Early-strength and rapid-setting shotcrete material and its processing technology

Abstract

The present application relates to the technical field of concrete, in particular to a kind of early strength rapid setting shotcrete material and its processing technology.The present application uses different chitosan derivatives to modify shell and core emulsion respectively;Cationic chitosan quaternary ammonium salt is selected to mix with soft monomer in core emulsion;Para ethylene benzene sulfonic acid sodium is selected as hard monomer in shell emulsion, and carboxymethyl chitosan is added;Chitosan derivative can improve the stability of emulsion, and also can occur polymerization reaction with monomer;Para ethylene benzene sulfonic acid sodium has electronegativity in shell emulsion, and can produce electrostatic effect with the positively charged chitosan quaternary ammonium salt in core emulsion, to realize uniform coating.Chitosan modified renewable dispersible latex powder is used to prepare shotcrete, which not only can produce synergistic effect with water reducing agent, promote cement particle dispersion, but also can cause mutual connection between cement particles, improve the pore structure of concrete interface, improve mechanical properties and impermeability, and reduce slump.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to an early-strength, fast-setting sprayed concrete material and its processing technology. Background Technology

[0002] Shotcrete is a type of concrete produced by spraying concrete or its mixture at high speed and instantly compacting it through an inflatable hose or pipe under high-pressure air. It is commonly used for pouring tunnel linings, walls, ceilings, and other thin-walled structures, as well as for the lining of steel structures and as a protective layer. Compared to ordinary concrete, shotcrete offers advantages such as simpler and more economical operation, higher structural density, better impermeability, and greater flexibility during construction. Its wide applicability has led to its widespread use in civil engineering, road and bridge construction, and other fields.

[0003] In practical applications, shotcrete suffers from problems such as decreased strength and poor durability, which affect its performance. Therefore, it is essential to invent a new type of shotcrete material to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide an early-strength, rapid-setting sprayed concrete material and its processing technology to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an early-strength, rapid-setting sprayed concrete material and its processing technology, comprising the following steps:

[0006] Step 1:

[0007] S11: Mix butyl acrylate, ethyl acrylate and water until homogeneous to obtain mixed monomer A, for later use;

[0008] S12: Mix monomer A, chitosan quaternary ammonium salt, sodium chloride, and V-50 initiator to react and obtain a core emulsion;

[0009] Step 2:

[0010] S21: Mix carboxymethyl chitosan and sodium p-vinylbenzenesulfonate and stir to react, then add methyl methacrylate and acrylamide to obtain mixed monomer B;

[0011] S22: Add S21 mixed monomer B to the core emulsion of S12, add V-50 initiator, keep the reaction at a constant temperature, cool naturally, filter, and discharge to obtain a core-shell emulsion;

[0012] S23: Mix the core-shell emulsion, PVA-205 and water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0013] Step 3:

[0014] Crushed stone, sand, cement, polyethylene fiber, chitosan-modified renewable dispersion latex powder, water, mineral powder, sodium sulfate, magnesium sulfate, sodium gluconate, and water-reducing agent are mixed to obtain sprayed concrete material.

[0015] Furthermore, in S11, the content of each component in the mixed monomer A, by weight, is 40-44 parts butyl acrylate, 10-16 parts ethyl acrylate, and 40-50 parts water.

[0016] Further, in S12, the specific preparation method of the nuclear emulsion is as follows: Take 8-10 parts of mixed monomer A, 2-4 parts of chitosan quaternary ammonium salt, and 0.1-0.3 parts of sodium chloride, mix them, and rapidly stir and emulsify for 20-30 minutes while heating to 75-85℃; add 0.1-0.2 parts of V-50 initiator, react for 0.5-1 hour, and then add the remaining mixed monomer A and 0.1-0.15 parts of V-50 initiator dropwise over a period of 1-2 hours. After the addition is complete, keep the reaction at the temperature for 0.5-1 hour to obtain the nuclear emulsion.

[0017] Furthermore, in S21, the content of each component in mixed monomer B, by weight, is 1-2 parts carboxymethyl chitosan, 25-32 parts sodium p-vinylbenzenesulfonate, 3-4 parts methyl methacrylate, and 3-5 parts acrylamide.

[0018] Furthermore, in S22, the preparation method of the core-shell emulsion is as follows: add the mixed monomer B of S21 to the core emulsion of S12, add V-50 initiator, keep the reaction at 80-85℃ for 0.5h; after natural cooling, filter and discharge to obtain the core-shell emulsion.

[0019] Furthermore, in S23, the content of each component in the dispersion, by weight, is 20-30 parts core-shell emulsion, 3-5 parts PVA-205, and 5-7 parts water.

[0020] Further, in step 3, the content of each component in the sprayed concrete material, by weight, is as follows: 30-33 parts crushed stone, 34-38 parts sand, 15-18 parts cement, 0.5-1 part polyethylene fiber, 0.5-1.2 parts chitosan-modified renewable dispersion latex powder, 7-10 parts water, 0.3-0.8 parts mineral powder, 0.1-0.3 parts sodium sulfate, 0.1-0.2 parts magnesium sulfate, 0.1-0.15 parts sodium gluconate, and 0.2-0.3 parts polycarboxylate superplasticizer.

[0021] Furthermore, in step 3, the water-reducing agent is either a polycarboxylate water-reducing agent or a naphthalene sulfonate water-reducing agent.

[0022] Furthermore, in step 3, the polyethylene fiber length is 8–12 mm; the crushed stone particle size is 5–10 mm.

[0023] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: The sprayed concrete prepared by this invention incorporates chitosan-modified renewable dispersed latex powder prepared from a core-shell emulsion. In preparing the core-shell emulsion, different chitosan derivatives are added to both the shell and core emulsions for modification. In the core emulsion, chitosan quaternary ammonium salt is selected and mixed with the soft monomers butyl acrylate and ethyl acrylate. The chitosan quaternary ammonium salt has properties similar to cationic surfactants, which can improve the stability of the emulsion and participate in the polymerization reaction under the action of an initiator. In preparing the shell emulsion, sodium p-ethylenebenzenesulfonate, methyl methacrylate, and acrylamide are selected as monomers, and carboxymethyl chitosan is added simultaneously. Carboxymethyl chitosan also has the effect of a surfactant, which can improve the stability of the emulsion. Furthermore, the amino groups of carboxymethyl chitosan can react with the sulfonic acid groups of sodium p-ethylenebenzenesulfonate and undergo polymerization reactions with other monomers in the shell emulsion under the action of an initiator. Because the core emulsion contains positively charged chitosan quaternary ammonium salt, while the shell emulsion contains sodium p-ethylenebenzenesulfonate which is electronegative, the two have an electrostatic adsorption effect, which can improve the coating effect and form a stable core-shell emulsion.

[0024] Chitosan-modified renewable dispersible latex powder is obtained by spray drying the core-shell emulsion. In actual use, the chitosan-modified renewable dispersible latex powder decomposes upon contact with water, releasing emulsion particles. Both chitosan quaternary ammonium salt and carboxymethyl chitosan have thickening effects, and carboxymethyl chitosan and sodium p-ethylenebenzenesulfonate can adsorb onto positively charged cement particles. On the one hand, this has a synergistic effect with water-reducing agents, jointly promoting cement particle dispersion and improving the workability of concrete; on the other hand, polymerization causes interconnection between cement particles, which is beneficial to improving the pore structure of the concrete interface, enhancing mechanical properties and impermeability, and reducing slump. It should be noted that excessive amounts of sodium p-ethylenebenzenesulfonate and carboxymethyl chitosan can delay cement particle hydration and affect early strength. Therefore, when preparing the core-shell emulsion, the amount of core-shell emulsion should be controlled to not exceed 40% of the total amount of core-shell emulsion. The concrete material prepared by this invention achieves a 3-hour strength of 2 MPa and a 28-day strength of 40 MPa. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The materials used in this invention and their sources are as follows: Chitosan quaternary ammonium salt is from Yuanye Biotechnology, product number S26618; carboxymethyl chitosan is from Yuanye Biotechnology, product number S30948; crushed stone is from Anxinda, with a particle size of 5-8 mm; sand is from Chuanqing Minerals, grade II medium sand; cement is from Qianxinfeng Building Materials, PO42.5 grade cement; polyethylene fiber is from Kuraray, with a length of 9-10 mm; PVA-205 is from Kuraray, brand name PVA2050588; mineral powder is from Kefa Building Materials, model S95; polycarboxylate superplasticizer is from Hongke Chemical, superior grade, with a content ≥99%.

[0027] Example 1: A processing technology for an early-strength, rapid-setting shotcrete material, comprising the following steps:

[0028] Step 1:

[0029] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0030] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 20 min. Heat to 75℃ and add 0.1 kg of V-50 initiator. After reacting for 0.5 h, add the remaining mixed monomer A and 0.1 kg of V-50 initiator dropwise over 1 h. After the addition is complete, keep the mixture warm for 0.5 h to obtain the core emulsion.

[0031] Step 2:

[0032] S21: Mix 1.2 kg of carboxymethyl chitosan and 30 kg of sodium p-vinylbenzenesulfonate and stir for 0.5 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0033] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 80°C for 0.5 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0034] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0035] Step 3:

[0036] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0037] Example 2: A processing technology for an early-strength, rapid-setting shotcrete material, comprising the following steps:

[0038] Step 1:

[0039] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0040] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 25 min. Heat to 75℃ and add 0.1 kg of V-50 initiator. After reacting for 0.5 h, add the remaining mixed monomer A and 0.12 kg of V-50 initiator dropwise over 1 h. After the addition is complete, keep the mixture at the temperature for 0.5 h to obtain the core emulsion.

[0041] Step 2:

[0042] S21: Mix 1.2 kg of carboxymethyl chitosan and 30 kg of sodium p-vinylbenzenesulfonate and stir for 0.75 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0043] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 80°C for 1 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0044] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0045] Step 3:

[0046] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0047] Example 3: A processing technology for an early-strength, rapid-setting shotcrete material, comprising the following steps:

[0048] Step 1:

[0049] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0050] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 25 min. Heat to 75℃ and add 0.14 kg of V-50 initiator. After reacting for 0.8 h, add the remaining mixed monomer A and 0.13 kg of V-50 initiator dropwise over a period of 1.5 h. After the addition is complete, keep the mixture at the temperature for 0.5 h to obtain the core emulsion.

[0051] Step 2:

[0052] S21: Mix 1.2 kg of carboxymethyl chitosan and 30 kg of sodium p-vinylbenzenesulfonate and stir for 0.5 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0053] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 82℃ for 0.5 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0054] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0055] Step 3:

[0056] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0057] Example 4: A processing technology for an early-strength, rapid-setting shotcrete material, comprising the following steps:

[0058] Step 1:

[0059] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0060] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 26 min. Heat to 80℃ and add 0.17 kg of V-50 initiator. After reacting for 0.75 h, add the remaining mixed monomer A and 0.13 kg of V-50 initiator dropwise over a period of 1.5 h. After the addition is complete, keep the mixture at the temperature for 1 h to obtain the core emulsion.

[0061] Step 2:

[0062] S21: Mix 1.2 kg of carboxymethyl chitosan and 30 kg of sodium p-vinylbenzenesulfonate and stir for 1 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0063] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 81°C for 0.8 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0064] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0065] Step 3:

[0066] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0067] Example 5: A processing technology for an early-strength, rapid-setting shotcrete material, comprising the following steps:

[0068] Step 1:

[0069] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0070] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 23 min. Heat to 85℃ and add 0.2 kg of V-50 initiator. After reacting for 0.5 h, add the remaining mixed monomer A and 0.11 kg of V-50 initiator dropwise over a period of 1.5 h. After the addition is complete, keep the mixture at the temperature for 0.9 h to obtain the core emulsion.

[0071] Step 2:

[0072] S21: Mix 1.2 kg of carboxymethyl chitosan and 30 kg of sodium p-vinylbenzenesulfonate and stir for 0.5 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0073] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 84℃ for 0.75 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0074] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0075] Step 3:

[0076] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0077] Example 6: A processing technology for an early-strength, rapid-setting shotcrete material, comprising the following steps:

[0078] Step 1:

[0079] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0080] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 23 min. Heat to 78℃ and add 0.17 kg of V-50 initiator. After reacting for 0.75 h, add the remaining mixed monomer A and 0.14 kg of V-50 initiator dropwise over a period of 1.8 h. After the addition is complete, keep the mixture at the temperature for 0.85 h to obtain the core emulsion.

[0081] Step 2:

[0082] S21: Mix 1.2 kg of carboxymethyl chitosan and 30 kg of sodium p-vinylbenzenesulfonate and stir for 1 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0083] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 85°C for 1 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0084] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0085] Step 3:

[0086] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0087] Comparative Example 1: Shotcrete material was prepared without the addition of chitosan-modified renewable dispersible latex powder, and the other parameters were the same as in Example 1.

[0088] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0089] Comparative Example 2:

[0090] Chitosan-modified renewable dispersion latex powder was prepared without the addition of chitosan derivatives, and the obtained renewable dispersion latex powder was used to prepare sprayed concrete materials. The remaining parameters were the same as in Example 2.

[0091] Step 1:

[0092] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0093] S12: Take 10 kg of mixed monomer A and 0.28 kg of sodium chloride, mix them, and stir rapidly to emulsify for 25 min; heat to 75℃ and add 0.1 kg of V-50 initiator, react for 0.5 h, then add the remaining mixed monomer A and 0.12 kg of V-50 initiator dropwise over 1 h, and keep the reaction at the temperature for 0.5 h after the addition is complete to obtain the nuclear emulsion;

[0094] Step 2:

[0095] S21: Mix 30 kg of sodium p-ethylenebenzenesulfonate, 3 kg of methyl methacrylate, and 4.8 kg of acrylamide to obtain mixed monomer B;

[0096] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 80°C for 1 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0097] S23: Mix 20 kg of core-shell emulsion, 3.5 kg of PVA-205 and 6.3 kg of water to obtain a dispersion, and spray dry to obtain a renewable dispersion latex powder;

[0098] Step 3:

[0099] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0100] Comparative Example 3: The amount of carboxymethyl chitosan and sodium p-ethylenebenzenesulfonate in mixed monomer B was increased, and the resulting chitosan-modified renewable dispersion latex powder was used to prepare sprayed concrete material. The remaining parameters were the same as in Example 3.

[0101] Step 1:

[0102] S11: Mix 42kg butyl acrylate, 15kg ethyl acrylate and 43kg water until homogeneous to obtain mixed monomer A, and set aside.

[0103] S12: Take 10 kg of mixed monomer A, 3.5 kg of chitosan quaternary ammonium salt, and 0.28 kg of sodium chloride and mix them. Stir and emulsify rapidly for 25 min. Heat to 75℃ and add 0.14 kg of V-50 initiator. After reacting for 0.8 h, add the remaining mixed monomer A and 0.13 kg of V-50 initiator dropwise over a period of 1.5 h. After the addition is complete, keep the mixture at the temperature for 0.5 h to obtain the core emulsion.

[0104] Step 2:

[0105] S21: Mix 5 kg of carboxymethyl chitosan and 50 kg of sodium p-vinylbenzenesulfonate and stir for 0.5 h. Then add 3 kg of methyl methacrylate and 4.8 kg of acrylamide to obtain mixed monomer B.

[0106] S22: Add the mixed monomer B from S21 to the core emulsion of S12, add 0.3 kg of V-50 initiator, and keep the reaction at 82℃ for 0.5 h; after natural cooling, filter and discharge to obtain the core-shell emulsion;

[0107] S23: Mix 20kg of core-shell emulsion, 3.5kg of PVA-205 and 6.3kg of water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder;

[0108] Step 3:

[0109] Mix 30kg crushed stone, 34kg sand, 18kg cement, 1kg polyethylene fiber, 1kg chitosan-modified renewable dispersion latex powder, 8.6kg water, 0.5kg mineral powder, 0.14kg sodium sulfate, 0.2kg magnesium sulfate, 0.15kg sodium gluconate, and 0.3kg polycarboxylate superplasticizer to obtain sprayed concrete material.

[0110] experiment:

[0111] Using the on-site spraying method, the sprayed concrete materials prepared in Examples 1-6 and Comparative Examples 1-3 were sprayed into a 3m×3m×3m model, cut into 1m×1m×1m test blocks, and the 7-day, 14-day, and 28-day compressive strengths of the test blocks were tested.

[0112] Mechanical performance testing: The compressive strength test was conducted in accordance with GB / T5081 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and the results are shown in the table below.

[0113]

[0114]

[0115] in conclusion:

[0116] Data from Examples 1-6 show that the early-strength concrete provided by the present invention can reach a strength of more than 2 MPa in 3 hours, more than 25 MPa in 7 days, more than 32 MPa in 14 days, and more than 40 MPa in 28 days.

[0117] In contrast, Comparative Example 1, serving as the control group for Example 1, did not contain chitosan-modified renewable dispersion latex powder. Its strength at 3h, 7d, 14d, and 28d was lower than that of Example 1, indicating that chitosan-modified renewable dispersion latex powder promotes concrete curing. In Comparative Example 2, no chitosan derivatives were added during the preparation of the chitosan-modified renewable dispersion latex powder, resulting in higher concrete strength. In Comparative Example 3, the amount of chitosan emulsion was increased, leading to higher contents of carboxymethyl chitosan and sodium p-ethylenebenzenesulfonate in the chitosan-modified renewable dispersion latex powder. This delayed cement particle hydration, resulting in lower early-stage concrete strength in Comparative Example 3 compared to Example 3.

[0118] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A processing technology for early-strength, rapid-setting shotcrete material, characterized in that: It consists of the following steps: Step 1: S11: Mix butyl acrylate, ethyl acrylate and water until homogeneous to obtain mixed monomer A, for later use; S12: Mix monomer A, chitosan quaternary ammonium salt, sodium chloride, and V-50 initiator in S11 to react and obtain a core emulsion; Step 2: S21: Mix carboxymethyl chitosan and sodium p-vinylbenzenesulfonate and stir to react, then add methyl methacrylate and acrylamide to obtain mixed monomer B; S22: Add the mixed monomer B from S21 to the core emulsion of S12, add V-50 initiator, keep the reaction at a constant temperature, cool naturally, filter, and discharge to obtain a core-shell emulsion; S23: Mix the core-shell emulsion, PVA-205 and water to obtain a dispersion, and spray dry to obtain chitosan-modified renewable dispersion latex powder; Step 3: Crushed stone, sand, cement, polyethylene fiber, chitosan-modified renewable dispersion latex powder, water, mineral powder, sodium sulfate, magnesium sulfate, sodium gluconate, and water-reducing agent are mixed to obtain sprayed concrete material. In S12, the specific preparation method of the nuclear emulsion is as follows: Take 8-10 parts of mixed monomer A, 2-4 parts of chitosan quaternary ammonium salt, and 0.1-0.3 parts of sodium chloride, mix them, and stir and emulsify rapidly for 20-30 minutes while heating to 75-85℃; add 0.1-0.2 parts of V-50 initiator, react for 0.5-1 hour, and then add the remaining mixed monomer A and 0.1-0.15 parts of V-50 initiator from S11 dropwise over a period of 1-2 hours. After the addition is complete, keep the mixture at the temperature for 0.5-1 hour.

2. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In S11, the content of each component in mixed monomer A, by weight, is 40-44 parts butyl acrylate, 10-16 parts ethyl acrylate, and 40-50 parts water.

3. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In S21, the content of each component in mixed monomer B, by weight, is 1-2 parts carboxymethyl chitosan, 25-32 parts sodium p-vinylbenzenesulfonate, 3-4 parts methyl methacrylate, and 3-5 parts acrylamide.

4. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In S22, the preparation method of the core-shell emulsion is as follows: add S21 mixed monomer B to the core emulsion of S12, add 0.3 parts of V-50 initiator, keep the reaction at 80-85℃ for 0.5h, filter and discharge after natural cooling to obtain the core-shell emulsion.

5. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In S23, the content of each component in the dispersion, by weight, is 20-30 parts core-shell emulsion, 3-5 parts PVA-205, and 5-7 parts water.

6. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In step 3, the content of each component in the shotcrete material, by weight, is as follows: 30-33 parts crushed stone, 34-38 parts sand, 15-18 parts cement, 0.5-1 part polyethylene fiber, 0.5-1.2 parts chitosan-modified renewable dispersion latex powder, 7-10 parts water, 0.3-0.8 parts mineral powder, 0.1-0.3 parts sodium sulfate, 0.1-0.2 parts magnesium sulfate, 0.1-0.15 parts sodium gluconate, and 0.2-0.3 parts water-reducing agent.

7. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In step 3, the water-reducing agent is either a polycarboxylate water-reducing agent or a naphthalene sulfonate water-reducing agent.

8. The processing technology of an early-strength, rapid-setting sprayed concrete material according to claim 1, characterized in that: In step 3, the polyethylene fiber length is 8-12 mm; the crushed stone particle size is 5-10 mm.

9. The sprayed concrete material obtained by the processing technology of the early-strength and rapid-setting sprayed concrete material according to any one of claims 1-8.

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