JP2557074B2 - ALC manufacturing raw material adjustment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to steam-cured lightweight cellular concrete (hereinafter referred to as AL
Abbreviated as C) This relates to the handling of raw materials in the manufacturing process.

[Conventional technology]

ALC is a calcareous raw material powder such as cement and quicklime,
Water and additives are added to siliceous raw material powder such as silica stone and silica sand to make a slurry, and then aluminum powder is added to foam.
It is manufactured by being semi-plasticized, then transferred to an autoclave and subjected to high temperature and high pressure steam curing. Ordinary Portland cement is usually used as the cement.

In general, the siliceous raw material may be wet pulverized, and is often put into the raw material mixer in the form of slurry.
However, regarding calcareous raw materials, Japanese Patent Publication No.
As disclosed in the publication, there is also an example in which quick lime is partially digested and used to obtain an excellent one in terms of physical properties, but this is also not to be mixed in the form of slurry, and usually cement and quick lime are both used. It is common to add it to a raw material mixer as a dry powder. At this time, for example, dry powder raw materials such as quick lime and cement are air-fed from the raw material silo and stored in a holding tank, metered by a metering device such as a load cell, and then charged into a mixer. At this time, the accuracy of measuring the powder is low, the equipment cost of the batcher plant is high, and it takes time to maintain the equipment. In addition, dust collection equipment is also indispensable as a measure against dust. As described above, handling raw materials in a dry state has a serious problem in terms of equipment.

On the other hand, in the production of ALC, the difference in the quality of the raw materials affects the difference in foaming and the curing speed in the manufacturing process, and has many adverse effects such as lowering the physical properties of the product. Not only is the quality of raw materials different every day, but there are variations within the same silo, and mitigating the difference in raw material quality is a major issue in operational management.

[Problems to be solved by the invention]

An object of the present invention is to provide a method for handling and adjusting raw materials in an ALC manufacturing process for solving or alleviating the above problems.

[Means for solving problems]

In order to achieve this object, the present invention is one in which a single or a plurality of raw materials are slurried and all raw materials are metered and mixed in a slurry state in the ALC manufacturing process.

That is, for example, ordinary Portland cement, lime,
Each of the siliceous raw materials is separately slurried and weighed, and then the raw material mixer is simultaneously charged and mixed together with the process repeating slurry. In this way, compared to the case of mixing with a mixer using dry powder raw materials, the stirring can be completed in a short time and the energy required for stirring can be reduced. In addition, the raw material slurry cannot be slurried together with cement and lime because lime promotes the hydration reaction of cement, but it is a slurry combined with any of siliceous raw materials, additive materials such as gypsum, and process repeating slurry. May be turned into.

Generally, the storage conditions of Portland cement slurries affect the half-setting time, so the storage conditions should be selected according to the purpose. Cement is slurried alone or together with silica stone, but when slurried cement, the slurry temperature rises due to the heat of hydration, but if the slurry temperature exceeds 40 ° C, in order to obtain an appropriate semi-hardened state, the slurry It is preferable to keep the storage time within 5 to 6 hours. In order to store it for a longer time than this, set the cement slurry temperature to
It is desirable to keep it at 30 ° C or lower, and if kept at 30 ° C or lower, a proper semi-cured state was obtained even if it was stored for more than 10 hours. However, if stored for more than 20 hours, the mechanical strength of the product after curing in an autoclave will show a slight decrease and should be avoided.

On the other hand, for lime slurry, since the digestibility of quick lime does not matter in the method of the present invention, there is no particular limitation on the slurry temperature and storage time, if it is necessary to manage the storage state of the lime slurry, It is preferable to use the digestibility as an index.

The amount of water added during slurrying is 40 parts by weight or more of water for 100 parts by weight of cement in cement slurry, 500 parts by weight or more of water for 100 parts by weight of quick lime in lime slurry,
In the siliceous raw material slurry, 30 parts by weight or more of water is mixed with 100 parts by weight of the siliceous raw material. Even when a plurality of raw materials are slurried, it is desirable to mix them according to the amount of water. Further, it is preferable that the total amount of water is 50 to 80 parts by weight with respect to 100 parts by weight of total solids. If the amount of water added is less than this, it becomes difficult to mix, and conversely, if it is more than this, the latter half-curing time of casting becomes extremely long.

The stirring time after each slurry is put into the mixer is 2 minutes or more with strong stirring at about 160 rpm when using dry raw materials, while 30 seconds or more with weak stirring at about 60 rpm.

At the time of casting, adjusting the temperature of the mixed slurry to 40 to 65 ° C is effective for shortening the curing time. If the pouring temperature exceeds 65 ° C, the slurry viscosity at the time of pouring will rapidly increase, the air bubbles of the product will be disturbed, and the compressive strength will also decrease.

〔Example〕

 Examples will be described below.

Examples 1 to 3 Ordinary Portland cement was used as the cement, and each of the main raw materials for ALC production was singly or partially mixed and a predetermined amount of water was added and mixed for a predetermined time to form a slurry, and each raw material was prepared. Weighed into a mixer so that it is almost the same as the conventional raw material mixing ratio, and after adding the process repeating slurry and stirring for a predetermined time, adjusting to a predetermined casting temperature, size 6.0 mL × 1.5 mW × 0.6 mH After casting in a mold, ALC was manufactured according to the usual method, and half-curing time and physical properties of the product were measured until it could be cut with a piano wire in the meantime.

The half-curing time is determined by dropping an iron ball with a diameter of 45 mm from the height of 50 mm on the semi-cured product, measuring the diameter of the recess formed on the falling surface, and making it necessary until the diameter becomes 25 mm or less. Went in time.

The compressive strength of the product was measured according to JIS A 5416, paragraph 7, by taking 30 10 cm square samples from random positions in the mold. The compounding conditions and the results are shown in Table 1.

From the results shown in Table 1, the product obtained by the method of the present invention has a compressive strength of 56-59 kg / cm ² , which is prepared by mixing the raw materials in a dry state at the same mixing ratio and adding water and stirring. About 20% compared to the product obtained by compression with a compressive strength of 48 kg / cm ^2.
Has improved.

The standard deviation of the compressive strength in the same mold was about 3.2 kg / cm ² in the conventional method, but 1.0 to 1.
At 2 kg / cm ² , it decreased to about 1/3, showing that the product was homogenized.

The half-curing time of the conventional 240-300 minutes was reduced to about 50-75%.

〔effect〕

The following effects were obtained by slurrying and using most or all of the raw materials conventionally handled in a dry state under predetermined conditions.

As for the raw material handling equipment, the equipment cost of the batcher plant will be low, and no dust collection equipment will be required. Further, the raw material can be easily transported and metered, high metering accuracy can be obtained, and the power consumption of the stirring gas can be reduced.

Since the raw materials are slurried in advance, variations in quality can be mitigated, and the range of selection of raw materials can be expanded. Further, the raw material can be pulverized by a wet method.

In the manufacturing process, the state of dispersion of the raw materials becomes more uniform, and the slurry temperature during casting of the mold can be controlled freely. Further, since the heat generation of the raw material in the mold becomes small, the temperature distribution becomes small and the reaction becomes uniform. Therefore, the cured state at the time of semi-curing becomes homogenous, and the hydrothermal reaction in the autoclave also occurs uniformly, so that the chipping of corners which is a great damage to the product is reduced. Further, since uniform foaming is obtained, pinholes and cavities are less likely to occur, variations in specific gravity of the product are reduced, and mechanical strength is increased, and variations are also reduced.

Claims (1)

(57) [Claims] 1. A method for producing a steam-curing lightweight aerated concrete comprising a calcareous raw material composed of ordinary Portland cement and lime, a siliceous raw material such as silica stone and silica sand, and water as a main raw material, or a plurality of raw materials are respectively slurried. A method for preparing ALC production raw materials, characterized in that all raw materials are metered and mixed in a slurry state.