JPWO2018012437A1 - Liquid early strengthening agent for cement concrete - Google Patents

Abstract

The liquid early strengthening agent which has fluidity and is excellent in strength development is provided. The concentration of the water-soluble aluminum salt is 15 to 40% by mass in terms of solid content, the concentration of carboxylic acids is 1 to 20% by mass in terms of solid content, and the concentration of bisphenol-based condensate is 0.1 to 3% by mass in terms of solid content Liquid fastener for cement and concrete, the rest being water. The structural unit of the bisphenol-based condensate is preferably bisphenol S. The liquid concrete early strengthening agent may further contain an alkanolamine.

Description

  The present invention relates to, for example, an early strengthening agent for cement concrete used in civil engineering and construction.

  Concrete products are manufactured by pouring a mixture of cement, aggregate, water and admixture into a mold, curing it properly, and removing it. Here, expressing high strength at the early stage of material age is important in terms of improving productivity, that is, the rate of rotation of the formwork. Increasing the rate of rotation of the form leads to a reduction in the number of expensive forms required. As a method for enhancing the initial strength, it is known to use early-strength cement, to mix concrete with a low water-cement ratio by using a water reducing agent, to perform steam curing, and the like.

  In recent years, the energy cost associated with the use of steam has risen, and a method that can shorten the steam curing time and a method that does not require steam curing have been desired. Moreover, also from the requirement of higher productivity, further shortening of the curing process may be desired, and for example, it may be necessary to develop high strength in a curing period of 16 hours in the production of a concrete product. Usually, complex processes such as heating process using steam etc. are incorporated in curing process, but it is difficult to become a practical method even if trying to improve such initial process by changing such process . Therefore, a method of easily obtaining a concrete product having high initial strength without process change is strongly desired in the market from the viewpoint of production cost and the like.

  Known admixtures for enhancing strength include those comprising mainly calcium oxide, gypsum, sulfates of alkali metals, etc., and those wherein an alkali metal sulfate is used in combination with a specific compound such as glycerin (Patent Document 1) ~ 4). In addition, those which use aluminum salt and carboxylic acid as a hardening accelerator are also reported (patent documents 5-7). Although curing accelerators containing chlorine such as sodium chloride and calcium chloride are also known, their use is not preferable from the viewpoint of salt damage.

  Aluminum salts are known to form alumina gel in the neutral region and to harden cement compositions, but this hardening reaction is fast and it is difficult to secure fluidity. In addition, although the strength is expressed by the formation of alumina gel at the very beginning, when a large amount of alumina gel is formed, the alumina gel covers the surface of cement, so that the dissolution of cement component is inhibited and the strength decreases in the long term. There was a problem that it was easy.

  Fastening agents for shotcrete containing aluminum sulfate and bisphenol condensates have been reported (Patent Documents 8 to 9). However, the shotcrete is a physical property that is particularly required to blow to the rock, to be cured instantaneously, and not to be exfoliated, and is different from the cast-in-place concrete or the precast concrete because the required physical properties are different.

JP 2001-294460 A JP, 2011-153068, A Unexamined-Japanese-Patent No. 2000-233959 JP 2008-519752 JP 2012-121804 A JP, 2011-1266, A JP 2001-348255 A Japanese Patent Publication No. 2003-502269 JP, 2015-231931, A

  The inventors of the present invention have completed the present invention by obtaining the knowledge for solving the above-mentioned problems.

  That is, in the embodiment of the present invention, the concentration of the water-soluble aluminum salt is 15 to 40% by mass in terms of solid content, the concentration of carboxylic acids is 1 to 20% by mass in terms of solid content, and the concentration of bisphenol-based condensate is solid content It is 0.1-3 mass% in conversion, and the remainder can provide the liquid early strengthening agent for cement concrete which is water.

  In the embodiment of the present invention, in the liquid early strengthening agent for cement concrete, the weight average molecular weight of the bisphenol-based condensate may be 1,000 to 30,000, and the structural unit of the bisphenol-based condensate is bisphenol S. And may further contain an alkanolamine, and may further contain a compound having a hydroxyl group. In the embodiment of the present invention, the liquid quick fixer for cement concrete may be used for cast-in-place cement concrete or precast cement concrete.

  Moreover, in the embodiment of the present invention, it is also possible to provide a pre-strength cement concrete containing the liquid pre-hardening agent for cement concrete and the cement concrete. The amount of the liquid early strengthening agent for cement concrete used may be 0.1 to 10 parts by mass in terms of solid content with respect to 100 parts by mass of cement.

  In the embodiment of the present invention, it is also possible to provide a method for producing early-strength cement concrete, wherein the liquid early strength agent for cement concrete is post-added to cement concrete in an agitator car to produce early-strength cement concrete.

  The liquid early strengthening agent of the present invention has fluidity and is excellent in strength development.

  Hereinafter, the present invention will be described in detail.

  Cement concrete in the present invention is a generic term for cement paste, mortar and concrete. The liquid early strength agent for cement concrete in the present invention (hereinafter sometimes simply referred to as "early strengthening agent") includes a liquid early strengthening agent and a slurry early strengthening agent. In the present invention, a cement-hardened body is a generic term for secondary concrete products and concrete structures manufactured from cement paste, mortar, concrete, or composited with reinforcing bars or the like.

  In the present specification, “parts” and “%” indicate parts by mass and% by mass, respectively, unless otherwise specified. Moreover, the concentration in the present specification refers to the solid concentration, unless otherwise specified. Further, in the present specification, the numerical range means a range including the upper limit value and the lower limit value unless otherwise specified.

  The early strengthening agent of the present invention contains a water-soluble aluminum salt, a carboxylic acid, a bisphenol-based condensate, and water. The early strengthening agent of the present invention may further contain an alkanolamine.

  As the water-soluble aluminum salt used in the present invention, either an anhydride or a hydrate can be used. Examples of the water-soluble aluminum salt include aluminum nitrate, aluminum sulfate, potassium aluminum sulfate, aluminum monobasic phosphate, aluminum lactate and the like. One or more of these can be used. Among these, aluminum sulfate is preferable in terms of excellent strength development.

  The concentration of the water-soluble aluminum salt is preferably 15 to 40%, more preferably 20 to 35%, in terms of anhydride. The% of the water-soluble aluminum salt is the value in terms of solid content. If the concentration of the water-soluble aluminum salt is less than 15%, excellent strength development may not be obtained, and if it exceeds 40%, the slump may decrease or the long-term strength may decrease.

  The carboxylic acids used in the present invention refer to carboxylic acids or salts thereof. In the present specification, carboxylic acids are considered to be a generic name of organic compounds having a carboxyl group, salts of organic compounds having a carboxyl group, and mixtures of salts of organic compounds having a carboxyl group and organic compounds having a carboxyl group. Can.

  As carboxylic acids, monocarboxylic acids such as formic acid, acetic acid and propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, dicarboxylic acids such as maleic acid, fumaric acid and phthalic acid, trimellitic acid Acids, tricarboxylic acids such as tricarbaryllic acid, oxymonocarboxylic acids such as hydroxybutyric acid, lactic acid and salicylic acid, oxydicarboxylic acids such as malic acid, aminocarboxylic acids such as aspartic acid and glutamic acid, ethylenediaminetetraacetic acid (EDTA) and trans Aminopolycarboxylic acids such as-1, 2-diaminocyclohexanetetraacetic acid (CyDTA) and salts thereof. As a salt which comprises carboxylate, an alkali metal, alkaline-earth metal, etc. are mentioned. One or more of these can be used. Among carboxylic acids, sodium formate is preferred in terms of excellent strength development.

  1-20% is preferable in conversion of solid content, and, as for the density | concentration of carboxylic acids, 4-15% is more preferable. When the concentration of carboxylic acids is less than 1%, excellent strength development may not be obtained, and when it exceeds 20%, long-term strength may be reduced.

  The bisphenol-based condensate used in the present invention is a generic term of, for example, a product obtained by condensation reaction of a compound in which two phenols are crosslinked by a functional group and formaldehyde. The structural unit of the bisphenol-based condensate used in the present invention is bisphenol. Examples of the functional group which crosslinks two phenols include methylene, ethylidene, propylidene, butylidene, cyclohexylidene, vinylidene, carbonyl, imino, ether, sulfide, sulfonyl and the like. . Furthermore, the thing by which the arbitrary hydrogen atoms of these groups were substituted by the C1-C4 alkyl group, a phenyl group, an amino group, a hydroxyl group, a fluoro group, a chloro group, a bromo group, an iodo group etc. is also mentioned. The term "phenol" as used herein means that any hydrogen atom bonded to the aromatic ring is an alkyl group having 1 to 4 carbon atoms, cyclohexyl group, phenyl group, amino group, carboxyl group, hydroxyl group, fluoro group, chloro group And compounds which are substituted by a bromo group, an iodo group or the like, or compounds in which a part of hydrogen atoms of a hydroxyl group is substituted by an alkali metal atom or the like. One or more kinds of bisphenol-based condensates can be used. Among these, bis (4-hydroxyphenyl) sulfone (generally called bisphenol S) in which two phenols are crosslinked by a sulfonyl group is preferable in terms of suppressing reduction in slump and being excellent in initial strength development.

  The bisphenol-based condensate may be a salt thereof. As a bisphenol, the compound of following formula (1) is mentioned, for example.

(In formula (1), X represents either of following formula (2), Formula (3), Formula (4), Formula (5), O (oxygen atom), or S (sulfur atom). Phenylene group The hydrogen atom of may be substituted by an alkyl group or a halogen group, and the hydrogen atom of the alkyl group may be substituted by a halogen group.)

(In the formulas (2) and (3), R ₁ , R ₂ and R ₃ each independently represent hydrogen, a halogen group or an alkyl group, and R ₄ represents an alkylene group. Of the alkyl group and the alkylene group A hydrogen atom may be substituted by a halogen group.)

  1,000-30,000 are preferable and, as for the average molecular weight of a bisphenol type condensate, 5,000-20,000 are more preferable. If the average molecular weight is out of the range of 1,000 to 30,000, suppression of slump reduction and improvement of initial strength development may not be excellent. In addition, an average molecular weight here refers to a weight average molecular weight. Average molecular weight is measured by gel permeation chromatography analysis (standard substance is sodium polystyrene sulfonate). The bisphenol-based condensate is obtained, for example, by condensing each component by heating under aqueous conditions in the presence of an alkali.

  0.1-3% is preferable in conversion of solid content, and, as for the density | concentration of a bisphenol-type condensate, 0.2-2% is more preferable. Outside this range, it may not be excellent in the improvement of initial strength development.

  The early strengthening agent of the present invention may contain an alkanolamine. Alkanolamines are used to improve the initial strength of the cement composition.

  Although the alkanolamine is not particularly limited, it can be used if it can be dissolved in the early strengthening agent. An alkanolamine is an organic compound having a> N-R-OH structure in the structural formula. Here, R is an atomic group usually called an alkylene group or an arylene group, and is a linear alkylene group such as methylene group, ethylene group or n-propylene group, or an alkylene group having a branched structure such as isopropylene group, And arylene groups having an aromatic ring such as phenylene group and benzylene group. R may be bonded to the nitrogen atom at two or more places, and part or all of R may have a cyclic structure. R may be bonded to a plurality of hydroxyl groups. R may have an element other than carbon and an element other than hydrogen, such as sulfur, fluorine, chlorine and oxygen, as a part of the alkylene group. R may have a plurality of hydroxyl groups bonded thereto. As the alkanolamine, ethanolamine, diethanolamine, diisopropanolamine, triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, N, N-dibutylethanolamine, N- (2-aminoethyl) ethanolamine, Boron trifluoride triethanolamine and derivatives thereof can be mentioned. One or more of these can be used. Among the alkanolamines, diethanolamine is preferable in that it is excellent in the improvement of fluidity and strength development.

  1-15% is preferable in conversion of solid content, and, as for the density | concentration of the alkanolamine used by this invention, 2-10% is more preferable. If the concentration of alkanolamine is less than 1%, the improvement in initial strength may be small, and if it exceeds 15%, the fluidity may be reduced.

The early strengthening agent of the present invention may contain a compound having a hydroxyl group. The compound having a hydroxyl group is used for the purpose of improving the initial strength of the cement composition. Examples of the compound having a hydroxyl group include low molecular weight compounds such as glycerin, ethylene glycol and propylene glycol, and polyoxyethylene alkyl ethers or derivatives thereof. Among the compounds having a hydroxyl group, glycerin is preferable in terms of excellent fluidity improvement. Glycerin used in the present invention is, for example, a compound represented by a chemical formula of C ₃ H ₈ O ₃ , a chemical name of 1,2,3-propanetriol or glycerol.

  The concentration of the compound having a hydroxyl group used in the present invention is preferably 1 to 10%, more preferably 3 to 7%, in terms of solid content. If the concentration of the compound having a hydroxyl group is less than 1%, the improvement in early strength may be small, and if it exceeds 10%, the long-term strength may be reduced.

  When the early strengthening agent of the present invention is mixed with cement concrete, an early strengthening cement concrete is obtained.

  The amount of the early strengthening agent of the present invention is preferably 0.1 to 10 parts, more preferably 0.5 to 7 parts, and most preferably 1 to 5 parts, in terms of solid content, per 100 parts of cement. If the amount of the early strengthening agent used is less than 0.1 part, it may not be excellent in improving the strength development, and if it exceeds 10 parts, the slump may be reduced or the long-term strength development may be reduced.

  Here, cement includes various Portland cements such as normal, early strength, moderate heat and super early strength, and various mixed cements in which fly ash, blast furnace slag and the like are mixed with these various portland cements. . It is also possible to use these in micronized form.

  The present invention may use a water reducing agent on the cement concrete side. Water reducing agents include water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, and the like. Among water reducing agents, naphthalene sulfonic acid is preferred. As a naphthalene sulfonic acid type, a naphthalene sulfonic acid-formaldehyde condensate or a salt thereof is preferable. Examples of the naphthalenesulfonic acid-formaldehyde condensate or a salt thereof include (trade name “MAITY 150”, manufactured by Kao Corporation) and the like. As the water reducing agent, either liquid or powdery one can be used.

  0.05-5 parts are preferable in conversion of solid content with respect to 100 parts of cements, and, as for the usage-amount of water reducing agent, 0.1-3 parts is more preferable.

  The cement concrete used in the present invention contains cement and aggregate. Here, as the aggregate, one having a low water absorption rate and a high aggregate strength is preferable. As fine aggregate, river sand, mountain sand, lime sand, silica sand, etc. can be used, and as coarse aggregate, river gravel, mountain gravel, lime gravel, etc. can be used.

  The water-cement ratio used for cement concrete is preferably 30% or more, more preferably 33 to 55%, in terms of strength development. If it is less than 30%, cement and concrete may not be mixed sufficiently.

  The mechanism of the onset of the effect of the early strengthening agent of the present invention is not to be bound by a particular theory, but can be considered as follows. The water-soluble aluminum salt reacts with hydroxide ions supplied from cement to form an alumina gel, thereby promoting the hardening of the cement composition. Although this effect alone is not sufficient for strength development, it is considered that the carboxylate ion supplied from the carboxylic acids used together promotes the elution of the cement component and promotes the hydration reaction. . Furthermore, by using a bisphenol-based condensate, it is considered that the water-soluble aluminum salt and the carboxylic acids are easily dispersed in the entire cement composition, thereby further promoting the hardening and hydration promotion. The present invention uses water as a solvent, and the use of the present invention as a liquid has a higher promoting effect than using a water-soluble aluminum salt or carboxylate as a solid. The reason for this is considered to be that the dispersing effect of the bisphenol-based condensate becomes more effective by passing mobile water in the cement composition before and after curing. For this reason, according to the embodiment of the present invention, it is excellent in versatility with cast-in-place concrete which is difficult to control, for example, convey cement concrete to the site with the agitator car and cement cement concrete with quick strengthening agent immediately before casting on the site. By post-addition, cement concrete and early strengthening agent are mixed without segregation, and there is an effect that early strengthening concrete can be manufactured.

  The early strengthening agent of the present invention is used for cast-in-place cement concrete or precast cement concrete. In cast-in-place cement concrete or precast cement concrete, cemented concrete having a predetermined shape is manufactured by pouring the kneaded cement concrete into a mold and demolding after hardening. As it is necessary to pour into the formwork, these cement concretes need to have a certain level of fluidity and harden slowly, and a certain pot life needs to be ensured for the surface finish. Such properties are quite different from shotcrete. Since the early strengthening agent of the present invention has fluidity, it can not form a rock pocket in cement concrete and the surface becomes uniform.

  Hereinafter, the present invention will be described in detail based on experimental examples.

"Experimental Example 1"
Water-soluble aluminum salts, carboxylic acids, and bisphenol-based condensates are added to water so that the solid concentration shown in Tables 1 to 3 (also referred to as concentration below) may be obtained, and stirring is performed for 4 hours for various liquids. A strong agent was prepared. The concentration is expressed by mass% in terms of solid content in the liquid early strengthening agent. The prepared liquid early strengthening agent was added to concrete, and the physical properties were evaluated.

Unit water quantity 145 kg / m ³ , cement quantity 440 kg / m ³ , water reducing agent 2.5 kg / m ³ , s / a (fine aggregate rate) 39.4%, air quantity 4.5% as the basic composition of concrete The slump of concrete was measured using a liquid early strengthening agent having a composition shown in Tables 1 to 3 under an environment of 20 ° C. 8.8 kg / m ³ equivalent to 2 parts in terms of solid content per 100 parts of cement was measured as a liquid early strengthening agent and added to concrete. Thereafter, the formwork was filled with concrete, held at 20 ° C., and demolded after 8 hours, and the compressive strength was measured.

  In addition, as a comparative example (Experiment No. 1-46), it was also carried out in the case of using a powder early strengthening agent instead of a liquid early strengthening agent. Powdered early strengthening agent consisting of a water-soluble aluminum salt [B]: carboxylic acid [b]: bisphenolic condensate [co] = 25: 10: 1 (mass ratio) as a powdered early strengthening agent and containing no water It was used. The results are shown in Tables 1 to 3.

<Material used>
Water soluble aluminum salt [A]: aluminum nitrate, commercially available water soluble aluminum salt [B]: aluminum sulfate, 14 hydrates, commercially available water soluble aluminum salt [C]: aluminum potassium sulfate, commercially available water soluble aluminum salt [D] ]: Aluminum primary phosphate, Commercially available water-soluble aluminum salt [E]: Aluminum lactate, Commercially available carboxylic acid [a]: Formic acid, Commercially available carboxylic acid [b]: Sodium formate, Commercially available carboxylic acid [c]: Potassium formate, commercially available carboxylic acids [d]: sodium acetate, commercially available carboxylic acids [e]: sodium oxalate, commercially available carboxylic acids [f]: sodium lactate, commercially available carboxylic acids [g]: sodium aspartate, commercially available Bisphenol-based condensate [a]: condensate of bis (4-hydroxyphenyl) methane, average molecular weight Commercially available bisphenol-based condensate [a]: condensate of 2,2-bis (4-hydroxyphenyl) propane, average molecular weight 12,000, commercially available bisphenol-based condensate [c]: 2, 2- Condensate of bis (4-hydroxyphenyl) hexafluoropropane, average molecular weight 12,000, commercially available bisphenol-based condensate [E]: condensate of 2,2-bis (3-methyl-4-hydroxyphenyl) propane, Average molecular weight 12,000, commercially available bisphenol-based condensate [O]: condensate of 4,4'-dihydroxybenzophenone, average molecular weight 12,000, commercially available bisphenol-based condensate [Ca]: bis (4-hydroxyphenyl) Condensate of sulfide, average molecular weight 12,000, commercially available bisphenol-based condensate [ii]: bis (4-hydroxyphenyl) Condensate of sulfone, average molecular weight 800, commercially available bisphenol-based condensate [d]: condensate of bis (4-hydroxyphenyl) sulfone, average molecular weight 1,000, commercially available bisphenol-based condensate [b]: bis (4 -Hydroxyphenyl) sulfone condensate, average molecular weight 5,000, commercially available bisphenol-based condensate [co]: condensate of bis (4-hydroxyphenyl) sulfone, average molecular weight 12,000, commercially available bisphenol-based condensate [ [A]: Condensate of bis (4-hydroxyphenyl) sulfone, average molecular weight 20,000, commercially available bisphenol-based condensate [B]: Condensate of bis (4-hydroxyphenyl) sulfone, average molecular weight 30,000, commercially available Bisphenol-based condensate [S]: condensate of bis (4-hydroxyphenyl) sulfone, average molecule 35,000, commercially available water: industrial water Cement: ordinary Portland cement, Blaine value 3,150cm ² / g, a specific gravity of 3.14, commercially available fine aggregate: Niigata Prefecture Himekawa production of Japan, 5mm under, density 2.62g / Cm ³ , Commercially available coarse aggregate: From Himekawa, Niigata, Japan, under 25 mm, density 2.64 g / cm ³ , Commercially available water reducing agent: Naphthalene sulfonic acid, trade name "Mighty 150", Kao Corporation

<Measurement method>
Slump: According to JIS A 1101.
Compressive strength: in accordance with JIS A 1108. The concrete was sealed and cured at 20 ° C. until the age of 24 hours and thereafter cured in water at 20 ° C.

  From Tables 1 to 3, the initial strength is improved that the concentration of the water-soluble aluminum salt is 15 to 40%, the concentration of the carboxylic acids is 1 to 20%, and the concentration of the bisphenol condensate is 0.1 to 3%. The impact on slump and long-term strength is also small. Among the water soluble aluminum salts, aluminum sulfate is preferred. Among the carboxylic acids, sodium formate is particularly desirable. Among the bisphenol-based condensates, those having an average molecular weight of 1,000 to 30,000 and in which bisphenol S is a part of the structural unit are preferable. Use of the liquid early strengthening agent of the present invention makes it easy to pour since the fluidity is not impaired, and the initial strength is improved, so that the curing period necessary to develop the strength necessary for demolding can be shortened. , Leads to the improvement of concrete productivity. On the other hand, when the powder early strengthening agent is used, the initial strength is low and the effect of the present invention can not be obtained.

"Experimental example 2"
The concentration of aluminum sulfate (as converted to anhydride) is 25%, the concentration of sodium formate is 10%, the concentration of bisphenol condensate [1] is 1%, the concentration of alkanolamine is shown in Table 4, and the concentration of glycerin 4 and adding to water, and stirring for 4 hours, except that various liquid quickening agents were prepared, in the same manner as in Experimental Example 1 (corresponding to Experiment No. 1-6), and physical properties Was evaluated. The results are shown in Table 4.

<Material used>
Alkanolamine or glycerin [a]: monoethanolamine, commercially available alkanolamine or glycerin [a]: diethanolamine, commercially available alkanolamine or glycerin [c]: triethanolamine, commercially available alkanolamine or glycerine [a]: diisopropanol Amine, commercially available alkanolamine or glycerin [O]: glycerin, commercially available product

  From Table 4, when the liquid early strengthening agent contains an alkanolamine or glycerin, it is excellent in the improvement of the initial strength. Among the alkanolamines, diethanolamine is preferred. It is preferable that the concentration of alkanolamine is 1 to 15% and the concentration of glycerin is 1 to 10% from the viewpoint of fluidity and strength development.

"Experimental Example 3"
100 parts of a liquid quick strengthening agent containing 25% of aluminum sulfate (in terms of anhydride), 10% of sodium formate, and 1% of bisphenol-based condensate [1], the rest being water The physical properties were evaluated in the same manner as in Experimental Example 1 (corresponding to Experiment No. 1-6) except that the amount shown in Table 5 was used in solid content conversion with respect to. Moreover, what does not use a early strengthening agent was also implemented as a comparative example (experiment No. 1-45). The results are shown in Table 5.

  From Table 5, even when the amount of use of the liquid early strengthening agent is varied, the improvement of the initial strength is excellent. The use amount of the liquid early strengthening agent is preferably 0.1 part to 10 parts with respect to 100 parts of cement from the viewpoint of suppressing the slump fluctuation and being excellent in strength development.

"Experimental Example 4"
Concrete with a unit water volume of 145 kg / m ³ , a cement volume of 440 kg / m ³ , a water reducing agent 2.5 kg / m ³ , a s / a 39.4%, and an air volume of 4.5% was mixed. After 30 minutes of mixing the concrete, the liquid early strengthening agent (Experiment No. 1-6) prepared in "Experimental Example 1" was post-added, the concrete was mixed again, and the slump of the concrete was measured. The early strengthening agent weighed 8.8 kg / m ³ equivalent to 2 parts in terms of solid content with respect to 100 parts of cement, and was post-added. Thereafter, the formwork was filled with concrete, held at 20 ° C., and demolded after 8 hours, and the compressive strength was evaluated. Except the above, it carried out similarly to Experimental example 1. For comparison, the physical properties without using a liquid early strengthening agent were also evaluated. The results are shown in Table 6.

<Material used>
The same as the material used in "Experimental Example 1".

  From Table 6, the liquid early strengthening agent of the present invention exhibits the same degree of slump and strength development regardless of the timing of the addition of the liquid early strengthening agent. This is an excellent performance especially when carrying in advance the concrete which has been mixed in advance to the site and post-adding the liquid early strengthening agent to the agitator car etc. at the site.

  Cast-in-place cement concrete or precast cement concrete needs to have a certain fluidity, and a certain pot life needs to be ensured for surface finish. If these properties are not excellent, junka may be formed in cement concrete or the surface may not be uniform.

  There is a method of increasing the amount of water reducing agent in cement concrete in order to secure fluidity, and a method of increasing the amount of water, and in order to secure the pot life, a method of using a retarder in combination is also available. there were. However, these methods are likely to lose strength development and are not preferable from the viewpoint of cost.

  The liquid early strengthening agent of the present invention has a small influence on fluidity and is excellent in strength development. The early strengthening agent of the present invention is particularly excellent in initial strength development. The present invention has high flowability and can secure a pot life for surface finish.

  The liquid early strength agent of the present invention is useful for the production of concrete products, and the method for producing early-strength cement concrete using the liquid early strength agent of the present invention is a method for enhancing the productivity of concrete products with less environmental impact. Available.

Claims (9)

The concentration of the water-soluble aluminum salt is 15 to 40% by mass in terms of solid content, the concentration of carboxylic acids is 1 to 20% by mass in terms of solid content, and the concentration of bisphenol-based condensate is 0.1 to 3% by mass in terms of solid content Liquid fastener for cement and concrete, the rest being water. The liquid early strengthening agent for cement concrete according to claim 1, wherein the weight average molecular weight of the bisphenol-based condensate is 1,000 to 30,000. The liquid early strengthening agent for cement concrete according to claim 1 or 2, wherein the structural unit of the bisphenol-based condensate is bisphenol S. Furthermore, the liquid early strengthening agent for cement concrete according to any one of claims 1 to 3, further comprising an alkanolamine. Furthermore, the liquid early strengthening agent for cement concrete according to any one of claims 1 to 4, further comprising a compound having a hydroxyl group. The liquid early strengthening agent for cement concrete according to any one of claims 1 to 5, which is used for cast-in-place cement concrete or precast cement concrete. A early-strength cement concrete containing the liquid early strength agent for cement concrete according to any one of claims 1 to 6 and cement concrete. The early-strength cement concrete according to claim 7, wherein the amount of the liquid early strength agent for cement concrete used is 0.1 to 10 parts by mass in terms of solid content with respect to 100 parts by mass of cement. A method for producing early-strength cement concrete, which comprises adding a liquid early strength agent for cement concrete according to any one of claims 1 to 6 to cement concrete in an agitator vehicle to produce early-strength cement concrete.