JPS6021839A - Manufacture of cement moldings - 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 a method for producing a cement molded body in an extremely short time (1 to 3 hours) by rapid high temperature curing. As a cement molded body.

Asbestos cement board, pulp cement board, wood wool cement board,
Wood chip cement board, GRC, cement tile, mortar board, terrazzo block, concrete board, concrete pile, humid pipe, U-shaped groove, concrete block, tetrapod, concrete sleeper, ALC, etc. Civil engineering and architectural cement, mortar, concrete Products can be given.

Although it varies depending on the product, conventionally, to manufacture cement molded bodies, Portland cement, water, and aggregate are mixed and mixed, filled into molds, and then pre-cured at room temperature (normal temperature) for 2 to 4 hours. do. Next, using a water heater, the mold is heated to 15-70°C, and after maintaining this curing temperature for 4-8 hours, the steam is turned off, and the mold is removed after natural cooling.

In the conventional method, the production cycle of cement moldings is 1~
3 cycles/1'', and simply shortening the production time will not cure the concrete sufficiently. In addition, in open formwork, if the pre-curing time is shortened and the A temperature rate and curing temperature are increased compared to the conventional curing conditions, expansion, foaming, and cracking occur in the cement molded body, resulting in a loss of quality in the wholesale product. is not obtained.

By the way, ACI's 517 Committee Report [Steam Curing J (8
So Master Builders ■Technical Data NoL-001 Showa 3
According to August 1, 1988 (J), the A temperature rate is 15°C to 22°C.
The most desirable temperature is 33°C or less even with sufficient and appropriate pre-curing; if the pre-curing period is 3 hours or less and the heating rate exceeds 22°C, it can cause quite severe damage. It has been reported that they will receive it.

However, the present inventors have discovered that if a specific sulfate or sulfate double salt is mixed with hydraulic cement, it can be used even in open formwork.
There is no need for pre-curing, and rapid high-temperature curing can be performed immediately after molding at a heating rate of 40°C/hour or more and a curing temperature of 80°C or more, which allows for a curing time of 1 to 3 hours without any defects. It was discovered that a stable cement molded body could be obtained, and that the production cycle could be longer than 10 cycles/day.
We have arrived at the present invention.

That is, the present invention provides hydraulic cement with lithium,
0.1 to 1 or more of sulfates of aluminum, gallium, thallium and double sulfate salts containing these metals
The present invention provides a method for manufacturing a cement molded body, which comprises molding a hydraulic cement mixture added at a ratio of 20% by weight and then curing at a high temperature.

In the practice of the present invention, examples of the hydraulic cement include ordinary Portland cement, early strength Portland cement, moderate heat Portland cement, sulfate-resistant Portland cement, white Portland cement, blast furnace cement, silica cement, fly ash cement, and the like.

Preferred examples of these sulfates and sulfate double salts include f&
Examples include aluminum acid, lithium sulfate, gallium sulfate, thallium sulfate, and ammonium aluminum sulfate. These sulfuric acid salts and sulfuric acid double salts can be used in either anhydrous or hydrated form, and can also be used in powder form or aqueous solution.

Other sulfates include potassium sulfate, sodium sulfate,!
Sodium sulfate and chromium sulfate have low compressive strength and poor surface quality when demolded, while potassium sulfate has relatively high compressive strength when demolded but has poor surface quality. Both are unsuitable for use. In addition, other sulfate double salts include chromium ammonium sulfate and M
There are M chromium potassium, etc., but these have poor compressive strength and poor surface properties, and are therefore unsuitable for use.

As for how to use it, it is generally added during kneading of hydraulic cement mixtures such as concrete. The amount of sulfate or sulfate double salt added is 0.1 to 0.1 to hydraulic cement.
20% by weight, preferably in the range from 1 to 10% by weight. It can also be added to the hydraulic cement itself from the beginning. It may also be used in combination with a water reducing agent or setting regulator. - Concrete with a large unit water volume or air volume tends to expand when rapidly cured at high temperatures. Therefore, using a water reducing agent reduces the unit water volume. This is preferable because it allows As the water reducing agent, what is called a high performance water reducing agent is effective. For example, naphthalene sulfonic acid formalin condensate [
Product names include chemical soap Mighty 150], trimethylolmelamine monosulfonate condensate [product name is Hozorisu Bussan's NL-40001], and tar sulfonate [product name is Hozorisu Bussan's NL-14].
00J etc.

In addition, the use of aluminum hydroxide, Ca5O+, sucrose, etc., which act as a retarder against the acceleration of coagulation caused by sulfate, is effective in improving workability. Furthermore, in consideration of economic efficiency, aluminum chloride or polyaluminum chloride may be used instead of aluminum hydroxide or ram.

Since AE agents increase the air content of concrete, it has been thought that they are not suitable for rapid high-temperature curing, but when used in combination with the above-mentioned specific sulfates or double sulfates, 1.
No foaming or expansion was observed on the surface or internal structure of the cement molded body, and good surface texture and structure were obtained. This is presumably because a skeleton is formed at the early stage of curing and the skeleton acts in the direction of suppressing expansion, so that no thermal expansion of the air entrained by the AE agent occurs. In any case, in the method of the present invention, the AE agent can be used without fear of expansion phenomenon, and the inherent effects of the AE agent can be fully exhibited, so that the freeze-thaw resistance can be improved.

The above hydraulic cement, specific sulfate or sulfate double salt, water and aggregate (one or both of fine aggregate such as sand and coarse aggregate such as gravel and crushed stone), and other accelerators and retarders as necessary. Admixtures such as water reducing agents are added and kneaded, and the mixture is charged and filled into molds. Immediately after molding, this hydraulic cement mixture is subjected to rapid high-temperature curing.

Although a preheating time may be allowed at room temperature, in order to increase the production cycle of the cement molding, rapid heating is performed immediately after molding is completed without any preheating. The heating rate is 40℃/hour or more,
Preferably it is 60 to 120"0/hour, and no adverse effects occur in this speed range. The curing temperature may be maintained at a high temperature of 80°C or higher, preferably 90 to 110°C, for 15 to 60 minutes. 100 When performing high temperature curing exceeding 'C!, an airtight curing device is required. For example, if the molded body is wrapped in a sheet and pressurized steam is vented, high temperature curing exceeding 1OOoC can be achieved.

As a heating medium for high-temperature curing, high-temperature pressurized water and steam used in general steam curing are suitable. Other heat curing methods such as electric curing, electric heat curing, high frequency curing, heated air curing and infrared heating curing can also be used without any problems.

The cement molded body is immediately demolded after the above-mentioned high temperature curing,
All manufacturing processes are completed. In order to increase the thermal efficiency of curing by -E, it is effective to perform some natural cooling (soaking).

In this way, the cement molded product (cement, mortar or concrete product) obtained after a curing time of 1 to 3 hours has no defects such as swelling, foaming, or cracks on the surface and internal structure of the product, and has undergone necessary and sufficient demolding. Strength (100-200
kg/cm), and the increase in strength after demolding is equivalent to that of ordinary steam-cured products.

In the practice of the present invention, the mechanism by which a specific sulfate or sulfate double salt inhibits expansion, foaming, and cracking of a hydraulic cement mixture and promotes hardening during rapid high-temperature curing of the cement mixture is as follows: Although it is not clear yet, calcium hydroxide produced by hydration of cement components reacts with aluminum sulfate as shown in formula (1), and calcium sulfate and aluminum hydroxide are produced, and this calcium sulfate can be expressed by formula (2). ), it reacts with tricalcium aluminate, which is a constituent compound of cement, to produce tricalcium aluminate hydrate (ettringite).

3Ca(OH) 2 +AI2 (So)3 +81(
20+3(C:asO4'+ 2 H20)+2AI(
OH) 3- (1) C3A + 3(CaSO3”
2H20) + 26H20→Cr A ・3GaS04
・32820 ・=-(2) Even though the reaction processes of equations (1) and (2) are somewhat different from the actual ones, the reaction force of equation (1) (occurs) at the same time as water is added, and calcium sulfate and hydroxide during this nascent stage. If we assume that aluminum plays an important role and the reaction of formula (2) occurs at the beginning of heat curing, and that ettringite is rapidly formed, the following inference can be made.

That is, excess water in the cement paste is temporarily adsorbed and held on the colloidal surface of the generated aluminum hydroxide and ett-1 non-guide, and at the same time, due to the initial hardening due to the acicular structure of ettringite, it is rapidly heated to high temperatures. Expansion of water and air is suppressed even when the temperature is increased. followed by 8
At high temperatures above 0°C, the hydration reaction of poppy trilime, the main component of cement, progresses rapidly, resulting in a strength of 100 to 200 kg/cs+ in a short period of time.

As described above, in the cement molding manufacturing method of the present invention, which uses a specific sulfate or sulfate double salt as an active ingredient, rapid high-temperature curing is applied to a hydraulic cement mixture using an open mold under atmospheric pressure. Even if applied, the cement molded product will not expand, foam, or
Cracks do not occur, and the desired dense and solid product can be obtained in a short time.

In addition, unlike autoclave curing, it is not necessary to secure a large steam pressure in the compartment, so there is no need for special pressure retention means in the curing equipment, and conventional normal pressure steam curing equipment can be used as is. I can do it. As for the formwork, there is no need to use a closed formwork that requires high equipment and operating costs, and a normal open formwork can be used as is.

That is, according to the present invention, rapid high-temperature curing can be safely performed without fear of expansion phenomena, and the problems of developing early strength, shortening curing time, and increasing production cycles can be solved by reducing equipment costs for formwork and curing equipment. This can be easily achieved without causing an excessive increase in operating costs.In addition, in terms of the quality of the molded product itself, it is possible to reduce the pore volume in relatively large pore radii and improve freeze-thaw resistance. This has the effect of reducing carbonation and suppressing carbonation.

Next, Tables 1 to 5 summarize Examples and Comparative Examples of the present invention in which hydraulic cement mixtures were steam-cured with various changes in the type, amount added, and curing temperature of sulfate and sulfuric acid complex 1a. and showed.

Example 1 Ordinary Portland cement = 100, fine aggregate = 200,
A mortar molded body was manufactured using a hydraulic cement mixture in which various sulfates were added to mortar with a weight mixing ratio of water = 45 and Mighty 150 = 2. This curing is carried out at 60°C/hour for 9 hours immediately after filling the hydraulic cement mixture into the formwork.
It was heated to 0°C for 51 minutes and then held at 90°C for 60 minutes. Table 1 shows the physical properties and strength test results of each molded product thus obtained.

Compressive strength is the strength when demolded immediately after curing. The surface properties were determined by visually observing the presence, size, and number of expansion, foaming, and cracks on the entire molded body.

Table 1 *: Comparative Example Example 2 Ordinary Portland cement = 100, capillary material = 200,
A mortar molded body was manufactured using a hydraulic cement mixture in which various sulfuric acid double salts were added to mortar with a weight mixing ratio of water = 45 and NL-4000 = 2. This curing is performed immediately after filling the formwork with the hydraulic cement mixture at 60°C/hour for 90 minutes.
The temperature was raised to 0°C and then maintained at 90°C for 60 minutes.

Table 2 shows the physical properties and compressive strength test results of each molded product thus obtained. Compressive strength is the strength when demolded immediately after curing. The surface quality was determined by visual observation of the entire surface as in Example 1.

Example 3 A mortar molded body was manufactured using a hydraulic cement mixture in which aluminum sulfate (anhydrous) was added to a mortar with a ratio of 200 ordinary Portland cement, 45 water, and 3 NL-4000. This curing is carried out by immediately raising the temperature to 90°C at a rate of 60°C/hour after filling the formwork with the hydraulic cement mixture, and then raising the temperature to 90°C at a rate of 60°C/hour.
was held for 60 minutes.

Table 3 shows the physical properties and compressive strength test results of each of the molded bodies thus prepared. Compressive strength is the strength when demolded immediately after curing. The surface quality was determined by visual observation of the entire surface as in Example 1.

Table 2 Wood: Comparative Example Table 3 Example 4 Ordinary Portland cement = 360Kg/m3. Water cement ratio -48%, fine aggregate ratio = 36%, Mighty 150
= 2%, ^12 (SO4): + = 3%, and concrete molded bodies were manufactured by changing the curing temperature. This regimen is
Immediately after molding (20°C), the temperature was raised to the curing temperature at 60°C/hour, and the curing temperature/time product (maturity) was 17.
The curing temperature was maintained at around 0°C.

Table 4 shows the results of the compressive strength test for each of the molded bodies thus prepared. Compressive strength is the strength when demolded immediately after curing.

The surface texture was determined by visual observation of the entire surface as in Example 1.

Table 4 *: Comparative Example Example 5 Hotsu Portland cement was used as the cement, and sand from Shiroishi in the Abusumi water system was used as the fine aggregate (physical properties are shown in Table 5).
) was used as the coarse aggregate, and crushed stone (the physical properties are shown in Table 6) was used as the coarse aggregate.
), and aluminum sulfate [A1
．． , (SO4) 3] A concrete molded body to which powder was added and a concrete molded body using the same cement, fine aggregate, and coarse aggregate but without the addition of sulfate or double sulfate, including aluminum sulfate. Manufactured. The formulation of each concrete is as shown in Table 7, and the water-cement ratio is 48% in each case.

Table 5 Fine aggregate Table 6 Coarse aggregate Table 7 Concrete mixture There are three types of curing methods after concrete is poured into formwork:

(1) The day after pouring the standard curing concrete, remove it from the mold, immediately immerse it in water, and continue to cure it in water until the start of the test.

(2) 18-pass steam curing concrete 1 - After pouring, pre-curing is performed for 2 hours. After that, the curing temperature was raised to 65°C at a heating rate of 20°C/hour.
This curing temperature was maintained for 3 hours and allowed to cool naturally for 14 hours. After demolding, it was cured in water for one week, and then left in a constant temperature room at 20"O until the start of the test.

(3) Rapid high-temperature steam curing After pouring concrete, start curing immediately without pre-curing, bring the curing temperature to 100°C at a temperature rate of 50''C/hour, and maintain this curing temperature for 11 hours.Natural cooling Don't do it.

For each of the concrete molded bodies thus obtained, a compressive strength test was conducted for each material example, and the results shown in Table 8 were obtained.

The specimen symbol TR0N used in Table 8 indicates concrete that has been fully cured without the addition of aluminum sulfate, symbol TR3N indicates concrete that has undergone standard curing with the addition of aluminum sulfate, and symbol TRO3 indicates concrete that has been cured as standard without the addition of aluminum sulfate. Showing steam-cured concrete,
The symbol TR3S indicates concrete that has been steam-cured for 18 passes with the addition of aluminum sulfate, the symbol TROH indicates concrete that has been rapidly cured in high-temperature steam without the addition of aluminum sulfate, and the symbol TR3H indicates that concrete has been rapidly cured in high-temperature steam with the addition of I and aluminum sulfate. Showing concrete.

Table 8 *Two Comparative Examples After collecting the crushed concrete pieces after this compression test, they were immediately dehydrated and dried, and adjusted to a diameter of about 5 to 63111 mm.
This was used as a specimen for observation using a scanning electron microscope.

As shown in Table 9, the observation material age of the specimen was 1 [1st, 7th, and 28th day] as standards, and for specimens cured at a rapid high temperature, observation was performed immediately after curing instead of the 1-day material age.

Also, while observing, the surface of the specimen was
Two types of magnification: 00x (some have an additional 5000x magnification)
I took a photo. For reference, a photograph of the aluminum sulfate powder itself was also taken.

From this microscopic observation, crystals thought to be calcium hydroxide were clearly observed in specimens aged at a young age, and in specimens cured at higher temperatures, and the overall structure tended to grow significantly. was recognized.

Similarly to the case of the young material order, for the specimen of the 7-day material order,
The organization as a whole was growing significantly.

At the age of 28 days, the structure became more dense as the chemical reaction progressed, and sword-shaped crystals of ettrin guide were observed in the depressions where crystals thought to be calcium hydroxide overlapped. .

In conclusion, it is clearly recognized that there are differences in the formation of structures in young specimens due to differences in curing temperature. This microscopic structural observation also demonstrated the effect of inhibiting expansion due to skeleton formation in the early stages of curing.

Table 9 *: Comparative example In addition, for pore volume measurement, each concrete molded body of material age 28B (TRON, TR3N, TRO3, TR3
After removing the coarse aggregate from S and TR3H) and collecting only the mortar part, and letting the mortar pieces air dry, 1
The sample was dried at 00±5°C and adjusted to an appropriate size.

The pore volume was calculated according to a known measurement and calculation method using a commercially available porosimeter, and the results shown in Table 10 were 11
)is.

° 10 Thinness of concrete P'CII + 3/Wood: Comparative example The graph in Figure 1 shows the pore distribution of these five specimens on the same page.
．． The volumes of pores with a radius of 24 g or less are both minute amounts.

The maximum value of the specimen TRON is the smallest compared to other specimens. In addition, TR3, which is a specimen with aluminum sulfate added,
N,TR3S has a particularly large pore volume with a radius ranging from 240λ to 43OA.

On the other hand, specimen TR3H, which was rapidly cured at high temperature with the addition of aluminum sulfate, had a radius of 0. A partial increase in pores h is observed in the range from ta to 430A.

The graph in Figure 2 calculates the relative pore volume ratio by dividing the pore volume in each pore range by the total volume, and as the curing temperature increases, the pore volume of 0.147L or less increases. It is recognized that there is a trend.

The graph in Figure 3 shows the pore volume at each pore radius as a ratio of the value of the specimen TR0N, and it can be seen that the addition of aluminum sulfate tends to suppress the volume of relatively large pore radii. is recognized. This has a positive effect on the progress of frost damage and carbonation. According to the test results of up to 80Ll of carbonation acceleration tests conducted by the wood inventors,
It was confirmed that neutralization was suppressed by about 15 to 25%.

In addition, the results of a freeze-thaw test conducted separately also show that it is effective in improving frost damage resistance.

Example 6 As shown in Table 11, ordinary Portland cement l-=3
60kg/m1, fine aggregate - (1, = 36%, water cement ratio = 48%, 812' (SO4) 9 = 3%, AE
Agent (u Q't Master Pilda's Hozolith 5L)
-〇, concrete molded bodies were manufactured by changing the curing warm melon with a 25% blend. A compressive strength test was performed on the concrete molded body, and the results shown in Table 12 were obtained. All specimens had no expansion, foaming, or cracking, and had excellent surface texture and fine microstructure fj).

Table 11 Concrete mixture Table 12

[Brief explanation of the drawing]

FIG. 1 is a graph showing the pore distribution in a concrete molded body according to an example of the present invention and a concrete molded body according to a comparative example, and FIG. 2 is a graph showing the relative pore volume distribution of these molded bodies. FIG. 3 is a graph showing the relative pore distribution in comparison to a molded body produced by standard curing without adding aluminum sulfate. Patent Applicant Norihiro Umezawa Agent JP Rishi Masu 11] Mamoru 41 Reigyu 1 Motomi 212 1000 II Crime 1000 Patent Office Commissioner Kazuo Wakasugi Tono 1. Display of the case 1982 Patent Application No. 125571 2 Name of the invention Method for manufacturing cement molded bodies 3 Person making the amendment Relationship to the case Patent applicant Address 6-3 Uramachi, Kakuda, Kakuda City, Miyagi Prefecture Name Bianku Takijuu 4, Agent 441 Address 906 Takigen Building, 1-24-1 Nishigotanda, Parts Ward, Tokyo @495-130111 October 1988
On October 1st (October 25th of the same year) 6, Figure 1, Figure 2, and Figure FF13 will be corrected as shown in the attached drawing 7 and details of the amendment. 5l-r437tshisom4)6riHa,14oaa4
aif Address: 6-3 Uramachi, Kakuda, Kakuda City, Miyagi Prefecture Norihi U Tsumezuwa Name: Tokuhiro Tokuhiro 4, Agent: 141 Address: 906 Takigen Building, 1-24-1 Nishigotanda, Parts Ward, Tokyo ?) 1.495-E1091 Voluntary correction 6. Column 7 for detailed explanation of the invention in the specification to be amended is the content of the amendment. ” is inserted.

Claims (6)

[Claims] (1) Water to which one or more of sulfates of lithium, aluminum, gallium, thallium, and double sulfate salts containing these metals are added at a ratio of 0.1 to 20% by weight based on hydraulic cement. After molding the hard cement mixture,
A method for producing a cement molded body characterized by high temperature curing. (2) The method for producing a cement molded body according to claim 1, wherein the sulfate is aluminum sulfate. (3) The method for producing a cement molded body according to claim 1, wherein the sulfate double salt is aluminum ammonium sulfate. (4) A method for manufacturing a cement molded body according to claim 1, 2, or 3, characterized in that the curing temperature is 80° C. or higher. (5) A method for manufacturing a cement molded body according to claim 4, characterized in that the temperature increase rate is 40°C/hour or more. (6) A method for producing a cement molded body according to claim 5, characterized in that high temperature curing is performed without pre-curing.