A kind of low temperature resistant ferroaluminate cement concrete and preparation method thereof

Abstract

The invention discloses a low-temperature resistant alumina-ferrocement concrete and a preparation method thereof, and belongs to the technical field of cement concrete preparation. The preparation method comprises the following steps: 53 to 85 parts by weight of alumina-ferrocement, 32 to 47 parts by weight of water, 3 to 8 parts by weight of antifreeze modified fiber, 111 to 138 parts by weight of modified aggregate and 0.5 to 0.9 parts by weight of polycarboxylate water reducer are mixed and stirred to obtain the low-temperature resistant alumina-ferrocement concrete. The invention pre-treats the coarse aggregate used in cement, then mixes it with fine aggregate to form modified aggregate, and then prepares an antifreeze modified fiber with chemical cross-linking function, and realizes low-temperature resistance modification of cement concrete through the coordinated cooperation of modified aggregate and antifreeze modified fiber.

Description

Technical Field

[0001] The invention belongs to the technical field of cement concrete preparation, and in particular relates to low-temperature resistant ferroaluminate cement concrete and a preparation method thereof. Background Art

[0002] Cement concrete is a building material made of a mixture of cement, aggregates (such as sand, gravel) and water. Its unique physical and chemical properties make it play a vital role in the construction industry. Cement concrete is widely used in various construction projects, including residential, commercial buildings, infrastructure and industrial facilities. In building structures, cement concrete is mainly used in the following aspects: (1) Infrastructure: such as roads, bridges, tunnels and subways, these structures usually require high-strength and durable concrete to ensure safety and service life. (2) Building structures: including high-rise buildings, office buildings, residential buildings, etc., concrete is used in structural parts such as load-bearing walls, floor slabs, beams and columns. (3) Decoration and landscape: Concrete is not only used for structures, but is also often used for decorative applications, such as concrete art, garden landscaping, urban street design, etc. Cement concrete has the following notable characteristics: (1) High strength: Cement concrete can achieve high compressive strength after curing, making it suitable for load-bearing structures. (2) Strong durability: It has strong tolerance to environmental changes, weathering, chemical corrosion, etc. (3) Good plasticity: Concrete can be molded by molds before hardening, and is suitable for building structures of various complex shapes. (4) Economical: The cost of raw materials is relatively low, and the construction technology is mature, which can achieve cost-effectiveness in large-scale construction. (5) Good thermal insulation performance: Concrete has good thermal insulation performance and can regulate the temperature inside the building to a certain extent. Although ordinary cement concrete performs well in many applications, due to the uncertainty of the application environment, the performance of ordinary cement concrete in cold climate areas may be significantly affected under cold climate conditions. In low temperature environments, the setting and hardening process of concrete will slow down, resulting in slow strength development and even possible damage caused by freeze-thaw cycles. In low temperature environments, the hydration reaction rate of cement concrete slows down, which prolongs the setting time, thereby affecting the construction progress and the timely formation of structural strength. During the freeze-thaw cycle, the water in the cement concrete will freeze and expand, causing damage such as cracking and spalling of the concrete, affecting its durability.

[0003] Low-temperature resistant cement is mainly used in construction projects in cold climate areas. Its main application areas include: Construction in cold northern regions: (1) Residential, commercial buildings and infrastructure projects in cold regions such as Northern Europe, Russia, and Canada. (2) High-altitude mountain projects: such as mountain roads, tunnels, and bridges, these projects usually need to be constructed and used for a long time in low-temperature environments. (3) Polar research stations and military bases: These regions have harsh climates and require higher low-temperature resistance of building materials. (4) Ice and snow tourism facilities: such as ski resorts, ice and snow theme parks, etc. require low-temperature resistant cement concrete to ensure the safety and durability of the facilities.

[0004] Patent CN112745094A discloses a low-temperature resistant modified cement and a preparation method thereof. The invention obtains a low-temperature resistant modified cement by mixing silicate cement, fly ash, diatomaceous earth, bentonite, gypsum powder, calcium fluoride mineral powder and an early strength agent.

[0005] Patent CN114716192A discloses a method for preparing low-temperature early-strength concrete by organic-inorganic composite modification. The invention uses diethanol monoisopropanolamine and hydroxypropyl methylcellulose to organically modify inorganic components, and uses multiple solid wastes to synergistically prepare low-temperature early-strength concrete.

[0006] Patent CN116023092A discloses a high-strength and low-temperature-resistant modified cement and a preparation method thereof. The invention obtains a modified cement with low-temperature resistance by rationally adjusting the amount of raw materials.

[0007] Patent CN115819030A discloses a frost-resistant and corrosion-resistant low-temperature phase-change heat storage concrete, its preparation method and application. The invention constructs a buffer structure with frost-resistant heave by combining the effects of cold-resistant plasticizer and water-based epoxy resin.

[0008] Patent CN114477925A discloses a high-temperature resistant asphalt concrete and a preparation method thereof. The invention improves the polarity of SBS by grafting maleic anhydride onto SBS, which can better chemically bond with the asphalt concrete matrix and improve its compatibility in the matrix. Since SBS itself has two segment structures and two different glass transition temperatures, it exhibits very good high-temperature plasticity and low-temperature rubber properties, thereby significantly improving the low-temperature and high-temperature resistance of asphalt concrete.

[0009] Most of the above patents achieve cold-resistant modification of cement concrete by adjusting the proportion of raw materials. One of the important factors that cement concrete cannot withstand low temperatures is that traditional silicate cement has a slow hydration rate and cannot reach the critical strength before freezing under low temperature conditions. In addition, its porosity is relatively high, and external water can easily enter the internal structure of the concrete. The pore structure existing in these concrete structures will cause the water in the pore structure to freeze at low temperatures, changing from liquid to solid, and the volume will expand and increase, thereby causing cracking and damage to the cement concrete. Therefore, on the one hand, it is considered to use early-strength and fast-hardening ferroaluminate cement to replace traditional silicate cement, and on the other hand, it is considered to modify the raw materials for preparing cement concrete, reduce the pore structure, reduce the water absorption rate, and improve the compactness of cement concrete, which is of great significance to the development of low-temperature resistant cement. Summary of the invention

[0010] In view of the deficiencies of the prior art, the present invention pre-treats the coarse aggregate used in cement, then mixes it with fine aggregate to form a modified aggregate, and then prepares an antifreeze modified fiber with chemical cross-linking function. Through the coordinated cooperation of the modified aggregate and the antifreeze modified fiber, the low-temperature resistance of cement concrete is modified, and the technical problems raised in the background technology are solved. Specifically, the technical solution of the present invention includes the following contents:

[0011] A low temperature resistant ferroaluminate cement concrete, the low temperature resistant ferroaluminate cement concrete comprises the following raw materials in parts by weight:

[0012] Ferroaluminate cement: 53-85 parts by weight;

[0013] Water: 32-47 parts by weight;

[0014] Antifreeze modified fiber: 3-8 parts by weight;

[0015] Modified aggregate: 111-138 parts by weight;

[0016] Polycarboxylic acid water reducer: 0.5-0.9 parts by weight.

[0017] Furthermore, the alumina ferrocement includes alumina ferrocement with a strength grade of 42.5 or alumina ferrocement with a strength grade of 52.5.

[0018] Furthermore, the method for preparing the antifreeze modified fiber comprises the following steps:

[0019] After the water-insoluble fiber raw material containing an ester structure is dissolved in a mixed solvent, an alkaline catalyst is added, and the mixture is heated to 30° C. to 40° C. and reacted for 30 min to 50 min to obtain a reaction solution;

[0020] The reaction solution is dried and dehydrated, and then the pH is adjusted to neutral, and then the silanol monomer compound is added, mixed, heated to 100° C. to 105° C., and refluxed for 1 h to 2 h to obtain the antifreeze modified fiber.

[0021] Furthermore, the water-insoluble fiber raw material containing an ester structure includes poly(ethylene adipate) or polyvinyl acetate.

[0022] Furthermore, the mixed solvent is prepared by mixing water and dimethyl sulfoxide in a mass ratio of 1:1.

[0023] Further, the alkaline catalyst includes sodium hydroxide or potassium hydroxide.

[0024] Further, the silanol monomer compound includes 3-aminopropyltrihydroxysilane, diphenylsilanediol or triphenylsilanol.

[0025] Furthermore, the weight ratio of the water-insoluble fiber raw material containing an ester structure: the mixed solvent: the alkaline catalyst: the silanol monomer compound is 1:2-3:0.1-0.3:0.5-1.

[0026] Furthermore, the preparation method of the modified aggregate comprises the following steps:

[0027] The coarse aggregate with a particle size of 10 mm to 15 mm is completely immersed in an oxalic acid solution for 20 min to 25 min to obtain an acid-treated coarse aggregate;

[0028] The acid-treated coarse aggregate is completely immersed in silicate and mixed and stirred for 15 hours to 20 hours to obtain pretreated coarse aggregate;

[0029] The pretreated coarse aggregate and fine aggregate are mixed in a weight ratio of 2 to 4:1 to form the modified aggregate.

[0030] Furthermore, the mass concentration of the oxalic acid is 2% to 3%.

[0031] Furthermore, the fine aggregate is obtained by screening through a 200-mesh sieve.

[0032] Furthermore, the silicate includes tetramethyl silicate, tetraethyl silicate or propyl orthosilicate.

[0033] Furthermore, the polycarboxylate water reducer is commercially available -Ⅰ series polycarboxylic acid high performance water reducing agent.

[0034] A method for preparing low-temperature resistant ferroaluminate cement concrete, the preparation method comprising the following steps:

[0035] The low-temperature resistant alumina-ferrocement concrete is obtained by mixing and stirring 53-85 parts by weight of alumina-ferrocement, 32-47 parts by weight of water, 3-8 parts by weight of antifreeze modified fibers, 111-138 parts by weight of modified aggregates and 0.5-0.9 parts by weight of polycarboxylate water reducer.

[0036] Furthermore, the mixing and stirring conditions include a stirring speed of 50 r / min to 100 r / min and a stirring time of 5 min to 10 min.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The invention comprises the following steps: mixing and stirring ferroaluminate cement, water, antifreeze modified fiber and modified aggregate, wherein the ferroaluminate cement has good corrosion resistance and low shrinkage performance; the water-insoluble fiber raw material containing an ester structure is catalyzed by an alkaline catalyst, hydrolyzed and broken under specific conditions to generate hydroxyl groups, and a chemical cross-linked network structure of siloxane bonds is formed through condensation of the hydroxyl groups and the silanol groups of silanol monomer compounds, wherein the cross-linked network structure reduces the pore structure of the cement concrete and improves the compressive strength of the cement concrete; the coarse aggregate is pre-treated by soaking in oxalic acid to remove insoluble impurities such as calcium hydroxide on the surface to obtain acid-treated coarse aggregate, the silanol groups on the acid-treated coarse aggregate are combined with silicate through hydrogen bond cross-linking, the silicate is wrapped on the surface of the coarse aggregate, and then the coarse aggregate is mixed with fine aggregate to form a more compact filling structure to reduce pores. Under the stirring of water, the hydrated silicate obtained by the hydration reaction of ferroaluminate cement is combined with the antifreeze modified fiber and modified aggregate through physical adsorption. With the synergistic cooperation of the antifreeze modified fiber and modified aggregate, the pore structure is reduced, the water absorption rate is reduced, the density of the cement concrete is improved, and finally the ferroaluminate cement concrete with good low temperature resistance is obtained. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0040] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0041] Ferroaluminate cement was purchased from Guangxi Yunyan Special Cement Building Materials Co., Ltd.

[0042] -Ⅰ series polycarboxylic acid high performance water reducer was purchased from Jiangsu Subote New Materials Co., Ltd.

[0043] Preparation Example 1:

[0044] The preparation method of the antifreeze modified fiber specifically includes the following processes:

[0045] Add 1 part by weight of poly(ethylene adipate) to 2 parts by weight of a mixed solvent (the mixed solvent is prepared by mixing equal amounts of water and equal amounts of dimethyl sulfoxide) and stir until completely dissolved, then add 0.1 parts by weight of solid sodium hydroxide and control the temperature at 30°C, stir and react for 30 minutes to obtain a reaction solution. Add a desiccant to the reaction solution to remove the remaining water, filter and remove the desiccant, then add hydrochloric acid to slowly adjust the pH of the solution to neutral, then add 0.5 parts by weight of 3-aminopropyltrihydroxysilane to the solution with a neutral pH, mix and heat to 100°C, and reflux for 1 hour. After the reaction is completed, cool naturally to obtain an antifreeze modified fiber.

[0046] Preparation Example 2:

[0047] The preparation method of the antifreeze modified fiber specifically includes the following processes:

[0048] Add 1 part by weight of poly(ethylene adipate) to 2 parts by weight of a mixed solvent (the mixed solvent is prepared by mixing equal amounts of water and equal amounts of dimethyl sulfoxide) and stir until completely dissolved, then add 0.15 parts by weight of solid sodium hydroxide and control the temperature at 30°C, stir and react for 35 minutes to obtain a reaction solution. Add a desiccant to the reaction solution to remove the remaining water, filter and remove the desiccant, then add hydrochloric acid to slowly adjust the pH of the solution to neutral, then add 0.7 parts by weight of diphenylsilanediol to the solution with a neutral pH, mix and heat to 100°C, and reflux for 1.5 hours. After the reaction is completed, cool naturally to obtain an antifreeze modified fiber.

[0049] Preparation Example 3:

[0050] The preparation method of the antifreeze modified fiber specifically includes the following steps:

[0051] 1 part by weight of poly(ethylene adipate) was added to 2.5 parts by weight of a mixed solvent (the mixed solvent was prepared by mixing equal amounts of water and dimethyl sulfoxide) and stirred until completely dissolved, then 0.2 parts by weight of solid sodium hydroxide was added and the temperature was controlled at 35°C, and the reaction was stirred for 40 minutes to obtain a reaction solution. A desiccant was added to the reaction solution to remove the remaining water, and after filtering to remove the desiccant, hydrochloric acid was added to slowly adjust the pH of the solution to neutral. At this time, 0.8 parts by weight of diphenylsilanediol was added to the solution with a neutral pH, mixed and heated to 102°C, and the reaction was refluxed for 1.5 hours. After the reaction was completed, the solution was cooled naturally to obtain an antifreeze modified fiber.

[0052] Preparation Example 4:

[0053] The preparation method of the antifreeze modified fiber specifically includes the following processes:

[0054] Add 1 part by weight of polyvinyl acetate to 2.5 parts by weight of a mixed solvent (the mixed solvent is prepared by mixing equal amounts of water and equal amounts of dimethyl sulfoxide) and stir until completely dissolved, then add 0.25 parts by weight of potassium hydroxide solid and control the temperature at 35°C, stir and react for 45 minutes to obtain a reaction solution. Add a desiccant to the reaction solution to remove the remaining water, filter and remove the desiccant, then add hydrochloric acid to slowly adjust the pH of the solution to neutral, then add 0.9 parts by weight of triphenylsilanol to the solution with a neutral pH, mix and heat to 104°C, and reflux for 2 hours. After the reaction is completed, cool naturally to obtain an antifreeze modified fiber.

[0055] Preparation Example 5:

[0056] The preparation method of the antifreeze modified fiber specifically includes the following processes:

[0057] Add 1 part by weight of polyvinyl acetate to 3 parts by weight of a mixed solvent (the mixed solvent is prepared by mixing equal amounts of water and equal amounts of dimethyl sulfoxide) and stir until completely dissolved, then add 0.3 parts by weight of potassium hydroxide solid and control the temperature at 40°C, stir and react for 50 minutes to obtain a reaction solution. Add a desiccant to the reaction solution to remove the remaining water, filter and remove the desiccant, then add hydrochloric acid to slowly adjust the solution pH to neutral, then add 1 part by weight of triphenylsilanol to the solution with a neutral pH, mix and heat to 105°C, and reflux for 2 hours. After the reaction is completed, cool naturally to obtain an antifreeze modified fiber.

[0058] Preparation Example 6:

[0059] The preparation method of modified aggregate specifically includes the following processes:

[0060] Use a jaw crusher to crush large coarse aggregate, then use a vibrating screen to screen coarse aggregate with a particle size of 10mm to 15mm, and completely immerse the screened coarse aggregate in an oxalic acid solution with a mass concentration of 2% and mix and stir for 20 minutes. After the treatment, pour out the oxalic acid solution, and completely immerse the remaining acid-treated coarse aggregate in tetramethyl silicate and mix and stir for 15 hours. After the treatment, pour out the tetramethyl silicate, take out the coarse aggregate at this time, and ventilate and dry it in a natural environment to obtain pretreated coarse aggregate.

[0061] The fine aggregate was screened with a 200-mesh sieve, and 2 parts by weight of the pretreated coarse aggregate was mixed with 1 part by weight of the screened fine aggregate to obtain a modified aggregate.

[0062] Preparation Example 7:

[0063] The preparation method of modified aggregate specifically includes the following processes:

[0064] Use a jaw crusher to crush large coarse aggregate, then use a vibrating screen to screen coarse aggregate with a particle size of 10mm to 15mm, and completely immerse the screened coarse aggregate in an oxalic acid solution with a mass concentration of 2% and mix and stir for 22 minutes. After the treatment, pour out the oxalic acid solution, and completely immerse the remaining acid-treated coarse aggregate in tetramethyl silicate and mix and stir for 17 hours. After the treatment, pour out the tetramethyl silicate, take out the coarse aggregate at this time, and ventilate and dry it in a natural environment to obtain pretreated coarse aggregate.

[0065] The fine aggregate was screened with a 200-mesh sieve, and 2.5 parts by weight of the pretreated coarse aggregate was mixed with 1 part by weight of the screened fine aggregate to obtain a modified aggregate.

[0066] Preparation Example 8:

[0067] The preparation method of modified aggregate specifically includes the following processes:

[0068] Use a jaw crusher to crush large coarse aggregate, then use a vibrating screen to screen coarse aggregate with a particle size of 10mm to 15mm, and completely immerse the screened coarse aggregate in an oxalic acid solution with a mass concentration of 2.5% and mix and stir for 24 minutes. After the treatment, pour out the oxalic acid solution, and completely immerse the remaining acid-treated coarse aggregate in tetraethyl silicate and mix and stir for 19 hours. After the treatment, pour out the tetraethyl silicate, take out the coarse aggregate at this time, and ventilate and dry it in a natural environment to obtain pretreated coarse aggregate.

[0069] The fine aggregate was screened with a 200-mesh sieve, and 3 parts by weight of the pretreated coarse aggregate was mixed with 1 part by weight of the screened fine aggregate to obtain a modified aggregate.

[0070] Preparation Example 9:

[0071] The preparation method of modified aggregate specifically includes the following processes:

[0072] Use a jaw crusher to crush large coarse aggregate, then use a vibrating screen to screen coarse aggregate with a particle size of 10mm to 15mm, and completely immerse the screened coarse aggregate in an oxalic acid solution with a mass concentration of 2.5% and mix and stir for 25 minutes. After the treatment, pour out the oxalic acid solution, and completely immerse the remaining acid-treated coarse aggregate in tetraethyl silicate and mix and stir for 20 hours. After the treatment, pour out the tetraethyl silicate, take out the coarse aggregate at this time, and ventilate and dry it in a natural environment to obtain the pretreated coarse aggregate.

[0073] The fine aggregate was screened with a 200-mesh sieve, and 3.5 parts by weight of the pretreated coarse aggregate was mixed with 1 part by weight of the screened fine aggregate to obtain a modified aggregate.

[0074] Preparation Example 10:

[0075] The preparation method of modified aggregate specifically includes the following processes:

[0076] Use a jaw crusher to crush large coarse aggregate, then use a vibrating screen to screen coarse aggregate with a particle size of 10mm to 15mm, and completely immerse the screened coarse aggregate in an oxalic acid solution with a mass concentration of 3% and mix and stir for 25 minutes. After the treatment, pour out the oxalic acid solution, and completely immerse the remaining acid-treated coarse aggregate in propyl orthosilicate and mix and stir for 20 hours. After the treatment, pour out the propyl orthosilicate, take out the coarse aggregate at this time, and ventilate and dry it in a natural environment to obtain the pretreated coarse aggregate.

[0077] The fine aggregate was screened with a 200-mesh sieve, and 4 parts by weight of the pretreated coarse aggregate was mixed with 1 part by weight of the screened fine aggregate to obtain a modified aggregate.

[0078] Preparation Example 11:

[0079] The preparation method of modified aggregate specifically includes the following processes:

[0080] Use a jaw crusher to crush large coarse aggregate, then use a vibrating screen to screen coarse aggregate with a particle size of 10mm to 15mm, and completely immerse the screened coarse aggregate in an oxalic acid solution with a mass concentration of 4% and mix and stir for 27 minutes. After the treatment, pour out the oxalic acid solution, and completely immerse the remaining acid-treated coarse aggregate in propyl orthosilicate and mix and stir for 20 hours. After the treatment, pour out the propyl orthosilicate, take out the coarse aggregate at this time, and ventilate and dry it in a natural environment to obtain the pretreated coarse aggregate.

[0081] The fine aggregate was screened with a 200-mesh sieve, and 4 parts by weight of the pretreated coarse aggregate was mixed with 1 part by weight of the screened fine aggregate to obtain a modified aggregate.

[0082] Preparation Example 12:

[0083] The preparation method of modified aggregate specifically includes the following processes:

[0084] After the oxalic acid treatment in Preparation Example 10, propyl orthosilicate was directly added without pouring it out, and the other conditions were kept the same as in Preparation Example 10.

[0085] Embodiment 1:

[0086] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0087] 53 parts by weight of ferroaluminate cement (strength grade 42.5), 32 parts by weight of water, 3 parts by weight of the antifreeze modified fiber obtained in Preparation Example 1, 111 parts by weight of the modified aggregate obtained in Preparation Example 6 and 0.5 parts by weight of -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 50r / min for 5min to obtain low temperature resistant ferroaluminate cement concrete.

[0088] Embodiment 2:

[0089] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0090] 60 parts by weight of ferroaluminate cement (strength grade 42.5), 35 parts by weight of water, 5 parts by weight of the antifreeze modified fiber obtained in Preparation Example 2, 120 parts by weight of the modified aggregate obtained in Preparation Example 7 and 0.6 parts by weight of -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 70r / min for 7min to obtain low temperature resistant ferroaluminate cement concrete.

[0091] Embodiment 3:

[0092] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0093] 67 parts by weight of ferroaluminate cement (strength grade 42.5), 40 parts by weight of water, 7 parts by weight of the antifreeze modified fiber obtained in Preparation Example 3, 127 parts by weight of the modified aggregate obtained in Preparation Example 8 and 0.7 parts by weight of -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 80r / min for 8min to obtain low temperature resistant ferroaluminate cement concrete.

[0094] Embodiment 4:

[0095] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0096] 75 parts by weight of ferroaluminate cement (strength grade 52.5), 44 parts by weight of water, 8 parts by weight of the antifreeze modified fiber obtained in Preparation Example 4, 134 parts by weight of the modified aggregate obtained in Preparation Example 9 and 0.8 parts by weight of the -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 80r / min for 9min to obtain low temperature resistant ferroaluminate cement concrete.

[0097] Embodiment 5:

[0098] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0099] 85 parts by weight of ferroaluminate cement (strength grade 52.5), 47 parts by weight of water, 8 parts by weight of the antifreeze modified fiber obtained in Preparation Example 5, 138 parts by weight of the modified aggregate obtained in Preparation Example 10 and 0.9 parts by weight of -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 100 r / min for 10 min to obtain low temperature resistant ferroaluminate cement concrete.

[0100] Comparative Example 1:

[0101] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0102] 85 parts by weight of ferroaluminate cement (strength grade 52.5), 47 parts by weight of water, 8 parts by weight of the antifreeze modified fiber obtained in Preparation Example 5, 138 parts by weight of the modified aggregate obtained in Preparation Example 11 and 0.9 parts by weight of -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 100 r / min for 10 min to obtain low temperature resistant ferroaluminate cement concrete.

[0103] Comparative Example 2:

[0104] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0105] 85 parts by weight of ferroaluminate cement (strength grade 52.5), 47 parts by weight of water, 8 parts by weight of the antifreeze modified fiber obtained in Preparation Example 5, 138 parts by weight of the modified aggregate obtained in Preparation Example 12 and 0.9 parts by weight of the -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 100 r / min for 10 min to obtain low temperature resistant ferroaluminate cement concrete.

[0106] Comparative Example 3:

[0107] A method for preparing low-temperature resistant ferroaluminate cement concrete specifically comprises the following steps:

[0108] 85 parts by weight of ferroaluminate cement (strength grade 52.5), 47 parts by weight of water, 8 parts by weight of the antifreeze modified fiber obtained in Preparation Example 5, 138 parts by weight of aggregate (directly obtained by mixing coarse aggregate with a particle size of 10 mm to 15 mm and fine aggregate with a weight ratio of 200 meshes in a ratio of 4:1) and 0.9 parts by weight of -Ⅰ series polycarboxylic acid high performance water reducing agent was mixed in a mixer and stirred at a speed of 100 r / min for 10 min to obtain low temperature resistant ferroaluminate cement concrete.

[0109] After the ferroaluminate cement concrete obtained in Examples 1 to 5 and Comparative Examples 1 to 3 was poured into a mold for forming, it was treated according to the steps of curing at 25°C for 3 days, curing at -25°C for 3 days, curing at -50°C for 3 days and curing at -75°C for 3 days, and then the compressive strength was tested according to the "GB / T 50081-2019 Standard for Test Methods for Physical and Mechanical Properties of Concrete". The results are as follows:

[0110]

[0111] The water absorption of the alumina-ferroferrocement concrete obtained in Examples 1 to 5 and Comparative Examples 1 to 3 was tested according to GB / T 50081-2019 Standard for Test Methods for Physical and Mechanical Properties of Concrete. The results are shown in the following table:

[0112]

[0113]

[0114] Based on the above test data, the following conclusions can be drawn:

[0115] (1) It can be seen from Example 5 and Comparative Example 1 that after removing insoluble precipitates such as calcium hydroxide on the surface of Comparative Example 1, the excessively high oxalic acid concentration and the excessively long treatment time may also react to the internal components of the aggregate, causing the aggregate structure to be destroyed, resulting in increased porosity and higher water absorption, which has an adverse effect on the low-temperature resistance of cement concrete and cannot be used in practice.

[0116] (2) It can be seen from Example 5 and Comparative Example 2 that oxalic acid has a hydrolysis effect on propyl orthosilicate, which may cause propyl orthosilicate to decompose and fail to wrap the coarse aggregate. The water absorption rate is high, which is not conducive to the low-temperature resistance modification of cement concrete and cannot be used in practice.

[0117] (3) It can be seen from Example 5 and Comparative Example 3 that the aggregate obtained by directly mixing untreated coarse aggregate and fine aggregate and relying solely on the chemically cross-linked network structure of the antifreeze modified fiber to achieve low-temperature protection of cement concrete has a poor effect and a high water absorption rate, and cannot be used in practice.

[0118] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A low temperature resistant ferroaluminate cement concrete, characterized in that: The low temperature resistant ferroaluminate cement concrete comprises the following raw materials in parts by weight: Ferroaluminate cement: 53-85 parts by weight; Water: 32-47 parts by weight; Antifreeze modified fiber: 3-8 parts by weight; Modified aggregate: 111-138 parts by weight; Polycarboxylate water reducer: 0.5-0.9 parts by weight; The method for preparing the antifreeze modified fiber comprises the following steps: After the water-insoluble fiber raw material containing an ester structure is dissolved in a mixed solvent, an alkaline catalyst is added, and the mixture is heated to 30° C. to 40° C. and reacted for 30 min to 50 min to obtain a reaction solution; The reaction solution is dried and dehydrated, and the pH is adjusted to neutral, and then a silanol monomer compound is added, mixed, heated to 100° C. to 105° C., and refluxed for 1 h to 2 h to obtain the antifreeze modified fiber; The water-insoluble fiber raw material containing an ester structure is polyethylene adipate or polyvinyl acetate; The preparation method of the modified aggregate comprises the following steps: The coarse aggregate with a particle size of 10 mm to 15 mm is completely immersed in an oxalic acid solution for 20 min to 25 min to obtain an acid-treated coarse aggregate; The acid-treated coarse aggregate is completely immersed in silicate and mixed and stirred for 15 hours to 20 hours to obtain pretreated coarse aggregate; The pretreated coarse aggregate and fine aggregate are mixed in a weight ratio of 2-4:1 to form the modified aggregate.

2. The low temperature resistant ferroaluminate cement concrete according to claim 1, characterized in that: Basic catalysts include sodium hydroxide or potassium hydroxide.

3. The low temperature resistant ferroaluminate cement concrete according to claim 1, characterized in that: The silanol monomer compound includes 3-aminopropyltrihydroxysilane, diphenylsilanediol or triphenylsilanol.

4. The low temperature resistant ferroaluminate cement concrete according to claim 1, characterized in that: The weight ratio of the water-insoluble fiber raw material containing an ester structure: the mixed solvent: the alkaline catalyst: the silanol monomer compound is 1:2-3:0.1-0.3:0.5-1.

5. The low temperature resistant ferroaluminate cement concrete according to claim 1, characterized in that: The mass concentration of the oxalic acid is 2% to 3%.

6. The low temperature resistant ferroaluminate cement concrete according to claim 1, characterized in that: The silicate includes tetramethyl silicate, tetraethyl silicate or propyl orthosilicate.

7. A method for preparing a low-temperature resistant ferroaluminate cement concrete according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: The low-temperature resistant alumina-ferrocement concrete is obtained by mixing and stirring 53-85 parts by weight of alumina-ferrocement, 32-47 parts by weight of water, 3-8 parts by weight of antifreeze modified fibers, 111-138 parts by weight of modified aggregates and 0.5-0.9 parts by weight of polycarboxylate water reducer.

Images