JP2014080337A - Method for forcibly feeding concrete by pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forcibly feeding concrete, in which the pump forced feedability of poor mix concrete having 8-15 cm slump value is improved so that the slump value is restrained from being changed before and after the poor mix concrete is forcibly fed by a pump and excellent executability can be imparted thereto.SOLUTION: In the method for forcibly feeding concrete by the pump, the predetermined concrete containing water, cement, a mixing agent, a polysaccharide derivative and an aggregate is forcibly fed by the pump. The polysaccharide derivative is obtained by substituting hydrophobic substituents, each of which has a 8-40C hydrocarbon chain as a partial structure, or ionic hydrophilic groups, each of which has one or more groups selected from the group consisting of a sulfonic acid group and a sulfonate group as another partial structure, for hydrogen atoms of a part or the whole of hydroxyl groups of a polysaccharide, an alkylated derivative thereof, or a hydroxyalkylated derivative thereof.

Description

  The present invention relates to a method for pumping concrete.

  Conventionally, it has been practiced to pump concrete and place it. In recent years, the ratio of pumping concrete to concrete has been increasing year by year. In the background, pump cars and cement dispersants have been improved and improved performance, which is thought to be one of the reasons why stable pumpability can be secured. Even pumping is becoming possible.

  Patent Document 1 discloses a cement-based composition for pumping by adding a water-soluble nonionic cellulose ether, a polycarboxylate-based dispersant, and an antifoaming agent. The cement-based composition of Patent Document 1 is said to have little change in quality such as slump loss before and after pumping. For example, when pumping concrete having a slump value of 21 cm before pumping, the slump value after pumping No. in Table 1 was 21 cm. It is described as 5.

Patent Document 2 contains an artificial lightweight coarse aggregate used without prior water absorption having an absolute dry specific gravity of 1.5 or less and a water absorption rate of 5 wt% or less, and a unit cement amount of 320 to 550 kg / m ³ . A lightweight concrete composition is disclosed in which the unit amount is 300 to 400 L / m ³ and the fresh concrete is pumped and the slump flow value is 40 cm or more. In Patent Document 2, it is described that the slump value of fresh concrete is preferably 8 to 21 cm, and in the example, for example, concrete having a slump value of 12.5 cm before pumping is pumped, and the slump after pumping is used. No. in Table 3 indicates that the value was 12.0 cm. It is described as 4.

  Patent Document 3 describes a method for producing concrete that increases the fluidity by adding a polysaccharide derivative and a polycarboxylic acid-based dispersant at a construction site after transporting the concrete. As the polysaccharide derivative, a hydrophobic substituent in which part or all of the hydroxyl groups of the polysaccharide or its alkylated or hydroxyalkylated derivative have a hydrocarbon chain having 8 to 40 carbon atoms, a sulfonic acid group, and a carboxyl group , A polysaccharide derivative substituted with an ionic hydrophilic substituent having at least one group selected from the group consisting of a phosphate group, a sulfate group, and a salt thereof.

JP-A 61-146748 JP 2001-089262 A JP 2007-105899 A

  In the construction scene of civil engineering, concrete with a small amount of unit cement used, so-called poor blended concrete may be used. However, pumping is difficult for poorly-mixed concrete at present, and even if it can be pumped, there is a large difference in fluidity before and after pumping, a significant decrease in workability, and problems such as poor discharge and clogging during pumping. There are many cases where this occurs. The main cause is considered to be that separation of water is likely to occur during pumping because poor blended concrete has a small amount of unit cement. In order to solve this problem, there are a method of increasing the slump value to increase fluidity and a method of increasing the unit cement amount. However, when the slump value is increased, material separation is likely to occur, and when the unit cement amount is increased, the hardened concrete obtained exceeds the required performance in terms of strength and so on. You will be forced to produce economical concrete. Therefore, there is a demand for a pumping method that can ensure good pumpability even in poorly blended concrete.

  The object of the present invention is to improve the pumpability by pumping concrete with a lower discharge pressure at the time of pumping in poor blended concrete having a slump value of 8 cm or more and 15 cm or less, and suppressing the slump change before and after pumping. It is to provide a concrete pressure feeding method capable of imparting workability.

The present invention is a concrete pumping method of pumping concrete containing water, cement, admixture, polysaccharide derivative and aggregate by a pump,
A hydrophobic substituent in which the polysaccharide derivative is a polysaccharide or an alkylated derivative or a hydroxyalkylated derivative thereof, wherein a part or all of the hydroxyl atoms have a hydrocarbon chain having 8 to 40 carbon atoms as a partial structure; A polysaccharide derivative substituted with an ionic hydrophilic group having a partial structure of one or more groups selected from the group consisting of sulfonic acid groups and salts of sulfonic acid groups,
The unit cement amount of the concrete is 250 kg / m ³ or more and 360 kg / m ³ or less,
The water-cement ratio of the concrete is 0.45 or more and 0.60 or less,
The slump value of the concrete before pumping is 8 cm or more and 15 cm or less,
The present invention relates to a concrete pumping method.

  According to the present invention, in poor blended concrete having a slump value of 8 cm or more and 15 cm or less, the concrete is pumped at a lower discharge pressure at the time of pumping to improve pump pumpability, and the slump change before and after pumping is suppressed, which is good. A concrete pressure-feeding method capable of imparting workability is provided.

The graph which shows the result of the pressure bleeding test using the concrete of an Example and a comparative example

  The concrete according to the present invention is so-called poor blended concrete and has the above-mentioned problems. In the present invention, by adding a specific polysaccharide derivative in a specific amount to concrete, pumping can be performed, and a change in slump value can be reduced even after pumping. The reason for this is not clear, but is estimated as follows. Even if the content of the polysaccharide derivative (A) is such that the viscosity of the concrete does not increase, the hydrophobic substituent and the sulfonic acid group possessed by the polysaccharide derivative (A) are considered to form a large network in water. This formed network exists in an adsorbed state between cement particles in the hydraulic composition and between the aggregate surfaces, and bridges between the materials (cement-cement, cement-aggregate, aggregate-aggregate). It is estimated that Since this network structure is easily cut by receiving external force and is reconstructed without external force, the separation of the concrete is suppressed, and the change in the physical properties of the concrete during pumping and the lower discharge pressure can be secured. it is conceivable that.

  As the concrete water according to the present invention, those usually used for the preparation of concrete can be used, and examples thereof include tap water.

  Examples of the cement according to the present invention include ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, sulfate-resistant Portland cement, low heat Portland cement, white cement, and ecocement (for example, JIS R5214).

  Further, the cement may include blast furnace slag, fly ash, silica fume and the like as other hydraulic powders, and may include non-hydraulic limestone fine powders and the like. Silica fume cement or blast furnace cement mixed with cement may be used.

Unit cement content of the concrete according to the present invention is less 250 kg / m ³ or more 360 kg / m ^3, from the viewpoint of obtaining good pumpability in poor compounding concrete, 270 kg / m ³ or more preferably, 300 kg / m ³ The above is more preferable, and from the viewpoint of suppressing the amount of cement used, 340 kg / m ³ or less is preferable, and 320 kg / m ³ or less is more preferable.

  The water-cement ratio (weight of water / weight of cement) of the concrete according to the present invention is 0.45 or more and 0.60 or less, and from the viewpoint of obtaining good pumpability in poor blended concrete, 0.47 or more. Preferably, 0.50 or more is more preferable, 0.57 or less is preferable, and 0.55 or less is more preferable.

The unit water amount of the concrete according to the present invention is preferably 113 kg / m ³ or more, more preferably 127 kg / m ³ or more, more preferably 150 kg / m ³ or more, and 216 kg / m ² from the viewpoint of obtaining good pumpability in poor blended concrete. m ³ or less, further 194Kg / m ³ or less, further 176 kg / m ³ or less.

  The polysaccharide derivative according to the present invention is a hydrophobic substitution in which the hydrogen atoms of some or all of the hydroxyl groups of the polysaccharide or its alkylated derivative or hydroxyalkylated derivative have a hydrocarbon chain having 8 to 40 carbon atoms as a partial structure. A polysaccharide derivative substituted with a group and an ionic hydrophilic group having a partial structure of one or more groups selected from the group consisting of sulfonic acid groups and salts of sulfonic acid groups. Hereinafter, the hydrophobic substituent is referred to as a hydrophobic substituent (P), the ionic hydrophilic group is referred to as an ionic hydrophilic group (Q), and the polysaccharide derivative according to the present invention is referred to as a polysaccharide derivative (A).

  The hydrophobic substituent (P) has 8 or more carbon atoms, preferably 12 or more, more preferably 16 or more, and 40 or less, preferably 36 or less, from the viewpoint of obtaining good pumpability in poor blended concrete. An alkyl glyceryl ether group having a linear or branched alkyl group of preferably 24 or less, having 8 or more carbon atoms, preferably 12 or more, more preferably 16 or more, and 40 or less, preferably 36 or less, more preferably 24 The following alkenyl glyceryl ether group having a linear or branched alkenyl group, a hydroxyl group may be substituted, and an oxycarbonyl group may be inserted, having 8 or more carbon atoms, preferably 12 or more, more preferably 16 or more and 40 or less, preferably 36 or less, more preferably 24 or less linear or branched Alkyl group, an alkenyl group or an acyl group. From the viewpoint of easy production and good pumpability in poor blended concrete, alkyl glyceryl ether groups, long-chain alkyl groups, and 2-hydroxy long-chain alkyl groups are preferable, and alkyl glyceryl ether groups are more preferable. Here, the alkyl glyceryl ether group refers to the structure of the remaining portion excluding one hydroxyl group of the alkyl glyceryl ether. More specifically, examples of the alkyl glyceryl ether group include 2-hydroxy-3-alkoxypropyl group, 2-alkoxy-1- (hydroxymethyl) ethyl group, 2-hydroxy-3-alkenyloxypropyl group, 2-alkenyloxy- A 1- (hydroxymethyl) ethyl group may be mentioned. These hydrophobic substituents (P) may be substituted with a hydrogen atom of a hydroxyl group of a hydroxyethyl group or a hydroxypropyl group bonded to a polysaccharide molecule.

  The ionic hydrophilic substituent (Q) is a substituent having, as a partial structure, one or more groups selected from the group consisting of sulfonic acid groups and salts of sulfonic acid groups from the viewpoint of salt resistance in the hydraulic composition. is there. Specifically, from the viewpoint of salt resistance in the hydraulic composition, a sulfoalkyl group having 1 to 5 carbon atoms which may be substituted with a hydroxyl group or a salt thereof may be mentioned. More specifically, a 2-sulfoethyl group, a 3-sulfopropyl group, a 3-sulfo-2-hydroxypropyl group, a 2-sulfo-1- (hydroxymethyl) ethyl group, and these sulfonic acid groups are converted into salts. One or more ionic hydrophilic groups selected from the group consisting of All or a part of the sulfonic acid group of the above group is a salt with an alkali metal such as sodium or potassium, an alkaline earth metal such as calcium or magnesium, an organic cation group such as an amine, or an ammonium ion. It may be.

  The degree of substitution between the hydrophobic substituent (P) and the ionic hydrophilic substituent (Q) in the polysaccharide (A) is determined from the viewpoint of obtaining appropriate solubility in kneaded water and pumpability. The degree of substitution by P) is preferably 0.0001 or more, more preferably 0.0005 or more, more preferably 1 or less, and more preferably 0.01 or less per unit of constituent monosaccharide residue. The degree of substitution with the ionic polar substituent (Q) is preferably 0.001 or more, more preferably 0.01 or more, more preferably 2 or less, and more preferably 1 or less per unit of constituent monosaccharide residue.

  Polysaccharides used as the raw material of the polysaccharide derivative (A) include cellulose; starch; rhizome polysaccharides such as konjac mannan and troolloi sticky substances; sap polysaccharides such as gum arabic, tragacanth and karaya; locust bean gum, guar gum and tamarind gum Seed polysaccharides such as agar, seaweed polysaccharides such as agar, carrageenan, and algin; animal polysaccharides such as chitin, chitosan heparin, and chondroitin sulfate; and microbial polysaccharides such as dextran and xanthan gum. Examples of alkylated derivatives or hydroxyalkylated derivatives of polysaccharides include cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, and hydroxypropyl cellulose. Further, the substituents such as methyl group, ethyl group, hydroxyethyl group, hydroxypropyl group and the like of these polysaccharides may be substituted with a single substituent or may be substituted with a plurality of substituents. The degree of substitution per constituent monosaccharide residue is preferably 0.1 or more, more preferably 0.5 or more, and 5 or less, further preferably 3 or less. When the substituent is an alkyleneoxy group, the degree of substitution, that is, the number of moles added per constituent monosaccharide residue is preferably 0.1 or more, more preferably 0.5 or more, and 10 or less, further 5 or less. Is preferred.

  The weight average molecular weight of the polysaccharide used as the raw material for the polysaccharide derivative (A) is preferably 100,000 or more, more preferably 200,000 or more, more preferably 500,000 or more from the viewpoint of obtaining solubility in water and pumpability in concrete. Is more preferably 5 million or less, more preferably 2 million or less, and even more preferably 1 million or less.

  The weight average molecular weight of the polysaccharide derivative (A) is preferably 100,000 or more, more preferably 200,000 or more, still more preferably 500,000 or more, from the viewpoint of obtaining solubility in water and pumpability in concrete. 5 million or less is preferable, 2 million or less is more preferable, and 1 million or less is more preferable.

  In the polysaccharide derivative (A), the hydrogen atom of the hydroxyl group of the polysaccharide or its alkylated derivative or hydroxyalkylated derivative is partially hydrophobized (introduction of a hydrophobic substituent (P)) or hydrophilized (ionic hydrophilic substitution). After introduction of the group (Q), it is obtained by hydrophilizing or hydrophobizing part or all of the remaining hydroxyl groups, respectively, or by simultaneously hydrophobizing and hydrophilizing.

  The introduction of substituents can be performed as follows as an example. That is, a polysaccharide or an alkylated derivative or hydroxyalkylated derivative thereof in the presence of an alkali is an alkyl or alkenyl glycidyl ether having an alkyl group having 8 to 40 carbon atoms or an alkenyl group, or a straight chain having 8 to 40 carbon atoms. Hydrophobic substituents (P) by reacting with chain or branched chain saturated or unsaturated hydrocarbon epoxides, halides, halohydrins or acyl halides, or esters or carboxylic acid anhydrides having 8 to 40 carbon atoms. ), And in the presence of an alkali, it is further reacted with a vinyl sulfonic acid or a haloalkane sulfonic acid having 1 to 5 carbon atoms which may be substituted with a hydroxyl group, or a salt thereof.

  In the polysaccharide derivative (A), the hydrogen atoms of a part or all of the hydroxyl group of a polysaccharide derivative selected from an alkylated derivative of a polysaccharide and a hydroxyalkylated derivative of a polysaccharide have a hydrophobic substituent (P) and an ionic hydrophilic property. A polysaccharide derivative substituted with the group (Q) is preferred. Furthermore, in the polysaccharide derivative (A), a part or all of the hydroxyl groups of the polysaccharide derivative selected from an alkylated derivative of cellulose and a hydroxyalkylated derivative of cellulose have a hydrophobic substituent (P) and an ionic hydrophilic property. A polysaccharide derivative substituted with the group (Q) is preferred. Furthermore, in the polysaccharide derivative (A), a part or all of the hydroxyl groups of the polysaccharide derivative (preferably hydroxyethylcellulose) selected from the hydroxyalkylated derivatives of the polysaccharide are ionic with the hydrophobic substituent (P). A polysaccharide derivative substituted with a hydrophilic group (Q) is preferred.

  In the concrete according to the present invention, the content of the polysaccharide derivative (A) is 0 with respect to 100 parts by weight of cement from the viewpoint of obtaining pumpability and adjusting to a predetermined slump value and maintaining the slump after pumping. 0.002 part by weight or more is preferable, 0.01 part by weight or more is more preferable, 0.013 part by weight or more is further preferable, 0.030 part by weight or less is preferable, 0.020 part by weight or less is more preferable, 0 .018 parts by weight or less is more preferable.

  In the concrete according to the present invention, the content of the polysaccharide derivative (A) is 0.002 parts by weight or more with respect to 100 parts by weight of cement from the viewpoint of obtaining pumpability and suppressing the discharge pressure of the pump. Preferably, 0.005 parts by weight or more is more preferable, 0.008 parts by weight or more is more preferable, 0.015 parts by weight or less is preferable, 0.013 parts by weight or less is more preferable, and 0.010 parts by weight or less is preferable. Further preferred.

  The admixture is a chemical admixture for concrete, and a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent and the like specified in JIS A6204 can be used. Admixtures include naphthalene formalin condensate, melamine sulfonic acid metal salt formaldehyde condensate, phenol sulfonic acid formaldehyde compound (compound described in JP-A-49-104919), phenol / sulfanilic acid formaldehyde co-condensate (special And compounds described in Japanese Utility Model Laid-Open No. 1-113419), phosphoric acid ester polymers (compounds described in JP-A-2006-52381), polycarboxylic acid polymers, and the like. From the viewpoint of compatibility with the polysaccharide derivative (A), a polycarboxylic acid polymer is preferred. The polycarboxylic acid-based polymer includes a compound represented by the following general formula (I) [hereinafter referred to as compound (I)] and a compound represented by the following general formula (II) [hereinafter referred to as compound (II). And a polycarboxylic acid polymer obtained by polymerization of

[Wherein, R ¹ represents a hydrogen atom or a methyl group, m1 represents an integer of 0 to 2, AO represents an oxyalkylene group having 2 to 3 carbon atoms, and n represents an average added mole number. It is a number of -30, X represents a hydrogen atom or a C1-C4 alkyl group. ]

[Wherein, R ^{2 to} R ⁴ are each a hydrogen atom, a methyl group or (CH ₂ ) _m2 COOM ² , and M ¹ and M ² are a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, and an alkyl, respectively. It is ammonium or substituted alkylammonium, m2 represents the number of 0-2. ]

  The composition of the above polycarboxylic acid polymer is such that the proportion of the compound (I) in the constituent monomer of the polycarboxylic acid polymer is at least 5 mol%, more preferably at least 10 mol%, from the viewpoint of improving the fluidity of the concrete. Further, it is preferably 20 mol% or more, preferably 75 mol% or less, further 65 mol% or less, and more preferably 55 mol% or less. Furthermore, the ratio of the compound (II) in the constituent monomer of the polycarboxylic acid polymer is preferably 20 mol% or more, more preferably 30 mol% or more, and further preferably 40 mol% or more, and more preferably 95 mol% or less. It is preferably 85 mol% or less, more preferably 75 mol% or less.

  The polycarboxylic acid polymer has a weight average molecular weight of 25,000 or more, more preferably 35,000 or more, and further preferably 45,000 or more, and 95,000 or less, further 85,000 or less. Further, it is preferably 75,000 or less.

  The amount of admixture added is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more with respect to 100 parts by weight of cement from the viewpoint of adjusting the slump to a predetermined range and ensuring pumpability. The amount is preferably 2 parts by weight or less, more preferably 1.0 part by weight or less, and still more preferably 0.8 part by weight or less.

  When the admixture is a polycarboxylic acid polymer, the weight ratio of the admixture / polysaccharide derivative (A) is preferably 30 or more, preferably 250 or less, and 200 or less from the viewpoint of maintaining slump even after pumping. More preferably, 120 or less is still more preferable, 80 or less is still more preferable, 60 or less is still more preferable, 55 or less is still more preferable, and 45 or less is still more preferable. When the admixture is a polycarboxylic acid polymer, the weight ratio of the admixture / polysaccharide derivative (A) is preferably 35 or more, more preferably 45 or more, and more preferably 60 or more from the viewpoint of suppressing pump discharge pressure. Further preferred is 80 or less.

  Examples of the aggregate include fine aggregate and coarse aggregate. The fine aggregate is preferably mountain sand, land sand, river sand and crushed sand, and the coarse aggregate is preferably mountain gravel, land gravel, river gravel and crushed stone. The term “aggregate” is based on “Concrete Overview” (published on June 10, 1998, published by Technical Shoin). The content of the aggregate can be used in a range of mortar or concrete that is usually used. The concrete according to the present invention preferably contains fine aggregates and coarse aggregates as aggregates.

The amount of fine fine aggregate is preferably 700 kg / m ³ or more, more preferably 750 kg / m ³ or more, and further preferably 800 kg / m ³ or more, and 1000 kg / m ³ from the viewpoint of obtaining good pumpability in poor blended concrete. Hereinafter, it is preferably 950 kg / m ³ or less, more preferably 900 kg / m ³ or less.

The amount of unit coarse aggregate is preferably 850 kg / m ³ or more, more preferably 900 kg / m ³ or more, and further preferably 950 kg / m ³ or more, and 1150 kg / m ³ from the viewpoint of obtaining good pumpability in poor blended concrete. hereinafter, further 1100 kg / m ³ or less, further 1050 kg / m ³ or less.

The total aggregate amount, from the viewpoint of obtaining good pumpability in poor compounding concrete, as the unit aggregate weight, 1550kg / m ³ or more, further 1650kg / m ³ or more, preferably more 1750 kg / m ³ or more, and , 2150kg / m ³ or less, further 2050kg / m ³ or less, further 1950kg / m ³ or less.

  The proportion s / a of the fine aggregate in the aggregate is preferably 39.0% or more, more preferably 41.7% or more, and 44.4% or more from the viewpoint of obtaining good pumpability in poor blended concrete. Further, 55.3% or less is preferable, 52.6% or less is more preferable, and 49.9% or less is still more preferable. In addition, s / a represents the ratio of the volume of the fine aggregate (s) and the volume of the whole aggregate (a) in percentage.

The density of fine aggregate, from the viewpoint of obtaining good pumpability in poor compounding concrete, preferably 2.35 g / cm ³ or more, more preferably 2.45 g / cm ³ or more, 2.50 g / cm ³ or higher more preferably, and preferably from 2.85 g / cm ³ or less, more preferably 2.70 g / cm ³ or less, more preferably 2.65 g / cm ³ or less.

The density of the coarse aggregate, from the viewpoint of obtaining good pumpability in poor compounding concrete, preferably 2.55 g / cm ³ or more, more preferably 2.60 g / cm ³ or more, 2.65 g / cm ³ or higher more preferably, and preferably from 2.85 g / cm ³ or less, more preferably 2.80 g / cm ³ or less, more preferably 2.75 g / cm ³ or less.

  The concrete according to the present invention can be prepared by mixing water, cement, admixture, polysaccharide derivative (A) and aggregate with a mixer or the like. From the viewpoint of mixing the material to be blended with the concrete uniformly, kneading water containing water, an admixture and a polysaccharide derivative (A) is prepared in advance, and after mixing cement and aggregate, kneading water is added, Furthermore, the method of mixing is preferable.

  In the present invention, the concrete slump value before pumping is adjusted to 8 cm or more and 15 cm or less, and the concrete is pumped by a pump. From the viewpoint of workability, the slump value of the concrete before pressure feeding is 8 cm or more, preferably 10 cm or more, and more preferably 11 cm or more. Moreover, from a viewpoint of material separation suppression, it is 15 cm or less, 14 cm or less is preferable and 13.5 cm or less is more preferable.

  The concrete pumping method of the present invention can be carried out by pumping concrete that has been adjusted to have desired physical properties and has been kneaded into a suitably arranged pipe. Concrete can be pumped using a pump such as a pump car after being transported by a mixer car or the like.

  Examples of the type of pump include a squeeze type and a piston type, and the piston type is preferable from the viewpoint of the pumping capacity.

Okuryou per unit of concrete time by the pump, from the viewpoint of workability of the concrete is preferably more than 10 m ³ / h, more preferably at least 15 m ³ / h, more preferably more than 20 m ³ / h, and,耐材fees From the viewpoint of separation resistance, 50 m ³ / h or less is preferable, 40 m ³ / h or less is more preferable, and 35 m ³ / h or less is still more preferable.

  The outer diameter of the pumping pipe used for pumping is preferably 89.1 mm (nominal diameter 80 A) or more, more preferably 101.6 mm (nominal diameter 90 A) or more, and 114.3 mm (nominal diameter) from the viewpoint of concrete workability. More preferably, the diameter is 100A) or more, and is preferably 318.5 mm (nominal diameter 300 A) or less, more preferably 216.3 mm (nominal diameter 200 A) or less, more preferably 165.2 mm (nominal diameter 150 A) from the viewpoint of the pumping capacity of the pump. The following is more preferable.

  The inner diameter of the pumping pipe used for pumping is preferably 75 mm or more, more preferably 90 mm or more, still more preferably 100 mm or more from the viewpoint of concrete workability, and 300 mm or less is preferable from the viewpoint of pumping capacity of the pump, 200 mm The following is preferable, and 160 mm or less is still more preferable.

Discharge pressure of the pump is at 0N / mm ² or more, from the viewpoint of suppressing the load of the pump is preferably 8.0 N / mm ² or less, more preferably 7.0 N / mm ² or less, 6.5 N / mm ² The following is more preferable.

  The pumping method of the present invention is preferably used when the pumping distance is 300 m or more in terms of horizontal transfer distance from the viewpoint of resistance to material separation resistance, more preferably when it is 400 m or more, and when it is 500 m or more. Further preferably used. From the viewpoint of pressure loss, it is preferably used when it is 1000 m or less, more preferably when it is 800 m or less, and further preferably when it is 600 m or less. The height difference (the height difference from the start point to the end point with reference to the starting point of pumping) is preferably 150 m or less when the height rises from the position of the pump that is the starting point of pumping, from the viewpoint of suppressing the load on the pump. 100 m or less is more preferable. When the height is lowered from the position of the pump that is the starting point of the pressure feeding, there is no limit to the height difference. The pumping distance refers to the distance from the discharge port of the pump to the discharge port of the pipe where the concrete is conveyed (the total length of the pipes used).

  The pumping method according to the present invention is preferably used in a situation where a road is not maintained such as in a mountain and it is difficult for a mixer car to enter.

<Synthesis example 1 of polysaccharide derivative>
(1) In a 1000 ml glass separable reaction vessel equipped with a stirrer, thermometer and cooling tube, 50 g of hydroxyethyl cellulose having a weight average molecular weight of about 800,000 and a hydroxyethyl group substitution degree of 1.8 (HEC-QP4400, manufactured by Union Carbide) Then, 400 g of 88% isopropyl alcohol and 3.5 g of 48% aqueous sodium hydroxide solution were added to prepare a slurry, which was stirred at room temperature for 30 minutes in a nitrogen atmosphere. To this, 4.0 g of stearyl glycidyl ether was added and reacted at 80 ° C. for 7 hours for hydrophobicity. After completion of the hydrophobic reaction, the reaction solution was neutralized with acetic acid, and the reaction product was filtered off. The reaction product was washed twice with 500 g of 80% acetone (20% water) and then twice with 500 g of acetone and dried under reduced pressure at 70 ° C. for one day to obtain 49.4 g of a hydrophobized hydroxyethyl cellulose derivative.

(2) In a 500 ml glass separable reaction vessel equipped with a stirrer, thermometer and cooling tube, 10.0 g of the hydrophobized hydroxyethylcellulose derivative obtained in (1), 80.0 g of isopropyl alcohol and 0.33 g of 48% sodium hydroxide aqueous solution Was prepared to prepare a slurry, and the mixture was stirred at room temperature for 30 minutes under a nitrogen stream. A mixture of 6.4 g of sodium 3-chloro-2-hydroxypropanesulfonate, 2.7 g of 48% aqueous sodium hydroxide and 20.0 g of water was added to the reaction solution, and sulfonation was performed at 50 ° C. for 9 hours. After completion of the reaction, the reaction solution was neutralized with acetic acid and the product was filtered off. The product was washed three times with 500 g of 80% acetone (20% water) and then twice with 500 g of acetone, and then dried at 70 ° C. for one day under reduced pressure to obtain stearyl glyceryl ether groups and 3-sulfo-2-hydroxypropyl groups. 7.2 g of a substituted hydroxyethylcellulose derivative (SPS) was obtained.

  The degree of substitution of stearyl glyceryl ether group (hydrophobic substituent (P)) of the resulting hydroxyethyl cellulose derivative is 0.008, and the degree of substitution of 3-sulfo-2-hydroxypropyl group (ionic hydrophilic group (Q)) is 0.15. Met.

  The weight average molecular weight of hydroxyethyl cellulose used as a raw material, the degree of substitution of the obtained hydroxyethyl cellulose derivative, stearyl glyceryl ether (Mw: 310, degree of substitution: 0.008), 3-sulfo-2-hydroxypropyl (Mw) : 160, substitution degree: 0.15), the weight average molecular weight is calculated to be 826,000.

  The degree of substitution of the hydrophobic substituent (P) in the polysaccharide derivative was quantified by the Zeisel method (D.G. Anderson, Anal. Chem., 43, 894 (1971)). The degree of substitution of the substituent (Q) was determined by colloid titration method. That is, a polysaccharide derivative solution having a known concentration was prepared, and a methyl glycol chitosan titrant (N / 200) (Wako Pure Chemical Industries, Ltd., for colloid titration) with a known weight was added to this while stirring, and a toluidine blue indicator solution was further added. A few drops of Wako Pure Chemical Industries, Ltd. (for colloid titration) were added. This was back titrated with a potassium potassium sulfate titrant (N / 400) (manufactured by Wako Pure Chemical Industries, Ltd., for colloid titration), and the degree of substitution was calculated from the titer. The “degree of substitution” indicates the average number of substituents per constituent monosaccharide residue.

<Concrete blending and manufacturing method>
Concrete was manufactured with the formulation shown in Table 1. The kneading method was as follows. After the coarse aggregate (G) was charged into the forced biaxial mixer, the fine aggregate (S) and cement (C) were charged and stirring was started. Kneading water (W) prepared by mixing tap water, admixture, and polysaccharide derivative or comparative compound so that the amount of admixture added, the amount of polysaccharide derivative or comparative compound is the value shown in Table 2. The mixture was added at the same time as the stirring of the mixer was started. After 90 seconds from the start, the concrete was discharged from the mixer and adjusted. As the content of the admixture, an amount that gives a slump value of 12.5 ± 0.5 was used except for Comparative Examples 3 to 5, 8, 11, and 14. Comparative Examples 3 to 5 were the same as Comparative Example 2, Comparative Example 8 was Comparative Example 7, Comparative Example 11 was Comparative Example 10, and Comparative Example 14 was Comparative Example 13.

  And the slump value of concrete and the amount of air were measured by JIS A1011 method and JIS A1128 (physical property before pressure feeding). The slump value and the amount of air were also measured on the concrete after being pumped in the evaluation of pumpability described later. The value obtained by subtracting the physical property value before pumping from the physical property value after pumping is shown in the table as “difference”.

In the table, the following were used for C, S, and G.
C: Normal Portland cement, density 3.16 g / cm ³ (a 1: 1 (weight ratio) mixture of ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd. and ordinary Portland cement manufactured by Sumitomo Osaka Cement Co., Ltd.)
S: Crushed sand from Iejima, density 2.62 g / cm ³
G: Limestone from Torigatayama, density 2.75 g / cm ³

The admixture used was a mixture of the following copolymer (1) and copolymer (2) in a weight ratio of copolymer (1) / copolymer (2) = 35/65. .
Copolymer (1): Copolymer of methacrylic acid and methanol ethylene oxide (average number of added moles 23) Copolymer of methacrylic acid ester (weight average molecular weight 51,000, methacrylic acid / methanol ethylene oxide adduct, methacrylic acid Ester weight ratio 0.21, methacrylic acid 73 mol% in polymer, methanol ethylene oxide adduct / methacrylic acid ester 27 mol%)
Copolymer (2): methacrylic acid and methanol ethylene oxide (average addition mole number 9) adduct copolymer of methacrylic acid ester (weight average molecular weight 65,000, methacrylic acid / methanol ethylene oxide adduct methacrylic acid Ester weight ratio 0.15, 47% by mole of methacrylic acid in polymer, 53% by mole of methanol ethylene oxide adduct / methacrylic acid ester)

The weight average molecular weight of the copolymer was measured by a gel permeation chromatography (GPC) method under the following measurement conditions.
[GPC conditions]
Column used: TSK guard column PWxl manufactured by Tosoh Corporation
TSKgel G4000PWxl + G2500PWxl
Eluent: 0.2 mol / L phosphate buffer (manufactured by Shinyo Chemical Co., Ltd.) / Acetonitrile for high performance liquid chromatography (manufactured by Wako Pure Chemical Industries, Ltd.) = 9/1 (vol%)
Flow rate: 1.0mL / min.
Column temperature: 40 ° C
Detection: RI
Injection volume: 10 μL (0.5 wt% aqueous solution)
Standard substance: polyethylene glycol, weight average molecular weight (Mw) 875000, 540000, 235000, 145000, 107000, 24000
Calibration curve order: cubic equation Device: HLC-8320GPC (manufactured by Tosoh Corporation)
Software: EcoSEC-WS (manufactured by Tosoh Corporation)

<Evaluation>
・ Pressure bleeding
Performed according to JSCE-F 502-2010. Concrete, which is a sample, was placed in a pressurized bleeding container, and the amount of dewatering when the concrete was pressed at a pressure of 3.5 MPa was measured with a graduated cylinder at regular intervals up to 4 minutes after pressing. FIG. 1 shows the cumulative amount of dehydration over time for the examples and some comparative examples. According to the Japan Society of Civil Engineers Concrete Library No. 100 (Concrete Pump Construction Guidelines [2000]), the pumpability is judged to be good if it is within the range of the standard curve B and standard curve C in FIG. The table shows the cumulative amount of dehydration after 4 minutes (after 240 seconds). For example, the standard curve B and the standard curve C are the bottom and side of the 63rd annual lecture meeting of the Japan Society of Civil Engineers (September 2008, CS05-26). Figure 2 of "Study on partial return material construction confirmation test (Part 3) -Consideration on bleeding and construction performance of concrete mixed with a large amount of fine limestone powder".

-Pump pumpability Using a pump vehicle (DC-SL1400BDH-M28, manufactured by Nikko Diacrete Co., Ltd., piston type pump), a pumping distance of 549 m (tube material: iron, nominal diameter: 125 A (tube outer diameter: 139. 8 mm), pipe inner diameter: 130.8 mm, straight pipe 3 m: 155, bent piping location: 84 locations), and pumping with a pipe having a height difference of 80 m (rising from the discharge port of the pump toward the cylinder tip). The pumping conditions were 25 m ³ / h and 32 m ³ / h, and the condition of the concrete at the tube tip (pipe outlet) was visually observed, and the pump pumpability was determined as follows. The pump discharge pressure was also confirmed with a pressure gauge attached to the pump car.
A: No separation of aggregate and water B: Separation of aggregate and water

The following were used in the table.
SPS: hydroxyethyl cellulose derivative substituted with stearyl glyceryl ether group and 3-sulfo-2-hydroxypropyl group obtained in Synthesis Example 1;
-HEC: SP600, manufactured by Daicel Chemical Industries, Ltd., hydroxyethyl cellulose, weight average molecular weight 1,200,000-CMC: CMC2280, manufactured by Daicel Chemical Industries, Ltd., carboxyl methyl cellulose, weight average molecular weight 1 million-polyAA: Carbopol 941, Goodrich Manufactured by sodium polyacrylate, HPMC: 90SH-4000, manufactured by Shin-Etsu Chemical Co., Ltd., hydroxypropyl methylcellulose, weight average molecular weight 300,000

  From Table 2, it can be seen that Examples 1 to 5 have little change in the slump value before and after pumping, suppress the increase in pump discharge pressure, and have good pumping performance.

  In Comparative Examples 3, 7, 10 and 13 in which a comparative compound is used instead of the polysaccharide derivative according to the present invention, even if the content equivalent to Example 2 or 5 is used, the cumulative dehydration amount becomes large, and pumping is difficult. is there. Comparative Examples 6, 9, 12 and 15 are examples in which the content of the comparative compound is increased to improve the pumpability, but there is a decrease in the slump value after pumping and an increase in the pump discharge pressure. I understand that.

  Since the amount of the comparative compound of Comparative Examples 2 to 15 was adjusted so that the cumulative dehydration amount of the pressure bleeding was close to the range between the standard curve B and the standard curve C, compared with the polysaccharide derivatives of Examples 1 to 5. The amount added is large. When the addition amount of the comparative compound is reduced and the addition amount is the same as in Examples 1 to 5, the cumulative dehydration amount of the pressure bleeding is further increased as compared with Comparative Examples 2 to 15, and pumping becomes difficult. The change in slump before and after pumping is also expected to increase.

Claims (5)

A concrete pumping method of pumping concrete containing water, cement, admixture, polysaccharide derivative and aggregate by a pump,
A hydrophobic substituent in which the polysaccharide derivative is a polysaccharide or an alkylated derivative or a hydroxyalkylated derivative thereof, wherein a part or all of the hydroxyl atoms have a hydrocarbon chain having 8 to 40 carbon atoms as a partial structure; A polysaccharide derivative substituted with an ionic hydrophilic group having a partial structure of one or more groups selected from the group consisting of sulfonic acid groups and salts of sulfonic acid groups,
The unit cement amount of the concrete is 250 kg / m ³ or more and 360 kg / m ³ or less,
The water-cement ratio of the concrete is 0.45 or more and 0.60 or less,
The slump value of the concrete before pumping is 8 cm or more and 15 cm or less,
Concrete pumping method.   The pumping method according to claim 1, wherein the concrete contains 0.002 parts by weight or more and 0.030 parts by weight or less of the polysaccharide derivative with respect to 100 parts by weight of cement. The unit water content of concrete or less 113 kg / m ³ or more 216 kg / m ^3, the unit aggregate weight is less than 1550kg / m ³ or more 2150kg / m ^3, pumped according to any one of claims 1 to 2 Method.   The pumping method according to any one of claims 1 to 3, wherein the admixture is a polycarboxylic acid polymer, and the admixture / polysaccharide derivative weight ratio is 30 or more and 250 or less.   The pumping method according to any one of claims 1 to 4, wherein the pumping distance is 300 m or more.

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