Concrete with high fire resistance and preparation method thereof

Abstract

The invention provides high-fire-resistance concrete and a preparation method thereof. The high-fire-resistance concrete is prepared from sulphoaluminate cement, coarse aggregate, fine aggregate, a fire-resistant modifier, a water reducing agent, an internal curing agent and a proper amount of water, wherein the fire-resistant modifier is composed of a transition metal salt-hydroxide compound, fire-resistant modified nylon fibers and a fire-resistant modified waterborne polyurethane emulsion, and the transition metal salt-hydroxide compound is of a three-dimensional layered structure. The fire-resistant modified nylon fibers are matched with the fire-resistant modified polyurethane emulsion to collide with the three-dimensional layered structure to form a three-dimensional net-shaped flame-retardant unit, and the three-dimensional net-shaped structure forms a compact graphite heat-insulating layer under the action of high temperature, so that heat is prevented from being conducted into the concrete member, the stability of the internal structure is ensured, and the service life of the concrete member is prolonged. The fireproof cable can meet the use requirements in harsh use scenes, and has the advantages of excellent fireproof performance, wide application prospect and convenience in popularization and implementation.

Description

Technical Field

[0001] This application belongs to the technical field of building engineering materials, and specifically relates to a high-fire-resistant concrete and a preparation method thereof. Background Art

[0002] In the prior art, refractory concrete is a special concrete that can maintain a certain mechanical strength and good resistance to sudden cooling and heating in a high-temperature environment. It is prepared by mixing appropriate binders, heat-resistant coarse and fine aggregates, and water in a certain proportion. Refractory concrete is widely used in fields such as petrochemical industry, hydropower, construction, and machinery. Especially in industrial kilns such as steel, cement, and glass, refractory concrete is widely used due to its excellent high-temperature stability.

[0003] In the prior art, in order to improve the fire resistance of concrete, the traditional method is to incorporate inorganic refractory materials such as calcium carbonate, alumina, magnesia, and ceramic particles into the aggregate. In order to ensure the thermal stability of refractory concrete under the temperature conditions of 1200°C - 1500°C, it is necessary to significantly increase the addition amount of inorganic refractory materials. With the obvious increase in the addition amount of inorganic refractory materials, the addition amount of cement will also increase accordingly, and the concrete curing time will also increase significantly. Moreover, during the concrete preparation process, the dispersion uniformity of inorganic refractory materials will significantly affect the fire resistance of concrete, resulting in uneven quality of refractory concrete on the market. Therefore, in order to improve the fire resistance and thermal stability of concrete and make the concrete adapt to more severe working environments, improvements are urgently needed now. Summary of the Invention

[0004] This application aims to solve the technical problem in the prior art that in order to improve the fire resistance of concrete, usually by increasing the proportion of refractory aggregates in the concrete, with the increase in the proportion of refractory aggregates, the structural stability and workability of the concrete will both decrease, and the high proportion of aggregates in the concrete preparation process will significantly reduce the dispersion performance of the aggregates. Affected by the aggregate dispersion performance, the quality of refractory concrete on the market is uneven and cannot meet the use requirements in harsh concrete use scenarios, and proposes a high-fire-resistant concrete.

[0005] In order to solve the technical problems proposed in this application, this application also proposes a preparation method for a high-fire-resistant concrete;

[0006] In order to solve the technical problems proposed in this application, this application also proposes an application of a high-fire-resistant concrete.

[0007] This application adopts the following scheme. A high-fire-resistant concrete is composed of the following components by weight: 34 parts - 46 parts of sulfoaluminate cement, 85 parts - 93 parts of coarse aggregate, 55 parts - 69 parts of fine aggregate, 33 parts - 41 parts of refractory modifier, 2 parts - 5 parts of water reducer, 1 part - 3 parts of internal curing agent, and an appropriate amount of water;

[0008] Among them, calculated by the weight parts of the total amount of the fire-resistant modifier, the fire-resistant modifier is composed of the following components: 8 parts - 11 parts of transition metal salt-hydroxide complex, 13 parts - 19 parts of fire-resistant modified nylon fiber, and 10 parts - 15 parts of fire-resistant modified waterborne polyurethane emulsion;

[0009] Among them, the fire-resistant modified waterborne polyurethane emulsion is prepared by co-modifying polyurethane with diethyl-N,N-diaminomethylphosphonate and terminal hydroxymethyl polydimethylsiloxane;

[0010] Among them, both the transition metal salt-hydroxide complex and the fire-resistant modified nylon fiber are subjected to surface modification treatment.

[0011] In some possible embodiments, the preparation method of the fire-resistant modified nylon fiber includes the following steps:

[0012] Step 101. Put the nylon particles after vacuum drying and guanidinium butylamine sulfate powder into a twin-screw extruder in a mass ratio of (11.5 - 12.5):1 in sequence. After melt blending and extruding under the conditions of 1200 rpm - 1600 rpm and 210°C - 220°C, then successively through cooling, pelletizing, and vacuum drying, the fire-resistant modified nylon is obtained;

[0013] Step 102. Transfer the fire-resistant modified nylon prepared in Step 101 to a melt spinning machine. Under the condition that the spinning temperature is 245°C - 260°C, extrude the molten fire-resistant modified nylon through the spinneret of the melt spinning machine, and the fire-resistant modified nylon fiber is obtained.

[0014] In some possible embodiments, the preparation method of the transition metal salt-hydroxide complex includes the following steps:

[0015] Step 201. Put aluminum nitrate, magnesium nitrate, and sodium dodecyl sulfonate into a stirring kettle in a mass ratio of (3.1 - 4.5):(7.9 - 9.3):(4.7 - 5.8) in sequence. Disperse for 5 min under the conditions of a water bath at 55°C - 65°C, a nitrogen atmosphere, and 1200 rpm - 1500 rpm, and the reaction system A is obtained;

[0016] Step 202. Drop a 15% sodium hydroxide solution into the reaction system A prepared in Step 201. React for 40 min - 55 min under the conditions of a water bath at 55°C - 65°C, a nitrogen atmosphere, and 500 rpm - 800 rpm. During the reaction process, measure the pH value of the mixed system in the reaction kettle every 2 min. By adjusting the dropping amount of the sodium hydroxide solution, control the pH value of the mixed system at 8 - 9. After the reaction is completed, successively through filtration, washing until neutral, and drying, the double hydroxide complex is obtained;

[0017] Step 203. The double hydroxide complex prepared in Step 202, deionized water, and sodium molybdate solution are successively added into a reaction kettle. Under the conditions of a water bath at 55°C - 65°C, a nitrogen atmosphere, and 500 rpm - 800 rpm, after reacting for 8 h - 10 h, it is successively filtered and washed to obtain the hybrid B to be purified;

[0018] Step 204. The hybrid B to be purified prepared in Step 203, deionized water, and a copper nitrate solution with a mass fraction of 30% are successively added into a reaction kettle. After the reaction until no more precipitation occurs, it is successively filtered, washed, and dried by hot air to obtain the transition metal salt - hydroxide complex.

[0019] In some possible embodiments, the preparation method of the fire - resistant modified water - borne polyurethane emulsion includes the following steps:

[0020] Step 301. The polyurethane prepolymer, diethyl - N,N - diaminomethylphosphonate, and terminal hydroxymethyl polydimethylsiloxane are successively added into a stirring kettle according to a mass ratio of 1:(2.5 - 3.3):(1.8 - 2.3). Under the conditions of a water bath at 45°C - 55°C and 1200 rpm - 1500 rpm, after activation for 6 min, the activated reactant is obtained;

[0021] Step 302. Triethylamine is added to the activated reactant prepared in Step 301. Under the conditions of a water bath at 40°C - 45°C, a pH value of 7, and 1600 rpm - 2000 rpm, after reacting for 10 min - 15 min, the crude fire - resistant modified polyurethane is obtained;

[0022] Step 303. The crude fire - resistant modified polyurethane prepared in Step 302 and deionized water are successively added into a high - speed shearing kettle. Under the conditions of 60°C - 66°C and 2500 rpm - 2800 rpm, after high - speed shearing for 3 min - 5 min, the fire - resistant modified polyurethane emulsion is obtained.

[0023] In some possible embodiments, the surface modification treatment of the transition metal salt - hydroxide complex and the fire - resistant modified nylon fiber includes the following steps:

[0024] Step 401. The transition metal salt - hydroxide complex, the fire - resistant modified nylon fiber, and a sodium hydroxide solution with a mass fraction of 5% are successively added into a reaction kettle. Under the conditions of a water bath at 45°C and 200 rpm, after reacting for 10 min, it is successively filtered, washed with acetic acid, washed with deionized water, and dried by hot air to obtain the system D to be modified;

[0025] Step 402. The to-be-modified system D prepared in Step 401, phosphoric acid monoalkoxy titanate, and absolute ethanol are sequentially put into a stirring kettle according to a mass ratio of 1:(12.5 - 16.3):25. After reacting for 20 min - 40 min under the conditions of a water bath at 35°C and a stirring speed of 500 rpm - 800 rpm, it is successively filtered, washed with absolute ethanol, and dried with hot air, thus completing the surface modification of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber.

[0026] In some possible embodiments, the diameter of the fire-resistant modified nylon fiber is 10 μm - 15 μm, the length of the fire-resistant modified nylon fiber is 1.5 mm - 5.5 mm, and the elastic modulus of the fire-resistant modified nylon fiber is 5.5 GPa - 6.9 GPa.

[0027] In some possible embodiments, the coarse aggregate is selected from any one or a mixture of more than one of basalt, dolomite, limestone, granite, gabbro, spinel, and marble.

[0028] In some possible embodiments, the fine aggregate is selected from any one or a mixture of more than one of zeolite powder, nano magnesium carbonate, fumed silica, alumina, nano calcium carbonate, coal powder, and microsilica.

[0029] In some possible embodiments, the particle size of the coarse aggregate is 10 mm - 15 mm; the particle size of the fine aggregate is 0.08 mm - 1.5 mm.

[0030] To solve the technical problems proposed by this application, this application also provides a preparation method for high-fire-resistant performance concrete, including the following steps:

[0031] Step 501. Batching: Weigh each component for standby according to a preset target ratio;

[0032] Step 502. Primary mixing: Put the sulfoaluminate cement and the coarse aggregate into a concrete mixer, and stir for 16 min under the conditions of room temperature and a stirring frequency of 1550 rpm to obtain the primary mixture;

[0033] Step 503. Secondary mixing: Put the primary mixture, the fine aggregate, the fire-resistant modifier, the water reducer, the internal curing agent, and an appropriate amount of water into the concrete mixer in sequence, and stir for 25 min under the conditions of a stirring temperature of 65°C and a stirring frequency of 1600 rpm to obtain the finished product of high-fire-resistant performance concrete.

[0034] To solve the technical problems proposed by this application, this application also provides an application of high-fire-resistant performance concrete, which is used for preparing a kiln for steel smelting.

[0035] Compared with the prior art, this application has the following beneficial effects:

[0036] The present application provides a high fire-resistant concrete and a preparation method thereof. The high fire-resistant concrete is composed of sulfoaluminate cement, coarse aggregate, fine aggregate, fire-resistant modifier, water reducer, internal curing agent and appropriate amount of water. The fire-resistant modifier is composed of a transition metal salt-hydroxide complex, fire-resistant modified nylon fiber and fire-resistant modified waterborne polyurethane emulsion. The transition metal salt-hydroxide complex has a three-dimensional layered structure. During the concrete preparation process, the fire-resistant modified nylon fiber cooperates with the fire-resistant modified polyurethane emulsion to form a three-dimensional network flame retardant unit after colliding with the three-dimensional layered structure. Under high temperature, the three-dimensional network structure will form a dense heat insulation layer to avoid heat conduction to the inside of the concrete member, ensure the stability of its internal structure, meet the use requirements under harsh use scenarios, have excellent fire resistance, broad application prospects, and are easy to promote and implement.

[0037] Description of the drawings

[0038] Figure 1 It is the infrared spectrogram of the fire-resistant modified nylon in Example 3 of the present application.

[0039] Figure 2 It is the infrared spectrogram of the fire-resistant modified polyurethane in Example 3 of the present application.

[0040] Figure 3 It is the SEM image of the high fire-resistant concrete prepared in Example 3 of the present application. Detailed implementation manners

[0041] Combined with Figures 1-3 Examples 1-3 and Comparative Examples 1-5, the technical solutions provided by the present application are further described.

[0042] Specifically, the polyurethane prepolymer is purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0043] Diethyl-N,N-diaminomethylphosphonate is purchased from Shanghai Macklin Biochemical Technology Co., Ltd.

[0044] Hydroxylmethyl-terminated polydimethylsiloxane is purchased from Tianjin Yongda Chemical Reagent Co., Ltd.

[0045] The coarse aggregate is obtained by compounding basalt, dolomite and limestone according to a mass ratio of 4:3:1.

[0046] The fine aggregate is obtained by compounding nano magnesium carbonate, fumed silica and microsilica according to a mass ratio of 3:3:5.

[0047] The average particle size of the coarse aggregate is 12.5 mm, and the particle size of the fine aggregate is 1.5 mm.

[0048] When preparing the concrete, the water-binder ratio of the concrete is controlled to be 0.7 by the amount of water added.

[0049] Example 1

[0050] (1) Prepare the fire-resistant modified nylon fiber through the following steps:

[0051] Step 101. Put the nylon particles after vacuum drying and the powder of guanidinium butylamine sulfate into a twin-screw extruder in a mass ratio of 11.5:1 in sequence. After melting and blending and extruding at 1280 rpm and 212 °C, then successively through cooling, pelletizing, and vacuum drying, the fire-resistant modified nylon is obtained.

[0052] Step 102. Transfer the fire-resistant modified nylon prepared in Step 101 to a melt spinning machine. Under the condition that the spinning temperature is 246 °C, extrude the molten fire-resistant modified nylon through the spinneret of the melt spinning machine, and the fire-resistant modified nylon fiber is obtained.

[0053] Among them, the average diameter of the fire-resistant modified nylon fiber is 11.4 μm, the average length is 3.5 mm, and the average elastic modulus is 5.9 GPa.

[0054] (2) Prepare the transition metal salt-hydroxide composite through the following steps:

[0055] Step 201. Put aluminum nitrate, magnesium nitrate, and sodium dodecyl sulfonate into a stirring kettle in a mass ratio of 3.1:7.9:4.7 in sequence. Under the conditions of a water bath at 55 °C, a nitrogen atmosphere, and 1320 rpm, disperse for 5 min, and the reaction system A is obtained.

[0056] Step 202. Drop the sodium hydroxide solution with a mass fraction of 15% into the reaction system A prepared in Step 201. Under the conditions of a water bath at 55 °C, a nitrogen atmosphere, and 520 rpm, react for 40 min. During the reaction process, measure the pH value of the mixed system in the reaction kettle every 2 min. By adjusting the dropping amount of the sodium hydroxide solution, control the pH value of the mixed system at 8. After the reaction is completed, successively through filtration, washing until neutral, and drying, the double hydroxide composite is obtained.

[0057] Step 203. Put the double hydroxide composite prepared in Step 202, deionized water, and sodium molybdate solution into a reaction kettle in sequence. Under the conditions of a water bath at 55 °C, a nitrogen atmosphere, and 520 rpm, react for 8 h, and then successively through filtration and washing to obtain the hybrid B.

[0058] Step 204. The prepared hybrid B, deionized water, and a copper nitrate solution with a mass fraction of 30% are successively added into a reaction kettle. After the reaction until no more precipitate is produced, the addition of the copper nitrate solution is terminated, and then it is successively filtered, washed, and dried with hot air to obtain a transition metal salt-hydroxide composite.

[0059] (3) Prepare a fire-resistant modified waterborne polyurethane emulsion through the following steps:

[0060] Step 301. The polyurethane prepolymer, diethyl-N,N-diaminomethylphosphonate, and terminal hydroxymethyl polydimethylsiloxane are successively added into a stirring kettle according to a mass ratio of 1:2.5:1.8. After activation at 45°C in a water bath and 1250 rpm for 6 min, an activated reactant is obtained.

[0061] Step 302. Triethylamine is added to the activated reactant prepared in Step 301, and after reaction at 40°C in a water bath, pH value of 7, and 1650 rpm for 10 min, a fire-resistant modified polyurethane crude product is obtained.

[0062] Step 303. The fire-resistant modified polyurethane crude product prepared in Step 302 and deionized water are successively added into a high-speed shearing kettle, and after high-speed shearing at 60°C and 2500 rpm for 3 min, a fire-resistant modified polyurethane emulsion is obtained.

[0063] (4) Modify the surface of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber through the following steps:

[0064] Step 401. The transition metal salt-hydroxide composite, the fire-resistant modified nylon fiber, and a sodium hydroxide solution with a mass fraction of 5% are successively added into a reaction kettle. After reaction at 45°C in a water bath and 200 rpm for 10 min, it is successively filtered, washed with acetic acid, washed with deionized water, and dried with hot air to obtain a system D to be modified.

[0065] Among them, the total volume V1 of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber and the total volume V2 of the sodium hydroxide solution satisfy the following relationship: V1:V2 = 1:4.8;

[0066] Step 402. The system D to be modified prepared in Step 401, a phosphoric acid-based monoalkoxy titanate, and absolute ethanol are successively added into a stirring kettle according to a mass ratio of 1:12.5:25. After reaction at 35°C in a water bath and 500 rpm for 20 min, it is successively filtered, washed with absolute ethanol, and dried with hot air to complete the surface modification of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber.

[0067] (5) Prepare high-fire-resistant performance concrete through the following steps:

[0068] Step 501. Batching: Weigh each component according to the component table shown in Table 1 for standby.

[0069] Step 502. Premixing: Put the sulfoaluminate cement and coarse aggregate into a concrete mixer. Stir at room temperature for 16 minutes under the condition of a stirring frequency of 1550 rpm to obtain the primary mixture.

[0070] Step 503. Secondary mixing: Put the primary mixture, fine aggregate, refractory modifier, water reducer, internal curing agent and appropriate amount of water into the concrete mixer in sequence. Stir at a stirring temperature of 65 °C for 25 minutes under the condition of a stirring frequency of 1600 rpm to obtain the finished high-refractory-performance concrete.

[0071] Example 2

[0072] (1) Prepare refractory modified nylon fiber through the following steps:

[0073] Step 101. Put the vacuum-dried nylon particles and guanidinium butylamine sulfate powder into a twin-screw extruder in a mass ratio of 12.2:1. After melting and blending and extruding under the conditions of 1400 rpm and 215 °C, then successively through cooling, pelletizing and vacuum drying to obtain the refractory modified nylon.

[0074] Step 102. Transfer the refractory modified nylon prepared in Step 101 to a melt spinning machine. Under the condition of a spinning temperature of 250 °C, extrude the molten refractory modified nylon through the spinneret of the melt spinning machine to obtain the refractory modified nylon fiber.

[0075] Among them, the average diameter of the refractory modified nylon fiber is 12.5 μm, the average length is 4.6 mm, and the average elastic modulus is 6.3 GPa.

[0076] (2) Prepare the transition metal salt-hydroxide composite through the following steps:

[0077] Step 201. Put aluminum nitrate, magnesium nitrate and sodium dodecyl sulfonate into a stirring kettle in a mass ratio of 4.2:8.5:5.2. Disperse for 5 minutes under the conditions of a water bath at 60 °C, a nitrogen atmosphere and 1350 rpm to obtain the reaction system A.

[0078] Step 202. A sodium hydroxide solution with a mass fraction of 15% was dropped into the reaction system A prepared in Step 201. The reaction was carried out at 60 °C in a water bath under a nitrogen atmosphere at 650 rpm for 48 min. During the reaction, the pH value of the mixed system in the reaction kettle was measured every 2 min. By adjusting the dropping amount of the sodium hydroxide solution, the pH value of the mixed system was controlled at 8. After the reaction was completed, it was successively filtered, washed to neutrality, and dried to obtain the double hydroxide complex;

[0079] Step 203. The double hydroxide complex, deionized water, and sodium molybdate solution prepared in Step 202 were successively put into the reaction kettle. After reacting at 60 °C in a water bath under a nitrogen atmosphere at 650 rpm for 9 h, it was successively filtered and washed to obtain the to-be-impurified product B;

[0080] Step 204. The to-be-impurified product B, deionized water, and copper nitrate solution with a mass fraction of 30% prepared in Step 203 were successively put into the reaction kettle. After the reaction until no more precipitate was produced, the addition of the copper nitrate solution was terminated. Then it was successively filtered, washed, and dried by hot air to obtain the transition metal salt-hydroxide complex.

[0081] (3) The fire-resistant modified waterborne polyurethane emulsion was prepared through the following steps:

[0082] Step 301. The polyurethane prepolymer, diethyl-N,N-diaminomethylphosphonate, and terminal hydroxymethyl polydimethylsiloxane were successively put into the stirring kettle according to the mass ratio of 1:2.8:2.1. After activating at 50 °C in a water bath at 1350 rpm for 6 min, the activated reactant was obtained;

[0083] Step 302. Triethylamine was added to the activated reactant prepared in Step 301. After reacting at 42 °C in a water bath with a pH value of 7 at 1800 rpm for 12 min, the fire-resistant modified polyurethane crude product was obtained;

[0084] Step 303. The fire-resistant modified polyurethane crude product and deionized water prepared in Step 302 were successively added to the high-speed shearing kettle. After high-speed shearing at 63 °C and 2650 rpm for 4 min, the fire-resistant modified polyurethane emulsion was obtained.

[0085] (4) The surface modification of the transition metal salt-hydroxide complex and the fire-resistant modified nylon fiber was carried out through the following steps:

[0086] Step 401. The transition metal salt-hydroxide complex, the fire-resistant modified nylon fiber, and a sodium hydroxide solution with a mass fraction of 5% were successively put into the reaction kettle. After reacting at 45 °C in a water bath at 200 rpm for 10 min, it was successively filtered, washed with acetic acid, washed with deionized water, and dried by hot air to obtain the to-be-modified system D;

[0087] Among them, the total volume V1 of the transition metal salt-hydroxide complex and the fire-resistant modified nylon fiber and the total volume V2 of the sodium hydroxide solution satisfy the following relationship: V1:V2 = 1:4.8;

[0088] Step 402. Put the to-be-modified system D prepared in Step 401, the phosphoric acid type monoalkoxy titanate, and absolute ethanol into the stirring kettle in sequence according to the mass ratio of 1:14.2:25. After reacting for 30 min under the conditions of a water bath at 35°C and 650 rpm, filter, wash with absolute ethanol, and dry with hot air in sequence, and the surface modification of the transition metal salt-hydroxide complex and the fire-resistant modified nylon fiber is completed.

[0089] (5) Prepare high fire-resistant performance concrete through the following steps:

[0090] Step 501. Batching: Weigh each component for standby according to the component table shown in Table 1;

[0091] Step 502. Premixing: Put the sulfoaluminate cement and the coarse aggregate into the concrete mixer, and stir for 16 min under the conditions of room temperature and a stirring frequency of 1550 rpm to obtain the primary mixture;

[0092] Step 503. Secondary mixing: Put the primary mixture, the fine aggregate, the fire-resistant modifier, the water reducer, the internal curing agent, and an appropriate amount of water into the concrete mixer in sequence, and stir for 25 min under the conditions of a stirring temperature of 65°C and a stirring frequency of 1600 rpm to obtain the finished product of high fire-resistant performance concrete.

[0093] Example 3

[0094] (1) Prepare fire-resistant modified nylon fiber through the following steps:

[0095] Step 101. Put the nylon particles after vacuum drying and the powder of guanidinobutylamine sulfate into the twin-screw extruder in sequence according to the mass ratio of 12.5:1. After melt-blending and extruding under the conditions of 1600 rpm and 220°C, cool, granulate, and vacuum dry in sequence to obtain the fire-resistant modified nylon;

[0096] Step 102. Transfer the fire-resistant modified nylon prepared in Step 101 to the melt spinning machine. Under the condition that the spinning temperature is 260°C, extrude the molten fire-resistant modified nylon through the spinneret of the melt spinning machine to obtain the fire-resistant modified nylon fiber.

[0097] Among them, the average diameter of the fire-resistant modified nylon fiber is 12.4 μm, the average length is 4.6 mm, and the average elastic modulus is 6.4 GPa.

[0098] (2) The transition metal salt-hydroxide complex is prepared through the following steps:

[0099] Step 201. Aluminum nitrate, magnesium nitrate, and sodium dodecyl sulfonate are successively added into a stirring kettle according to a mass ratio of 4.5:9.3:5.8. After dispersing for 5 min under the conditions of a water bath at 65 °C, a nitrogen atmosphere, and 1500 rpm, the reaction system A is obtained.

[0100] Step 202. A sodium hydroxide solution with a mass fraction of 15% is dropped into the reaction system A prepared in Step 201. The reaction is carried out for 55 min under the conditions of a water bath at 65 °C, a nitrogen atmosphere, and 800 rpm. During the reaction process, the pH value of the mixed system in the reaction kettle is measured every 2 min. By adjusting the dropping amount of the sodium hydroxide solution, the pH value of the mixed system is controlled at 9. After the reaction is completed, it is successively filtered, washed until neutral, and dried to obtain the double hydroxide complex.

[0101] Step 203. The double hydroxide complex prepared in Step 202, deionized water, and a sodium molybdate solution are successively added into a reaction kettle. After reacting for 10 h under the conditions of a water bath at 65 °C, a nitrogen atmosphere, and 800 rpm, it is successively filtered and washed to obtain the hybrid B.

[0102] Step 204. The hybrid B prepared in Step 203, deionized water, and a copper nitrate solution with a mass fraction of 30% are successively added into a reaction kettle. After the reaction until no more precipitation occurs, it is successively filtered, washed, and dried by hot air to obtain the transition metal salt-hydroxide complex.

[0103] (3) The fire-resistant modified aqueous polyurethane emulsion is prepared through the following steps:

[0104] Step 301. A polyurethane prepolymer, diethyl-N,N-diaminomethylphosphonate, and terminal hydroxymethyl polydimethylsiloxane are successively added into a stirring kettle according to a mass ratio of 1:3.3:2.3. After activating for 6 min under the conditions of a water bath at 55 °C and 1500 rpm, the activated reactant is obtained.

[0105] Step 302. Triethylamine is added to the activated reactant prepared in Step 301. The reaction is carried out for 15 min under the conditions of a water bath at 45 °C, a pH value of 7, and 2000 rpm to obtain the crude fire-resistant modified polyurethane.

[0106] Step 303. The crude fire-resistant modified polyurethane prepared in Step 302 and deionized water are successively added into a high-speed shearing kettle. After high-speed shearing for 5 min under the conditions of 66 °C and 2800 rpm, the fire-resistant modified polyurethane emulsion is obtained.

[0107] (4) Modify the surfaces of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber through the following steps:

[0108] Step 401. Sequentially put the transition metal salt-hydroxide composite, the fire-resistant modified nylon fiber, and a sodium hydroxide solution with a mass fraction of 5% into a reaction kettle. After reacting for 10 min under the conditions of a water bath at 45°C and 200 rpm, filter, wash with acetic acid, wash with deionized water, and then dry with hot air to obtain the system D to be modified.

[0109] Among them, the total volume V1 of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber and the total volume V2 of the sodium hydroxide solution satisfy the following relationship: V1:V2 = 1:4.8.

[0110] Step 402. Sequentially put the system D to be modified prepared in Step 401, a phosphoric acid-based monoalkoxy titanate, and absolute ethanol into a stirring kettle according to a mass ratio of 1:16.3:25. After reacting for 40 min under the conditions of a water bath at 35°C and 800 rpm, filter, wash with absolute ethanol, and then dry with hot air to complete the surface modification of the transition metal salt-hydroxide composite and the fire-resistant modified nylon fiber.

[0111] (5) Prepare high fire-resistant performance concrete through the following steps:

[0112] Step 501. Weighing: Weigh each component according to a preset target ratio for standby.

[0113] Step 502. Premixing: Put the sulfoaluminate cement and the coarse aggregate into a concrete mixer. After stirring for 16 min at room temperature and a stirring frequency of 1550 rpm, the primary mixture is obtained.

[0114] Step 503. Secondary mixing: Sequentially put the primary mixture, the fine aggregate, the fire-resistant modifier, the water reducer, the internal curing agent, and an appropriate amount of water into the concrete mixer. After stirring for 25 min at a stirring temperature of 65°C and a stirring frequency of 1600 rpm, the finished product of high fire-resistant performance concrete is obtained.

[0115] Comparative Example 1

[0116] The difference between Comparative Example 1 and Example 3 is that the fire-resistant modifier in Example 3 is removed and supplemented with sulfoaluminate cement, coarse aggregate, and fine aggregate, and the processes of the remaining components remain unchanged.

[0117] Comparative Example 2

[0118] The difference between Comparative Example 2 and Example 3 is that the transition metal salt-hydroxide composite in the fire-resistant modifier in Example 3 is removed and supplemented with fine aggregate, and the processes of the remaining components remain unchanged.

[0119] Comparative Example 3

[0120] The difference between Comparative Example 3 and Example 3 is that the fire-resistant modified nylon fiber in the fire-resistant modifier in Example 3 is removed and supplemented with fine aggregate, and the processes of the remaining components remain unchanged.

[0121] Comparative Example 4

[0122] The difference between Comparative Example 4 and Example 3 is that the fire-resistant modified waterborne polyurethane emulsion in the fire-resistant modifier in Example 3 is removed and supplemented with sulfoaluminate cement, and the processes of the remaining components remain unchanged.

[0123] Comparative Example 5

[0124] The difference between Comparative Example 5 and Example 3 is that the fire-resistant modifier in Example 3 is removed and supplemented with refractory aggregate A and refractory aggregate B, and the processes of the remaining components remain unchanged. Refractory aggregate A is calcium carbonate with a particle size range of 20 mm - 30 mm, and refractory aggregate B is alumina with a particle size range of 20 mm - 30 mm. Both refractory aggregate A and refractory aggregate B are commercially available common refractory aggregates.

[0125] Table 1 Component Table of Examples 1 - 3 and Comparative Examples 1 - 5

[0126]

[0127] Continued Table 1

[0128]

[0129]

[0130] Continued Table 1 Again

[0131]

[0132] The concretes prepared in Examples 1 - 3 and Comparative Examples 1 - 5 are subjected to the following tests:

[0133] Test 1: Referring to GB / T 4513.6 - 2017, after the concrete products prepared in Examples 1 - 3 and Comparative Examples 1 - 5 are respectively made into test specimens and cured for 28 days, their flexural strengths are respectively tested.

[0134] Test 2: Referring to GB / T 50081 - 2019, after the concrete products prepared in Examples 1 - 3 and Comparative Examples 1 - 5 are respectively made into test specimens and cured for 28 days, their compressive strengths are respectively tested.

[0135] Test 3: Referring to GJB 1597A-2018, after the concrete products prepared in Examples 1-3 and Comparative Examples 1-5 are respectively made into test members and cured for 28 days, their ablation rates are respectively tested to basically evaluate the fire resistance of the concrete;

[0136] Test 4: After the concrete products prepared in Examples 1-3 and Comparative Examples 1-5 are respectively made into test members and cured for 28 days, all the test members are transferred to a roasting furnace and kept warm at 1200 °C and 1500 °C for 4 h respectively. Then all the test members are cooled to room temperature, and their compressive strengths are respectively tested with reference to GB / T 50081-2019. Define the compressive strength of the test member before calcination as X and the compressive strength after calcination as Y. The influence of high-temperature conditions on the structural stability of the test member is evaluated by Y / X to further evaluate the fire resistance of the concrete. The test results are shown in Table 2 below.

[0137] Table 2 Test Results

[0138]

[0139] Continued Table 2

[0140]

[0141] Continued Table 2 Again

[0142]

[0143]

[0144] As can be seen from the above, such as Figures 1-3As shown, in Examples 1-3, a fire-resistant modifier composed of a transition metal salt-hydroxide complex, fire-resistant modified nylon fibers, and a fire-resistant modified aqueous polyurethane emulsion was introduced into the concrete gel system. The transition metal salt-hydroxide complex is a three-dimensional layered structure containing transition metal salts. A large number of flame retardant groups were introduced into the fire-resistant modified nylon fibers, and a large number of flame retardant groups were introduced into the aqueous polyurethane emulsion. During the concrete preparation process, the fire-resistant modified nylon fibers cooperate with the gel system containing the fire-resistant modified polyurethane emulsion to collide with the three-dimensional layered structure and form disordered three-dimensional network flame retardant units in the concrete gel system. On the one hand, by introducing three-dimensional network flame retardant units into the concrete gel system, the three-dimensional network flame retardant units will coat the aggregates, making the components in the concrete tightly connected, significantly improving the connection performance of the components in the concrete, significantly improving the thermal stability of the concrete components, and avoiding high-temperature cracking of the concrete. On the other hand, under high-temperature conditions, the flame retardant groups in the three-dimensional network flame retardant units will decompose at high temperature. During the high-temperature decomposition process of the flame retardant groups, the oxygen concentration and free radical concentration on the surface of the concrete components will be reduced, and the surface temperature of the concrete components will be reduced. Moreover, the hydroxides in the three-dimensional network flame retardant units will decompose into metal oxides, and under the catalysis of transition metals, a dense graphite isolation layer will be formed on the surface of the concrete components, preventing heat from further conducting to the inside of the concrete components and reducing the strength loss of the concrete components, thereby effectively ensuring the stability of the concrete components and meeting the use requirements of the concrete in the harsh use scenarios of 1200°C - 1500°C.

[0145] It can be seen from the test results in Table 2 that in Comparative Example 1, the fire-resistant modifier was removed, and three-dimensional network flame retardant units were not introduced into the concrete gel system. The connection performance between the components was weak, the flexural strength and compressive strength were low, and under high-temperature conditions, the strength loss of the concrete components was high, and it could not meet the use requirements of the concrete in the harsh use scenarios of 1200°C - 1500°C.

[0146] In Comparative Example 2, the transition metal salt-hydroxide complex in the fire-resistant modifier was removed, and the three-dimensional layered structure was not introduced into the concrete gel system. The compatibility between the concrete gel system and the organic fibers decreased, and it was difficult to form a three-dimensional network structure. The connection performance between the components was weak, and the flexural strength and compressive strength decreased to some extent. On the other hand, without the introduction of transition metals, under high-temperature conditions, it was difficult to catalytically generate a dense graphite isolation layer on the surface of the concrete components, and it was difficult to isolate external heat. The strength loss of the concrete components was high, and it could not meet the use requirements of the concrete in the harsh use scenarios of 1200°C - 1500°C.

[0147] In Comparative Example 3, the fire-resistant modified nylon fiber in the fire-resistant modifier was removed, and no organic flame-retardant fiber was introduced into the concrete gel. On the one hand, the flame-retardant groups in the concrete gel system decreased, and under high-temperature conditions, the oxygen concentration and free radical concentration on the surface of the concrete component increased significantly, resulting in a high ablation rate of the concrete component. On the other hand, without the introduction of organic flame-retardant fiber, the compatibility of each component in the concrete decreased, making it difficult to form a three-dimensional network structure, the connection performance between components was weak, the flexural strength and compressive strength decreased, and it was difficult to catalytically generate a dense and continuous graphite isolation layer on the surface of the concrete component, unable to meet the usage requirements of the concrete under the harsh usage scenarios of 1200°C - 1500°C.

[0148] In Comparative Example 4, the fire-resistant modified waterborne polyurethane emulsion in the fire-resistant modifier was removed. On the one hand, the flame-retardant groups in the concrete gel system decreased, and under high-temperature conditions, the oxygen concentration and free radical concentration on the surface of the concrete component increased significantly, resulting in a high ablation rate of the concrete component. On the other hand, through the combination of two gel systems of calcium sulfoaluminate cement and fire-resistant modified polyurethane emulsion, the compatibility between the organic components and the inorganic components could be significantly improved. After removing the fire-resistant modified waterborne polyurethane emulsion, the connection performance between the organic fiber and each component decreased, the content of three-dimensional network flame-retardant units in the system decreased, and it was difficult to catalytically generate a dense and continuous graphite isolation layer on the surface of the concrete component, unable to meet the usage requirements of the concrete under the harsh usage scenarios of 1200°C - 1500°C.

[0149] In Comparative Example 5, the fire-resistant modifier was removed and calcium carbonate and alumina were added in equal amounts. No three-dimensional network flame-retardant unit was introduced into the concrete gel system. As the proportion of aggregate increased, the connection performance between each group in the concrete decreased significantly, and the flexural and compressive strengths decreased significantly. Under high-temperature conditions, the concrete component would crack due to heat, unable to meet the usage requirements of the concrete under the harsh usage scenarios of 1200°C - 1500°C.

[0150] The present application provides a high fire-resistant performance concrete, its preparation method and its application. The high fire-resistant performance concrete is composed of sulfoaluminate cement, coarse aggregate, fine aggregate, fire-resistant modifier, water reducer, internal curing agent and an appropriate amount of water. The fire-resistant modifier is composed of a transition metal salt-hydroxide complex, fire-resistant modified nylon fiber and fire-resistant modified waterborne polyurethane emulsion. Among them, the transition metal salt-hydroxide complex has a three-dimensional layered structure. During the concrete preparation process, the fire-resistant modified nylon fiber will cooperate with the fire-resistant modified polyurethane emulsion to collide with the three-dimensional layered structure and form a three-dimensional network flame retardant unit in the concrete. Under high temperature conditions, on the one hand, the three-dimensional network flame retardant unit can make the interior of the concrete tightly connected, avoid high temperature cracking of the concrete, and enable the concrete to still have excellent thermal stability under high temperature conditions. On the other hand, under the action of high temperature, the three-dimensional network structure will form a dense heat insulation layer to prevent heat from being conducted to the interior of the concrete component and ensure the stability of its internal structure, meeting the use requirements in harsh use scenarios.

[0151] The above are only the embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high refractory concrete, characterized in that: The material is composed of the following components by weight: 34-46 parts of sulphoaluminate cement, 85-93 parts of coarse aggregate, 55-69 parts of fine aggregate, 33-41 parts of refractory modifier, 2-5 parts of water reducing agent, 1-3 parts of internal curing agent and appropriate amount of water; Wherein, the fire-resistant modifier is composed of the following components, calculated by weight of the total amount of the fire-resistant modifier: 8-11 parts of transition metal salt-hydroxide complex, 13-19 parts of fire-resistant modified nylon fiber, and 10-15 parts of fire-resistant modified waterborne polyurethane emulsion; The fire-resistant modified waterborne polyurethane emulsion is prepared by synergistically modifying polyurethane with diethyl-N, N-diaminomethylphosphonate and terminal hydroxymethyl polydimethylsiloxane; Among them, the transition metal salt-hydroxide complex and the fire-resistant modified nylon fiber are both surface-modified.

2. A high refractory concrete according to claim 1, characterized in that: The method for preparing fire-resistant modified nylon fiber comprises the following steps: Step 101. The vacuum-dried nylon particles and agmatine sulfate powder are sequentially put into a twin-screw extruder, melt-blended and extruded at 1200 rpm-1600 rpm and 210° C.-220° C., and then sequentially cooled, granulated and vacuum-dried to obtain fire-resistant modified nylon; Step 102. The fire-resistant modified nylon prepared in step 101 is transferred to a melt spinning machine, and the molten fire-resistant modified nylon is extruded through the spinneret of the melt spinning machine at a spinning temperature of 245°C-260°C to obtain fire-resistant modified nylon fiber.

3. The high refractory concrete according to claim 1, characterized in that: The preparation method of the transition metal salt-hydroxide complex comprises the following steps: Step 201. Aluminum nitrate, magnesium nitrate and sodium dodecyl sulfate are sequentially placed in a stirred tank, and dispersed for 5 minutes in a water bath at 55° C.-65° C., under a nitrogen atmosphere, at 1200 rpm-1500 rpm to obtain a reaction system A; Step 202. Add a 15% sodium hydroxide solution by mass to the reaction system A prepared in step 201, and react for 40 min to 55 min in a water bath at 55° C. to 65° C., under a nitrogen atmosphere, at 500 rpm to 800 rpm. During the reaction, measure the pH value of the mixed system in the reactor every 2 min, and adjust the amount of sodium hydroxide solution added to control the pH value of the mixed system to 8 to 9. After the reaction is completed, filter, wash, and dry in sequence to obtain a double hydroxide complex. Step 203. The double hydroxide complex prepared in step 202, deionized water and sodium molybdate solution are sequentially added into a reaction kettle, reacted for 8h-10h in a water bath at 55°C-65°C, under a nitrogen atmosphere, at 500rpm-800rpm, and then filtered and washed to obtain a hybrid B; Step 204. The hybridized material B prepared in step 203, deionized water and 30% copper nitrate solution are sequentially added into a reaction kettle, reacted until precipitation is no longer produced, and then filtered, washed and dried with hot air to obtain a transition metal salt-hydroxide complex.

4. The high refractory concrete according to claim 1, characterized in that: The preparation method of the fire-resistant modified waterborne polyurethane emulsion comprises the following steps: Step 301. Put the polyurethane prepolymer, diethyl-N, N-diaminomethylphosphonate, and terminal hydroxymethyl polydimethylsiloxane into a stirring kettle in sequence, and activate them in a water bath at 45° C.-55° C. and 1200 rpm-1500 rpm for 6 minutes to obtain an activated reactant; Step 302. Add triethylamine to the activated reactant prepared in step 301, and react for 10 min-15 min in a water bath at 40° C.-45° C., pH 7, and 1600 rpm-2000 rpm to obtain a crude fire-resistant modified polyurethane; Step 303. The crude fire-resistant modified polyurethane prepared in step 302 and deionized water are sequentially added into a high-speed shearing kettle, and high-speed shearing is performed for 3 min-5 min at 60°C-66°C and 2500 rpm-2800 rpm to obtain a fire-resistant modified polyurethane emulsion.

5. The high refractory concrete according to claim 1, characterized in that: The surface modification treatment of transition metal salt-hydroxide complex and fire-resistant modified nylon fiber comprises the following steps: Step 401. The transition metal salt-hydroxide complex, the fire-resistant modified nylon fiber and a 5% sodium hydroxide solution are sequentially put into a reaction kettle, reacted for 10 minutes in a water bath at 45° C. and 200 rpm, and then filtered, washed with acetic acid, washed with deionized water, and dried with hot air to obtain a system D to be modified; Step 402. The modified system D, phosphoric acid type monoalkoxy titanate and anhydrous ethanol prepared in step 401 are sequentially put into a stirring kettle, reacted in a water bath at 35°C and 500-800rpm for 20-40min, filtered, washed with anhydrous ethanol and dried with hot air, thereby completing the surface modification of the transition metal salt-hydroxide complex and the fire-resistant modified nylon fiber.

6. The high refractory concrete according to claim 1, characterized in that: The diameter of the fire-resistant modified nylon fiber is 10 μm-15 μm, the length of the fire-resistant modified nylon fiber is 1.5 mm-5.5 mm, and the elastic modulus of the fire-resistant modified nylon fiber is 5.5 GPa-6.9 GPa.

7. The high refractory concrete according to claim 1, characterized in that: The coarse aggregate is selected from any one of basalt, dolomite, limestone, granite, gabbro, alumina-magnesium spinel, marble, or a mixture of more than one of them.

8. The high refractory concrete according to claim 1, characterized in that: The fine aggregate is selected from any one of zeolite powder, nano magnesium carbonate, fumed silica, alumina, nano calcium carbonate, coal powder, micro silicon powder or a mixture of more than one of them.

9. The high refractory concrete according to claim 1, characterized in that: The particle size of the coarse aggregate is 10mm-15mm; the particle size of the fine aggregate is 0.08mm-1.5mm.

10. A method for preparing high refractory concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: Ingredients: weigh each component according to the preset target ratio; Premixing: Put sulphoaluminate cement and coarse aggregate into a concrete mixer and stir for 16 minutes at room temperature and a stirring frequency of 1550 rpm to obtain the primary mixture; Secondary mixing: Put the primary mixture, fine aggregate, refractory modifier, water reducer, internal curing agent and appropriate amount of water into the concrete mixer in turn. After stirring for 25 minutes at a stirring temperature of 65°C and a stirring frequency of 1600rpm, a high refractory concrete product is obtained.

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