JPH03231805A - Water content adjusting method for dry consistency concrete - Google Patents

Abstract

PURPOSE:To feed dry consistency concrete of stabilized water content all the time and upgrade the guality of a product by replenishing short supply of water correspond ing to the zero value set by measuring hydrated aggregate by means of a water content measuring instrument, forming a water film composed only of a moisture content on the surface of aggregate and kneading with the given amount of cement. CONSTITUTION:The overall aggregate surfaces are wetted by jetting water or vapor out of a nozzle 5 onto aggregate layers of respective conveyors 1 set up inclinedly for feeding the given quantities of aggregates from a stockyard hopper to a meter 11 successively and excessive water is discharged for primary hydration, and then air is sprayed from nozzles 10 while the water is fed down to the meter by starting the conveyors for secondary hydration of water content out of the aggregate surface and said aggregate are metered by the meter. Said metered aggregate surface form only the hydrated moisutre surfaces and the aggregates can be kneaded by a mixer under the good condition, and measurement by the water content measuring instrument is carried out correctly, securely and quickly. Then, the short supply of water content is replenished to control the water content of zero slump dry consistency concrete.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is capable of controlling the moisture content of zero-slump hard-mixed concrete used for forming concrete products by uniformly spreading the surface of all aggregates to be mixed by instant demolding. This invention relates to a moisture adjustment method for obtaining zero slump hard-mixed concrete with stable moisture content, by dehydrating the aggregate, accurately and quickly measuring the moisture content, and supplying water to compensate for insufficient water, forming a water film of only moisture on the surface of the aggregate.

[Conventional technology]

Conventionally, products molded using zero-slump hard-mixed concrete, which is formed by instant demolding, had a large amount of variation, resulting in products with reduced product value such as defective products or second-grade products. . This moisture error has many drawbacks, such as having an adverse effect on the molding machine, causing it to malfunction and reducing manufacturing capacity.

[Problem to be solved by the invention]

A fundamental review of the shortcomings revealed that there was a problem with errors in moisture change during cross-contact in zero-slump hard-mixed concrete, which affected everything from forming to products and production. Even though it is called zero slump hard-mixed concrete, errors in moisture change due to concrete with a moisture content close to zero or concrete with a harder moisture content are the predisposing factors for the occurrence of the above-mentioned drawbacks.

If we dig deeper and review this predisposition, we can see that the gravel used,
Weigh dry aggregates such as sand, wet aggregates, aggregates with irregular temperatures, and aggregates in their original state regardless of their particle size, feed them to a mixer, and add cement. The moisture content of hard mixed concrete obtained by supplying insufficient water during stirring using an automatic electric or mechanical moisture meter is as follows:
As mentioned above, since the aggregate has variations in dryness, humidity, temperature, particle size, etc., it is impossible to accurately measure the moisture content because the aggregate remains in one pile in the storage area.Therefore, the water supply for insufficient water is also unstable. This will provide a good water supply.

This moisture error in zero-slump hard-mixed concrete has had a major drawback, not only affecting immediately demolded concrete products but also the production process. It is clear from this that moisture in zero slump hard-mixed concrete is a difficult problem, and it is no exaggeration to say that the predisposing factor lies in the aggregate.

[Means for Solving the Problems] The present invention provides for conveying a predetermined amount of gravel and sand (hereinafter referred to as aggregate) from a stockyard hopper to a measuring device on an inclined conveyor. Water or steam is injected into the layer to wet all the aggregate surfaces, excess water is drained to perform primary dewatering, and then air is blown during the fall when the conveyor is started to feed the meter to further aggregate the aggregate. Since moisture is removed from the surface secondarily and this aggregate is weighed with a scale, the surface of the weighed aggregate forms only a completely dehydrated moisture surface.
This hard-mixed concrete is made by mixing with a mixer under favorable conditions, measuring accurately and quickly with a moisture measuring device, and then supplying water to compensate for the lack of moisture to control the moisture content of zero-slump hard-mixed concrete. Unlike conventional hard-mixed concrete, which has a moisture content error, the moisture content of concrete is measured correctly, so the moisture content is always stable, resulting in a product that meets a certain standard.In addition, the product is formed with smooth operation during the forming process, which only improves productivity. In addition, since moisture is formed on the entire surface of the aggregate, it can be mixed quickly and evenly with cement, resulting in a high-strength product.

[Effect].

The method of this invention is as described above, and its gist is that a gutter-shaped canopy is provided on top of the conveyor that transports each aggregate from the stockyard hopper to a weighing machine that weighs a predetermined amount of aggregate, and within this canopy, the aggregate is transported to the weighing machine. Water or steam is injected into each aggregate layer just before the water or steam is applied to form a moisture film on the surface of all the aggregates, and excess water in the form of water droplets is drained from the lower layer to dehydrate the aggregate. The water is further dehydrated by blowing air when it is dropped into a measuring device, and the water is completely dehydrated before being sent to the measuring device.

The aggregate with the moisture film formed on its surface is fed into a mixer for kneading, a certain amount of cement is also fed, and during the kneading, the water content of the mixed concrete is quickly and accurately measured using a water measuring instrument. Supply water to compensate for the shortage. In the hard mixed concrete obtained in this way, the moisture content is properly adjusted and a moisture film is formed on the surface of all the aggregates, so that the cement components are evenly mixed in all the aggregates after forming. The strength of the product is also improved and the crosstalk time is shortened.

Furthermore, when aggregates freeze in winter in cold regions, steam injection thaws the freeze and forms steam moisture on the aggregate surface, forming a moist water film on the aggregate surface in the same way as the water injection described above. Furthermore, this steam injection to the aggregate can be used not only in cold regions, but also as needed.

〔Example〕

To explain the moisture adjustment method for hard mixed concrete of the present invention with reference to the accompanying drawings, Fig. 1 is a plan view of a device showing an embodiment of the method of the present invention, and Fig. 2 is a sectional view of the main part of the device. show. Moreover, FIG. 3 shows a sectional view taken along the line AA in FIG.

In the figure, G is a hopper that stocks gravel, and M
is a hopper that stores fine gravel. And S indicates a hopper for stocking sand. (1) is a belt conveyor device installed at the bottom of each of the G, M, and S hoppers in an upwardly inclined manner to send each aggregate to a weighing device;
2) shows a conveyor belt. A gutter-like canopy (3) is installed on the top of this conveyor belt, and this canopy prevents the surface of the aggregate sent to the conveyor by the belt conveyor (2) from becoming dry and wet due to solar radiation, wind, and rain. At the same time, the room formed by the canopy is filled with moisture. (4) is a dual-purpose pipe that sends water or steam into the canopy room, and the pipe runs in an inclined manner above the canopy (3) installed on each belt conveyor (2) for gravel G, fine gravel M, and sand S. has been done. (5) is inclined piping (4)
An injection nozzle is provided with an opening above the canopy and suspended in the room, and injects water or steam onto the entire layer of aggregate being transferred on a belt conveyor. (6) is a water on/off switching valve, and (7) is a steam on/off switching valve.

Therefore, when the aggregate freezes in winter, the water valve (6) is closed and steam is sent to thaw the aggregate and form a moisture film on the surface of the aggregate.

In this example, the treatment to form a moisture film on the surface of the aggregate is carried out immediately before the aggregate is weighed, but depending on the processing conditions, the aggregate may be mixed and fed immediately before being fed to the mixer after the aggregate has been weighed. Water or steam may be sprayed onto this aggregate layer to wet it, and water droplets may be completely removed from the surface of the aggregate using a centrifugal dehydrator.

(8) is an air supply pipe, and (9) is an on-off valve for air sent from the air supply pipe (8), which is opened as necessary to send the air to the injection nozzle (10). This air injection nozzle (10) is connected to the belt conveyor (2).
When the aggregate with a moisture film formed on it is fed to the measuring device (11) at the upper end, secondary excess water droplets are further completely dehydrated by air injection, so that the surface of the entire aggregate is covered with only moisture. It forms a water film. (11) indicates a gravel scale, a fine gravel scale, and a sand scale, respectively;
) transfers the aggregate from the bottom of the scale (11) to the mixer (17).
(13) is a total of one container for cement. (141 is a screw conveyor for supplying cement from a cement silo (not shown) to the scale (13).

(15), (15), and (15) are a series of automatic moisture measurements that electrically and mechanically measure the moisture content of concrete mixed by the mixer (11), correct for insufficient water, and supply water. and a correction water supply metering device. (161 is a spray water supply nozzle for supplying insufficient make-up water indicated by the correction water supply metering device to mixed concrete, (17) is a mixer, (18) is a starter motor of the mixer, and (19) is This is a trolley hopper that transports the zero-slump hard-mixed concrete mixed by the mixer to the molding machine. (201 is a drainage ditch that drains excess water from the aggregate on the belt conveyor (1) and drains the wastewater. In addition, the conveyor belt (
2) is curved as shown in FIG. 3 during the transfer of aggregate, so excess water quickly flows down into the drain (20).

As described above, the present invention wets the entire surface of the aggregate immediately before weighing a predetermined amount, completely removes excess water, and uses the aggregate having only surface moisture under favorable conditions of a constant moisture content. Since cement is added and the zero slump hard mixed concrete is mixed, the automatic moisture measuring device measures it, so the measurement can be done accurately and quickly.It also corrects water shortages and constantly supplies stable hard mixed concrete to the molding machine. What it can do is adapt to the automation of various molding machines, which have become faster in recent years.

〔effect〕

This invention differs from conventional zero-slump hard-mixed concrete in that automatic moisture measurement is performed correctly when concrete is mixed, and water can be supplied correctly to replenish water shortages according to the measurement, so the desired zero-slump concrete is always delivered to the molding machine. Although we can supply it.

In other words, when water is supplied to compensate for insufficient water during automatic moisture measurement, all aggregate surfaces are covered with moisture, so moisture can be measured accurately and quickly, so there is almost no error in changes in the moisture content of hard-mixed concrete, unlike in the conventional method. Since hard mixed concrete with stable moisture is always sent to the molding machine, not only the quality of the product is improved, but also superior effects can be achieved from the molding process to production compared to conventional products.

Of course, even if the method of the present invention is applied to aggregates for poured concrete that have a lot of slump, the moisture content can be measured accurately, so the molded products can be made homogeneous and products with high product strength can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the method of the present invention, and FIG.
The figure shows a cross-sectional view of the side of the same main part, Figure 3 is Figure 2 A-A
It shows a cross-sectional view. 1)... Belt conveyor, 3)... Gutter-like canopy, (4)... Piping 5)...
Water or steam injection nozzle, 8) Air supply pipe, 10) Air injection nozzle,

Claims (1)

[Claims] 1. Immediately before the aggregate is kneaded with a mixer, water or steam is injected onto a conveyor that transfers the aggregate at an incline to wet the surface of the aggregate to uniformly form water-containing aggregate, and this excess water is allowed to flow down on the conveyor to form a primary The aggregate is dehydrated, then air is blown onto the aggregate to perform secondary dehydration, the dehydrated aggregate is measured with a moisture measuring device, and water is corrected to compensate for the lack of water in accordance with the set zero slump value. A method for adjusting the moisture content of hard-mixed concrete with zero slump, which is characterized by forming a water film of only moisture on the surface and mixing it with a predetermined amount of cement.