JP2013014479A - Underwater anti-washout thickening agent composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-fluidity concrete which can exhibit early-age strength and has a good anti-washout property under water and good workability.SOLUTION: There is provided an underwater anti-washout thickening agent composition comprising a cellulose ether, diutan gum, polyacrylamide, bentonite and calcium carbonate. The composition may additionally contain at least one calcium salt selected from the group consisting of calcium nitrite, calcium nitrate, calcium formate, calcium thiocyanate and calcium acetate, cement and an antifoaming agent.

Description

  The present invention relates to an inseparable thickener composition in water containing cellulose ether, detan gum, polyacrylamide, bentonite and calcium carbonate.

  Conventionally, various thickeners such as cellulose ether, polyacrylamide, polyethylene oxide, and gums have been used for water-inseparable concrete so that cement components are not dispersed and dissolved in water.

JP-A-6-206753 Japanese Patent Laid-Open No. 7-232949 Japanese Patent Laid-Open No. 9-268045 JP-A-9-208287 JP-A-7-267715 International Publication No. 2010/047408 Pamphlet

  These thickeners prevent viscosity of cement from separating and dispersing in water by giving viscosity to water in concrete and adhering solids to each other. However, if the adhesiveness is too strong, the workability deteriorates, and if the addition amount is large, a setting delay occurs.

  In the case of construction, there has been a demand for an underwater inseparable thickener composition having a good workability in which underwater inseparability is ensured and having a small setting delay.

  1 selected from the group consisting of hydroxyalkylcellulose and hydroxyalkylalkylcellulose as a concrete composition containing cement binder, aggregate and water reducing agent as an underwater inseparable concrete composition for underwater construction using an antifoaming agent The thing which added the acetylene glycol derivative as a seed | species or 2 or more types of water-soluble cellulose ether and an antifoamer is proposed (refer patent document 1).

  Patent Document 1 has a description of cellulose ether, but there is no description of using detan gum, acrylamide, bentonite, and calcium carbonate in combination.

  As an embankment material for underwater placement, an underwater embankment material is proposed which is made by mixing and kneading a hydraulic powder material such as cement, granulated / powdered slag, thickener and water (patent document). 2). Patent Document 2 discloses that, as a thickener, nonionic cellulose ether alone or in combination with a group consisting of polyacrylamide, polyethylene oxide, gums and the like is preferable, a hydraulic powder material, water granulation and / or wind. An underwater embankment material characterized by blending and kneading crushed slag, thickener and / or bentonite with water is described.

  Patent Document 2 describes that cellulose ether may be used in combination with polyacrylamide, gums, and bentonite. However, there is no description of using cellulose ether, detan gum, acrylamide, bentonite and calcium carbonate in combination.

  Water-soluble materials such as cement and other non-ionic cellulose ethers such as hydroxypropylmethylcellulose and water-soluble polysaccharides such as welan gum, water-soluble acrylic derivatives such as polyacrylamide, and hydroxypropylated starch A flowable composition for non-cutting method characterized in that at least one substance selected from starch derivatives is an essential component, and the ratio of water-soluble cellulose ether to aggregating substance is 99: 1 to 20:80. Has been proposed (see Patent Document 3).

  Patent Document 3 describes the combined use of cellulose ether, polyacrylamide, and gums. However, there is no description of using cellulose ether, detan gum, acrylamide, bentonite and calcium carbonate in combination.

  Cement mortar composition characterized by adding 0.02 to 3 parts by weight of nonionic water-soluble cellulose ether and 0.001 to 1 part by weight of water-soluble polysaccharide to 100 parts by weight of cement The thing is proposed (refer patent document 4).

  Patent Document 4 describes the combined use of cellulose ether and water-soluble polysaccharides. However, there is no description of using cellulose ether, detan gum, acrylamide, bentonite and calcium carbonate in combination.

  (A) a high-performance water reducing agent, a high-performance AE water-reducing agent admixture; (B), a swellable, low-substituted hydroxypropyl cellulose that is not completely soluble in water; and ( C) Concrete obtained by adding an admixture containing each component of a nonionic water-soluble cellulose ether has been proposed (see Patent Document 5).

  Patent Document 5 describes a cellulose ether. However, there is no description of using cellulose ether, detan gum, acrylamide, bentonite and calcium carbonate in combination.

  Patent Document 6 describes cellulose ether, detan gum, acrylamide, and bentonite. However, there is no description of using cellulose ether, detan gum, acrylamide, bentonite and calcium carbonate in combination.

  As a result of intensive studies, the present inventor has solved the above problem by using an underwater non-separable thickener composition containing cellulose ether, detan gum, polyacrylamide, bentonite, and calcium carbonate. The present invention has been completed by obtaining the knowledge that it is possible.

  The present invention is an inseparable thickener composition in water containing cellulose ether, detan gum, polyacrylamide, bentonite, calcium carbonate, cellulose ether 30 to 75% by mass, detan gum 3 to 40% by mass, A non-separable thickener composition in water containing 0.2 to 5% by mass of polyacrylamide, 5 to 25% by mass of bentonite, and 5 to 25% by mass of calcium carbonate, and further, calcium nitrite, calcium nitrate, calcium formate A water-insoluble separable thickener composition containing at least one calcium salt selected from the group consisting of calcium thiocyanate and calcium acetate, containing cement and the water-inseparable thickener composition A cement composition further comprising an antifoaming agent, and further comprising a water reducing agent It is a formed product.

By using the underwater inseparable thickener composition (hereinafter sometimes referred to as the thickener composition) of the present invention, the initial age strength can be obtained. It is possible to provide high-fluidity concrete with good workability.

The present invention will be described in detail below.
Parts and% used in the present invention are based on mass unless otherwise specified.

  The cellulose ether used in the present invention is hydroxyalkyl cellulose and / or hydroxyalkylalkyl cellulose. Examples of the hydroxyalkyl cellulose include hydroxyethyl cellulose and hydroxypropyl cellulose, and examples of the hydroxyalkyl alkyl cellulose include hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl ethyl cellulose, which are used alone or in combination of two or more. Of these, hydroxypropylmethylcellulose is particularly preferred.

The chemical structure of hydroxypropylmethylcellulose used in the present invention is shown in the figure below.
Wherein R is —H, —CH ₃ or —CH ₂ CH (OH) CH ₃ , provided that at least one of the three R is —CH ₂ CH (OH) CH ₃ .

  The viscosity of the cellulose ether is preferably 5,000 to 50,000 mPa · s, preferably 8,000 to 25,000 mPas, in the viscosity of a 1% aqueous solution measured using a B-type viscometer at 20 ° C. and 10 rpm. -S is more preferable. The moisture content of the powder is preferably 15% or less.

  The proportion of cellulose ether in the thickener composition is preferably 30 to 75%, more preferably 35 to 70%. If it is less than 30%, it may be difficult to obtain inseparability in water, and if it exceeds 70%, workability may be deteriorated.

  Cellulose ether generally has air entrainment properties, so when there is a large amount of air in the concrete and the strength may be reduced, it is desirable to control the amount of air to a predetermined level with an antifoaming agent.

  Examples of the antifoaming agent include silicone-based, nonionic-based, alcohol-based, fatty acid-based, ether-based, fatty acid ester-based, phosphate ester-based, polyether-based, and fluorine-based agents.

The amount of the antifoaming agent used is preferably 0.01 to 1 kg / m ^{3 and} more preferably 0.1 to 0.5 kg / m ^{3 in} 1 m ³ of the water-inseparable high-fluidity cement composition.

The detan gum used in the present invention is a natural high-molecular polysaccharide having two glucose, one glucuronic acid, and three rhamnose as structural units. The chemical structure is shown in the figure below.

  The viscosity of the dutan gum is preferably 2800 mPa · s or more, more preferably 3000 to 5500 mPa · s in the viscosity of a 0.25% aqueous solution measured using a B-type viscometer at 20 ° C. and 10 rpm.

  The proportion of dutan gum in the thickener composition is preferably 3 to 40%, more preferably 5 to 35%. If it is less than 3%, it may be difficult to obtain inseparability in water, and if it exceeds 40%, workability may be deteriorated.

  The polyacrylamide used in the present invention contains a highly reactive acid amide group in the polymer. Of these, methacrylic cationic polymers are preferred. The viscosity of the polyacrylamide is preferably 40 to 80 mPa · s, more preferably 50 to 70 mPa · s in the viscosity of a 0.2 mass% aqueous solution measured at 20 ° C. and 10 rpm using a B-type viscometer. .

  The proportion of polyacrylamide in the thickener composition is preferably 0.2 to 5%, more preferably 0.5 to 3%. If it is less than 0.2%, it may be difficult to obtain retainability in water, and if it exceeds 5%, workability may be deteriorated.

  The bentonite used in the present invention is a kind of clay mineral and mainly contains montmorillonite. Examples of bentonite include calcium bentonite, sodium bentonite, and potassium bentonite.

  The swelling degree of bentonite is preferably 20 ml / 2 g or more. The water content of bentonite is preferably 10% or less. The particle size of bentonite is preferably 90% or more through 80 mesh.

  The proportion of bentonite in the thickener composition is preferably 5 to 25%, more preferably 8 to 23%. If it is less than 5%, dispersion during kneading may be difficult to obtain, and if it exceeds 25%, the inseparability in water may be deteriorated.

The calcium carbonate used in the present invention is preferably heavy calcium carbonate obtained by mechanically pulverizing and classifying natural raw materials mainly composed of CaCO ₃ such as limestone. The particle size of calcium carbonate is preferably 90% or more when passing through 100 mesh.

  The proportion of calcium carbonate in the thickener composition is preferably 5 to 25%, more preferably 8 to 23%. If it is less than 5%, dispersion during kneading may be difficult to obtain, and if it exceeds 25%, the inseparability in water may be deteriorated.

The amount of the inseparable thickener composition used in water is preferably 0.1 to ³ kg, more preferably 0.2 to 2 kg per 1 m3 of concrete. If it is less than 0.1 kg, the inseparability in water may deteriorate, and if it exceeds 3 kg, workability may deteriorate.

  In the present invention, one or more calcium salts selected from the group consisting of calcium nitrite, calcium nitrate, calcium formate, calcium thiocyanate, and calcium acetate can be used.

  Calcium salts have high fluidity retention performance and a relatively high curing rate. Therefore, when construction is performed, a predetermined initial strength is obtained, so that demolding is quickened, the construction period is shortened, and productivity is improved.

  The amount of calcium salt used is preferably 0.01 to 1.0 part and more preferably 0.02 to 0.6 part with respect to 100 parts of cement. If it is less than 0.01 part, the effect of promoting the setting time may be small, and if it exceeds 1.0 part, the setting time may be short and it may be difficult to maintain fluidity.

  In the present invention, a water reducing agent can be used. Of the water reducing agents, polycarboxylic acid-based water reducing agents are preferred.

The amount of water reducing agent used is preferably 0.1 to 10 kg / m ³ , more preferably 0.2 to 5 kg / m ^{3 in} terms of solid content per 1 m ^{3 of} concrete.
The water reducing agent is used as a powder or liquid. In the case of liquid, it is used as a solution mixed with water. When used as a liquid, the solid content concentration of the water reducing agent is preferably 3 to 70%, more preferably 10 to 50%.

  As for cement, there are various ordinary Portland cements such as normal, early strength, medium heat, low heat, and super early strength, various mixed cements in which fly ash, blast furnace slag, etc. are mixed, and eco-friendly. For example, cement.

The typical example of the concrete mixing of this invention is shown.
・ Cement 350-600kg / m ³
Aggregate 1650-1900 kg / m ³
・ Water 160-210kg / m ³

  The cement composition of the present invention can be produced according to an ordinary method. For example, a thickener composition and an antifoaming agent are added to cement, aggregate and water at a raw plant or a setting site, It is prepared by adding a polycarboxylic acid water reducing agent and stirring and mixing. The polycarboxylic acid-based water reducing agent used as a water reducing agent can be used as a so-called post-addition which is added to the kneaded concrete or added to the kneaded concrete. Moreover, the method of preparing mortar first and using a coarse aggregate after that can also be used.

  The water cement ratio of the cement composition of the present invention is preferably 25 to 60%, more preferably 30 to 50%.

  The fine aggregate ratio of the cement composition of the present invention is preferably 20% or more, more preferably 30 to 70% in volume ratio.

Action

In the present invention, an inseparable thickener composition in water in which cellulose ether, detan gum, polyacrylamide, bentonite, and calcium carbonate are mixed in advance and powdered is added to water and other compositions and kneaded. As a result, there is no sudden water absorption and the occurrence of this disappears, and the thickening effect is exhibited, and the cement composition of the present invention is completed. When bentonite and calcium carbonate are not added in advance, water is rapidly absorbed and a so-called cocoon state is obtained, and the thickening mechanism may not be sufficiently exhibited.

Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise stated, it was carried out at 20 ° C.
Examples are shown in Experiment No. 1-1 to 1-17, and the comparative example is an experiment No. 1-18 to 1-21.
Coarse aggregate maximum size 13 mm, fine aggregate rate (s / a) 44%, fine aggregate 717 kg / m ³ , coarse aggregate 924 kg / m ³ , cement 500 kg / m ³ , water 195 kg / m ³ (water cement Ratio: 39%), water reducing agent (in terms of solid content) 5 kg / m ³ , antifoaming agent 0.5 kg / m ³ , in-water non-separable thickener composition shown in Table 1 (hereinafter referred to as thickener) The amount shown in Table 1 was used.
A 55L biaxial mixer was used. Mix cement and fine aggregate and knead mortar for 30 seconds. Add water, water reducing agent and thickener composition, knead for 3 minutes, add coarse aggregate and mix for 0.5 minutes. Prepared. The concrete was measured for slump flow (fluidity), 50 cm arrival time, suspension amount, pH, and compressive strength collected in water, and the results are shown in Table 2. In each example, the materials used and the measurement methods are as follows.

<Materials used>
Fine aggregate: ・ Himekawa sand (water absorption rate: 1.94%, density: 2.61, FM: 2.80)
Coarse aggregate:-Crushed stone 5mm-13mm (Water absorption: 1.0%, density: 2.64, FM: 6.10)
Cement: Hayashi Portland Cement (Density: 3.12, manufactured by Denki Kagaku Kogyo)
Cellulose ether (Ms in the table): hydroxypropyl methylcellulose, 1% aqueous solution viscosity 20,000 mPa · s (10 rpm), manufactured by Shin-Etsu Chemical Co., Ltd. Viscosity 4,350 mPa · s (10 rpm), C.I. P. Kelco, commercially available polyacrylamide (denoted as Pa in the table): 0.2% aqueous solution viscosity 63 mPa · s (10 rpm), Nippon Kasei Co., Ltd., commercially available bentonite (denoted as Bn in the table): US commercial product potassium bentonite, Swelling degree 27.0 ml / 2 g, moisture content 8.9%, particle size wet residue 45 μm 5.0%, loss on ignition 7.0%, density 2.5 g / cm ³
Calcium carbonate (denoted as Tk in the table): Density: 2.68, 100 mesh product, water-reducing agent, Joetsu Mining Co., Ltd .: polycarboxylic acid-based water reducing agent: FTN, Grace Chemicals, solid content concentration 20%
Antifoaming agent: SN-14HP, San Nopco, main component silicone

<Measurement method>
Slump flow (fluidity): Conforms to “JIS A1150 slump flow”.
50 cm arrival time: Conforms to “JIS A1150 Slump Flow”.
pH: Compliant with JSCE-D104, Appendix 2 “Standards for the quality of non-separable admixture in water for concrete” (draft).
Suspension amount (amount of suspended solids): Conforms to JSCE-D104, Annex 2 of the Japan Society of Civil Engineers Standard: Quality Standards for Water Inseparable Admixtures for Concrete (Draft).
Compressive strength: Conforms to “JSCE-F 504”, “Journal of Japan Society of Civil Engineers: How to make underwater preparation specimen for compressive strength test of underwater inseparable concrete”. Measure the compressive strength of underwater specimens with a material age of 24H.
Determination of slump shape: Visually evaluated according to the following shape when measuring slump flow.

  Experiment No. of the embodiment of the present invention. 1-1 to 1-17, the time of 50 cm slump flow representing the viscosity of the concrete is moderate, the fluidity and its retention performance are good, and the inseparability in water expressed in the suspension amount and pH is also good. There is also a good value for the initial compressive strength. On the other hand, comparative experiment No. In 1-18 to 1-21, the fluidity is excessive, and the inseparability in water expressed in the suspension amount and pH is poor.

  A test was conducted in the same manner as in Example 1 except that the amounts of the thickener composition and the water reducing agent shown in Table 3 were changed. The results are shown in Table 4.

  Experiment No. of the embodiment of the present invention. In 2-1 to 2-8, the time of 50 cm slump flow representing the viscosity of the concrete is moderate, the fluidity and its retention performance are good, and the inseparability in water expressed in the suspension amount and pH is also good. There is also a good value for the initial compressive strength. In contrast, Experiment No. 2-9 has excessive fluidity and poor inseparability in water expressed in the amount of suspension and pH. Experiment No. with a large amount of thickener composition used. In 2-10, the slump shape is not bad, but the viscosity is high and the workability is poor.

  Experiment No. 1 in Table-1. The same procedure as in Example 1 was performed except that the amount of calcium salt shown in Table 5 was used using the formulation 1-4. The test results are shown in Table-6.

<Materials used>
Calcium acetate: Grade 1 reagent

  Experiment No. of the Example which added the appropriate quantity of calcium salt of this invention. In 3-1 to 3-3, the initial strength is obtained and the fluidity is improved. In contrast, in Experiment No. in which a large amount of calcium salt was added. In 3-4, although concrete slump shape is not bad, underwater non-separation performance worsens.

  The underwater non-separable high-fluidity cement composition of the present invention has fluidity and retention as compared with conventional underwater non-separable concrete, and has good underwater inseparability and high initial strength. I can do it.

Claims (6)

  A non-separable thickener composition in water containing cellulose ether, detan gum, polyacrylamide, bentonite and calcium carbonate.   Non-separable thickening in water containing cellulose ether 30-75%, detan gum 3-40%, polyacrylamide 0.2-5%, bentonite 5-25%, calcium carbonate 5-25% Agent composition.   The water-inseparable thickener composition according to claim 1, further comprising one or more calcium salts selected from the group consisting of calcium nitrite, calcium nitrate, calcium formate, calcium thiocyanate, and calcium acetate.   A cement composition containing cement and the underwater non-separable thickener composition according to claim 1.   Furthermore, the cement composition of Claim 4 containing an antifoamer.   Furthermore, the cement composition of Claim 4 or 5 containing a water reducing agent.