JPH107445A - Agent for maintaining initial slump time of concrete or mortar for long period of time - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a maintaining agent for the initial slump time of a concrete or a mortar for a long period of time, capable of maintaining the initial high slump on kneading and mixing of the mortar or concrete for 1-5 days by blend ing the same with the mortar or concrete. SOLUTION: This maintaining agent for the initial slump time of a concrete or a mortar for a long period of time, consists of a coagulation retarding agent and a high performance AE water-reducing agent. In this case, the coagulation retarding agent is an oxycarbosylic acid or salt threrod selected from gluconic acid, glucoheptonic acid and saccharic acid, and the high performance AE waterreducing agent is a compound selected from an aminosulfonic acid-based, a polycarboxylic acid-based, a naphthalene sulfonic acid-based and a melamine sulfonic acid-based compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for maintaining an initial high slump of concrete or mortar for a long period of several days by a specific combination of a setting retarder and a high-performance AE water reducing agent, and by a specific addition rate. The present invention relates to a concrete or mortar used to maintain an initial slump for a long time.

[0002]

2. Description of the Related Art The maintenance of fluidity of fresh concrete or fresh mortar and the delay of setting are caused by the extension of workable time, continuous construction without a splice when a large amount of concrete or mortar is poured, and a long casting cycle. Various effects are expected such as construction work, improvement of working conditions by avoiding casting at night, reduction of environmental problems around the casting site, long-term storage of fresh concrete or fresh mortar, long-distance long-term transportation, etc. . For this reason,
Methods of maintaining slumps in concrete or mortar using setting retarders and AE water reducing agents have been studied.

[0003]

If it is possible to maintain the slump of the concrete or mortar with retarded setting for a long period of time, the use of retarded concrete or retarded mortar will be greatly expanded. However, there is no known technology capable of maintaining a slump for one day or longer. Accordingly, the present invention has been made to maintain the initial high slump of concrete or mortar for a long period of several days.

[0004]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have determined that a certain set retarder and a high-performance AE water reducing agent are specified in a specific combination and specified. The present inventors have found a method for maintaining the initial slump of concrete or mortar over a long period of several days by adding the compound according to the addition ratio, and completed the present invention.

[0005] That is, the present invention provides a setting retarder and a high-performance A
E. A water-reducing agent for the concrete or mortar, which is an initial slump long-lasting agent, wherein the setting retarder is an oxycarboxylic acid selected from gluconic acid, glucoheptonic acid and saccharic acid or a salt thereof; The water reducing agent is a compound selected from an aminosulfonic acid type, a polycarboxylic acid type, a naphthalenesulfonic acid type, and a melaminesulfonic acid type.

The concrete or mortar to which the initial slump long-term maintenance agent for concrete or mortar according to the present invention is applied includes basically all concrete or mortar composed of cement, water and aggregate, but other components. May be included. Here, the cement includes ordinary cement (ordinary Portland cement, early-strength cement, ultra-high-strength cement, blast-furnace cement, fly ash cement, etc.) as well as cement-based solidifying agents such as soil cement. Aggregate is fine aggregate (sand, etc.)
And coarse aggregate (pebble, crushed stone, etc.).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Examples of the setting retarder in the present invention include oxycarboxylic acids selected from gluconic acid, glucoheptonic acid, and saccharic acid, or salts thereof.

The above-mentioned salts of oxycarboxylic acids include ammonium salts, alkali metal salts (eg, sodium salts, potassium salts, etc.) and alkaline earth metal salts (eg, calcium salts, magnesium salts, etc.), and are preferred. Is an alkali metal salt.

The high-performance AE water reducing agent in the present invention includes compounds selected from aminosulfonic acids, polycarboxylic acids, naphthalenesulfonic acids, and melaminesulfonic acids.

In the present invention, in order to maintain the initial high slump, gluconic acid as a setting retarder and high performance A
A combination using a polycarboxylic acid-based compound as the E water reducing agent is preferred. The maintenance period can be adjusted mainly by changing the addition rate of gluconic acid, and secondarily by changing the addition rate of a polycarboxylic acid-based high-performance AE water reducing agent.

Furthermore, in order to maintain a high slump, gluconic acid is preferably used in an amount of 0.04 to 0.04 to cement weight.
0.50% and polycarboxylic acid-based high-performance AE water reducing agent 0.5
It is good to combine with 3.5%.

More preferably, in order to maintain the high slump for 1 to 5 days, 0.15-0.35% of gluconic acid and a polycarboxylic acid-based high-performance AE water reducing agent of 1.0-2. It is good to combine with 2%. If the gluconic acid and polycarboxylic acid-based high-performance AE water reducing agent is less than the above range, high slump cannot be maintained for one day or more, and if it is more than the above range, the high slump state will be too long.

The method for blending the initial slump long-lasting agent for concrete or mortar of the present invention is a conventional method.

The method for adding the initial slump long-term maintenance agent for concrete or mortar of the present invention is a conventional method. That is, it may be added to water at the time of kneading, or may be added to concrete or mortar which does not solidify during kneading or after kneading.

It is considered that the setting retarding action and water reducing action of concrete or mortar are mainly caused by the adsorbing action of the setting retarder and the high-performance AE water reducing agent to cement. It is said that the polycarboxylic acid-based high-performance AE water reducing agent which has been effective in combination with the setting retardant in the present invention exhibits dispersibility due to steric hindrance on the surface of cement particles. On the other hand, gluconic acid has five hydroxyl groups (-OH) in its chemical structure.
Is presumed to exhibit the effect of adsorbing on the surface of cement particles. Gluconic acid has no significant difference in the amount of adsorption between the case of single addition and the case of combined use.
It is considered that the water is preferentially adsorbed without being disturbed by the water reducing agent. On the other hand, the amount of solids adsorbed by the polycarboxylic acid-based high-performance AE water reducing agent is small, and even less when gluconic acid is used, but the specificity of the adsorption form and the carboxyl group (-COOH) having the same functional group in the chemical structure are the same. It seems that the point is to exert the mutual performance sufficiently.

The gluconic acid and polycarboxylic acid-based high-performance AE water reducing agent used in the present invention has almost no adverse effect on the compressive strength of concrete or mortar.

Next, the effects of the present invention will be described with reference to test examples.
The materials used for the test and the test method are described below. (1) Materials used City water is used as the mixing water for concrete and mortar.
Was. Other materials used are shown below. (A) Cement: ordinary Portland cement (Chichibu Ono
(B) Blast furnace type B Portland cement manufactured by Toda Cement Co., Ltd. (b) Fine aggregate: Oigawa river sand (specific gravity 2.62, water absorption rate)
1.38%, coarse particle rate 2.70) (c) Coarse aggregate: crushed stone from Ome (specific gravity 2.73, water absorption rate 0.3%)
56%, coarse particle rate 6.06, actual rate 58.7%) (d) Setting retarder (hereinafter abbreviated as retarder) As test examples of the present invention, gluconic acid, glucoheptone
Acid, saccharic acid was used. Also, as a comparative example
Is gluconic acid, glucoheptonic acid, saccharic acid
It has almost the same delay of cement hydration reaction,
Conventionally used citric acid and α-ketoglutar
Acid, glucuronic acid, α-ketogluconic acid, glucose,
Sorbitol was used. (E) High-performance AE water reducing agent (hereinafter abbreviated as SP):
As a test example, the following four types of SPs were used.
Was. Amino sulfonic acid type (FPK Co., Ltd.
FP200H, abbreviated as SPA) Polycarboxylic acid type (Palic, manufactured by FPC Corporation)
FP300U, abbreviated as SPB) Naphthalenesulfonic acid (Mighty-15 manufactured by Kao Corporation)
0, abbreviated as SPC) Melamine sulfonic acid (Sika 10 manufactured by Nippon Sika Co., Ltd.)
00N, abbreviated as SPD) In addition, the addition rates showing the same dispersibility are concrete or concrete.
Is the result of preliminary test with mortar, the unit water volume is 10kg / m
^Three For the purpose of reduction, SPA 1.4 and SPB 1.
1, SPC 1.4 and SPD 1.5% × C
did. In this specification, the weight of cement
Addition rate (%) of setting retarder and high performance AE water reducing agent
(% × C).

(2) Composition of concrete and mortar Table 1 shows the composition of mortar, and Table 2 shows the composition of concrete.

[Table 1] Mortar composition

[Table 2] Formulation of concrete

(3) Test method Test method 1 Measurement of kneading and slump change with time The mortar was about 1 liter with a mortar mixer, and the concrete was about 50 liter with a forced kneading pan type mixer.
After kneading for 90 seconds, the mixture was kneaded for 90 seconds. It was stored in a polypropylene container or polyethylene bag for a predetermined time in a room at 20 ° C. Slump is JI in mortar
SA 1173, JIS A 1 in concrete
Slump cone for mortar *
Is a half scale size of a concrete slump cone. The amount of air in mortar is determined by the weight method.
The measurement was performed according to JIS A1128. * Upper surface 5cmφ × Lower surface 10cmφ × Height 15cm Test method 2 Measurement of time to reach maximum temperature of hydration heat generation of mortar Put 350g of kneaded mortar in a polyethylene bag and put it in a 10cm thick styrofoam container. The temperature rise was measured over time by an IC temperature sensor. The time that showed the highest temperature of the measurements was assumed to be the cure time. This time almost corresponds to the end time of the visual observation or the setting test according to Annex 1 of JIS A 6204 [Table 3].

[Table 3] Relationship between maximum temperature arrival time and setting time Test Method 3 Compressive Strength Test The compressive strength test was performed according to JIS A 1108 by preparing a test body in accordance with JIS A 1132.

Hereinafter, test examples will be described. Test Example 1 In order to evaluate the effects of the type of retarder and the addition rate on the time to reach the maximum temperature of the mortar (≒ setting time) for the case of adding the retarder alone and the case of adding the SPB together, the following table was used. No. 1]. Mortar in which 9 kinds of retarders were added to mortar at an addition rate of 0 to 0.3% × C; For the mortar obtained by adding 9 kinds of retarders to the mortar of No. 2 at an addition rate of 0 to 0.3% × C and SPB of 1.1% × C, the mortar of Test Method 2 was measured for the time to reach the maximum exothermic hydration temperature. The results are shown in [Table 4].

[Table 4] Influence of the type of retarder and the addition rate on the time to reach the maximum temperature (when the retarder alone is added and when it is added together with SPB) In the case of adding the retarder alone, 0.1% × C
As the addition rate increases from 0.3% to 0.3% × C, the time to reach the maximum temperature corresponding to the setting time of the mortar increases. By setting the condition not to cure for at least 50 hours, most of the retarders can be used at an addition rate of about 0.3% × C. The mortar when the retarder 0.1-0.3% × C and SPB (polycarboxylic acid type) 1.1% × C are added together is as follows:
Compared with the case of adding the retarder alone, the oxycarboxylic acids gluconic acid, glucoheptonic acid, saccharic acid and citric acid have a longer time to reach the maximum temperature, whereas α
-Ketoglutaric acid, glucuronic acid and sorbitol are less variable, and α-ketogluconic acid and glucose accelerate curing.

Test Example 2 In order to evaluate the effects of the type and addition rate of the retarder on the aging of the mortar slump with respect to the case of adding the retarder alone and the case of adding it in combination with SPB, Test Example 1 was used. With respect to the mortar used, the time-dependent change of the slump of Test Method 1 was measured. The evaluation results are shown in [Table 5].

[Table 5] Influence of the type and addition rate of the retarder on the aging of the mortar slump (in the case of adding the retarder alone and in the case of S
In the case of combined use with PB) It is thought that the combination of a retarder exhibiting a maximum temperature reaching time significantly exceeding 50 hours and SP can maintain a high slump for a long time, and excluding α-ketogluconic acid, glucose and sorbitol. Six kinds of retarders 0.1-0.3% C and SPB (polycarboxylic acid type)
The change over time of the mortar slump when 1.1% × C was added in combination was examined. Citric acid, glucuronic acid and α
-When ketoglutaric acid is added at a rate of 0.1 to 0.2%,
One day after mixing, initial slump is about 10cm to 5cm
After that, it rapidly decreases, and after that, a state of almost no fluidity with a slump of 1 cm or less continues until curing. In addition, as shown in [Table 7] of Test Example 4, the effect of the type of SP is not much observed. When the rate of addition of the retarder is increased to 0.3%,
After one day of kneading, the slump value is slightly improved to 5 to 8 cm, but after two days the slump value is still 5 cm.
cm or less. On the other hand, gluconic acid, glucoheptonic acid and saccharic acid are added at a rate of 0.2-0.3% ×
In the case of C, the initial slump is maintained almost until 2 days after mixing. In particular, gluconic acid and glucoheptonic acid increase the retention time of the initial slump as the addition rate increases,
Addition of 0.3% reaches 9 days for gluconic acid and about 6 days for glucoheptonic acid. It seems that increasing the amount of saccharic acid to 0.3% × C does not increase the maintaining time of the initial slump compared to the case of adding 0.2% × C.

Test Example 3 Effect of S on time to reach maximum temperature of mortar (≒ setting time)
In order to evaluate the effect of the type of P on the case of the combined use of a retarder and SP, the formulation No. in Table 1 was used. Mortar in which 9 kinds of retarders were added to mortar at an addition rate of 0.2% × C; No. 2 mortar and 9 kinds of retarders were added at a rate of 0.2% × C and SP was set to SPA1.
4% × C, SPB1.1% × C, SPC1.4% × C,
For each mortar blended with SPD 1.5% × C, the mortar of mortar of Test Method 2 was measured for the time to reach the maximum exothermic heat of hydration. The evaluation results are shown in [Table 6].

[Table 6] Effect of type of SP on time to reach maximum temperature (in case of combined use of retarder and SP) In the case of combined use of a retarder and SP, the effect of the type of SP on the time to reach the maximum temperature is determined by SPA, SPC, SPD.
In the case of (1), the same tendency as in the case of SPB is observed. In the case of the three types of retarders, gluconic acid, glucoheptonic acid, and citric acid, the other three types of SP have greater retardation than SPB. Since the delay time of SP alone is within 1 day at most in the range of the addition rate of 1.0 to 1.5% × C, gluconic acid, glucoheptonic acid, saccharic acid, and citric acid show a considerably large synergistic effect. Will be.

Test Example 4 In order to evaluate the effect of the type of SP on the aging of the mortar slump with respect to the case of adding a retarder and SP in combination, the mortar using SP in Test Example 3 was used. The slump of the test method 1 was measured over time. The evaluation results are shown in [Table 7].

Table 7 Effect of SP on mortar slump over time
Of the type of (in the case of combined use of retarder and SP) In the case of gluconic acid, glucoheptonic acid and saccharic acid which show a long-lasting effect of the initial slump by addition in combination with SPB, citric acid which does not show a remarkable long-term maintaining effect,
In the case of glucuronic acid and α-ketoglutaric acid, the effect of the type of SP is not so large.

Test Example 5 In order to evaluate the effect of the type of SP and the addition rate on the time to reach the maximum temperature of the mortar in the case of adding gluconic acid (retarder) and SP in combination, the formulation No. in Table 1 was used. . 1
Gluconic acid as a retarder in mortar of 0.25
% × C blended mortar, and blended No. Glutaric acid as a retarder in mortar No. 2 was added at a rate of 0.25% × C, and SPA, SPB, SPC, and SPD were each added at 1.0%.
Test method 2 for each mortar containing ２．０2.0% × C
Was measured for the maximum temperature of the exothermic heat of hydration of the mortar. The evaluation results are shown in [Table 8].

[Table 8] Effect of SP type and addition rate on maximum temperature arrival time (in the case of combined use of gluconic acid (retarder) and SP) From the results of Test Examples 1 to 4, gluconic acid having stable slump maintaining performance was selected as a retarder, and the effects of the type of SP used in combination and the addition ratio were examined. The maximum temperature reaching time, which is a measure of the lag, tends to increase with an increase in the SP addition rate. SPA and SPB are slightly increased, while SPC and SPD are significantly increased. When SPC and SPD were added at 2.0% × C, the time to reach the maximum temperature reached 230 to 260 hours, which was about twice that of the case where 0.25% gluconic acid was added alone.

Test Example 6 The mortar used in Test Example 5 was used to evaluate the effect of the type of SP and the addition rate on the aging of the mortar slump with respect to the case of adding gluconic acid (retarder) and SP in combination. The slump of the test method 1 was measured over time. The evaluation results are shown in [Table 9].

Table 9 Effect of SP on mortar slump over time
Of type and addition rate (in the case of combined use of gluconic acid (retarder) and SP) The slump of SPC and SPD shows that the addition rate of SP with a small delay is 1.0% .times.C, which decreases in a very short time as in the case of gluconic acid alone, and is 1.5 to 2.0% with a large delay.
With the addition of × C, there is a tendency for the slump to gradually decrease until 8 to 10 days. 1.5-2.0% × C for SPA and SPB
With the addition, the maintenance limit period of the initial slump reaches about 3 days,
Thereafter, the slump drops rapidly and leads to hardening. [Table 8]
From the maximum temperature arrival time results, it is predicted that SPB will cure faster. From the above, the combination of the retarder gluconic acid and SPB is most suitable for maintaining the initial high slump of the mortar for 1 to 5 days, and the maintenance time is adjusted mainly by changing the gluconic acid addition rate. It is also possible to change the rate of addition of SPB as a secondary effect. In the following test examples, it was examined whether the results obtained with mortar could be obtained with concrete.

Test Example 7 In order to evaluate the effect of the addition rate of the retarder on the change with time of the slump of the concrete in the case of the combined use of gluconic acid (retarder) and SPB, the formulation of Table 2 was used. N
o. With respect to the concrete obtained by adding gluconic acid as a retarder to the concrete of No. 2 at a rate of addition of 0 to 0.60% × C and SPB 1.1% × C, the change with time of the slump of Test Method 1 was measured. The evaluation results are shown in [Table 10].

[Table 10] Influence of addition rate of retarder on aging of slump of concrete (gluconic acid (retardant) and SP
(In the case of combined use with B) Gluconic acid 0.15 in combination with SPB 1.1% × C
When 0.35% × C was added, the tendency of the slump with time was almost the same as that of the mortar shown in [Table 5]. Further, when the addition rate was increased to 0.6% × C, the slump was insufficiently maintained, indicating that there was a limit to the high slump maintenance period.

Test Example 8 In order to evaluate the effect of the addition rate of the retarder on the setting time, compressive strength, etc. of the concrete, in the case of the combined use of gluconic acid (retarder) and SPB, test example 7 was used. The compressive strength test of Test Method 3 was performed on the used concrete (excluding the gluconic acid addition rate of 0.18% × C and 0.60% × C). The evaluation results are shown in [Table 11].

[Table 11] Effect of addition rate of retarder on setting time and compressive strength of concrete (gluconic acid (retardant) and SP
(In the case of combined use with B) The setting time of the concrete is almost the same as the time to reach the maximum temperature of the mortar.

Test Example 9 In order to evaluate the effect of the addition rate of SP on the time-dependent change of the slump of the concrete, in the case of adding gluconic acid (retarder) and SPB together, the formulation No. in Table 2 was used. .
Concrete No. 1 containing gluconic acid as a retarding agent at an addition rate of 0.25% × C and [Table 2]]. Glucon 0.2 in concrete 2
The change with time of the slump of Test Method 1 was measured for concrete containing 5% × C and 1.1 to 2.2% × C of SPB. The evaluation results are shown in [Table 12].

[Table 12] Effect of SPB addition rate on aging of concrete slump (gluconic acid (retardant) and SP
(In the case of combined use with B) Regarding the effect of the addition ratio of SPB on the aging of the concrete slump, a more clear slump retention performance was obtained than in the case of the mortar shown in [Table 8].

Test Example 10 The effect of the addition rate of SP on the setting time, compressive strength, etc. of concrete was evaluated in Test Example 9 in order to evaluate the effect of the combined use of gluconic acid (retarder) and SPB. The compressed concrete was subjected to the compressive strength test of Test Method 3. The evaluation results are shown in [Table 13].

Table 13 Effect of SPB addition rate on setting time and compressive strength of concrete (gluconic acid (retardant) and SP
(In the case of combined use with B) The setting time of the concrete is almost the same as the time to reach the maximum temperature of the mortar. The above confirms the results of the examination using mortar,
It has been shown that the slump can be maintained at a high slump for several days, and that the maintenance time can be adjusted mainly by changing the addition rate of the retarder and, secondarily, by changing the addition rate of SP.

Tables 11 and 13 show the relationship between the age and the compressive strength from the time when the concrete was set. The effect of the gluconic acid addition rate was shown [Table 11].
Both of Table 13 and Table 13 show the effect of the addition rate of SPB, and it can be said that there is no problem in the compressive strength in consideration of the effect of the amount of air.

[0031]

【Example】

Example 1 600 g of ordinary Portland cement, 288 g of water, 1.86 kg of fine aggregates,
After kneading cement and fine aggregate with a mortar mixer for 5 seconds, 1.2 g of gluconic acid, polycarboxylic acid-based high-performance A
E 6.6 g of water reducing agent and water were simultaneously added and kneaded for 90 seconds to obtain about 1.2 l of raw mortar. Example 2 14.2 kg of ordinary Portland cement, 7.9 k of water
g, 45.2 kg of fine aggregate and 49.0 kg of coarse aggregate, to produce concrete containing cement, fine aggregate and coarse aggregate, after forcibly kneading with a forced kneading pan type mixer for 5 seconds,
Gluconic acid 60g, polycarboxylic acid high performance AE
330 g of water reducing agent and water were simultaneously added, and the mixture was further kneaded for 90 seconds to obtain about 50 l of ready-mixed concrete.

As can be seen from the above results, the concrete or mortar of the present invention has an initial slump long-term maintenance agent, which is a gluconic acid, a glucoheptonic acid, as a setting retarder.
An oxycarboxylic acid selected from saccharic acid or a salt thereof, and an aminosulfonic acid as a high-performance AE water reducing agent,
By combining a compound selected from polycarboxylic acid, naphthalene sulfonic acid, and melamine sulfonic acid into a mortar or concrete, the initial high slump when kneading the mortar or the concrete is 1 to 1. Can be maintained for 5 days. Among them, a combination with gluconic acid as a setting retarder and a polycarboxylic acid-based compound as a high-performance AE water reducing agent is most suitable, mainly by changing the addition rate of gluconic acid, and secondaryly by using polycarboxylic acid. By changing the rate of addition of the high-performance AE water reducing agent in the system, the maintenance period of the initial high slump can be adjusted.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location // C04B 103: 12 103: 30 103: 32

Claims (3)

[Claims] An oxycarboxylic acid selected from the group consisting of gluconic acid, glucoheptonic acid and saccharic acid, which is an agent for maintaining an initial slump for a concrete or mortar, comprising a setting retarder and a high-performance AE water reducing agent. An acid or a salt thereof, wherein the high-performance AE water reducing agent is a compound selected from the group consisting of aminosulfonic acid, polycarboxylic acid, naphthalenesulfonic acid, and melaminesulfonic acid. Slump long term maintenance agent. 2. Gluconic acid is added in an amount of 0.1 to the weight of cement.
The polycarboxylic acid-based high-performance AE water reducing agent is contained in an amount of 0.5 to 3.5%, and the polycarboxylic acid-based high-performance AE water reducing agent is contained in an amount of 0.5 to 3.5%.
The stated initial slump long term maintenance agent of concrete or mortar. 3. Gluconic acid is added in an amount of 0.1 to the weight of cement.
2. A polycarboxylic acid-based high-performance AE water reducing agent is contained in an amount of 1.0 to 2.2%.
The stated initial slump long term maintenance agent of concrete or mortar.