JPS62288145A - Manufacture of low water absorption artificial lightweight aggregate - 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 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing artificial lightweight aggregate with particularly low water absorption, which is used for the purpose of reducing the mass of concrete. .

[Conventional technology]

Conventionally, when producing artificial lightweight aggregates (hereinafter simply referred to as aggregates), the main raw materials are shale, blast furnace slag, fly ash, etc. that have been sieved in advance to a particle size of 100 mesh or less, and valve sludge, etc. The product is made into a product through the processes of mixing, humidity conditioning, granulation, and baking.

Aggregates manufactured by this conventional method have a high pressurized water absorption rate of 30 to 40%, so when Funkrete is pumped as aggregate for concrete after mixing, the high pressure during pumping causes water in the mortar to be absorbed into the aggregate. There was a risk that the fluidity of the concrete would be lost due to rapid absorption into the interior, resulting in blockage of the pumping pipe.

Conventionally, the water absorption rate of the product after firing is only 16-20%, but by adding a watering process to the aggregate, the water absorption rate of the product can be increased to 28-30%, thereby reducing the occurrence of accidents. was. However, if this type of additional curing treatment is applied, the number of mixed concrete pumping accidents will be reduced, but aggregates with high water absorption rates will be transported by trucks, which has a limit on the loading weight when transporting the aggregate itself. In addition to being expensive, the concrete had a large specific gravity when poured, and it took a long time to dry.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing aggregate with a low pressurized water absorption rate, which eliminates the disadvantages of aggregate and prevents clogging accidents during pumping of concrete.

[Means for solving problems]

The present invention adds one or more additives selected from the group consisting of soda ash, boric acid, and borax to shale with an average particle size of 30 μm or less.
It is added in an amount of 0.05 to 1.0% based on the total internal weight, mixed, humidified, granulated, and then fired by a known method.

In this specification, J Engs Ao203-1980, 3012
．． In accordance with the provisions of 3013, the water absorption rate is defined as the percentage of the total amount of water contained in the aggregate in the surface dry saturated state relative to the aggregate mass in the absolute dry state, and the water contained in the voids inside the aggregate grains and the surface water. The mass percentage of the total amount of water to the mass of aggregate in an absolutely dry state is called moisture content.

The details of the invention will be described below.

In the present invention, shale, which is the main raw material, is crushed to reduce the average particle size to 30 μm.
m or less, and add one or more additives selected from the group consisting of soda ash, boric acid, and borax to the total weight of 0.
Add 0.05 to 1.0%.

The main raw material to which additives have been added is made into a product by known means, for example, in the following process. After that, the granules are further pulverized and mixed using a vibrating mill, and the moisture content is adjusted to 15 to 17 wt 1% by sprinkling water, and then granulated using a pan-type pelletizer. The material is dried for 5 to 7 hours to reduce the water absorption to 1% or less, and then transferred to a firing furnace.

The firing is preferably carried out in a rotary kiln in an atmosphere with an oxygen concentration of about 8 to 13% capacity, at a temperature of 1050 to 1200'CW degrees, and for a firing time of about 20 to 30 minutes. The heated and fired granules are sequentially transferred from the outlet to a rotary cooler, where they are cooled to a predetermined temperature to produce aggregate.

In the present invention, the addition of additives is set at 90.05 to 1.0% by weight because if it is less than 0.05% by weight, the pressurized water absorption rate will increase, and if the aggregate is used in an uncured state, concrete This is because the pressure-feeding pipe is likely to become clogged during pressure-feeding, and furthermore, 1.
．． This is because the effect becomes saturated when it exceeds 0 weight and 1%.

[Effect]

According to the present invention, unlike conventional products, soda ash, boric acid, and borax added as additives are used during normal Funkrete pumping for the reason that it seems to be to seal the fine pores that exist on the surface and inner surface of the aggregate during the firing process. 40 times higher than the pressure
Even under severe pressure, the water absorption rate of the aggregate can be suppressed to 25% by weight or less.

〔Example〕

Examples will be described below.

Example 1 Massive shale having the composition shown in Table 1 was roughly crushed using a single toggle crusher, then dried using a rotary kiln dryer, further crushed using an impeller breaker, and finely crushed using a tube mill. A fine powder 3 having an average particle size of 30 μm was obtained as measured by a light transmission granulometer. Next, add 0.0% of soda ash e, which also has an average particle size of 30 μm, to the fine powder and falls within the range of the present invention.
5 to 1.0% by weight was added and pulverized and mixed for 30 minutes using a 0.5 m capacity vibration mill or a 0.4 m capacity concrete mixer. Further, the moisture content was adjusted to 15 to 17% by weight, and then granulated using a pan-shaped pelletizer to have an average particle size of 10%. The granules were dried in a hot air circulation dryer for 6 hours, then charged into a rotary kiln.
1050-1 while maintaining the oxygen concentration at 8-13% by volume.
Firing treatment was performed for 20 minutes at 200 tZ', and the mixture was further cooled to obtain aggregate. In addition, the aggregates shown below as comparative examples were produced in the same manner as in the present invention using a known procedure, except that the types of additives or the amounts added were different. Table 2 shows the specific gravity and pressurized water absorption rate of the finished aggregate. In this case, the specific gravity was measured according to the specific gravity and water absorption rate test method of J-Ko SA 1135 Lightweight coarse aggregate for structural use, and the pressurized water absorption rate was determined by charging 1 kg of aggregate into a 71-capacity ironclad pressure-resistant container. Then, fill the container with water, tighten the top cover with bolts, and add 100 c of water to the bottom of the container.
Pressure 'E' was maintained for 10 minutes while continuously supplying water from a glass cylinder with a volumetric scale using a manual pressure pump.
It was calculated based on the amount of water lost in a graduated glass cylinder when the pressure was kept constant at 40 kg/cm. In this case, the pressure is set at 40° because the pressure when concrete is pumped is usually about 30°, and does not exceed 40° at the maximum. Furthermore, the reason why the holding time was set at 10 minutes is because most of the pumping is completed within 10 minutes each time.

Table 1 (wt%) Table 2 As shown in Table 2, the aggregate of the present invention to which 3 soda ash was added has a significantly lower pressurized water absorption rate than that of Comparative Example &1.2. In Comparative Example A3, in which the amount added exceeds the invention, the effect is saturated.

Example 2 Aggregates having the properties shown in Table 3 were obtained in the same manner as in Example 1, except that boric acid was used instead of soda ash as an additive.

Table 3 As shown in Table 3, the aggregate of the present invention containing boric acid as an additive has a significantly lower pressurized water absorption rate than the comparative 9.10.

Further, in Comparative Example j811, in which the amount added exceeds that of the present invention, the effect is saturated.

Example 3 Aggregates having the properties shown in Table 4 were obtained in the same manner as in Example 1, except that borax was used instead of soda ash as an additive.

Table 4 As shown in Table 4, the aggregate of the present invention containing borax as an additive has a significantly lower pressurized water absorption rate than Comparative Example A17.1B. Moreover, in Comparative Example 19, in which the amount added exceeds that of the present invention, the effect is saturated.

Example 4 Aggregates having the properties shown in Table 5 were obtained in the same manner as in Example 1, except that borax, boric acid, and soda ash were added simultaneously as additives instead of soda ash.

Table 5 As shown in Table 5, the aggregate of the present invention to which borax, boric acid, and soda ash are added in combination has a significantly lower pressurized water absorption rate than that of the comparative example.

〔Effect of the invention〕

The aggregate produced by the conventional method has a pressurized water absorption rate of 30 to 40 weight i1.
%, the water in the mortar is rapidly absorbed into the aggregate when concrete is pumped, and when aggregate is used uncured, there is a risk of blockage of the pumping pipe. It was easy to invite.

When using the aggregate according to the present invention, the pressurized water absorption rate is 25
Not only does it not exceed the Jutan% mark, curing treatment (additional water supply) is not required when transporting aggregates, but also the transport costs are significantly reduced.3
The results showed that even if uncured aggregate 2 was used, the number of pumping pipe blockage accidents during concrete pumping could be drastically reduced. In addition, since the specific gravity of concrete is reduced during pouring, the load on the structure can be reduced, and the structure can be dried more efficiently.

As described above, the present invention provides a method for producing artificial lightweight aggregate with low water absorption that is particularly effective during concrete pumping. This is what we provide.

Claims (1)

[Claims] (1) Add 0.05 to 1.0% of the total weight of one or more additives selected from the group consisting of soda ash, boric acid, and borax to shale with an average particle size of 30 μm or less, and mix. , a method for producing a low water absorption artificial lightweight aggregate, characterized by humidity conditioning, granulation, and then firing.