement ratio decreases.

As described above, the dust-proof cement composition obtained by adding PTFE and a specific additive to cement, mixing and stirring to form a PTFE into fibrillated material is added when mortar or concrete is formed. It has been found that the compressive strength is higher than that of the conventional dustproof cement which is not used, and that the strength is equal to or higher than that of the original cement.

[0028]

The dust-proof cement composition of the present invention has the following effects: (1) it is difficult to generate dust; (2) it has good handling properties; and (3) it has high strength of concrete and mortar.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of a water reducing agent added and the compressive strength.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C04B 24:18) (71) Applicant 590002482 Nihonbudo Co., Ltd. 1-19-1 Kyobashi, Chuo-ku, Tokyo (72) Invention Person Hirofumi Tsutsumi 2468 Nakahara, Kasuya-cho, Kasuya-gun, Fukuoka Prefecture Central Research Laboratory, Aso Cement Co., Ltd. (72) Inventor Teruo Urano 775-3, Ishizuka-cho, Sano City, Tochigi Prefecture 72 -16-11 (72) Inventor Tetsuya Shimoda 1397-3 Hatsuzawa-cho, Hachioji-shi, Tokyo F-term (reference) 4G012 PB14 PB16 PB23 PB25 PB35 4J100 AC26P CA01 EA05 EA06 JA67

Claims (2)

[Claims] 1. A fibrillating polytetrafluoroethylene 0.01 to 0.1 part by weight, a lignin sulfonate, an oxycarboxylate, a polycarboxylate, a naphthalene sulfonate, and a melamine resin per 100 parts by weight of cement. A dustproof cement composition comprising 0.1 to 5.0 parts by weight of one or more additives selected from the group consisting of sulfonates and melanin condensates. 2. The dustproof cement composition according to claim 1, wherein the majority of the fibrillable polytetrafluoroethylene is fibrils.