JPS58204854A - Manufacture of high strength concrete with improved workability and endurability - 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 high strength concrete with improved workability and durability.

The term "high-strength concrete" as used in the present invention is a general term for mortar, concrete, and alabaster concrete, and refers to concrete having a design strength of 600 Kl f /cm2 or more.

Conventionally, high-performance water reducers 1 have been used to increase the strength of concrete, and even when added in relatively large amounts, side effects such as excessive setting delay and air entrainment are small, and they are highly dispersed without adversely affecting the hardening of concrete. This is done by adding a dispersant that can exhibit the properties of concrete IJ-concrete with a low water-to-cement ratio.

However, concrete to which such a high performance water reducing agent is added has the following drawbacks.

(1) Workability is poor because slump loss is extremely large.

(11) Concrete 11-t when cast in place is -1
Since it is not possible to provide adequate moisture IiA curing or thermal curing, the strength may deteriorate depending on the weather conditions of the four seasons, such as temperature, humidity, wind power, freezing, and sunlight.
If steam curing is used, strength growth will be small to promote water utilization in the early stage, and as a result, high strength cannot be obtained.

(1:0 Particularly when cast in place, as in the present invention, if you increase the amount of gypsum hemihydrate or soluble anhydrite, no cracking will occur when air-drying indoors, but when exposed outdoors) Cured concrete 11- cracks occur and its durability deteriorates.

As a result of various studies to solve these drawbacks, the inventor of the present invention added gypsum hemihydrate and/or soluble anhydrite to increase the (3aSO,it) in concrete to a specific range. It was discovered that it was sufficient to add a small amount of selected oxycarboxylic acids, and the present invention was completed.

That is, the first aspect of the present invention is that when producing concrete with a low water-to-cement ratio to which a high-performance water reducing agent has been added, a half-water ratio of 0aSO, equivalent to 2 to 14i1f, is added to the cement content of the concrete. One type selected from gypsum and/or soluble anhydrite and 0.05 to 1.0 it% of citric acid, tartaric acid, malic acid, and salts of these acids (hereinafter simply referred to as citric acid, etc.) is 2. The second invention is a method for producing high-strength concrete with improved workability and durability, characterized by further adding at most one layer of alkali metal carbonate. be.

The present invention will be explained in detail below.

The high-performance water reducing agent in the present invention has the above-mentioned properties, and from the chemical structure of the main component, for example, a bo-11 alkyl salt such as a high condensate salt of naphthalene sulfonic acid or its □ derivative and formalin. There are two main types: allyl sulfonate yarns and high condensation products of triazine derivatives, such as melamine forma-11 resin sulfonate.

If you mention commercially available products such as 7'L, all of them are listed under the trade name k)
However, Kako Soap Co., Ltd.'s "Mighty 100" and "Mighty 150", Monomoto Yushi Co., Ltd.'s 1-Ball Fine 510.
NJ, Sanyo Kokusaku Pulp Co., Ltd. [Sunflow PSJ, Hozo 11 Bussan Co., Ltd. r NL-1450J, [Ni
, -4000J, Showa Denko K.K.'s "Melment", etc.

Typically, these superplasticizers 1 have a 600 edge f/cy
When producing concrete of n2 or more, co/ri 11-
Out of effectiveness against cement breakage (+,!51 type conversion 3
k) is added in an amount of 0.5% by weight or more, and the water-cement ratio is adjusted to 35% or less. However, concrete to which only a high-performance water reducing agent has been added suffers a significant drop in slump, which not only makes it difficult to work, but also makes it difficult to use cast-in-place concrete11-, -). In cases where, as mentioned above, they are left to dry and cannot be cured sufficiently, so depending on the condition of -A, it is not uncommon for the crotch strength to be significantly lower than that, and even in the case of steaming, in order to promote initial water use. , the subsequent strength elongation becomes small and high strength cannot be obtained.

Particularly in the case of outdoor use, if the amount of hemihydrate-X or soluble anhydrite added is increased, cracks will occur during outdoor care and durability will deteriorate.

Therefore, in the present invention, such a high performance water reducing agent or simply caso, ? In order to solve the defects of concrete that has been added within a certain range, as explained below, a specific amount of gypsum hemihydrate and/or al-soluble anhydrite, citric acid, etc., and alkali-11 metal carbonates are mixed. It is something to do.

First, I will explain about hemihydrate gypsum and/or soluble anhydrite.

Industrially, these stones 1 can be obtained by heating and dehydrating at a moderate temperature such as dihydrite, and it is preferable to crush them in a mill or the like to destroy the crystal form. , these are calculated based on the cement content of concrete, ca
So, change ★, add 2 to 141゛.

Conventionally, when these stones 111-v are added to the present invention, they exhibit false setting and rapid setting in addition to the high sulfur content of the high performance water reducing agent itself, resulting in a low water-cement ratio. Mixed carp cannot be mixed with conch 1j-1. On the other hand, in the 4-invention, by adding citric acid, etc., (1) the km-binding property of these 6 members and rapid setting can be suppressed, and at the same time, slump loss can be prevented. This will solve the problem (1) above and improve the workability.

Also, only gypsum hemihydrate and/or soluble anhydrite? If it is added in large quantities as in the present invention, false setting and rapid setting will be caused by 1. However, without steam curing, the reaction with the aluminate phase will occur slowly under conditions of low water-cement ratio.
+17 guide is generated, but this reaction and the reaction with the silicate phase become heavy? When T is reached, unreacted Iko 1 tends to remain, and when CaSO 4 x Beta exceeds 2 layers, it is easy to crack due to outdoor exposure curing. Cow expansion] 11
The inventors have confirmed that durability can be clearly determined by the same amount of time.

In contrast, in the present invention, by using citric acid in combination as described above, the aluminate phase σ) reaction and the silicate phase reaction are completely separated and proceeded, and the unreacted 5 The aim is to achieve the intended purpose by ensuring that no waste remains.

That is, by using gypsum hemihydrate and/or soluble anhydrite in combination with citric acid, etc., the water utilization of the siecate phase is delayed, and during that time, the reaction of gypsum with the aluminate phase (etc.
1 ton completes the gypsum formation), and no unreacted gypsum remains, resulting in a major increase in durability.
This solves the problem of 0il). next,
The produced ethrin fills the voids in the concrete that has not yet hardened, thereby promoting the compaction of the structure, and at the same time, high strength is achieved by the water utilization of the silicate phase that is subsequently induced. The formation of ethrin-ite takes in a large amount of crystallized water11111. Therefore, for example, ethrin-ite produces an effect similar to the pressurized dehydration effect generally used to increase the brightness of concrete. As a result, the problem (11) above is solved. Father, if you use steam curing, this reaction will occur more smoothly.

Addition amount of ``hansui 5 awards and/or mouth'' bathing anhydrite is 0aS
The reason for fC is limited as mentioned above in terms of O4.
If the strength is less than 14 FQB, the effect of increasing the strength of concrete I+ will be small, and if it exceeds 14 fqb, unreacted gypsum will remain due to the amount of aluminate phase in the cement even if it is used in combination with citric acid. cannot achieve its purpose.

These dehydrated gypsums are usually so powdery that they cannot be measured using the plain method, and their solubility is also high, but this is because the ethylstone formation reaction and the hydration reaction of the silicate phase are separated. This is an advantageous property, and the degree of fineness is not particularly important.

Examples of citric acid, such as citric acid, tartaric acid, Citric acid, tartaric acid and their sodium 11um salts, 1) malic acid and sodium malate salts are preferred in consideration of economy, non-toxicity, performance, etc.
Most preferred is citric acid and its sodium, strength 11
It is um salt.

These can prevent the false setting and caking of soluble anhydrite, and also take on the slump loss prevention effect of concrete added with a high performance water reducer.
Alternatively, when used in combination with soluble anhydrite, the solubility of these gypsums is high and the formation of etho II ngite is actively carried out, so that the effect of preventing slump loss is reduced. Therefore, in the present invention, the amount of addition was determined to be 0.05 to 1 percent of the cement content of concrete, with consideration given to correcting this while implementing the water usage pattern. In other words, if the amount added is less than 0.05, the adjustment to the water usage pattern will not be complete, so problem (iii) cannot be solved, and problem K (1) will be solved. It is also insufficient. Also, if one car exceeds 1 iqb, the
Over-delayed hydration of the cate phase? This is not desirable because it occurs.

As described above, the first invention involves adding a specific amount of half water and/or soluble anhydrite and citric acid to concrete to which a high performance water reducing agent has been added. It is possible to obtain a hardened concrete 1) which is prevented from cracking due to exposure and curing, and from swelling in water (very durable).

In the second invention, an alkali-11 metal carbonate is used to promote the slump loss prevention effect of citric acid, etc., and to improve the rise after the silicate phase starts to hydrate, without impairing the expression of such effects. The amount of addition should be at most 1 part to the cement content of the concrete. become. As the alkali metal carbonate, 1 to 2 or more selected from carbonates of lithium, sodium, and lithium or important rv1 salts are used.

The components according to the present invention described above may be added to cement in advance, or may be added at the time of mixing of concrete. The types of cement used in this case are Portland cement of various grades, mixed cement,
In the case of mixed cement, it is the same as before that in order to obtain the same strength, it is necessary to increase the amount of cement per unit. and 0) due to coexistence,
The present invention is excellent for general concrete work and works that require wear resistance and durability, such as dam plowing aprons, sabo dams, coasts, river revetments, airport runways, and roads. In addition to being highly effective, it can also be applied to the production of concrete products such as piles and holes that undergo steam curing.

Hereinafter, the present invention will be further explained with reference to examples.

Example 1 A commercially available diurnal water-reduced field [Mighty 150J (product product manufactured by Kako Soap Co., Ltd.) containing bo-11 alkylallyl nulfonate as the main ingredient had a leather potential of 7.2 squares/m3, sodium citrate. is constant at 0-2ikiit% with respect to cement, and g
Using the concrete mix shown in Table i, in addition to the 5-prize noodles and the additive amount, concrete 11) was used as a moistening material.

Conc 11-t's Cla/Pross and 20'C%R1ti6
Compressive strength σ) measured at the age of 28 days in 5-ton JP x Kyu W
Table 2 shows the observation of the appearance of fins after 6 months of outdoor TM exposure. Labs 1, 2, 5, 10, and 11 are comparative examples, and labs 4 to 9 are examples of the present invention.

The cement used was 1111 Portranage cement with an 803 value of 2.1, the gypsum hemihydrate was a commercially available product, the town-soluble gypsum was ground gypsum hemihydrate at 200°C for 5 minutes in a dehydrating vibrating bot mill, and gravel. is completely crushed stone. Gypsum hemihydrate and anhydrous gypsum were mixed outside the cement by replacing sand with reeds, and sodium citrate was dissolved in mixing water. The slump image was adjusted visually by adding or subtracting water.

Chapter 1 Table Table 2 ,,1lli.

Note) Experiment A2 is a case in which curing in water at 20° C. is carried out, and Experimental House 11 is a case in which sodium II citrate is not added.

As shown in Table 2, in all of the comparative examples of Experiment A1.2, the strength development was small, and it can be seen that there was a significant decrease in strength due to curing. , also experiment A
It can be seen that Comparative Examples 6 and 10 contain 5-Prize added in an amount different from the scope of the present invention, and are inferior to the Examples of the present invention in terms of strength development, prevention of slump loss, and weather resistance. Regarding the type of gypsum, soluble anhydrous gypsum has better strength development than hemihydrate gypsum, and there is a peak strength. It can be inferred that this is based on the hydration of the silicate phase that occurs.In the comparative example of Experiment A11, the slump was significantly lowered due to false coagulation, and the weather resistance was not improved.

Example 2 A test similar to Example 11 was conducted by changing the type and addition of citric acid and the like in the formulation of Experiment A8 (addition of 711% soluble anhydrite). The results are shown in Table 6. Experiment 41
2.19 is a comparative example, and the others are examples of the present invention.

Note that as the amount of added citric acid and the like increases, the curing time becomes longer, so the mold was demolded at the time of curing.

1. ``Margin'' This is a product in which citric acid is added in a range different from that of the present invention.In that case, the weather resistance cannot be improved, and furthermore, the strength is reduced.The optimum additive amount is 0.1 to 0. .It turns out that he is in charge of 5 Juaya.

Example 3 A commercially available high-performance water reducing agent containing a high condensate of a 11 azone conductor as a main component [Melment F'-10J (Showa Denko K.K.)]
Product name) using ff, hemihydrate gypsum as CaSO4, 7-fold f coefficient, citric acid force 1) ram 0.2-fold Ill coefficient (both are external cutting additions to cement), and Conc 1 in Table 4.
Tests were carried out by changing the type and amount of alkali carbonate groups added according to the 1-t formulation.

The results are shown in Table 5. Experiment 446 is a comparative example;
The others are examples of the present invention.

Table 4 Example 4 Jl#A I and 10 (comparative example) and experimental plates 7, 8 and 9
Using the concrete I+ (example of the present invention), 20'X
After centrifugal molding using a conventional method in a cylindrical form with dimensions of 30' x 5 tctn, pre-curing for 4 hours, normal pressure steam curing at 60°C (heating up for 6 hours, holding at 60°C for 4 hours, cooling down in a curing tank) The strength was measured when the mold was removed after 24 hours when the mold was left to cool naturally inside the room, and when it was then cured for 28 days indoors at 20°C and Rf (65%).In addition, when it was cured outdoors for 6 months The cracks were observed.The results are shown in Table 6.

Table 6 As shown in Table 6 above, the case where the number of stones I11 added is increased (- increases the generation mini of Nitori/Guide), and the condition where the number of stone I11 additions is increased (- is 2 and #Al
It has been shown that higher strength can be obtained by performing raw materials. However, as in 7. Experiment A54, if the appropriate amount is exceeded, cracks can be observed.

Patent applicant: Keikagaku Kogyo Co., Ltd.

Claims (2)

[Claims] (1) When producing concrete with a low water-to-cement ratio with the addition of a high-performance water reducer, gypsum hemihydrate and /Father is a mouth [#! The work is characterized by the addition of 1,05 to 100% of citric acid, tartaric acid, II malic acid, and salts of these acids. High strength concrete with improved durability and durability 11-
Method of manufacturing. (2) When producing concrete with a low water-to-cement ratio from which a high-performance water reducer has been removed, 2 to 14 # of aaso4 is added to the cement content of the concrete. My father is bathing anhydrite 1 and 0.05 to 1 weight.
citric acid, 1 soap, malic acid and salts of these acids -is derived from 1 plant or 2 or more, and at most 1 fi
4J alkaline arm charcoal eltJA? A method for producing high-strength concrete with improved workability and durability, characterized by the addition of additives.