High-strength concrete viscosity-reducing functional additive and preparation method thereof

Abstract

The present invention provides a high-strength concrete viscosity-reducing functional additive and a preparation method thereof. The high-strength concrete viscosity-reducing functional additive is prepared by hydrolyzing and polymerizing cyclic dimethyl siloxane, and then subjecting the obtained product to a dehydration condensation reaction with a five-carbon diol or a six-carbon diol. The high-strength concrete viscosity-reducing functional additive can be compounded with a water reducer, mixed into concrete and uniformly dispersed in the concrete system. The ester group is hydrolyzed in an alkaline environment of cement, and free dihydroxy polydimethylsiloxane and small molecule diols are slowly released. The dihydroxy polydimethylsiloxane is attached to the surface of concrete particles to form a hydrophobic film to lubricate and reduce the friction resistance between particles. The small molecule non-adsorbed diol forms a co-dispersed system with PCE to release more free water to disperse and lubricate. The viscosity-reducing additive of the present invention will not cause problems such as agglomeration and bubbles during the process of adding concrete to mix, and will not affect the strength of concrete.

Description

Technical Field

[0001] The present invention relates to the field of concrete building materials, and in particular to a high-strength concrete viscosity-reducing functional additive. The present invention also relates to a preparation method of the high-strength concrete viscosity-reducing functional additive. Background Art

[0002] As concrete technology develops towards high strength, high durability, self-leveling and other functional directions, the strength of building concrete is often improved by using high-strength cement, increasing cement dosage, increasing gel material content, and reducing water-cement ratio in the process of concrete mixing. However, this type of operation will greatly increase the viscosity of concrete. In view of the phenomenon that concrete becomes hard and sticky under ultra-low water-cement ratio conditions, people use traditional admixtures (naphthalene, aminosulfonates and polycarboxylic acids, etc.) and cannot effectively solve it. Even if the concrete reaches a large slump (greater than 200 mm), the concrete is still hard and sticky. According to the feedback from the on-site construction site, some admixtures will even increase the viscosity of concrete, making it difficult for workers to turn over and mix concrete, and basically impossible to construct. The main reason is that the solid volume fraction of the suspended system is increased, and the viscosity of the system rises sharply. This is also a technical problem that currently plagues both at home and abroad, and it has brought obstacles to the widespread promotion of ultra-high strength and ultra-high replacement rate auxiliary cementitious material technology. Therefore, under the premise of ensuring the basic performance of concrete, how to effectively reduce the viscosity of concrete is an urgent problem to be solved. Summary of the invention

[0003] In view of this, the present invention proposes a high-strength concrete viscosity-reducing functional additive to reduce the viscosity of concrete.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A high-strength concrete viscosity-reducing functional additive, characterized in that the high-strength concrete viscosity-reducing functional additive is prepared by hydrolyzing and polymerizing cyclic dimethylsiloxane and then subjecting the resulting product to a dehydration condensation reaction with a five-carbon diol or a six-carbon diol.

[0006] Furthermore, the cyclic dimethylsiloxane includes at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane.

[0007] Furthermore, the five-carbon diol includes pentanediol.

[0008] Furthermore, the hexavalent alcohol includes 1,6-hexanediol and 4,2-methyl-2,4-pentanediol.

[0009] The present invention also proposes a method for preparing the above-mentioned high-strength concrete viscosity-reducing functional additive, which comprises the following steps:

[0010] By weight, 100-150 parts of cyclic dimethylsiloxane and 1-3 parts of catalyst are mixed uniformly; the temperature is controlled at 100-120°C, and vacuum dehydration is performed. When the dehydration amount reaches 3-5% of the total amount of the material, the dehydration is completed; after continuing to heat to 150-170°C, N2 is introduced to remove low molecules; the temperature is lowered to 100-130°C, 1-5 parts of five carbon glycol or six carbon glycol are added, and the reaction is carried out at a constant temperature; the temperature is heated to 130-150°C, the reaction is carried out at a constant temperature, and vacuum dehydration is performed until no liquid is removed and the dehydration is stopped; when the temperature is lowered to below 60°C, a high-strength concrete viscosity-reducing functional additive can be obtained.

[0011] Furthermore, the catalyst includes at least one of tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide, and dibutyltin dilaurate.

[0012] The high-strength concrete viscosity-reducing functional additive of the present invention is prepared by hydrolyzing and polymerizing cyclic dimethylsiloxane, and then reacting the resulting product with a five-carbon diol or a six-carbon diol to form an ester group. The product can be compounded with a water reducer, mixed into concrete, and evenly dispersed in the concrete system. The ester group is hydrolyzed in an alkaline environment of cement, and free dihydroxy polydimethylsiloxane and small molecule diols are slowly released. The dihydroxy polydimethylsiloxane is attached to the surface of concrete particles to form a hydrophobic film to lubricate and reduce the friction resistance between particles. The small molecule non-adsorbed diol and PCE form a co-dispersed system to release more free water to disperse and lubricate. The viscosity-reducing additive of the present invention will not have problems such as agglomeration and bubbles when added to concrete mixing, and will not affect the strength of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0014] Figure 1 The present invention provides a preparation route for the high-strength concrete viscosity-reducing functional additive; DETAILED DESCRIPTION

[0015] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0016] The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from conventional biochemical reagent stores unless otherwise specified. In addition, except for special instructions in this example, the terms and processes involved in this example are understood according to the general knowledge and conventional methods in the prior art.

[0017] A high-strength concrete viscosity-reducing functional additive is prepared by hydrolyzing and polymerizing cyclic dimethylsiloxane, and then subjecting the obtained product to a dehydration condensation reaction with a five-carbon diol or a six-carbon diol. The above-mentioned cyclic dimethylsiloxane is an organic-inorganic compound with a silicon-oxygen (Si-O) bond as the main chain and an organic group directly connected to the silicon atom, using dimethyldichlorosilane as the main raw material and synthesized by hydrolysis. It is a main intermediate of organic silicon, mainly including hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6). The viscosity-reducing functional additive is prepared by a dehydration condensation reaction between the hydrolysis and polymerization product of cyclic dimethylsiloxane and a small molecule alcohol (five-carbon diol or six-carbon diol), which can be compounded with a water reducer, mixed into concrete and evenly dispersed. The ester group hydrolyzes in the alkaline environment of cement, slowly releasing free dihydroxy polydimethylsiloxane and small molecular glycol. The dihydroxy polydimethylsiloxane is evenly dispersed in the concrete system and adheres to the surface of concrete particles to form a hydrophobic film to lubricate and reduce the friction resistance between particles. The small molecular non-adsorbable glycol forms a co-dispersed system with PCE to release more free water to play a dispersing and lubricating role.

[0018] The viscosity reducing agent of the present invention integrates the hydrolysis polymerization product of cyclic dimethyl siloxane and small molecular five-carbon diol or six-carbon diol together through esterification, which can open the ring and hydrolyze the water-insoluble cyclic dimethyl siloxane, connect the soluble group (hydroxyl group), so that the siloxymethyl bond can be fully and evenly mixed in the concrete, playing the role of lubrication and viscosity reduction, and can also release small molecular diols in the decomposition of the ester group, cooperate with the water reducer to disperse cement particles, and further reduce the viscosity of the concrete. When the viscosity reducing agent of the present invention is added to the concrete mixing process, no problems such as agglomeration and bubbles will occur, and the strength of the concrete will not be affected.

[0019] The five-carbon diol may be pentanediol, and the six-carbon diol may be at least one of 1,6-hexanediol and 4,2-methyl-2,4-pentanediol.

[0020] The present invention also proposes a method for preparing the above-mentioned high-strength concrete viscosity-reducing functional additive, which specifically comprises the following steps:

[0021] By weight, add 100-150 parts of cyclic dimethylsiloxane and 1-3 parts of catalyst to a four-necked flask. Turn on the cooling water of the condenser, start stirring, turn on the electric heating jacket for heating, control the material temperature at 100-120°C, slowly start the vacuum, and adjust the vacuum degree until the flow rate of the evaporated liquid is discontinuous droplets to evaporate the product as little as possible. When the dehydration amount reaches 3-5% of the total amount of the material, the dehydration is completed. After heating the four-necked flask to 150-170°C, pass N2 to remove low molecules for 2 hours. Cool down, when the temperature drops to 100-130°C, add 1-5 parts of small molecule five-carbon or six-carbon diols, and react at a constant temperature for 0.5-3h. Heat the four-necked flask and when the temperature reaches 130-150°C, react at a constant temperature for 1-2h, turn on the vacuum pump for vacuum dehydration, and stop vacuum dehydration when no liquid is removed. Cool down, when the temperature drops below 60°C, stop stirring and discharge the material to obtain a high-strength concrete viscosity-reducing functional additive.

[0022] The catalyst preferably includes at least one of tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide, and dibutyltin dilaurate.

[0023] The preparation route of the above high-strength concrete viscosity-reducing functional additive is as follows: Figure 1 shown.

[0024] The above reaction reagents can all be purchased from the market. The specific implementation scheme of the present invention is described in detail below. Example 1

[0025] (1) Into a four-necked flask, add 100 parts of decamethylcyclopentasiloxane and 2 parts of tetramethylammonium hydroxide crystals.

[0026] ⑵ Turn on the cooling water of the condenser, start stirring, turn on the electric heating jacket to heat, control the material temperature at 100-120℃, slowly start the vacuum, and adjust the vacuum degree until the flow rate of the evaporated liquid is in the form of discontinuous droplets. When the dehydration amount reaches 3-5% of the total amount of the material, the dehydration is completed. After heating the four-necked flask to 150-170℃, pass N2 to remove low molecules for 2 hours.

[0027] ⑶ Cool down. When the temperature reaches 120℃, add 3 parts of 1,6-hexanediol and react at constant temperature for 1 hour.

[0028] (4) Heat the four-necked flask and when the temperature reaches 150°C, keep the reaction at a constant temperature for 1 to 2 hours. Turn on the vacuum pump for vacuum dehydration until no liquid escapes.

[0029] ⑸ Cooling down. When the temperature drops below 60°C, stop stirring and discharge the material to obtain the viscosity reducing functional additive. Example 2

[0030] (1) Into a four-necked flask, add 150 parts of octamethylcyclotetrasiloxane and 1.5 parts of tetramethylammonium hydroxide crystals.

[0031] ⑵ Turn on the cooling water of the condenser, start stirring, turn on the electric heating jacket to heat, control the material temperature at 100-120℃, slowly start the vacuum, and adjust the vacuum degree until the flow rate of the evaporated liquid is in the form of discontinuous droplets to evaporate as little product as possible. When the dehydration amount reaches 3-5% of the total material, the dehydration is completed. After heating the four-necked flask to 150-170℃, pass N2 to remove low molecules for 2 hours.

[0032] ⑶ Cool down. When the temperature reaches 130°C, add 3 parts of neopentyl glycol and react at a constant temperature for 2 hours.

[0033] (4) Heat the four-necked flask and when the temperature reaches 150°C, keep the reaction at a constant temperature for 1 to 2 hours. Turn on the vacuum pump for vacuum dehydration until no liquid escapes.

[0034] ⑸ Stop heating, stop vacuum, and cool down. When the temperature drops below 60°C, stop stirring and discharge the material to obtain the viscosity reducing functional additive. Example 3

[0035] (1) Into a four-necked flask, 130 parts of hexamethylcyclotrisiloxane and 1.3 parts of potassium hydroxide were added.

[0036] ⑵ Turn on the cooling water of the condenser, start stirring, turn on the electric heating jacket to heat, control the material temperature at 100-120℃, slowly start the vacuum, and adjust the vacuum degree until the flow rate of the evaporated liquid is in the form of discontinuous droplets to evaporate as little product as possible. When the dehydration amount reaches 3-5% of the total material, the dehydration is completed. After heating the four-necked flask to 150-170℃, pass N2 to remove low molecules for 2 hours.

[0037] ⑶ Cool down. When the temperature reaches 100-130°C, add 3 parts of 4,2-methyl-2,4-pentanediol and react at a constant temperature for 3 hours.

[0038] (4) Heat the four-necked flask and when the temperature reaches 150°C, keep the reaction at a constant temperature for 1 to 2 hours. Turn on the vacuum pump for vacuum dehydration until no liquid escapes.

[0039] ⑸ Stop heating, stop vacuum, and cool down. When the temperature drops below 60°C, stop stirring and discharge the material to obtain the viscosity reducing agent.

[0040] Comparative Example 1

[0041] This comparative example adopts a commercially available viscosity-reducing product.

[0042] Comparative Example 2

[0043] In this comparative example, 100 parts of decamethylcyclopentasiloxane and 3 parts of 1,6-hexanediol were compounded without esterification to obtain a viscosity reducer.

[0044] Embodiment effect:

[0045] The performance of the above embodiment was tested by concrete test, wherein the cement was Esheng PO 42.5 cement, the sand was medium sand with a fineness modulus of 2.3 and coarse sand of 3.0, and the gravel was 5mm-20mm continuously graded crushed stone. The single cubic concrete mix ratio was cement: medium sand: coarse sand: stone: water = 480: 393: 262: 1165: 149, and the single ton concrete admixture formula was water-reducing polycarboxylic acid water-reducing agent: slump-retaining polycarboxylic acid water-reducing agent: water = 340: 150: 510. No viscosity-reducing functional additive was added to the blank. The viscosity-reducing functional additive of the embodiment and the comparative example added 0.1 / 1000 cementitious materials. According to GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", the initial slump, expansion, inverted lifting time and air content of the concrete were tested. The test results are shown in Table 1.

[0046] Table 1

[0047]

[0048] By comparing the test results of each embodiment, comparative example 1 (commercially available product), comparative example 2 and the blank group, the concrete viscosity reducing functional additive of the present invention can effectively reduce the viscosity of concrete, shorten the pouring time, and improve the working performance of concrete.

[0049] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0050] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A high-strength concrete viscosity-reducing functional additive, characterized in that: The high-strength concrete viscosity-reducing functional additive is prepared by hydrolyzing and polymerizing cyclic dimethylsiloxane, and then subjecting the obtained product to a dehydration condensation reaction with a five-carbon diol; The preparation method of the high-strength concrete viscosity-reducing functional additive comprises the following steps: By weight, 100-150 parts of cyclic dimethylsiloxane and 1-3 parts of a catalyst are mixed evenly; Control the temperature at 100-120℃ and vacuum dehydration. When the dehydration amount reaches 3-5% of the total amount of the material, the dehydration ends. Continue heating to 150-170°C, then introduce N2 to remove low molecular weight molecules; Cool down to 100-130℃, add 1-5 parts of pentanediol, and react at constant temperature; Heat to 130-150℃, react at constant temperature, and vacuum dehydrate until no liquid is released; When the temperature drops below 60°C, a high-strength concrete viscosity-reducing additive can be obtained; The catalyst includes at least one of tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide, and dibutyltin dilaurate.

2. The high-strength concrete viscosity-reducing functional additive according to claim 1, characterized in that: The cyclic dimethylsiloxane includes at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane.

3. The high-strength concrete viscosity-reducing functional additive according to claim 1, characterized in that: The five-carbon diol includes pentanediol.

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