JP6144500B2 - Thickener for hydraulic composition - Google Patents

Description

  The present invention relates to a thickener for a hydraulic composition, and more specifically, in concrete used for construction and civil engineering, not only maintains suitable fluidity at the time of placing, but also material separation regardless of operating temperature. The present invention relates to a thickener for hydraulic compositions that can be suppressed.

Concrete with high fluidity, also called self-compacting concrete, has the property that the fluidity of the concrete tends to fluctuate due to fluctuations in the surface water content of the fine aggregate and temperature changes. In order to solve such a problem, a method of adding a thickener such as welan gum has been proposed (patent documents, etc.).
In addition, in order to prevent bleeding and material separation during the curing process of fresh concrete, a method has been proposed in which a thickener is added to increase the viscosity of the concrete and improve material separation resistance (patent) Literature 2 etc.).

JP-A-5-139806 JP 2000-95552 A

In the thickeners proposed so far, it has been pointed out that the fluidity and material separation resistance fluctuate depending on the temperature. There has been no proposal of a thickener that can improve both the material separation resistance.
In general, in order to ensure separation resistance and suppress the generation of bleeding water, it is necessary to increase the unit amount of powder such as cement and admixture, but this is extremely high considering the design standard strength of concrete. There is a problem that the strength is too high and the cost becomes very high, and there is also a problem that it is difficult to manage the construction because the pressure loss becomes large when the concrete is pumped.
Furthermore, although it has been proposed to use a thickener and a water reducing agent in combination, it is said that it is difficult to make one component of the thickener component and the water reducing agent as a water reducing agent.

  As a result of studying the above problems and carrying out researches, the present inventors have used dutan gum and a polyalkylene oxide water-soluble polymer having spinnability as a thickener, without depending on the use temperature. The present inventors have found that the fluidity suitable for placing the concrete is maintained and the material separation resistance is excellent when the concrete is cured, and that bleeding can be suppressed.

That is, the present invention is (A) a water-soluble polymer having a dutan gum and (B) a polyalkylene oxide chain, and the string length L of a 0.5 mass% aqueous solution of the polymer at 20 ° C. is 5 to 200 mm. The present invention relates to a thickener for a hydraulic composition containing a water-soluble polymer.
Moreover, this invention relates also to the water reducing agent for concrete containing the said thickener for hydraulic compositions, and a water reducing agent.

The thickening agent for hydraulic composition and the water reducing agent for concrete of the present invention can maintain a suitable fluidity by suppressing the change of the fluidity of the concrete without being affected by the temperature change of the use environment, Moreover, the material separation resistance can be improved, and defects in the hardened concrete due to bleeding can be reduced.
Therefore, high-quality concrete with high fluidity can be stably produced by using the thickener for hydraulic composition and the water reducing agent for concrete of the present invention.

FIG. 1 is a diagram showing a measurement result of shear stress with respect to shear rate in Comparative Example 1 and Comparative Example 2 in Test 1 (rheology test). FIG. 2 is a diagram showing the measurement results of shear stress with respect to shear rate in Example 1 and Comparative Example 3 in Test 1 (rheology test).

  The thickener for hydraulic compositions of the present invention contains (A) detan gum and (B) a water-soluble polymer having spinnability.

The above (A) dutan gum is a microbial polysaccharide produced from the microorganism Xanthomonas campestris, ATCC 53159. The structure consists of a repeating unit of a linear tetrasaccharide of [D-glucose]-[D-glucuronic acid]-[D-glucose]-[L rhamnose], wherein two L rhamnoses are bound to the side chain. Have
The viscosity of the dutan gum is preferably 2,000 mPa · s or more, more preferably 3,000 mPa · s or more in a 0.25% aqueous solution at 25 ° C. The viscosity of the dutan gum is more preferably 4,000 to 5,000 mPa · s in a 0.25% aqueous solution at 25 ° C. Further, the particle size of the powder of the dutan gum is preferably 80% or more and 80% or more, more preferably 95% or more.

The (B) water-soluble polymer is a polymer having a polyalkylene oxide chain, and the water-soluble polymer (hereinafter referred to as poly-polymer) having a string length L of 5-0.5% by weight aqueous solution at 20 ° C. of 5 to 200 mm. Also referred to as an alkylene oxide water-soluble polymer). In this specification, the water-soluble polymer refers to a polymer having a solubility in 100 g of water at 25 ° C. of 1 g or more after neutralization.
The polyalkylene oxide chain is constituted by an alkyleneoxy group such as an ethyleneoxy group, a propyleneoxy group, or a butyleneoxy group, and these groups may constitute a single chain or a combination of two or more. You may comprise the chain | strand. When a chain is composed of two or more types of alkyleneoxy groups, the bond between different types of alkyleneoxy groups may be either a random bond or a block bond.
Preferably, the said thread length L is 10-150 mm, More preferably, it is 30-100 mm.
Among the above polyalkylene oxide water-soluble polymers, those having a polyalkylene oxide chain in the molecule of 90% by mass or more are preferable, and polyalkylene oxides composed only of polyalkylene oxides are more preferable, for example, polyethylene oxide, polypropylene oxide. Etc.

In the thickener for hydraulic composition of the present invention, the blending ratio of (A) detan gum and (B) polyalkylene oxide water-soluble polymer is 0.1 to 2.0: 0.1 to 10 in terms of mass ratio. More preferably, it is 0.5-1.0: 0.5-6.0.
Moreover, it is preferable to use the thickener for hydraulic compositions of this invention at 0.00015-0.20 mass% with respect to cement mass.

[Water reducing agent for concrete]
The present invention is also directed to a concrete water reducing agent containing the above-described hydraulic composition thickener and (C) a water reducing agent.
The (C) water reducing agent can be used for mortar and concrete and has a water reducing action, as long as it has a water reducing action, a dispersant, a high performance water reducing agent, an AE water reducing agent, a high performance AE water reducing agent, a fluidizing agent, etc. Any of what is called may be sufficient, and a component is not specifically limited. For example, water reducing agents such as polycarboxylic acid, naphthalene sulfonic acid, lignin sulfonic acid, and melamine sulfonic acid are listed. Among these, a polycarboxylic acid type is preferable.
The water reducing agent for concrete of the present invention can be used as a fluidizing agent for concrete.

In the concrete water reducing agent of the present invention, the blending amount of the (C) water reducing agent is 70.0 to 99.9% by mass with respect to the total mass of the water reducing agent for concrete.
Moreover, it is preferable to use the water reducing agent for concrete of this invention at 0.5-5 mass% with respect to cement mass.

In addition, the preferable ratio of (A) detan gum, (B) polyalkylene oxide water-soluble polymer and (C) water reducing agent in the water reducing agent for concrete of the present invention is 0.1 to 2.0: 0. It is 1-10: 10-30, More preferably, it is 0.5-1.0: 0.5-6.0: 20-25.
Moreover, in the water reducing agent for concrete of the present invention, the dutan gum, the polyalkylene oxide water-soluble polymer and the water reducing agent are each 0.000075 to 0.0015% by mass: 0.000075 to 0.0090% by mass with respect to the cement mass: It is preferable to use at 0.025-2.0 mass%.
By using these components in a more preferable ratio, the storage stability as a water reducing agent for concrete is excellent, and the thickener component can be kept in a uniformly dissolved state in the water reducing agent component. In addition, by using the water reducing agent for concrete blended in the above-mentioned preferred ratio with respect to concrete, the surface brittleness of the concrete after manufacture is improved, and the load on the pump is reduced during concrete pumping performed by the CFT method. A reduced effect is expected.

  In addition, in the water reducing agent for concrete of the present invention, a suitable publicly known additive can be blended according to various concrete production conditions. Specifically, additives that can be blended include air entraining agents, curing accelerators, separation reducing agents, curing agents, mold release agents, antifoaming agents, shrinkage reducing agents, surface aesthetics improving agents, water repellents, setting retarders. Concrete paints, surface repair materials and the like. In addition to these, various admixtures commonly used in cement compositions such as thickeners other than the above-described thickener components, expansion agents, rust inhibitors, organic fibers, inorganic fibers, organic polymers, and pigments can be blended.

The thickening agent for hydraulic composition and the water reducing agent for concrete according to the present invention can be used by adding a stock solution at the time of kneading concrete or mortar, or by diluting in advance to kneading water. Also, after mixing water, cement, fine aggregate and coarse aggregate to make fresh concrete, or after mixing water, cement and fine aggregate to make mortar, this fresh concrete or mortar is hydraulic. It is also possible to add a thickener for the composition or a water reducing agent for the concrete and knead it again uniformly.
Here, the components other than the thickener and the water reducing agent for the hydraulic composition are conventionally used hydraulic composition components, and cement (for example, ordinary Portland cement, early strong Portland cement, low heat / moderate heat Portland cement or blast furnace cement). Etc.), aggregate (ie fine aggregate and coarse aggregate), admixture (eg fly ash, silica fume, calcium carbonate powder, blast furnace slag powder), gypsum (eg dihydrate gypsum, hemi-gypsum and anhydrous gypsum), expansion material And water. And the thickener for hydraulic composition and the water reducing agent for concrete of the present invention include not only the production of concrete (ordinary concrete) by a general blending formula, but also blending admixtures such as fly ash and fine limestone powder.・ Applicable to the production of high fluidity concrete.
In addition to the thickener for hydraulic composition and the water reducing agent for concrete of the present invention, the admixture for concrete that can be added separately at the time of preparation includes the above-mentioned publicly known air entraining agent, setting retarder, accelerator, separation reduction There are agents, thickeners, antifoaming agents, shrinkage reducing agents, and the like, and these can be appropriately blended. The blending ratio of these components can be appropriately determined according to the type of the selected component and the purpose of use.

  One of the reasons why the thickener for hydraulic composition of the present invention realizes suitable fluidity and is excellent in material separation resistance is a synergistic effect by combining dutan gum and a water-soluble polymer having spinnability. It is inferred that Normally, polysaccharides used as thickeners exist as aggregates of one molecule or two or more molecules due to changes in concentration and temperature in an aqueous solution, but in any case of aggregates, a thickening effect is exhibited. The functional group necessary for this is taken into the aggregate, so that the expected thickening effect cannot be obtained. On the other hand, in the present invention, by using a combination of dutan gum and a water-soluble polymer having spinnability as a thickener component, these thickener components having different structures form a bimolecular aggregate in the concrete surplus water. I think that. At this time, the functional groups involved in the thickening present in these different thickening agent components are present without being taken into the aggregate and are considered to have an arrangement (structure) that can act effectively. Therefore, it is considered that a stable thickening effect can be obtained without depending on changes in concentration or temperature in the aqueous solution.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[Measurement method of thread length]
The string length of the water-soluble polymer was measured as follows.
In this example, various polyethylene oxides were used as the water-soluble polymer, and 200 ml of this 0.5% by mass aqueous solution was prepared. Next, the liquid temperature of the prepared aqueous solution was adjusted to 20 ° C. A glass sphere having a diameter of 10 mm was immersed in the liquid surface of the aqueous solution, and the glass sphere was pulled up at a speed of 14 mm / second. The height from the liquid surface at the time when the yarn was broken was defined as the kite length L.

[Test 1: Cement paste rheology test]
Mixing of the cement paste is performed only with a water reducing agent (SEICAMENT 1100NT (manufactured by Nippon Sika Co., Ltd.)) (Comparative Example 1), or a water reducing agent (same as above) and a thickener component (Dutan gum and / or polyethylene oxide) (Example) 1, Comparative Example 2 and Comparative Example 3) were added in advance and adjusted water (mixed water) was added to the cement, and hand-kneaded for 180 seconds using a stainless steel spatula. Here, the water reducing agent and the thickener component were used as part of the amount of water.
The cement paste (4 types) prepared in the above procedure was divided into two parts, and the temperature of each cement paste was adjusted to 25 ° C. or 35 ° C., and their viscosities were measured using a coaxial double cylinder viscometer (Rhetec) Viscosity behavior (change amount of shear stress generated when shear stress was changed) was measured using RC20 manufactured by RC20.
The composition of the test cement paste is shown in Table 1. The obtained results are shown in FIG. 1 and FIG. 2, and the shear stress (Pa) at shear rates D: 10 s ⁻¹ and 30 s ⁻¹ at 25 ° C. and 35 ° C. are shown in Table 2.

  As shown in FIG. 1 and FIG. 2 and Table 2, in the cement paste of Comparative Example 2 in which only the dutan gum was added as a thickener component, the peculiarity of shear stress at low speeds at both 25 ° C. and 35 ° C. The increase was confirmed by the addition of detan gum and polyalkylene oxide water-soluble polymer (polyethylene oxide) having spinnability as a thickener component (that is, the thickener for hydraulic composition of the present invention). In the cement paste of Example 1, such an increase in shear stress was not observed. Thus, the thickener for hydraulic compositions of the present invention suggests that the viscosity change of the thickener that can affect the fluidity of fresh concrete is small in the temperature range where concrete production is assumed. Results were obtained.

[Test 2: Mortar test]
For cement and fine aggregate, only water reducing agent (Seakament 1100NT, Seakament 1100NTR (manufactured by Nippon Seika Co., Ltd.)) (Comparative Example 4), or water reducing agent (same as above) and thickener component (Dutan gum and / or polyethylene oxide) (Examples 2 to 6 and Comparative Examples 5 to 7) were added in advance and added with kneading water, and a high power mixer (manufactured by Maruto Seisakusho) was used for 60 seconds at low speed, and then Kneading was carried out at a high speed for 30 seconds to prepare mortars with kneading temperatures of 20 ° C. and 30 ° C.
For these mortars just after kneading, the spread of the mortar (miniflow) is measured using a mini slump cone (top inner diameter 50 mm, lower end inner diameter 100 mm, height 150 mm) according to JIS A 1171 “Test method for polymer cement mortar”. did. After the miniflow measurement, the state of the mortar was visually confirmed. Moreover, the mortar produced in the J14 funnel described in the Japan Society of Civil Engineers concrete standard specification was filled, and the flow time of the mortar was measured.
Table 3 shows the unit amount of each material used, and Table 4 shows the test results.

As shown in Table 4, in Examples 2 to 6, the cement paste and sand are integrated at 20 ° C. and 30 ° C., and there is almost no water floating on the mortar surface. Was good. Moreover, the J14 funnel flow time used as a parameter | index of workability was shorter than any comparative example.
Thus, the result that the thickener for hydraulic compositions and the water reducing agent for concrete of the present invention can stably give viscosity suitable for construction to mortar even in different temperature ranges was obtained.

[Test 3: Concrete test Fluidized concrete]
Based on the formulation shown in Table 5, fresh concrete was prepared according to JIS A 1138. As the mixing method, a biaxial forced mixing mixer having a nominal capacity of 100 liters was used, and the concrete production amount of each batch was set to 40 liters × 1 batch.
First, cement, fine aggregate, mixed water, coarse aggregate and water reducing agent (Seakament 1100NT: 0.70% by mass with respect to cement) were added and mixed for 90 seconds, and the standard concrete (in Table 6, Comparative Example 8) was produced. The reference concrete was set to 0 minutes with lapse of time immediately after mixing and 30 minutes after 30 minutes.

After 15 minutes from the mixing of the reference concrete prepared by the same procedure as described above, the reference concrete is returned to the mixer, where a water reducing agent (Seakament 1100NT: 0.50% by mass with respect to cement) and a thickener component (Dutantham ( Admixture containing 0.0010% by mass) and polyethylene oxide (0.0050% by mass)) and kneading for 30 seconds to produce fluidized concrete (Example 7, Comparative Example 9 in Table 6). Was made. In the fluidized concrete, the time immediately after fluidization was 0 minute, and the time after 30 minutes was 30 minutes.

In accordance with JIS A 1101 and JIS A 1150, slump, slump flow, 50 cm flow arrival time, flow of various concretes (reference concrete, fluidized concrete) produced by the above procedure in accordance with JIS A 1101 and JIS A 1150. The flow stop time of was measured. After measuring the slump flow, the condition of the concrete was visually confirmed. Using the same sample, the O funnel flow time was measured in accordance with JSCE-F 512-2011. In addition, the amount of air was measured according to JIS A 1128.
Further, the amount of bleeding was measured according to JIS A 1123, and the setting time of concrete was measured according to JIS A 1147. Furthermore, a specimen for compressive strength test was prepared according to JIS A 1132, and the compressive strength was measured according to JIS A 1108.
The temperature of the fresh concrete used in the above test was 20 ± 3 ° C.
The results obtained are shown in Table 6.

As shown in Table 6, compared to the reference concrete to which only the water reducing agent was added (Comparative Example 8), in Example 7 to which the water reducing agent for concrete of the present invention was added, the amount of bleeding was greatly reduced, and coarse bone The material and fine aggregate were uniformly dispersed throughout the concrete, and the condition of the concrete was also good, resulting in improved material separation resistance.
Moreover, the concrete (Example 7) to which the water reducing agent for concrete of the present invention was added was compared with the concrete (Comparative Example 9) produced by adding a thickener component other than the thickener specified in the present invention. In addition to shortening the flow time of the O funnel, which is an index of the performance, the retention of the slump flow is improved and the bleeding amount is reduced. In addition, the effects of shortening the initial and final setting times and increasing the compressive strength were confirmed.
Thus, the result which suggests that the water reducing agent for concrete of this invention can manufacture the concrete excellent in workability and material-separation resistance was obtained by the present Example.

[Test 4: Application to concrete fluidized concrete]
Based on the formulation shown in Table 7, fresh concretes of Examples 8 to 10 and Comparative Examples 10 and 11 were prepared in the same procedure as the method for preparing the reference concrete of [Test 3]. The kneading time was 90 seconds. In Examples 8 to 10 and Comparative Example 11, a thickener component (Dutan gum and polyethylene oxide) was added together with a water reducing agent (Seakament 1100NT). Moreover, all the temperatures of the fresh concrete used for the test were 20 ± 3 ° C.

About the produced concrete, in the same procedure as the said test 3, the slump flow of 0-minute passage time, the flow stop time of the flow, and the air quantity were measured, and the separation state of concrete was confirmed visually. Similarly, bleeding amount, setting time, and compressive strength were measured.
In addition, for the purpose of confirming the deformability of concrete under vibration, Vol. 32, no. 1, 2010; Excitation of concrete after slump flow measurement based on the test procedure and evaluation method described in "Examination of applicability of medium-fluidity concrete using thickener to tunnel lining" The test was conducted. In this method, a rod-like vibrator is installed on the lower surface of the flow plate, the concrete is subjected to vibration for 10 seconds, and the amount of change in slump flow (cm) before and after vibration is measured. It can be evaluated that the amount of change in the vibration flow is within 10 ± 3 cm satisfies the required fluidity and material separation resistance as medium fluidity concrete.
Further, a concrete filling property test was performed by the test described in JSCE-F511. This is a test when there is no flow obstruction reinforcing bar from the U-shaped container (rank 3). Here, the filling height B _h (mm) was an average value at three locations at both ends and the center in the width direction of the container. When filling height B _h is more than 28cm, it can be evaluated that satisfies the required filling of the medium-fluidity concrete.
Table 8 shows the obtained results.

As shown in Table 8, Example 8 to Example 10 was added for concrete water-reducing agent of the present invention concrete, the amount of change in vibration flow 10 ± 3 cm, and the addition fill height B _h is more than 29cm Results are shown. In addition, coarse and fine aggregates are uniformly dispersed throughout the concrete, resulting in a good condition of the concrete and a small amount of bleeding. These concretes have the workability and material separation resistance necessary for medium-fluidity concrete. I got the result. In addition, as a result of the shortening of the setting time, it was expected that the side pressure acting time on the formwork could be shortened when applied to an actual structure.

Claims (3)

A water-soluble polymer having (A) dutan gum and (B) a polyalkylene oxide chain, wherein the string length L of a 0.5 mass% aqueous solution of the polymer at 20 ° C is 5 to 200 mm , (A) Thickener for hydraulic composition which the mixing ratio of a dutan gum and (B) water-soluble polymer contains in the ratio of 0.1-2.0: 0.1-10 by mass ratio . The thickener for hydraulic composition according to claim 1, wherein the water-soluble polymer (B) is a polyalkylene oxide. A water reducing agent for concrete containing the thickener for hydraulic composition according to claim 1 or 2, and (C) a water reducing agent.