A heat-source-free and alkali-free liquid quick-setting agent and a preparation method thereof

Abstract

The present invention provides a heat source-free alkali-free liquid quick-setting agent and a preparation method thereof, comprising the following raw materials in parts by weight: 10-15 parts of 50% sodium aluminate solution, 38-49 parts of aluminum sulfate, 13-21 parts of fluorosilicic acid, 1-5 parts of alcoholamine complexing agent, 1-6 parts of magnesium aluminum silicate, 1-8 parts of magnesium fluorosilicate and 10-20 parts of water. The heat source-free alkali-free liquid quick-setting agent and the preparation method thereof have the beneficial technical effects of no need for heating, less dosage and higher strength, simple preparation, and no wastewater, waste gas and waste residue discharge.

Description

Technical Field

[0001] The invention relates to the technology of alkali-free liquid quick-setting agent for shotcrete, and in particular to a heat-source-free alkali-free liquid quick-setting agent and a preparation method thereof. Background Art

[0002] Concrete accelerators are mainly used to prepare shotcrete, which is a type of concrete that is prepared by using compressed air and a spraying machine to transport a concrete mixture prepared in a certain proportion through a pipeline and spray it at high speed onto a rock wall or other structural surface to solidify and harden. It is widely used in mine shafts, railway and highway tunnels, underground caves, water conservancy and other shotcrete projects to complete rapid support. Obviously, the quality of shotcrete depends to a large extent on the quality of the accelerator.

[0003] With the continuous development of shotcrete technology, shotcrete has developed from dry spraying to wet spraying, and the quick-setting agent has also developed from powdered quick-setting agent to liquid quick-setting agent. The amount and market share of liquid quick-setting agent have increased by leaps and bounds, and are gradually replacing powdered quick-setting agent. At present, the most widely used quick-setting agents are alkaline liquid quick-setting agents. Although the alkaline liquid quick-setting agents have the advantages of good accelerating effect and low price, they also have the problems of high alkali content, large strength loss in the later stage, strong corrosiveness, poor durability and high spray rebound. In response to the above problems, alkali-free liquid quick-setting agents have emerged, which solve a series of problems caused by the high alkali content of traditional alkaline quick-setting agents, and have the advantages of safety, environmental protection, no corrosion, good durability, good mechanical properties and low spray rebound. However, the existing concrete alkali-free liquid quick-setting agents still have the disadvantages of needing heating during preparation, high energy consumption, high product dosage, poor quick-setting effect on high admixture cement dosage and low early strength. Summary of the invention

[0004] In view of the above problems, the present invention provides a heat source-free and alkali-free liquid quick-setting agent and a preparation method thereof.

[0005] The heat source-free and alkali-free liquid quick-setting agent of the invention comprises the following raw materials in parts by mass: 10-15 parts of 50% sodium aluminate solution, 38-49 parts of aluminum sulfate, 13-21 parts of fluorosilicic acid, 1-5 parts of alcoholamine complexing agent, 1-6 parts of magnesium aluminum silicate, 1-8 parts of magnesium fluorosilicate and 10-20 parts of water.

[0006] Preferably, the alcoholamine complexing agent is diethanolamine.

[0007] Preferably, the heat source-free and alkali-free liquid quick-setting agent of the present invention comprises the following raw materials in the following mass proportions: 12-13 parts of 50% sodium aluminate solution, 42-46 parts of aluminum sulfate, 17-18 parts of fluorosilicic acid, 3 parts of alcoholamine complexing agent, 1-2 parts of magnesium aluminum silicate, 3-5 parts of magnesium fluorosilicate and 15 parts of water.

[0008] The method for preparing the heat-source-free and alkali-free liquid quick-setting agent of the present invention comprises the following steps:

[0009] S1. Weigh the raw materials of each component in proportion and set aside;

[0010] S2, adding water into the reaction kettle, and adding 53-59% of the total amount of fluorosilicic acid and stirring until completely dissolved;

[0011] S3, add 48-54% of the total amount of aluminum sulfate and stir until completely dissolved;

[0012] S4, slowly dropwise add a 50% sodium aluminate solution, and complete the dropwise addition within 30-50 minutes, slowly raise the temperature in the reactor to 60-80°C; stir for 30 minutes after the dropwise addition is completed;

[0013] S5. Slowly add 41-47% of the total amount of fluorosilicic acid to the reactor, stir for 15 minutes, and keep the temperature at 60-80°C;

[0014] S6. Add 46-52% of the total amount of aluminum sulfate to the reactor and stir for 2 hours at a temperature of 60-80°C;

[0015] S7, add the alcohol amine complexing agent into the reactor and stir until completely dissolved, and keep warm for 30-60 minutes;

[0016] S8, adding magnesium fluorosilicate and magnesium aluminum silicate to the reactor and stirring continuously until completely dissolved, and keeping warm for 30-60 minutes;

[0017] S9. Cool naturally to room temperature to obtain the alkali-free accelerating setting agent.

[0018] The beneficial technical effects of the heat-source-free and alkali-free liquid quick-setting agent and the preparation method thereof of the present invention include:

[0019] 1. Carry out at room temperature, without heating the system, and save 167KJ / ton of energy;

[0020] 2. The dosage of alkali-free accelerating setting agent is 1-2% lower than that of commercially available alkali-free accelerating setting agent;

[0021] 3. The initial and final setting time of cementitious materials with 20% admixture (fly ash) meet the national standard requirements;

[0022] 4. The strength of alkali-free accelerating setting agent can reach more than 10MPa in one day;

[0023] 5. The production process is simple and easy to operate;

[0024] 6. The production process is environmentally friendly and pollution-free, with no wastewater, waste gas or waste residue discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attached Figure 1 The present invention is a flow chart of the method for preparing the heat source-free and alkali-free liquid quick-setting agent.

[0026] The heat-source-free and alkali-free liquid quick-setting agent and its preparation method of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0027] The heat source-free and alkali-free liquid quick-setting agent of the present invention comprises the following raw materials in parts by mass: 10-15 parts of 50% sodium aluminate solution, 38-49 parts of aluminum sulfate, 13-21 parts of fluorosilicic acid, 1-5 parts of alcoholamine complexing agent, 1-6 parts of magnesium aluminum silicate, 1-8 parts of magnesium fluorosilicate and 10-20 parts of water. In the process of making the heat source-free and alkali-free liquid quick-setting agent, the present invention adds sodium aluminate, aluminum sulfate, magnesium fluorosilicate and sodium aluminate to introduce fluoride salts, fluoroaluminates, sulfates, aluminates and sodium magnesium ions, and shortens the setting time by utilizing the super strong complexing ability of fluoride ions and aluminum ions and the super strong coagulant ability of fluoride ions. Among them, the reaction mechanism of fluorosilicic acid and sodium aluminate involves a double hydrolysis process, which is an exothermic reaction, and can increase the system temperature from 15°C to 60°C to generate sodium fluoride NaF, AlF 3 and SiO 2 This reaction is usually carried out under acidic conditions, and F is produced during the reaction. - 、A1 3+ It is still the main coagulant element. The specific reaction equation is as follows:

[0028] NaAlO 2 +H 2 SiF 6 →NaF+AlF 3 +H 2 O+SiO 2 (1)

[0029] The early hydration mechanism of silicate cement with aluminum sulfate-based accelerators includes: 2 (S04) 3 With Ca(OH) in the liquid phase 2 It can directly react to form ettringite without the need for C 3 The participation of A, that is, reaction (2):

[0030] Al 2 (S04) 3 +70H - →3S0 4 2- + [Al(0H) 4 ] - + Al(OH) 3 (2)

[0031] Al(OH) generated by the reaction 3 Generally, it cannot exist stably and will react with Ca(OH) 2 The reaction generates calcium aluminate, that is, reaction equations (3) and (4). The accelerator reacts with the Ca in the solution. 2+ and OH - The reaction generates ettringite:

[0032] 2[Al(0H)] - +3S0 4 2- +6Ca 2+ +40H - +26H 2 O→C 3 A.3C S - H 32 (3)

[0033] 2Al(0H) 3 +3S0 4 2- +6Ca 2+ +60H - +26H 2 O → C 3 A.3C S - H 32 (4)

[0034] C in cement 3 A and S0 4 2- The reaction generates ettringite: SO 4 2- With Ca 2+ The reaction generates secondary gypsum, which is easier to react with C 3 A reaction generates ettringite, that is, reaction formula (5):

[0035] C 3 A+3SO 4 2- +3Ca 2+ +32H→C 3 A.3C S - H 32 (5)

[0036] C in cement 3 S and C 3 Dissolution and hydration of A:

[0037] C 3 S+3H + →3Ca 2+ +OH- +H 2 SiO 4 2- →CSH (6)

[0038] C 3 S+3H + +[Al(0H) 4 ] - →3Ca 2+ +0H - +H 2 SiO 4 2- +[Al(0H) 4 ] - →CASH (7)

[0039] Aluminum sulfate is the main raw material of the heat-free and alkali-free liquid setting accelerator of the present invention. As the proportion of aluminum sulfate in the setting accelerator increases, the concentrations of aluminum ions, sulfate ions and hydrogen ions in the setting accelerator solution gradually increase; as the aluminum ions and sulfate ions increase, the solution gradually reaches the solubility of aluminum sulfate, and the stability of the setting accelerator deteriorates; at the same time, the increase of aluminum and sulfate ions will increase the amount of calcium sulfonate generated in the cement slurry, shortening the setting time of the cement slurry. A1 3+ It can also accelerate the aggregation of CSH gel particles and accelerate the 3 Hydration of S. Each reaction consumes Ca(OH) 2 , which promotes C 3 Hydration of S. More calcium sulfonate cross-links into a network to form the skeleton of the cement paste, while hydrated calcium silicate gel fills in between, promoting the coagulation of the cement paste. + Mg 2+ Can improve the early strength of cement for 6-24 hours, Na + Mg 2+ The higher the content of accelerator, the higher the one-day strength of mortar.

[0040] As one of the preferred technical solutions, the alcohol amine complexing agent of the heat-free and alkali-free liquid quick-setting agent of the present invention is diethanolamine, and the N atom in its molecular structure has a pair of lone electron pairs, which can react with the metal A1 that can provide an empty orbital. 3+ Complexation reaction occurs to form a stable soluble complex, increasing A1 3+ Solubility, thereby improving the stability of the accelerator system; at the same time, the soluble complex can increase the diffusion of hydration products to further hydrate, shorten the setting time and improve the early strength. Alcoholamine substances are organic early strength agents that can provide early strength of concrete.

[0041] The magnesium aluminum silicate of the heat-source-free and alkali-free liquid quick-setting agent of the present invention is used as a stabilizer, a suspending agent and a thickener, has good rheological properties and thixotropy, forms a "card palace" type associative network structure in an aqueous medium, and can enhance the product stability of the quick-setting agent.

[0042] As one of the preferred technical solutions, the heat source-free and alkali-free liquid quick-setting agent of the present invention comprises the following raw materials in the following weight proportions: 12-13 parts of sodium aluminate solution, 42-46 parts of aluminum sulfate, 17-18 parts of fluorosilicic acid, 3 parts of alcoholamine complexing agent, 1-2 parts of magnesium aluminum silicate, 3-5 parts of magnesium fluorosilicate and 15 parts of water.

[0043] The method for preparing the heat-source-free and alkali-free liquid quick-setting agent of the present invention comprises the following steps:

[0044] S1. Weigh the raw materials of each component in proportion and set aside;

[0045] S2, adding water into the reaction kettle, and adding 53-59% of the total amount of fluorosilicic acid and stirring until completely dissolved;

[0046] S3, add 48-54% of the total amount of aluminum sulfate and stir until completely dissolved;

[0047] S4, slowly drop the sodium aluminate solution and complete the dropwise addition within 30-50 minutes, slowly raise the temperature in the reactor to 60-80°C; stir for 30 minutes after the dropwise addition is completed;

[0048] S5. Slowly add 41-47% of the total amount of fluorosilicic acid to the reactor, stir for 15 minutes, and keep the temperature at 60-80°C;

[0049] S6. Add 46-52% of the total amount of aluminum sulfate to the reactor and stir for 2 hours at a temperature of 60-80°C;

[0050] S7, add the alcohol amine complexing agent into the reactor and stir until completely dissolved, and keep warm for 30-60 minutes;

[0051] S8, adding magnesium fluorosilicate and magnesium aluminum silicate to the reactor and stirring continuously until completely dissolved, and keeping warm for 30-60 minutes;

[0052] S9. Cool naturally to room temperature to obtain the alkali-free accelerating setting agent.

[0053] In order to verify the performance and function of the heat-source-free alkali-free liquid quick-setting agent of the present invention, the setting time and one-day strength of the heat-source-free alkali-free liquid quick-setting agent of the present invention were tested in accordance with the requirements of GB / T 35159-2017 "Accelerator for Shotcrete". Including:

[0054] 1. Determination method of setting time

[0055] Put the weighed water (140g minus the water in the heat-source-free and alkali-free liquid accelerator of the present invention) and 400g cement into the stirring pot in turn, start the mixer and stir at a low speed for 30 seconds before stopping. Use a 50 ml syringe to add the weighed heat-source-free and alkali-free liquid accelerator of the present invention in turn, stir at a low speed for 5 seconds, then stir at a high speed for 15 seconds, and the stirring is finished. Immediately put it into a round mold, tamp it with a knife, vibrate it gently several times, scrape off the excess pure slurry, and smooth the surface. Counting from the addition of the liquid accelerator, the total operation time should not exceed 50 seconds.

[0056] 2. Method for determining the one-day strength

[0057] Weighed water (450g minus the amount of water in the heat-source-free alkali-free liquid accelerator of the present invention) and 900g cement are placed in the mixing pot in sequence, and the mixer is started to stir at a low speed for 30s. Then, standard sand is evenly added during the second 30s of low-speed stirring, followed by high-speed stirring for 30s. Stop stirring for 90s, and use a rubber scraper to scrape the mortar on the blades and the pot wall into the mixing pot within the first 15s of the stop stirring. Continue stirring at high speed for another 30s. Then, immediately add the recommended amount of the heat-source-free alkali-free liquid accelerator of the present invention with a 100mL syringe, stir at a low speed for 5s, and then stir at a high speed for 15s, and the stirring is finished. All the stirred mortar is evenly loaded into the feeding funnel, and the vibration table is turned on, and the mortar flows into the test mold through the feeding funnel. The total operation time from adding the liquid accelerator to the mortar entering the mold should not exceed 50s. Use a vibration table to vibrate and mold, and the vibration time is 30s. Remove the test mold, scrape off the mortar that is higher than the test mold and smooth the surface. Mark the test mold and send it to the curing box or curing room. Each accelerator needs to form 3 groups of test mortar specimens and 1 group of reference mortar specimens, with 3 specimens in each group. Among them, the test body age for 1-day strength is 24h±15min, the specimen size is 40mm×40mm×160mm, and the test is carried out according to GB / T17671.

[0058] 3. Measurement results

[0059] In order to verify the influence of different components on the setting time and one-day strength of the heat-free alkali-free liquid quick-setting agent of the present invention, 9 components of the heat-free alkali-free liquid quick-setting agent of the present invention were prepared, and the setting time and one-day strength were tested according to the above method. The preparation of the heat-free alkali-free liquid quick-setting agent of the present invention with these 9 components was made according to the preparation method of the heat-free alkali-free liquid quick-setting agent of the present invention, and 80% P·O42.5 cement and 20% fly ash were used as cementitious materials, and the dosage was 6%; the test results are shown in Table 1 below:

[0060]

[0061] The heat-source-free alkali-free liquid accelerator concrete alkali-free liquid accelerator adopts aluminum sulfate as the main component and is supplemented with an organic acid complexing agent, which can greatly increase the F content in the accelerator. - 、Al 3+ and SO 4 2- The content of cement C 3 A and C 3 The hydration of S can improve the depolymerization of active ingredients in cement and admixtures. Alcoholamines can also improve the early performance of cement-based materials and the adhesion during shotcrete construction. Magnesium aluminum silicate is used as a stabilizer, suspending agent, and thickener. It has good rheological and thixotropic properties and forms a "card palace" type associative network structure in the water medium, which can enhance the product stability of the accelerator.

[0062] The active ingredients in the alkali-free liquid accelerator of the present invention can be adsorbed on the surface of cement particles to form a hydrophilic film, promote the hydration reaction of cement particles, expand the particle volume and increase the hardness, thereby accelerating the early strength development of concrete. The organic acid or polymer compound in the alkali-free liquid accelerator can combine with calcium ions in cement to form a new complex, thereby affecting the growth and maturation process of cement stone and minerals. The crystallization speed of cement crystals is accelerated, and the durability of cement stone and colloid is improved.

[0063] Obviously, the beneficial technical effects of the heat-source-free and alkali-free liquid quick-setting agent and the preparation method thereof of the present invention are that no heating is required, the dosage is small, the strength is high, and the preparation is simple, and no wastewater, waste gas, and waste residue are discharged.

Claims

1. A heat-source-free and alkali-free liquid quick-setting agent, characterized in that: The heat source-free and alkali-free liquid quick-setting agent comprises the following raw materials in the following mass parts: 10-15 parts of 50% sodium aluminate solution, 38-49 parts of aluminum sulfate, 13-21 parts of fluorosilicic acid, 1-5 parts of alcoholamine complexing agent, 1-6 parts of magnesium aluminum silicate, 1-8 parts of magnesium fluorosilicate and 10-20 parts of water.

2. The heat-source-free and alkali-free liquid quick-setting agent according to claim 1, characterized in that: The alcoholamine complexing agent is diethanolamine.

3. The heat-source-free and alkali-free liquid quick-setting agent according to claim 1 or 2, characterized in that: The heat source-free and alkali-free liquid quick-setting agent comprises the following raw materials in parts by mass: 12-13 parts of sodium aluminate solution, 42-46 parts of aluminum sulfate, 17-18 parts of fluorosilicic acid, 3 parts of alcoholamine complexing agent, 1-2 parts of magnesium aluminum silicate, 3-5 parts of magnesium fluorosilicate and 15 parts of water.

4. A method for preparing a heat-source-free and alkali-free liquid quick-setting agent, characterized in that: The component described in any one of claims 1 to 3 is used to prepare a heat-source-free and alkali-free liquid quick-setting agent, and the preparation method thereof comprises the following steps: S1. Weigh the raw materials of each component in proportion and set aside; S2, adding water into the reaction kettle, and adding 53-59% of the total amount of fluorosilicic acid and stirring until completely dissolved; S3, add 48-54% of the total amount of aluminum sulfate and stir until completely dissolved; S4, slowly add the sodium aluminate solution dropwise, and complete the addition within 30-50 minutes, slowly raise the temperature in the reactor to 60-80°C; stir for 30 minutes after the addition is completed; S5. Slowly add 41-47% of the total amount of fluorosilicic acid to the reactor, stir for 15 minutes, and keep the temperature at 60-80°C; S6. Add 46-52% of the total amount of aluminum sulfate to the reactor and stir for 2 hours at a temperature of 60-80°C; S7, add the alcohol amine complexing agent into the reactor and stir until completely dissolved, and keep warm for 30-60 minutes; S8, adding magnesium fluorosilicate and magnesium aluminum silicate to the reactor and stirring continuously until completely dissolved, and keeping warm for 30-60 minutes; S9. Cool naturally to room temperature to obtain the alkali-free accelerating setting agent.

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