JPS5820764A - Manufacture of cement product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for manufacturing cement products, and particularly in obtaining 11 products from a cement-based kneaded product. The purpose is to significantly improve the troweling process.

Conventionally, various efforts have been made to improve the workability of cement mixtures used in the production of cement products such as mortar, that is, mixtures consisting of cement, sand and/or fine aggregate, water, etc. It is being done.

For example, attempts have been made to improve the workability of cement-based kneaded materials by adding surfactants such as sodium dodecylbenzenesulfone butyrate and sodium oleic acid. When the application is mortar etc., there are disadvantages such as poor adhesion to the base material and melting of the paint finish. In addition, to improve workability, Asagijo etc. are also added to the mixture.
In this case, there is no effect unless the blending ratio in the light yellow layer is increased, and adding this large amount inevitably increases the water/cement ratio, which has the disadvantage of increasing problems such as shrinkage cracks. Therefore, there are cases where major general construction companies prohibit the use of this pale yellow mixture except for mortar applied to the lath base. On the other hand, cellulose ether, AH agent, etc. are used as water retaining agents and water reducing agents, but these are not necessarily satisfactory in terms of workability.

In general, increasing the water/cement ratio, cement/sand ratio, etc. improves the trowel sliding workability, but not only increases sag but also increases drying shrinkage, causing peeling and cracking.

As described above, placing importance on workability often has a negative impact on mortar properties such as adhesion and cracking properties, and there has been a strong desire to develop a manufacturing method for cement products that solves both of these problems. .

The present inventors have extensively studied additives to solve this technical problem, and found that by incorporating a small amount of functional bentonite particles into a cement-based mixed material, the workability of the material itself can be improved.
It was confirmed that the workability of troweling, etc.) was significantly improved without the disadvantages mentioned above, and that water retention and adhesion were further improved by adding a small amount of water-soluble cellulose ether together with bentonite. , completed the invention.

To explain this, bentonite has chemical properties similar to kaolin clay and white clay, but its physical properties are completely different.The powder is extremely fine and has a large surface area, and it has a high affinity for water and can absorb a lot of water. It exhibits the property of swelling. Furthermore, bentonite dispersions exhibit thixotropy and structural viscosity.

Bentonite has these properties, so adding it to mortar prevents material separation, reduces force at high shear speeds during troweling work, and improves trowel slippage and surface finish. It is possible to prevent sagging. Also, since it is effective when added in small amounts, the water/cement ratio does not increase and shrinkage cracks are less likely to occur.

Furthermore, by adding water-soluble cellulose ether together with bentonite, appropriate air mobility and viscosity are imparted, and it is possible to reduce mortar elongation and troweling force during troweling work.

In addition, since it has water-retaining properties, it prevents dryout, cracks, and peeling, making it possible to manufacture cement products with good adhesion.

The bentonite used in the present invention is a naturally occurring aluminum silicate whose main component is clay mineral, montmorillonite, and is generally produced through mining, over-mineralization, coarse crushing, drying, crushing, separation, and refining processes. This is what is being done.

As a result of examining the workability of bentonite with different particle sizes and degrees of swelling, we found that the more coarse particles there are, the smaller the effect of addition, and that in order to improve workability, a large amount of bentonite should be added. As a result, the water/cement ratio increases, causing negative effects such as shrinkage, cracking, and peeling.Also, even if the particle size is fine, if the degree of swelling is small, the addition effect is small, and similar It was confirmed that the results were obtained. As a result of detailed comparative studies based on these facts, we found that bentonite has a particle size of 50% or more in terms of passing through a 200 mesh sieve, and a degree of swelling of 3? /il” 24 hours or longer was found to be particularly desirable.

As mentioned above, it is desirable to adjust the amount of bentonite added to cement depending on the particle size of bentonite, degree of swelling, and required performance.
5 parts by weight) is appropriate.

Bentonite can be added by dispersing it in water in advance, or by adding mixing water with cement, sand, silica sand, etc. and kneading it.

Incidentally, the cement/sand ratio is not particularly limited, and may be within a commonly used range, and is generally set to be a sand/cement ratio of -1 to -3. In addition, the water/cement ratio depends on the sand/cement ratio, sand particle size, and the presence or absence of additives, but in general, the water/cement ratio should be increased by 1Ol% or less compared to when bentonite is not used. There is.

On the other hand, in the present invention, when appropriate mortar elongation, water retention, and adhesion are required, water-soluble cellulose ether is added together with the bentonite. As this cellulose ether, hydroxyethyl methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylethylcellulose, etc. are used. The amount of these cellulose ethers added is 0 and O per 100 parts by weight of cement.
It is desirable to add 1 to 0.5 parts by weight. When the substrate is dry or the temperature is high, it is desirable to add C2 multiple times.

In carrying out the present invention, there is no problem in incorporating various other additives into the cement-based kneaded product. , fiber materials, etc. It is also one of the features of the present invention that even if such various additives are used, the above-mentioned effects of the present invention are not hindered.

Next, specific examples will be given.

Example 1 Slump value 3.5±0.5 rs for two lath base C
t-th 1111I = Various mortar Y5-61 included
Ill thickness C was applied using a two-metal trowel. Temperature is 30-35℃
, warm temperature was 55-60% RH.

For each mortar, workability, water retention, and crack occurrence TM were ranked first! The results were as shown in 1.

Workability - Workability (trowel slippage, elongation): Excellent, Good, Fair
Judged in stages.

Water retention: Judged by the texture of water.

○: Excellent water retention.

×: Poor water retention.

Crack occurrence: The occurrence of cracks was visually judged in the following three stages.

A: No cracks were generated.

B: Slight occurrence of cracks.

0: Occurrence of cracks.

Type of bentonite used (particle size) Bentonite I: 300 mesh 2% or less, swelling It 5.59/924 hours Bentonite I: 300 mesh 2% or less, swelling degree 4.511/, 924 hours Bentonite I: aOO mesh 2% or less , Swelling degree 2.5.9/JJ 24 hours Bentonite ■: 200 mesh 20% or less, swelling degree 4.5 g/, 5124 hours Bentonite V: 200 mesh 50% or more, swelling degree 4.1/L used for 124 hours Type of cellulose ether HPMO hydroxypropyl methylcellulose (608
H-400) HEMO Hydroxyethyl Ethyl Cellulose (MH-4
000) Actual tub example 2 Slump value 4.5 against rough mortar base
±o, 5cxtl# Mortarun 8 of each building distributed to the target
Thickness I of ~10jLl: Coated with a metal trowel. The temperature is 30
The temperature and humidity were 55-60% R, and the base was pre-sprayed with water.

Each mortar was examined for workability, adhesion, surface finish (smoothness), water retention, crack occurrence after 28 days of curing, and counterfeit strength, and the results were as shown in s#ll2Hs=.

Surface finish (smooth 4:1) condition: Measured in the following four stages.

A: Excellent smoothness.

B: Excellent smoothness.

0: Poor smoothness.

D: Very poor smoothness.

Abbreviations in tables

Claims (1)

[Claims] 1 Bentonite is 0.2 to 100 parts by weight of cement.
A method for manufacturing a cement product, characterized by molding a cement-based kneaded product containing 101 parts by weight. 2i. Bentonite passes through 200 mesh sieves 4!
50% or more and has a degree of swelling of 3if/124 hours or more.Cement 100tli
per part lii, (a) 02 to 10 parts of bentonite, and (b) 00 to 0 of water-soluble cellulose ether.
．． 5. A method for producing a cement product, which comprises molding a cement-based kneaded material containing 5 parts by weight.