JP2012140265A - Polymer cement mortar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer cement mortar which hardly flows even when laid on a pitched place while vibrating and has excellent surface smoothness after execution.SOLUTION: The polymer cement mortar contains (a) a fine aggregate having a maximum grain size of ≤5 mm, (b) a polymer for cement blend, (c) a thickening agent and (d) cement. The mortar is characterized in that when the component (a) is divided into at least three groups by the magnitude of grain size and continuous three groups of the three or more groups are defined as the first, second and third groups, the content of the fine aggregate in each of the first, second and third groups is 10 pts.mass or more based on 100 pts.mass of the component (a), and the content of the fine aggregate in the second group is lower by ≥1 pt.mass than those of the first and third groups based on 100 pts.mass of the component (a).

Description

  The present invention relates to a polymer cement mortar.

In recent years, a lot of fatigue shear fractures due to the wheel load of RC slabs and fatigue damage from the U-rib root part of steel slabs have occurred in road bridges, etc., and a part of the pavement on the slabs was replaced with a high-strength material. Therefore, measures are taken to reduce the force acting on the floor slab.
As a method for increasing such strength, an upper surface thickening method is known in which the upper surface of the above-mentioned floor slab is reinforced with steel fiber reinforced concrete (Patent Document 1) or polymer cement mortar (Patent Document 2).

In order to enhance the adhesion to old concrete and steel plate, the polymer cement mortar used in the upper surface thickening method is required to have fluidity and the like, and the material is required to have high filling properties.
Moreover, this polymer cement mortar is constructed by vibration compaction or the like in order to obtain a uniform thickness (Patent Document 3).

JP 2005-314992 A JP 2008-179995 A JP 2008-179993 A

However, when reinforcing a floor slab with a gradient, the vibration applied during vibration compaction causes the polymer cement mortar to flow down the gradient, making it difficult to obtain a uniform thickness. Sometimes overflowed from the formwork.
On the other hand, if the vibration compaction time is shortened, the amount of mortar flowing downward in the gradient can be suppressed, but the surface smoothness cannot be sufficiently obtained, and there is a problem that undulation occurs.
Accordingly, an object of the present invention is to provide a polymer cement mortar that is difficult to flow even when a vibration is applied in a gradient and is excellent in surface smoothness after construction.

  Therefore, as a result of intensive studies, the present inventors have found that there is a gradient by including fine aggregates having a maximum particle size of 5 mm or less adjusted to a specific particle size distribution in cement polymer, thickener and cement. It has been found that polymer cement mortar is obtained which is difficult to flow even when vibration is applied and which has excellent surface smoothness after construction.

  That is, the present invention contains (a) a fine aggregate having a maximum particle diameter of 5 mm or less, (b) a polymer for cement, (c) a thickener and (d) cement, and contains at least three components (a). When the three consecutive groups among the three or more groups are defined as the first group, the second group, and the third group, the first group, the second group, and the third group. The content of fine aggregate in each group of the group is 10 parts by mass or more with respect to 100 parts by mass of the component (a), and the content of fine aggregate in the second group is that of the first group. The present invention provides a polymer cement mortar characterized by being 1 mass part or more lower than the fine aggregate content and the third group fine aggregate content.

  The polymer cement mortar of the present invention is difficult to flow even when it is vibrated where there is a gradient, and is excellent in surface smoothness and compressive strength after construction.

It is a figure which shows an example of the thickness measurement of the mortar after vibration compaction.

  The polymer cement mortar of the present invention contains the components (a) to (d). First, these components will be described in detail.

<(A) Fine aggregate with a maximum particle size of 5 mm or less>
Examples of the fine aggregate having a maximum particle size of 5 mm or less of the component (a) include river sand, land sand, sea sand, crushed sand, silica sand and artificial lightweight aggregate, and these are used alone or in combination of two or more. it can. Among these, silica sand is preferable in terms of low reactivity and low cost.
The particle size of the fine aggregate is preferably 0.01 to 5 mm, more preferably 0.05 to 5 mm, and particularly preferably 0.05 to 3 mm. The particle size of the present invention can be measured with a laser diffraction type particle size distribution measuring device as described in Examples below.

  As content of the said fine aggregate, 50-400 mass parts is preferable with respect to 100 mass parts of components (d) from the point of fluidity | liquidity, a filling property, shrinkage | contraction amount, and a heat | fever of hydration, and 100-350 mass parts is preferable. More preferred is 200 to 300 parts by mass.

  Here, in the present invention, the component (a) is divided into at least three or more groups according to particle size, and three consecutive groups among the three or more groups are divided into a first group, a second group, and The content of fine aggregates in each group of the first group, the second group, and the third group when it is set as the third group is 10 parts by mass or more with respect to 100 parts by mass of the component (a).

  The number of groups divided by the particle size is 3 or more, but from the viewpoint of fluidity and smoothness, 3 to 15 is preferable, 3 to 10 is more preferable, and 3 to 6 is particularly preferable. When there are three groupings, the groups are the first group, the second group, and the third group from the group having a larger particle size. On the other hand, when the grouping is five, among the five groups from 1 to 5 having a large particle size, the groups 1-3, 2-4, or 3-5 are the first group, the second group, and the third group. A group.

  As content of the said 1st group fine aggregate, 15-50 mass parts is preferable with respect to 100 mass parts of components (a) from the point of fluidity | liquidity and smoothness, 20-40 mass parts is more preferable, 20-30 mass parts is more preferable, and 25-28 mass parts is especially preferable.

As content of the said 2nd group fine aggregate, 10-25 mass parts is preferable with respect to 100 mass parts of component (a) from the point of fluidity | liquidity and smoothness, 10-20 mass parts is more preferable, 12-18 mass parts is more preferable, and 13.5-15.5 mass parts is especially preferable.
Further, the content of the fine aggregate of the second group is an amount that is 1 part by mass or more lower than the content of the fine aggregate of the first group and the content of the fine aggregate of the third group, From the viewpoint of fluidity and smoothness, it is preferably 5 to 30 parts by mass, particularly preferably 10 to 20 parts by mass.

  As content of the said 3rd group fine aggregate, 15-50 mass parts is preferable with respect to 100 mass parts of components (a) from the point of fluidity | liquidity and smoothness, 20-40 mass parts is more preferable, 20-35 mass parts is more preferable, and 28-35 mass parts is especially preferable.

The range of the particle size of the fine aggregates included in the first group, the second group, and the third group is, for example, 0.01 mm or more and less than 0.15 mm, 0.15 mm or more and less than 0.3 mm, or 0.3 mm or more. It is less than 0.6 mm, 0.6 mm or more and less than 1.18 mm, 1.18 mm or more and less than 2.26 mm, 2.26 mm or more and 5 mm or less.
As a combination of the first group, the second group and the third group, from the viewpoint of fluidity and smoothness, the particle size of the first group is 1.18 mm or more and less than 2.26 mm, and the particle size of the second group is A combination of 0.6 mm or more and less than 1.18 mm and a third group particle size of 0.3 mm or more and less than 0.6 mm; a first group particle size of 0.6 mm or more and less than 1.18 mm; A combination in which the particle size of the second group is 0.3 mm or more and less than 0.6 mm and the particle size of the third group is 0.15 mm or more and less than 0.3 mm is preferable.

<(B) Polymer for cement>
The polymer for cement of component (b) is preferably a polymer specified in JIS A 6203 “Polymer dispersion for cement admixture and re-emulsifying powder resin”. Examples of such cement polymers include polymer dispersions and re-emulsifying powder resins. The polymer dispersion is preferably a synthetic rubber such as styrene butadiene rubber; a natural rubber; a rubber asphalt; an ethylene vinyl acetate; an acrylate ester; or a resin asphalt. Among these, a synthetic rubber system is preferable, synthetic rubber latex, polyacrylic acid ester, and ethylene vinyl acetate are more preferable, and styrene butadiene rubber is particularly preferable from the viewpoint of adhesion to old concrete and steel plate.

  As content of the said polymer for cement, 9-30 mass parts is preferable with respect to 100 mass parts of components (d) from the point of adhesiveness and workability, and 15-20 mass parts is more preferable. By setting it as 9 mass parts or more, adhesiveness improves and the outstanding followable | trackability with respect to old concrete or a steel plate is obtained. On the other hand, the workability which was excellent by setting it as 30 mass parts or less is acquired.

<(C) Thickener>
As a thickener of component (c), from the viewpoint of showing water retention, a cellulose-based or acrylic-based polysaccharide-based or synthetic water-soluble polymer, or a polysaccharide-based water-insoluble polymer is a main component. It is preferable to use a polysaccharide as a main component.
Examples of the polysaccharide include cellulose-based water-soluble polymers, starch, pectin, guar gum, xanthan gum, and carrageenan.

  As content of the said thickener, 0.002-2.0 mass parts is preferable with respect to 100 mass parts of component (d), and 0.01-0.5 mass part is more preferable. By setting it as 0.01-0.5 mass part, the workability and filling property by vibration compaction improve.

<(D) Cement>
Examples of the component (d) cement include various ordinary Portland cements such as normal strength, early strength, ultra-high strength, low heat and moderate heat; alumina cement; fast-hardening cement; fly ash, blast furnace slag, silica or limestone fine powder, etc. Various mixed cements in which Portland cement is mixed.
Among these, Portland cement is preferable and normal Portland cement is particularly preferable from the viewpoint of hydration heat generation and long-term age strength.

  The polymer cement mortar of the present invention may contain (e) water, (f) short fibers, and (g) a water reducing agent in addition to the components (a) to (d).

  The water content of the component (e) is usually about 25 to 45 parts by mass with respect to 100 parts by mass of the component (d), but is preferably 26 to 32 parts by mass from the viewpoint of fluidity and workability.

Examples of the short fiber of component (f) include steel fiber, glass fiber, synthetic fiber, carbon fiber, polypropylene fiber, and aramid fiber.
Content of the said short fiber is about 0.01-0.3 mass part normally with respect to 100 mass parts of components (d).

As the water reducing agent of component (g), for example, a water reducing agent including a high performance water reducing agent, a high performance AE water reducing agent, an AE water reducing agent, and a fluidizing agent is preferable. Examples of such a water reducing agent include water reducing agents specified in JIS A 6204 “Chemical admixture for concrete”.
Among these, polycarboxylic acid type, naphthalene type, lignin sulfonic acid type, and acrylic type are preferable.
The content of the water reducing agent is usually about 0.1 to 5 parts by mass with respect to 100 parts by mass of the component (d).

In addition to the components (a) to (g) described above, the polymer cement mortar of the present invention is usually used in mortars, for example, retarders, curing accelerators, foaming agents, waterproofing agents, rust prevention agents, Shrinkage reducing agents, pigments, water repellents, white flower inhibitors, and the like may be included.
Examples of the retarder include inorganic substances such as fluoride, phosphate and borate, and organic substances such as sugars, lignin sulfonate and citrate.

The polymer cement mortar of the present invention can be produced according to a conventional method after obtaining a fine aggregate having a maximum particle size of 5 mm or less by operation such as sieving and mixing.
The polymer cement mortar of the present invention is less likely to flow even when it is vibrated where there is a gradient, and is excellent in surface smoothness and compressive strength after construction.
Therefore, it is particularly useful for the construction of sloped roads (roadbeds, etc.) and floor slabs, wall surfaces (outer walls, etc.) of buildings, or top surface pressure increasing methods by vibration compaction.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples.
The materials of the polymer cement mortar used in the examples are as follows.
Fine aggregate (silica sand): Maeda Kensetsu Kogyo Co., Ltd., Yamagata silica sand; Takano Shoji Co., Ltd., Kashima quartz sand Polymer for cement: Taiheiyo Material Co., Ltd., Pacific CX-B (main component: styrene butadiene rubber)
Thickener: BASF Pozzolith Co., Ltd., Starvis (main component: polysaccharide)
Cement: Taiheiyo Cement Co., Ltd., Normal Portland Cement Fiber (Glass fiber (fiber length: 10 mm)): Taiheiyo Material Co., Ltd. Anti-crack Water reducing agent (acrylic): Showa Denko Co., Ltd., Melment

<Manufacture of polymer cement mortar>
Example 1
A plurality of the above-mentioned commercially available fine aggregates were mixed, and this was sieved using an electric ro-tap sieve vibrator, and divided into the following particle sizes A to F. Subsequently, these fine aggregates having different particle diameters were mixed together to obtain fine aggregates having a particle size distribution shown in Table 1. The particle size of the fine aggregate was confirmed using a laser diffraction particle size distribution measuring device.
A: 2.26 mm or more B: 1.18 mm or more and less than 2.26 mm C: 0.6 mm or more and less than 1.18 mm D: 0.3 mm or more and less than 0.6 mm E: 0.15 mm or more and less than 0.3 mm F: 0. Less than 15 mm Next, the obtained fine aggregate, cement and thickener were mixed, water and cement polymer were added thereto, and the mixture was stirred for 90 seconds with a hand mixer to obtain a polymer cement mortar having the formulation shown below. It was.

Fine aggregate: 300 parts by weight Polymer for cement: 18 parts by weight Thickener: 0.02 parts by weight Cement: 100 parts by weight Water: 27 parts by weight

(Examples 2 to 4 and Comparative Examples 1 to 4)
A polymer cement mortar was obtained in the same manner as in Example 1 except that the particle size distribution of the fine aggregate was changed to the particle size distribution shown in Table 1.
In Table 1 below, B in Examples 1 to 3 and C in Example 4 are the first group, C in Examples 1 to 3 and D in Example 4 are the second group, and Example 1 D of ˜3 and E of Example 4 are the third group.

<Evaluation of polymer cement mortar>
Each polymer cement mortar obtained by the above operation was evaluated and tested as follows. The results are shown in Table 2.

(Measurement of mortar thickness after vibration compaction)
A polymer cement mortar with a height of 40 mm is placed on a steel plate of 3000 mm long and 1600 mm wide as shown in FIG. 1 (crossing gradient: 8%) and placed by vibration compaction and left for 5 minutes to measure the thickness (mm) of the mortar. did.
The measurement locations were 0 mm, 400 mm, 800 mm, 1200 mm, and 1600 mm in the transverse direction from the upper end of the construction surface.

(Evaluation of smoothness)
Evaluation by visual observation and finger touch ○: There are few partial irregularities, and no undulation on the mortar surface is observed.
(Triangle | delta): There exists an unevenness | corrugation of 2-3 mm partially, and there exists a part where the surface of a mortar waves.

(Measurement of compressive strength)
Three specimens having a diameter of 5 cm and a height of 10 cm were prepared, and after the specimens were cured in air until the age of 28 days, JSCE-G505-1999 “Method for testing compressive strength of mortar or cement paste using cylindrical specimens The compressive strength was measured according to the above. If the compressive strength was 25 N / mm ² or more, it was judged as “good”.

  From the above test results, it can be seen that the polymer cement mortars of Examples 1 to 4 are difficult to sag, have a uniform thickness, and have excellent surface smoothness even if they are applied by vibration compaction where there is a gradient. It was.

(Examples 5 and 6)
A polymer cement mortar was obtained in the same manner as in Example 1 except that the components listed in Table 3 were used in addition to the fine aggregate, cement thickener, water and cement polymer.
About the obtained polymer cement mortar, the thickness of the mortar after vibration compaction was measured in the same manner as described above. The results are shown in Table 4.

Claims (3)

(A) a fine aggregate having a maximum particle size of 5 mm or less, (b) a polymer for cement, (c) a thickener and (d) cement.
When component (a) is divided into at least three or more groups by particle size, and three consecutive groups of the three or more groups are defined as a first group, a second group, and a third group,
The fine aggregate content of each group of the first group, the second group and the third group is 10 parts by mass or more with respect to 100 parts by mass of the component (a),
The polymer characterized in that the content of the fine aggregate of the second group is 1 part by mass or more lower than the content of the fine aggregate of the first group and the content of the fine aggregate of the third group. Cement mortar.   The polymer cement mortar according to claim 1, further comprising one or more selected from (f) short fibers and (g) a water reducing agent.   The polymer cement mortar according to claim 1 or 2, wherein the polymer cement mortar is used for a top pressure increasing method by vibration compaction.

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