Crack resistance enhanced environment-friendly concrete accelerator and preparation method thereof

Abstract

The invention discloses an anti-cracking performance enhanced environment-friendly concrete accelerator and a preparation method thereof. The environment-friendly concrete accelerator comprises the following components in parts by weight: 40-60 parts of aluminum sulfate, 5-15 parts of potassium carbonate, 20-40 parts of composite fibers, 50-70 parts of nano silicon dioxide, 1-3 parts of fly ash, 0.3-1 part of steel slag micropowder, 1-3 parts of a curing agent and 0.2-1.2 parts of a calcium sulphoaluminate-magnesium oxide composite expanding agent, the curing agent is a super absorbent polymer; the invention belongs to the technical field of concrete accelerators, and particularly relates to an anti-cracking performance enhanced environment-friendly concrete accelerator and a preparation method thereof. Through the synergistic effect of the super absorbent polymer and the high-performance expanding agent, the problems of insufficient crack resistance and poor environmental protection property of the accelerator are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete accelerators, and particularly relates to an environment-friendly concrete accelerator with enhanced anti-cracking performance and a preparation method thereof. BACKGROUND

[0002] Concrete accelerator is an indispensable key material in tunnel support, underground engineering, emergency repair and other scenes. It significantly shortens the setting time of concrete by accelerating the cement hydration reaction, thereby meeting the rapid construction requirements. Traditional accelerators mainly take aluminate, silicate or alkaline compounds (such as sodium hydroxide, sodium carbonate) as the core component, and stimulate the rapid reaction of cement particles through a high-alkaline environment. However, with the increasing requirements of the building industry on material performance, environmental friendliness and sustainability, the limitations of traditional accelerators have become increasingly prominent, specifically manifested in poor environmental friendliness and insufficient anti-cracking performance. In the prior art, there have been studies on improving the anti-cracking performance by adding fibers or expanding agents, but often at the expense of setting speed or increased cost. In addition, traditional accelerators rely on non-renewable resources (such as bauxite), which does not meet the development trend of green building materials. Therefore, it is of great significance to develop a concrete accelerator that has the functions of accelerating, anti-cracking, environmental friendliness and cost control. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides an environment-friendly concrete accelerator with enhanced anti-cracking performance and a preparation method thereof. Through the synergistic effect of superabsorbent polymer and calcium sulphoaluminate-magnesium oxide composite expanding agent, the problems of insufficient anti-cracking performance and poor environmental friendliness of the accelerator are solved. The superabsorbent polymer forms gel particles after absorbing water, slowly releases water during the hardening process of concrete, and reduces plastic shrinkage. At the same time, its elastic modulus is lower than that of the cement matrix, which can buffer the internal stress and inhibit the expansion of micro-cracks. The calcium sulphoaluminate-magnesium oxide composite expanding agent produces moderate volume expansion to offset the shrinkage stress, and forms a "physical-chemical" dual anti-cracking mechanism with the superabsorbent polymer. Fly ash and steel slag micro-powder provide active SiO2 and Al2O3 to promote the hydration reaction, while reducing the cost and carbon footprint of raw materials.

[0004] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows: The present application provides an environment-friendly concrete accelerator with enhanced anti-cracking performance, which comprises the following components in parts by weight: aluminum sulfate 40-60 parts, potassium carbonate 5-15 parts, composite fiber 21-45 parts, nano-silicon dioxide 50-70 parts, fly ash 1-3 parts, steel slag micro-powder 0.3-1 part, curing agent 1-3 parts, and calcium sulphoaluminate-magnesium oxide composite expanding agent 0.2-1.2 parts.

[0005] Further, the composite fiber is mixed by polypropylene fiber and basalt short fiber at a ratio of 1:2 by weight.

[0006] Further, the specific surface area of the nanometer silicon dioxide is 200-400m 2 / g.

[0007] Further, the steel slag micro-powder is the product of industrial waste residue after calcination and activation at 600-700 DEG C for 2 hours, and is ground to a specific surface area of greater than or equal to 450m 2 / kg.

[0008] Further, the fly ash is the product of industrial waste residue after calcination and activation at 650-700 DEG C for 2 hours, and is ground to a specific surface area of greater than or equal to 450m 2 / kg.

[0009] Further, the curing agent is a superabsorbent polymer.

[0010] Further, the preparation process of the superabsorbent polymer comprises the following steps:

[0011] (1) the crosslinking agent is dissolved in ethanol, and is magnetically stirred for 10 minutes to completely dissolve, and is prepared into a crosslinking liquid of 1-5wt%;

[0012] (2) the crosslinking liquid is uniformly sprayed onto the surface of the sodium polyacrylate powder, the spraying amount is 0.5-2% of the mass of the sodium polyacrylate, and after spraying, the sodium polyacrylate crosslinking layer is obtained after standing for 5 minutes;

[0013] (3) the sodium polyacrylate crosslinking layer is moved to a forced air drying oven, and is heat treated at 60 DEG C for 1 hour to obtain the superabsorbent polymer.

[0014] Further, the crosslinking agent is ethylene glycol diglycidyl ether.

[0015] The application also provides a preparation method of the environment-friendly concrete accelerator with enhanced anti-cracking performance, and specifically comprises the following steps:

[0016] (1) aluminum sulfate, potassium carbonate and composite fibers are added into a high-speed mixer, and are stirred for 10 minutes to obtain a mixture A;

[0017] (2) nanometer silicon dioxide, fly ash and steel slag micro-powder are sequentially added into the mixture A, and are continuously stirred for 15 minutes to obtain a mixture B;

[0018] (3) the mixture B is further added with a curing agent and a calcium-magnesium aluminate-magnesium oxide composite expanding agent, and is continuously stirred for 10 minutes to obtain a mixture C, and the mixture C is crushed by using an airflow crusher to obtain the environment-friendly concrete accelerator.

[0019] Further, the stirring speed of the high-speed mixer is 800-1000r / min.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] (1) The present application realizes the dual anti-cracking mechanism of "physical water absorption-chemical expansion" by the internal curing effect of superabsorbent polymer and the chemical expansion compensation of calcium sulphoaluminate-magnesium oxide composite expansion agent, effectively inhibiting early plastic cracks and dry shrinkage cracks.

[0022] (2) The present application replaces traditional bauxite raw materials with industrial waste residues (fly ash, steel slag powder), reduces the consumption of natural resources, and meets the green building material standard.

[0023] (3) In the present application, an aluminum sulfate-potassium carbonate composite setting system is used, combined with the crystal nucleus effect of nano-silicon dioxide, and the setting effect is stable and has strong compatibility. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The compressive strength ratio of Examples 1-3 and Comparative Examples 1-2;

[0025] Figure 2 The 28-day dry shrinkage of Examples 1-3 and Comparative Examples 1-2;

[0026] Figure 3 The SEM images of superabsorbent polymer and calcium sulphoaluminate-magnesium oxide composite expansion agent in the present application;

[0027] Figure 4 The physical images of superabsorbent polymer and calcium sulphoaluminate-magnesium oxide composite expansion agent in the present application. DETAILED DESCRIPTION

[0028] The present application will be further described in detail through specific preferred embodiments, but the present application is not limited to the following examples.

[0029] It should be noted that, unless otherwise specified, the chemical reagents involved in the present application are purchased through commercial channels.

[0030] The aluminum sulfate (≥98%) used in the present application is purchased from Shandong Luxi Chemical Group Co., Ltd., potassium carbonate (≥99%) and sodium polyacrylate (≥95%) are purchased from Wanhua Chemical Group Co., Ltd., ethanol (≥99.5%) is purchased from China National Pharmaceutical Group Corporation, ethylene glycol diglycidyl ether (≥95%) is purchased from Shanghai Maikelin Biochemical Technology Co., Ltd., and calcium sulphoaluminate-magnesium oxide composite expansion agent (0.05-0.15%) is purchased from Jiangsu Boten New Material Co., Ltd.

[0031] Example 1

[0032] The present application provides an anti-cracking performance enhanced type of environment-friendly concrete setting accelerator

[0033] The environment-friendly concrete accelerator comprises the following components in parts by weight: 40 parts of aluminum sulfate, 5 parts of potassium carbonate, 7 parts of polypropylene fiber, 14 parts of basalt short fiber, 50 parts of nano-silica, 1 part of fly ash, 0.3 part of steel slag micro powder, 1 part of superabsorbent polymer and 0.2 part of calcium-magnesium oxide composite expansion agent.

[0034] The specific surface area of the nano-silica is 200 m 2 / g.

[0035] The steel slag micro powder is a product obtained by calcining and activating an industrial waste residue at 600 DEG C for 2 hours, and is ground to a specific surface area of 450 m 2 / kg.

[0036] The fly ash is a product obtained by calcining and activating an industrial waste residue at 600 DEG C for 2 hours, and is ground to a specific surface area of 450 m 2 / kg.

[0037] The preparation process of the superabsorbent polymer comprises the following steps:

[0038] (1) 1g of ethylene glycol diglycidyl ether is dissolved in 125.5mL of ethanol, and is magnetically stirred for 10 minutes until completely dissolved to prepare a 1wt% crosslinking solution;

[0039] (2) 0.25g of the crosslinking solution is uniformly sprayed onto the surface of 50g of polyacrylic acid sodium powder, and the spraying amount is 0.5% of the mass of the polyacrylic acid sodium, and after spraying, the polyacrylic acid sodium crosslinking layer is obtained by standing for 5 minutes;

[0040] (3) the polyacrylic acid sodium crosslinking layer is moved to a forced air drying oven, and is heat treated at 60 DEG C for 1 hour to obtain the superabsorbent polymer.

[0041] The application further provides a preparation method of the environment-friendly concrete accelerator with enhanced anti-cracking performance, and specifically comprises the following steps:

[0042] (1) 40 parts of aluminum sulfate, 5 parts of potassium carbonate, 7 parts of polypropylene fiber and 14 parts of basalt short fiber are added into a high-speed mixer, and are stirred for 10 minutes to obtain a mixture A;

[0043] (2) 50 parts of nano-silica, 1 part of fly ash and 0.3 part of steel slag micro powder are sequentially added into the mixture A, and are continuously stirred for 15 minutes to obtain a mixture B;

[0044] (3) 1 part of superabsorbent polymer and 0.2 part of calcium-magnesium oxide composite expansion agent are further added into the mixture B, and are continuously stirred for 10 minutes to obtain a mixture C, and the mixture C is crushed by using an airflow crusher to obtain the environment-friendly concrete accelerator.

[0045] The stirring speed of the high-speed mixer is 800 r / min.

[0046] Embodiment 2

[0047] The application provides an anti-cracking performance enhanced environment-friendly concrete accelerator

[0048] The environment-friendly concrete accelerator comprises the following components in parts by weight: 50 parts of aluminum sulfate, 10 parts of potassium carbonate, 10 parts of polypropylene fiber, 20 parts of basalt short-cut fiber, 60 parts of nano-silicon dioxide, 2 parts of fly ash, 0.6 parts of steel slag micro-powder, 2 parts of superabsorbent polymer and 0.8 parts of calcium-magnesium oxide composite expansive agent.

[0049] The specific surface area of the nano-silicon dioxide is 300 m 2 / g.

[0050] The steel slag micro-powder is a product obtained by calcining and activating an industrial waste residue at 650 DEG C for 2 hours, and is ground to have a specific surface area of 500 m 2 / kg.

[0051] The fly ash is a product obtained by calcining and activating an industrial waste residue at 650 DEG C for 2 hours, and is ground to have a specific surface area of 500 m 2 / kg.

[0052] The preparation process of the superabsorbent polymer comprises the following steps:

[0053] (1) 1g of ethylene glycol diglycidyl ether is dissolved in 62.1mL of ethanol, and is magnetically stirred for 10 minutes until completely dissolved to prepare a 2wt% crosslinking solution;

[0054] (2) 0.5g of the crosslinking solution is uniformly sprayed onto the surface of 50g of sodium polyacrylate powder, and the spraying amount is 1% of the mass of the sodium polyacrylate, and after spraying, the sodium polyacrylate crosslinking layer is obtained by standing for 5 minutes;

[0055] (3) the sodium polyacrylate crosslinking layer is moved to a blast drying oven, and is heat-treated at 60 DEG C for 1 hour to obtain the superabsorbent polymer.

[0056] The application further provides a preparation method of the anti-cracking performance enhanced environment-friendly concrete accelerator, and specifically comprises the following steps:

[0057] (1) 50 parts of aluminum sulfate, 10 parts of potassium carbonate, 10 parts of polypropylene fiber and 20 parts of basalt short-cut fiber are added into a high-speed mixer, and are stirred for 10 minutes to obtain a mixture A;

[0058] (2) 60 parts of nano-silicon dioxide, 2 parts of fly ash and 0.6 parts of steel slag micro-powder are sequentially added into the mixture A, and are continuously stirred for 15 minutes to obtain a mixture B;

[0059] (3) adding mixture B into 2 parts of superabsorbent polymer and 0.8 parts of calcium sulphoaluminate-magnesia composite expanding agent, continuing to stir for 10 minutes to obtain mixture C, and crushing mixture C by using an airflow crusher to obtain the environment-friendly concrete accelerator.

[0060] The stirring speed of the high-speed mixer is 900 r / min.

[0061] Example 3

[0062] The application provides an environment-friendly concrete accelerator with enhanced anti-cracking performance

[0063] The environment-friendly concrete accelerator comprises the following components in parts by weight: 60 parts of aluminum sulfate, 15 parts of potassium carbonate, 15 parts of polypropylene fiber, 30 parts of basalt chopped fiber, 70 parts of nano-silicon dioxide, 3 parts of fly ash, 1 part of steel slag micro-powder, 3 parts of superabsorbent polymer, and 1.2 parts of calcium sulphoaluminate-magnesia composite expanding agent.

[0064] The specific surface area of the nano-silicon dioxide is 400 m 2 / g.

[0065] The steel slag micro-powder is a product obtained by calcining and activating an industrial waste residue at 700 DEG C for 2 hours, and is ground to a specific surface area of 550 m 2 / kg.

[0066] The fly ash is a product obtained by calcining and activating an industrial waste residue at 700 DEG C for 2 hours, and is ground to a specific surface area of 550 m 2 / kg.

[0067] The preparation process of the superabsorbent polymer comprises the following steps:

[0068] (1) dissolving 1g of ethylene glycol diglycidyl ether in 24.1mL of ethanol, magnetically stirring for 10 minutes until completely dissolved, and preparing a 5wt% crosslinking solution;

[0069] (2) uniformly spraying 1g of the crosslinking solution onto the surface of 50g of polyacrylic acid sodium powder, the spraying amount being 2% of the mass of the polyacrylic acid sodium, and after spraying, standing for 5 minutes to obtain a polyacrylic acid sodium crosslinking layer;

[0070] (3) moving the polyacrylic acid sodium crosslinking layer to a blast drying oven, and heat-treating at 60 DEG C for 1 hour to obtain the superabsorbent polymer.

[0071] The application further provides a preparation method of the environment-friendly concrete accelerator with enhanced anti-cracking performance, and specifically comprises the following steps:

[0072] (1) aluminum sulfate 60 parts, potassium carbonate 15 parts, polypropylene fiber 15 parts and basalt chopped fiber 30 parts were added into a high-speed mixer and stirred for 10 minutes to obtain a mixture A;

[0073] (2) nano-silica 70 parts, fly ash 3 parts and steel slag powder 1 part were sequentially added into the mixture A, and stirring was continued for 15 minutes to obtain a mixture B;

[0074] (3) 3 parts of superabsorbent polymer and 1.2 parts of calcium sulfoaluminate-magnesium oxide composite expansion agent were further added into the mixture B, and stirring was continued for 10 minutes to obtain a mixture C, and the mixture C was crushed by using an airflow crusher to obtain the environment-friendly concrete accelerator.

[0075] The stirring speed of the high-speed mixer was 1000 r / min.

[0076] Comparative Example 1

[0077] This comparative example provides an anti-cracking performance enhanced environment-friendly concrete accelerator, which is different from Example 1 only in that it does not contain a curing agent, and the other components and component contents are the same as those of Example 1.

[0078] Comparative Example 2

[0079] This comparative example provides an anti-cracking performance enhanced environment-friendly concrete accelerator, which is different from Example 1 only in that it does not contain calcium sulfoaluminate-magnesium oxide composite expansion agent, and the other components and component contents are the same as those of Example 1.

[0080] Performance Test

[0081] The anti-corrosion mortar obtained in Examples 1-3 and Comparative Examples 1-2 was respectively subjected to performance tests such as contact angle, chloride ion adsorption capacity, self-repairing efficiency and mass loss rate, and the results are shown in Table 1.

[0082] Table 1: Performance Test

[0083]

[0084] The results show that, as shown in Table 1, Figures 1-4As shown, the dry shrinkage of the comparative example 1 is increased, the internal curing effect of the superabsorbent polymer is lacking, the water evaporation of the concrete is accelerated, and the shrinkage is increased by 66.7% compared with the example 1; the anti-cracking grade is reduced to III grade. The compressive strength ratio of the comparative example 2 is reduced, the lack of calcium sulphoaluminate-magnesium oxide composite expansion agent leads to insufficient chemical compensation shrinkage, and the compressive strength ratio is reduced by 12.5%; only relying on the physical buffer of the superabsorbent polymer, the anti-cracking grade is II grade, and the dry shrinkage is higher than that of the example 1 by 53.3%. The examples 1-3 have the dual effects of the superabsorbent polymer (internal curing) and the calcium sulphoaluminate-magnesium oxide composite expansion agent (chemical compensation), and the dry shrinkage is less than or equal to 0.017%, and the anti-cracking grade is I grade. Therefore, the superabsorbent polymer and the calcium sulphoaluminate-magnesium oxide composite expansion agent in the application synergistically exceed the comparative examples in the core performances of quick setting, anti-cracking, environmental protection and the like, and the scientificity and the innovation of the component design are verified.

[0085] It should be noted that, in this document, the terms such as first and second are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between such entities or operations. Moreover, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent to such a process, method, article or apparatus.

[0086] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

[0087] The above describes the present application and its embodiments, which are not limited, and the embodiments shown in the drawings are only one of the embodiments of the present application, and the actual structure is not limited thereto. In general, if a person skilled in the art is inspired thereby, without departing from the purpose of the present application, without creative design, similar structure and embodiments to the technical solution are not included in the protection scope of the present application.

Claims

1. An environmentally friendly concrete quick-setting agent with enhanced crack resistance, characterized in that, The environmentally friendly concrete quick-setting agent comprises the following components in parts by weight: 40-60 parts aluminum sulfate, 5-15 parts potassium carbonate, 20-40 parts composite fiber, 50-70 parts nano silica, 1-3 parts fly ash, 0.3-1 parts steel slag powder, 1-3 parts curing agent, and 0.2-1.2 parts calcium sulfoaluminate-magnesium oxide composite expansion agent.

2. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 1, characterized in that, The composite fiber is made by mixing polypropylene fiber and basalt chopped fiber in a weight ratio of 1:

2.

3. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 2, characterized in that, The specific surface area of ​​the nano-silica is 200-400 m². 2 / g.

4. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 3, characterized in that: The steel slag powder is a product of industrial waste slag that has been calcined and activated at 600-700℃ for 2 hours, and ground to a specific surface area ≥450m². 2 / kg.

5. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 4, characterized in that, The fly ash is a product of industrial waste residue calcined and activated at 650-700℃ for 2 hours, and ground to a specific surface area ≥450m². 2 / kg.

6. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 5, characterized in that: The curing agent is a superabsorbent polymer.

7. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 6, characterized in that: The preparation process of the superabsorbent polymer includes the following steps: (1) Dissolve the crosslinking agent in ethanol and stir magnetically for 10 minutes until completely dissolved to prepare a 1-5 wt% crosslinking solution; (2) Spray the crosslinking liquid evenly onto the surface of sodium polyacrylate powder. The amount of spraying is 0.5-2% of the mass of sodium polyacrylate. After spraying, let it stand for 5 minutes to obtain the sodium polyacrylate crosslinking layer. (3) The sodium polyacrylate crosslinked layer was transferred to a forced-air drying oven and heat-treated at 60°C for 1 hour to obtain a highly absorbent polymer.

8. The environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 7, characterized in that: The crosslinking agent is ethylene glycol diglycidyl ether.

9. The preparation method of an environmentally friendly concrete quick-setting agent with enhanced crack resistance according to claim 8, characterized in that: The preparation method includes the following steps: (1) Add aluminum sulfate, potassium carbonate and composite fiber to a high-speed mixer and stir for 10 minutes to obtain mixture A; (2) Add nano-silica, fly ash and steel slag powder to mixture A in sequence, and continue stirring for 15 minutes to obtain mixture B; (3) Add curing agent and calcium sulfoaluminate-magnesium oxide composite expansion agent to mixture B, and continue stirring for 10 minutes to obtain mixture C. Use an air jet mill to crush mixture C to obtain environmentally friendly concrete quick-setting agent.

10. The preparation method of a crack-resistant, environmentally friendly concrete quick-setting agent according to claim 9, characterized in that: The stirring speed of the high-speed mixer is 800-1000 r / min.

Images