Super-retarding concrete, super-retarding agent for super-retarding concrete and preparation method of super-retarding agent

Abstract

The invention discloses super-retarded concrete, a super retarder for the super-retarded concrete and a preparation method of the super-retarded concrete. The super retarder is composed of an amphiphilic polymer, super absorbent resin, calcium nitrate and aluminum sulfate. The amphiphilic polymer forms an adsorption layer on the surfaces of cement particles to block moisture; the super absorbent resin absorbs free water, and the local water cement ratio is reduced; calcium nitrate and aluminum sulfate release ions to inhibit cement hydration. Through the synergistic effect of multiple components, the setting time of the concrete is effectively prolonged by 3-5 times. The obtained super-retarded concrete has super-long flowable time, and the later strength meets the design requirements. During preparation, the super retarder and a concrete mixture are respectively metered and mixed at a discharge port, and the method is simple, convenient and feasible. The super-retarded concrete can be widely applied to large-volume concrete projects such as secant piles, the forming quality can be remarkably improved, the construction period is shortened, and the super-retarded concrete is economical and practical.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, in particular to a super slow setting concrete and a super retarder used therein and a preparation method thereof. Background Art

[0002] Interlocking piles are widely used in the field of civil engineering. They are a deep foundation pit bearing method used for giant bridges, docks, large buildings and other infrastructure that need support. Interlocking piles have the characteristics of strong bearing capacity, wide adaptability and convenient construction. They are usually used in the foundation treatment of buildings to increase the stability and bearing capacity of the foundation.

[0003] In the preparation process of the interlocking pile, a hole that meets the requirements must be excavated by an underground drilling machine, and then concrete is poured into the hole for pouring. When the concrete begins to flow into the hole, the concrete has a certain viscosity, and after forming a preliminary solidification state, friction will be generated, so that it can be firmly combined with the inner wall of the hole.

[0004] However, if the concrete has a high strength in the early stage of pouring, it will have a great obstacle to the flow and filling of the concrete, resulting in the concrete being unable to fully fill the hole, resulting in defects such as voids or cracks. Therefore, when pouring concrete for interlocking piles, the initial and final setting time of the concrete is required to be extended as much as possible so that it can fully flow and fill the entire hole. At the same time, as time goes by, the strength of the concrete will gradually increase and eventually reach the required bearing capacity.

[0005] Taking these factors into consideration, it is necessary to introduce super-slow-setting components into the concrete to ensure that the concrete has good fluidity and super-long setting time in the initial stage, and can reach sufficient strength in the later stage, thereby ensuring the construction quality of the bite piles and the stability of the structure. Summary of the invention

[0006] In order to solve the problems of the prior art, the embodiment of the present invention provides a super-slow setting concrete and a super-retarder used therein and a preparation method thereof. The technical solution is as follows:

[0007] On the one hand, a super retarder for preparing super retarded concrete is provided, wherein the super retarder is a mixture comprising the following components:

[0008] (1) Amphiphilic polymer 0-30%

[0009] (2) Super absorbent resin 0-20%

[0010] (3) Calcium nitrate powder 0-30%

[0011] (4) Aluminum sulfate powder 1-30%

[0012] The sum of the weight percentages of the above components is 100%.

[0013] Furthermore, the amphiphilic polymer is prepared by copolymerization of anionic monomers and cationic monomers; the anionic monomer is selected from at least one of methylene acrylic acid, maleic acid, maleic anhydride, and acrylic acid, and the cationic monomer is selected from at least one of methacryloyloxyethyltrimethylammonium chloride, diallyl quaternary ammonium salt, dimethyldiallylammonium chloride, and diallylmethylbenzylammonium chloride.

[0014] Specifically, the role of the amphiphilic polymer is to form a protective layer on the surface of the cementitious material particles. By regulating the molecular weight of the copolymer and the density of the functional monomer, different adsorption layer thicknesses are achieved on the surface of the cementitious material particles, preventing the contact between the cementitious material and water molecules, greatly reducing the hydration reaction rate of the cementitious material, and effectively prolonging the setting time of the concrete. At the same time, the alkaline ion environment of the pore solution of the cement paste is utilized to realize the consumption of the amphiphilic polymer adsorption layer formed on the surface of the cementitious material particles, thereby ensuring the effective hydration of the cementitious material in the later stage and ensuring the mechanical properties of the concrete in the later stage.

[0015] Furthermore, the super absorbent resin is prepared by copolymerizing at least one of acrylic acid, acrylamide and acrylonitrile with a crosslinking agent, and the particle size of the super absorbent resin ranges from 50 to 200 nm.

[0016] Specifically, the super absorbent resin is prepared by copolymerizing at least one of acrylic acid, acrylamide, and acrylonitrile with a crosslinking agent. The super absorbent resin presents a three-dimensional network structure, and its particle size is controlled to be between 50nm and 200nm. The super absorbent resin is usually used for water-retaining internal curing of concrete in a saturated state, but the present invention does not have this purpose. Instead, the super absorbent resin is added in a dry state, and its water absorption characteristics are utilized to absorb the moisture distributed around the cementitious material particles to reduce the actual water-binder ratio of the cementitious material and delay its initial hydration reaction rate; at the same time, its late water release characteristics are utilized to accelerate the late hydration reaction rate of the cementitious material and improve the late mechanical strength of the concrete.

[0017] The Ca(OH) 2 Powder and Al 2 (SO 4 ) 3 powder, by increasing the Ca content in the pore solution 2+ 、Al 3+ with SO 4 2- The ion concentration causes the dissolution and ion release reaction of the cement mineral phase to proceed in the opposite direction, thereby reducing the hydration rate of the cementitious material.

[0018] On the other hand, a super slow setting concrete is provided, comprising mixture 1 and mixture 2, wherein mixture 1 is the super retarder according to any one of claims 1 to 3; and the dosage ratio of mixture 1 to mixture 2 is 1:100 to 1:1000.

[0019] Furthermore, the mixture 2 comprises the following components:

[0020] (1) Cement 5-70%

[0021] (2) Water 5-15%

[0022] (3)Sand 0~33%

[0023] (4) Crushed stone 0-45%

[0024] (5) Auxiliary cementitious materials 0-10%

[0025] (6) Water reducing agent 0.02~15%.

[0026] Specifically, (1) cement is used as a cementitious material. The cementitious material cement includes but is not limited to general-purpose silicate cement, special cement, air-hardening cementitious material and hydraulic cementitious material, which mainly plays a cementing role;

[0027] (2) Sand, used as fine aggregate, including but not limited to manufactured sand, natural river sand, recycled aggregate and other materials that can serve as a skeleton for cement-based materials, or a mixture of two or more thereof;

[0028] (3) Crushed stone, used as coarse aggregate, including but not limited to crushed stone, recycled aggregate and other materials that can serve as a skeleton for cement-based materials, or a mixture of two or more thereof;

[0029] (4) Water, used as mixing water;

[0030] (5) water reducing agent, used as an admixture, including but not limited to polycarboxylic acid water reducing agent, naphthalene water reducing agent, anthracene water reducing agent, melamine water reducing agent and other admixtures with water reducing function, or a mixture of two or more thereof;

[0031] (6) Auxiliary cementitious materials, including but not limited to ultrafine slag with a specific surface area exceeding 500 m2 / kg, ultrafine cement, silica fume, ultrafine limestone powder, ultrafine fly ash, or a mixture of two or more thereof.

[0032] On the other hand, a method for preparing super slow setting concrete is provided, comprising the following steps:

[0033] (1) uniformly mixing the super retarder components to prepare a dry mixed super retarder;

[0034] (2) Mixing cement, water, sand, crushed stone, auxiliary cementitious materials and water reducing agent uniformly to obtain a concrete mixture;

[0035] (3) During concrete pouring, the dry-mixed super retarder and concrete mixture are metered and delivered simultaneously. The two are mixed at the discharge port and then poured into shape.

[0036] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0037] The invention provides a super retarder for preparing super retarded concrete, which realizes the regulation of the setting time of the super retarded concrete, controls the hydration time of the cementitious material in the concrete, enables the concrete to have a super long setting time, and ensures that the later strength of the concrete meets the mechanical requirements of the project. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below.

[0039] The present invention provides a super retarder, super retarded concrete and a method for preparing the super retarded concrete, which are specifically as follows:

[0040] 1. A super retarder for preparing super retarded concrete is a mixture 1, comprising the following materials:

[0041] (1) Amphiphilic polymers

[0042] (2) Super absorbent resin

[0043] (3) Ca(NO) 3 powder

[0044] (4)Al 2 (SO 4 ) 3 powder

[0045] The sum of the weight percentages of the above components is 100%.

[0046] The amphiphilic polymer is prepared by copolymerizing at least one of anionic functional monomers methylene acrylic acid, maleic acid, maleic anhydride, acrylic acid, and at least one of cationic functional monomers methacryloyloxyethyl trimethyl ammonium chloride (DMC), diallyl quaternary ammonium salt, dimethyl diallyl ammonium chloride (DMDAAC), and diallyl methyl benzyl ammonium chloride. The function of the amphiphilic polymer is to form a protective layer on the surface of the cementitious material particles. By regulating the molecular weight of the copolymer and the density of the functional monomer, different adsorption layer thicknesses on the surface of the cementitious material particles are achieved, preventing the contact between the cementitious material and water molecules, greatly reducing the hydration reaction rate of the cementitious material, and effectively prolonging the setting time of the concrete. At the same time, the alkaline ion environment of the cement paste pore solution is utilized to realize the consumption of the amphoteric polymer adsorption layer formed on the surface of the cementitious material particles, thereby ensuring the effective hydration of the cementitious material in the later stage and ensuring the mechanical properties of the concrete in the later stage.

[0047] The super absorbent resin is prepared by copolymerizing at least one of acrylic acid, acrylamide, and acrylonitrile with a crosslinking agent. The super absorbent resin presents a three-dimensional network structure, and its particle size is controlled to be between 50nm and 200nm. The super absorbent resin is usually used for water-retaining internal curing of concrete in a saturated state, but the present invention does not have this purpose. Instead, the super absorbent resin is added in a dry state, and its water absorption characteristics are utilized to absorb the moisture distributed around the cementitious material particles to reduce the actual water-binder ratio of the cementitious material and delay its initial hydration reaction rate; at the same time, its late water release characteristics are utilized to accelerate the late hydration reaction rate of the cementitious material and improve the late mechanical strength of the concrete.

[0048] The Ca(OH) 2 Powder and Al 2( SO 4 ) 3 powder, by increasing the Ca content in the pore solution 2+ 、Al 3+ with SO 4 2- The ion concentration causes the dissolution and ion release reaction of the cement mineral phase to proceed in the opposite direction, thereby reducing the hydration rate of the cementitious material.

[0049] 2. The material for super slow setting concrete is mixture 2, which includes the following materials:

[0050] (1) Cement, used as a cementitious material. The cementitious material includes but is not limited to general-purpose silicate cement, special cement, air-hardening cementitious material and hydraulic cementitious material, which mainly plays a cementing role;

[0051] (2) Sand, used as fine aggregate, including but not limited to manufactured sand, natural river sand, recycled aggregate and other materials that can serve as a skeleton for cement-based materials, or a mixture of two or more thereof;

[0052] (3) Crushed stone, used as coarse aggregate, including but not limited to crushed stone, recycled aggregate and other materials that can serve as a skeleton for cement-based materials, or a mixture of two or more thereof;

[0053] (4) Water, used as mixing water;

[0054] (5) water reducing agent, used as an admixture, including but not limited to polycarboxylic acid water reducing agent, naphthalene water reducing agent, anthracene water reducing agent, melamine water reducing agent and other admixtures with water reducing function, or a mixture of two or more thereof;

[0055] (6) Auxiliary cementitious materials, including but not limited to ultrafine slag with a specific surface area exceeding 500 m2 / kg, ultrafine cement, silica fume, ultrafine limestone powder, ultrafine fly ash, or a mixture of two or more thereof.

[0056] 3. The extension of setting time of super slow setting concrete is achieved by:

[0057] (1) Stir the dry mixed material 1 evenly.

[0058] (2) Stir the components in mixture 2 until uniform.

[0059] (3) When pouring concrete, the dry and uniformly mixed mixture 1 and the stirred and uniformly stirred mixture 2 are simultaneously discharged, and the two are mixed at the discharge port to form a mixture for pouring, thereby effectively extending the setting time of the concrete.

[0060] 4. The composition of mixture 1 is as follows:

[0061]

[0062] 5. The composition of mixture 2 is as follows:

[0063]

[0064] 6. The usage ratio of mixture 1 to mixture 2 is 1:100 to 1:1000.

[0065] Embodiment 1:

[0066] The weight of each component of the mixture 1 is: super absorbent resin: 0.5kg, amphiphilic polymer: 0.2kg, Ca(NO 3 ) 2 Powder: 0.8kg, Al 2 (SO 4 )3 Powder: 0.2kg.

[0067] The masses of the components of mixture 2 are: cement: 320kg, water: 130kg, crushed stone: 95kg, sand: 720kg, polycarboxylic acid water reducer: 1.5kg.

[0068] Mix 1 is mixed evenly in a dry state, and then the components in Mix 2 are stirred evenly. Mix 1 and Mix 2 are transported to the discharge port at the same time. After the two are mixed at the discharge port, they are poured to form super slow-setting concrete. During the setting and hardening process of concrete, the dry super absorbent resin quickly absorbs water and expands, reducing the moisture content around the cement particles and slowing down its hydration rate. At the same time, it also takes into account the role of water retention and internal curing, providing water for the hydration of cement particles in the later stage; the amphiphilic polymer is adsorbed on the surface of cement particles, cutting off the contact between cement particles and external moisture, and at the same time using the degradation effect of the alkaline environment on its molecules to ensure the hydration of cement particles in the later stage; Al 2 (SO 4 ) 3 Powder and Ca(NO 3 ) 2 Dissolved to form ions, preventing the hydration reaction of cement mineral phases tricalcium aluminate, tricalcium silicate and dicalcium silicate, and further preventing the hydration reaction process of cementitious materials. The combination of the three can achieve the purpose of delaying the setting time of concrete.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A super retarder for preparing super slow setting concrete, characterized in that: The super retarder is a mixture, comprising the following components: (1) Amphiphilic polymer 0-30% (2) Super absorbent resin 0-20% (3) Calcium nitrate powder 0-30% (4) Aluminum sulfate powder 1-30% The sum of the weight percentages of the above components is 100%.

2. The super retarder according to claim 1, characterized in that The amphiphilic polymer is prepared by copolymerization of anionic monomers and cationic monomers; the anionic monomer is selected from at least one of methylene acrylic acid, maleic acid, maleic anhydride, and acrylic acid, and the cationic monomer is selected from at least one of methacryloyloxyethyl trimethyl ammonium chloride, diallyl quaternary ammonium salt, dimethyl diallyl ammonium chloride, and diallyl methyl benzyl ammonium chloride.

3. The super retarder according to claim 1, characterized in that The super absorbent resin is prepared by copolymerizing at least one of acrylic acid, acrylamide and acrylonitrile with a crosslinking agent, and the particle size of the super absorbent resin ranges from 50 to 200 nm.

4. A super slow setting concrete, characterized in that: It comprises mixture 1 and mixture 2, wherein mixture 1 is the super retarder according to any one of claims 1 to 3; the dosage ratio of mixture 1 to mixture 2 is 1:100 to 1:1000.

5. The super slow setting concrete according to claim 4, characterized in that: The mixture 2 comprises the following components: (1) Cement 5-70% 6. A method for preparing super slow setting concrete, characterized in that: The following steps are involved: (1) uniformly mixing the super retarder components according to any one of claims 1 to 3 to prepare a dry mixed super retarder; (2) mixing cement, water, sand, crushed stone, auxiliary cementitious material and water reducing agent in the mixture 2 described in any one of claims 4 to 5 uniformly to obtain a concrete mixture; (3) During concrete pouring, the dry-mixed super retarder and concrete mixture are metered and delivered simultaneously. The two are mixed at the discharge port and then poured into shape.

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