A rapid-setting anti-freezing geopolymer pavement base material and a preparation method thereof

Abstract

The application provides a quick-setting anti-freezing geopolymer pavement base material and a preparation method thereof, and belongs to the technical field of geopolymer materials. The application takes red mud and titanium white slag as precursor materials, takes carbide slag as an alkali activator, and simultaneously adds anti-freezing reinforcing materials compounded by white mud, ceramic powder and brick powder. The geopolymer pavement base material is formed by compounding multiple components, fully utilizes multiple high-alkaline and silicon-aluminum-rich solid waste resources, has the comprehensive advantages of low carbon, environmental protection, low cost, short construction period, excellent anti-freezing performance and the like, breaks through the technical bottlenecks of slow low-temperature setting and poor durability of the pavement base material in cold regions, and is suitable for highway, municipal road and border road engineering in high-cold regions. The application has important engineering significance and popularization value for green traffic infrastructure construction in cold regions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geopolymer materials, and particularly relates to a rapid-setting anti-freezing geopolymer pavement base material and a preparation method thereof. BACKGROUND

[0002] The high-cold region is in a low-temperature or even extremely low-temperature environment all the year round, and has the characteristics of long winter, large temperature change and large diurnal temperature difference. Under such climatic conditions, the surface and roadbed material frequently undergo freeze-thaw cycles, which causes the concrete, base structure and pavement surface layer to have degradation phenomena such as cracking, spalling, bulging and instability, which not only shortens the service life of the road structure, but also seriously threatens the traffic safety. Especially in the severe cold environment of-20℃ or even lower temperature, the hydration reaction rate and early strength development of the material are significantly inhibited, and the traditional cement-based base material faces the problems of slow setting, poor early strength and insufficient frost resistance, which seriously restricts the construction progress and durability guarantee of the road engineering in the cold region.

[0003] As a new type of inorganic cementitious material, the geopolymer material has attracted more and more attention due to its early strength, fast hardening, high activity at low temperature, low carbon and environmental protection and other characteristics. The geopolymer is usually generated by a three-dimensional network gel structure through a polymerization reaction of solid raw materials rich in silicon and aluminum components and an alkaline activator at room temperature or low temperature, and has good mechanical properties and durability. However, the widely used geopolymer raw materials at present are industrial by-products such as fly ash and granulated blast furnace slag. These raw materials have potential activity, but they are not widely distributed in the high-cold region, are not easy to obtain, and mostly need high-temperature heat treatment or long-term curing to achieve high activity release, which is difficult to meet the demand of the cold region engineering for rapid construction, high early strength and frost resistance.

[0004] On the other hand, the activator commonly used in the geopolymer system at present includes strong alkaline chemicals such as NaOH and Na2SiO3. Although these activators can provide sufficient alkalinity to promote the geopolymer reaction, they have many engineering implementation obstacles such as strong corrosion, high operation safety risk, inconvenient storage and transportation, and high cost.

[0005] In addition, the geopolymer system in the related art has a slow polymerization reaction under low temperature conditions, a prolonged setting time and even a delayed strength development phenomenon, and the structural compactness and micro stability are difficult to resist the damage caused by repeated freeze-thaw cycles in the high-cold region, which causes problems such as material brittle cracking, peeling and instability, greatly limiting the actual engineering application.

[0006] Therefore, it is necessary to provide a rapid-setting anti-freezing geopolymer pavement base material and a preparation method thereof to solve the above problems. SUMMARY

[0007] The application provides a quick-setting anti-freezing geopolymer pavement base material and a preparation method thereof, which utilizes high-activity industrial solid waste as a main gelling material, is supplemented with an economic and safe alkaline activator and anti-freezing reinforced aggregate, constructs a geopolymer system with the characteristics of low-temperature fast hardening, high durability and green environmental protection, and is particularly suitable for use in areas with low temperature and multiple freeze-thaw cycles, thereby effectively solving at least one technical problem involved in the background art.

[0008] In order to solve the above technical problems, the application is implemented as follows:

[0009] A quick-setting anti-freezing geopolymer pavement base material, comprising a gel material and an anti-freezing reinforced material, wherein the gel material comprises the following components in percentage by weight: 20-40 parts of red mud, 30-50 parts of titanium white slag and 10-20 parts of carbide slag; the anti-freezing reinforced material has a mixing amount of 5%-10% of the total amount of the gelling material, and is composed of white mud, ceramic powder and brick powder.

[0010] As a preferred improvement, the red mud is a solid waste produced after extracting aluminum oxide from bauxite by the Bayer method, has a particle size of less than 75 mu m, an aluminum oxide content of 10%-20%, and an iron oxide content of 30%-60%;

[0011] The titanium white slag is a solid waste produced in the production of titanium dioxide by the sulfuric acid method, and has a ferrous sulfate content of more than 50%;

[0012] The carbide slag is a solid waste produced in the preparation process of acetylene gas, and has a calcium hydroxide content of more than 70%;

[0013] The white mud is a solid waste produced by recovering alkali in the papermaking process, and has a calcium carbonate content of more than 60%;

[0014] The total content of silicon dioxide and aluminum oxide in the ceramic powder is more than 60%;

[0015] The components of the brick powder include silicon dioxide, aluminum oxide, iron oxide and alkali metal and alkaline earth metal oxides with a total content of less than 5%.

[0016] As a preferred improvement, the red mud and the titanium white slag are dried and ground to a particle size of less than or equal to 75 mu m before use; and the carbide slag and the anti-freezing reinforced material are ground to a specific surface area of more than or equal to 400 m 2 / kg.

[0017] As a preferred improvement, the mass ratio of the white mud, the ceramic powder and the brick powder in the anti-freezing reinforced material is 1:1:1-2:1:1.

[0018] As a preferred improvement, the water-binder ratio of the quick-setting anti-freezing geopolymer pavement base material is 0.35-0.40.

[0019] As a preferred improvement, the freeze-resistant geopolymer pavement base material has freeze-thaw cycle times ≥ 300, initial setting time ≤ 45 minutes, 6-hour compressive strength ≥ 8 MPa, 28-day compressive strength not less than 40 MPa, compressive strength retention rate ≥ 95%, and relative dynamic elastic modulus retention rate ≥ 90%.

[0020] A preparation method of the freeze-resistant geopolymer pavement base material as described above, comprising the following steps:

[0021] Step S1, dry and sieve the red mud and titanium white slag, control the particle size to be below 75 μm; dry and grind the calcium carbide slag to a specific surface area ≥ 400 m 2 / kg; dry and finely grind the freeze-resistant reinforcing material to within 90 μm;

[0022] Step S2, dry mix the red mud, titanium white slag and freeze-resistant reinforcing material for 60 seconds to pre-disperse the raw materials and form a dry mixture;

[0023] Step S3, provide water according to a preset water-binder ratio, mix the calcium carbide slag with water in a proportion to form an activator, slowly pour the activator into the dry mixture and stir for 90-120 seconds to form a uniform slurry;

[0024] Step S4, complete paving, leveling and rolling of the slurry to ensure that the geopolymer completes the forming operation before initial setting.

[0025] As a preferred improvement, in step S3, the stirring process is controlled to have an ambient temperature not less than 5℃ and a stirring rate of 60-80 rpm.

[0026] As a preferred improvement, in the forming process of step S4, the compaction degree is ≥ 95%.

[0027] As a preferred improvement, the freeze-resistant geopolymer pavement base material is cured by the following method:

[0028] The initial curing in 0-24 hours is covered with heat preservation cloth or felt cloth, and the construction environment temperature is ensured to be higher than 5℃ and the humidity is maintained to be ≥ 85%;

[0029] Demolding is performed after 24 hours, and the post-curing stage is entered, and the natural curing, greenhouse curing or low-temperature steam assisted curing method is selected according to the site conditions, the curing temperature is 10-30℃, the relative humidity is ≥ 85%, and the curing period is 7-28 days.

[0030] The present application has the following advantages:

[0031] (1) Significantly improve the low-temperature setting and early strength performance of geopolymer: By introducing a synergistic silicon-aluminum reaction system of red mud and titanium white slag, combined with the high-alkali environment and active calcium source provided by carbide slag, the polymerization reaction rate is significantly accelerated, achieving initial setting within 45 minutes and obtaining early strength of 6-9 MPa within 6 hours at low temperature (below 10°C), effectively ensuring construction progress and early stability in high-cold regions.

[0032] (2) Greatly enhance the freeze-thaw resistance: Using paper white mud, ceramic powder and brick powder as anti-freezing components to fill pores, inhibit water migration and ice crystal expansion damage, optimize the microstructure of the material, and significantly improve the freeze-thaw stability. After 300 freeze-thaw cycles, the material mass loss rate is less than 1.5%, and the relative dynamic elastic modulus retention rate is more than 90%, which is much better than traditional cement concrete system.

[0033] (3) Realize green resource utilization: The invention makes full use of various high-alkali and silicon-rich industrial solid wastes, including red mud, titanium white slag, carbide slag, etc., as the main cementing and activating components, greatly reducing the dependence on traditional fly ash, slag and chemical activators, showing good resource recycling and solid waste reduction benefits, meeting the "double carbon" policy and green infrastructure construction needs.

[0034] (4) Strong construction adaptability and simple process: The construction process of the invention uses conventional dry-wet mixing process and staged curing mode at room temperature or low temperature, without high-temperature calcination or strong alkali liquid conditioning, safe storage and transportation of raw materials, simple on-site operation, strong adaptability, especially suitable for rapid batch construction in remote cold regions under low temperature and complex conditions.

[0035] (5) Improve structural stability and long-term durability: By optimizing the composition and reaction path of the cementitious product, dense and high-crosslinked C-A-S-H and N-A-S-H gels are generated, significantly improving the material's impermeability, crack resistance and structural stability, ensuring the stable bearing capacity of the road base during long-term service and the safety performance in freezing environment.

[0036] (6) Significant economic benefits: Using low-cost and large-volume solid waste to replace traditional cement, slag and other raw materials, while avoiding the use of expensive and corrosive chemical activators, the overall material cost is reduced by about 30%-50% compared with conventional geopolymer system, with good economic feasibility and industrial promotion value.

[0037] In summary, the invention has achieved breakthroughs in material composition design, performance indicators, green environmental protection and practical engineering application adaptability, solving the key problems of "fast hardening and difficult" "poor freeze resistance" "slow construction" and other key problems in cold regions. It is a new generation of high-performance base material system for road construction and maintenance in high-cold regions, with wide engineering promotion prospects and social and economic benefits. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of the present application.

[0039] The present embodiment provides a rapid setting type anti-freezing geopolymer pavement base material, which comprises a gel material and an anti-freezing reinforcing material, the gel material comprises the following components in percentage by weight: 20-40 parts of red mud, 30-50 parts of titanium white slag and 10-20 parts of carbide slag; the dosage of the anti-freezing reinforcing material is 5%-10% of the total amount of the gel material, and the anti-freezing reinforcing material is compounded by white mud, ceramic powder and brick powder.

[0040] The red mud is a solid waste produced after extracting aluminum oxide by the Bayer method, the particle size is less than 75 μm, and the main components are aluminum oxide and iron oxide, wherein the content of aluminum oxide is 10%-20%, and the content of iron oxide is 30%-60%.

[0041] The titanium white slag is a solid waste produced in the production of titanium dioxide by the sulfuric acid method, and the main component is a sulfate compound, wherein the content of ferrous sulfate is more than 50%.

[0042] The carbide slag is a solid waste produced in the preparation process of acetylene gas, and the main component is calcium hydroxide, with a content of more than 70%.

[0043] The white mud is a solid waste produced by recovering alkali in the papermaking process, and the main component is calcium carbonate, with a content of more than 60%.

[0044] The main components of the ceramic powder are silicon dioxide and aluminum oxide, which account for more than 60% of the total components.

[0045] The main components of the brick powder are silicon dioxide, aluminum oxide and iron oxide, and in addition, it also contains less than 5% of alkali metal and alkaline earth metal oxides.

[0046] The red mud and the titanium white slag are dried and ground to a particle size of ≤75 μm before use; the carbide slag and the anti-freezing reinforcing material are ground to a specific surface area of ≥400 m 2 / kg.

[0047] The mass ratio of the white mud, the ceramic powder and the brick powder in the anti-freezing reinforcing material is 1:1:1-2:1:1.

[0048] The reaction mechanism involved in the system is as follows:

[0049] The red mud is both Si / Al source and often carries soluble alkali, forming a "Na-Ca co-activation" environment with carbide slag, promoting the coexistence of N-A-S-H / C-(N)-A-S-H composite gel.

[0050] The carbide slag is used to provide a high pH environment to quickly dissolve active Si / Al in red mud / ceramic / brick powder, while providing a large amount of Ca 2+ Promote the early formation of C-(A)-S-H calcium-based gel, which is one of the sources of "fast setting and early strength".

[0051] The titanium white slag is used to provide a combination of SO4 2- , Ca 2+ , Al(OH)4 - , which is prone to generate acicular ettringite (AFt) network in the early stage, accelerate coagulation and fill capillary pores.

[0052] The white mud is used to achieve high-fineness micro-filling and nucleation effect, and to generate calcite with Ca(OH)2carbonation; it can also stabilize a part of aluminate to form calcium carboaluminate AFm-CO3, which is beneficial to the densification of microstructure.

[0053] The ceramic powder / brick powder is rich in amorphous and low-crystalline SiO2-Al2O3, which is a typical pozzolanic active source, continuously reacts with Ca(OH)2to generate secondary C-(A)-S-H, and supplements Al into the gel skeleton, further refining the pore size and improving the strength and impermeability.

[0054] The red mud and titanium white slag constitute the gel material in the low polymer material, the main effective component in the red mud is active alumina (Al2O3), in addition to which the main component is ferric oxide, which has excellent reactivity and stability. Under the conditions of high alkalinity environment formed by the dissolution of carbide slag and high concentration of Ca 2+ , the Al 3+ ions released by the red mud rapidly polymerize with silicon dioxide, alkali metal oxides and other substances in the ceramic powder and brick powder to form N-A-S-H and C-A-S-H gel-like aluminosilicate structures, providing early skeleton support for the geopolymer system. At the same time, the SO4 2- released by the dissolution of titanium white slag reacts with Ca 2+ and Al 3+ in the system to generate ettringite, which forms a network structure in the skeleton structure. The synergistic use of this double-source silicon-rich solid waste not only fully releases its potential activity, but also significantly improves the reaction rate, the denseness of the gel product and the freeze-thaw resistance of the overall structure.

[0055] The carbide slag is used as an activator to replace traditional chemical alkali such as NaOH and Na2SiO3. The main component of the carbide slag is Ca(OH)2, which has significant alkalinity and active calcium release capacity. After the carbide slag is dissolved in water, it can quickly provide high concentration of OH-ions to activate the dissolution and migration of silicon and aluminum components, and release Ca 2+ participate in the formation of C-S-H, C-A-S-H and other similar hydration products, further filling the pores in the gel material, thereby achieving rapid setting and early strength growth in low-temperature environments. This activation process not only reduces the risk of alkaline corrosion, but also significantly reduces costs and transportation difficulties, which is a key technical support for sustainable construction in high-cold regions.

[0056] The anti-freezing reinforcing material is used to further improve the anti-freezing property and low-temperature structural stability. Papermaking white mud is rich in CaCO3 and residual cellulose, which can release Ca 2+ slowly in an alkaline environment, and provides fine filler to optimize the pore structure of the gel material, forming a dense network structure with a closed porosity of ≥30%, thereby significantly inhibiting the internal pressure expansion caused by freeze-thaw, hindering water migration and ice crystal formation. Ceramic powder and brick powder are high-temperature sintered products with high particle hardness and large surface roughness, mainly serving as aggregates to constrain other microstructures within the system, significantly reducing stress concentration and structural degradation caused by frost heaving. The addition of the anti-freezing reinforcing material not only improves the material density, but also effectively reduces the risk of freeze-thaw crack initiation and propagation, enabling the oligomer material of the present application to resist more than 300 freeze-thaw cycles for a long time.

[0057] The ratio of each component in the rapid-setting anti-freezing geopolymer pavement base material can be flexibly adjusted according to the environmental temperature, construction period and freeze-thaw grade, for example, when constructing in a 5℃ environment, the proportion of carbide slag and titanium white slag can be appropriately increased to enhance early activity, and in summer curing conditions, the proportion of carbide slag and titanium white slag can be appropriately increased to control the setting rate.

[0058] The water-binder ratio of the rapid-setting anti-freezing geopolymer pavement base material is controlled at 0.35-0.40 to obtain a better balance between construction fluidity and strength development.

[0059] The involved chemical and mineralogical processes are as follows:

[0060] Dissolution stage:

[0061] (Si, Al)-O network + OH - → [SiO(OH)3] - , [Al(OH)4] -

[0062] Gelation stage:

[0063] Ca 2++ Na + + Si / Al tetrahedron → C-(N)-A-S-H / N-A-S-H

[0064] Early AFt (ettringite) formation stage:

[0065] Ca 2+ + Al(OH)4 - + SO4 2- + H2O → AFt

[0066] Secondary pozzolanic reaction stage:

[0067] Ca(OH)2+ SiO2(am) + H2O → C-S-H

[0068] Carbonate solidification stage:

[0069] Ca(OH)2+ CO2→ CaCO3 (calcite);

[0070] C-A-H + CO3 2- + Ca 2+ → AFm-CO3 (calcium carboaluminate).

[0071] The main anti-freezing mechanisms are microstructure regulation and pore water behavior, which are as follows:

[0072] (1) Pore size spectrum shift and critical saturation increase

[0073] The "needle-gel-crystal" composite filling of AFt + C-(A)-S-H + CaCO3 converts a large number of capillary pores larger than 50 nm into gel pores of 20-30 nm; effectively reduces the proportion of free / freezeable water, increases the critical saturation of the material, and significantly reduces the frost heaving driving force.

[0074] (2) Gibbs-Thomson effect / ice point depression

[0075] The ice point of water in fine pores is lowered by the pore size effect; at the same time, the osmotic pressure effect of high ionic strength (Na + , Ca 2+ , OH - , SO4 2- ) further reduces the ice point of pore solution and increases the proportion of non-freezable water.

[0076] (3) Anti-permeation / anti-ion invasion

[0077] The dense network reduces the permeability coefficient k, limits water migration before and after freezing, and suppresses the "freeze-thaw-seepage-refreeze" damage cycle; SO4 2- preferentially solidifies into AFt / AFm, reducing the risk of superimposed salt freezing and sulfate erosion in the later stage.

[0078] (4) Toughness and stress release:

[0079] The "needle beam" of early AFt interweaves with the "gel net" of C-(A)-S-H, providing "microfibrous" toughening; the gradation optimization of white mud / ceramics / brick powder and the nucleation effect passivate defects, relieving frost heaving stress concentration and microcrack propagation.

[0080] The mechanism of rapid setting is as follows:

[0081] (1) Ca-SO4 2- -Al synergistic (titanium slag + calcium carbide slag + red mud) promotes the rapid nucleation and growth of AFt;

[0082] (2) Ca-rich geopolymer / hydration-polymerization in parallel (C-(A)-S-H and N-A-S-H coexist) promotes the rapid establishment of early structural framework.

[0083] The rigid network formed rapidly shortens the "freezable water free migration window period", and together with densification, it improves the structural stability under freeze-thaw cycles.

[0084] The rapid setting type anti-frozen geopolymer pavement base material obtained by the application is suitable for pavement base structure of expressway, municipal road, border passway, etc. in high-cold region, the freeze-thaw cycle number is ≥300 times, the initial setting time is ≤45 minutes, the 6-hour compressive strength is ≥8MPa, the 28-day compressive strength is not less than 40MPa, the compressive strength retention rate is ≥95%, and the relative dynamic elastic modulus retention rate is ≥90%.

[0085] The embodiment further provides a preparation method of the rapid setting type anti-frozen geopolymer pavement base material, comprising the following steps:

[0086] Step S1, dry and sieve the red mud and titanium slag, control the particle size below 75μm; dry and grind the calcium carbide slag to a specific surface area ≥400m 2 / kg to ensure the dissolution speed and activity excitation; dry and finely grind the anti-frozen reinforcing material to within 90μm to ensure uniformity and activity release.

[0087] Step S2, dry mix the red mud, titanium slag and anti-frozen reinforcing material for 60 seconds to form a dry mixture by pre-dispersing each raw material.

[0088] Step S3, provide water according to the preset water-binder ratio, mix the calcium carbide slag and water in proportion to form an excitation liquid, slowly pour into the dry mixture and stir for 90-120 seconds to form a uniform slurry.

[0089] Step S4, complete the paving, leveling and rolling of the slurry to ensure that the geopolymer completes the forming operation before initial setting.

[0090] The compaction equipment is selected as a vibrating roller with a capacity of more than 10 tons, and the compaction degree is controlled to be greater than or equal to 95%, so as to ensure the compactness and durability of the structure.

[0091] The construction environment of the preparation method provided by the application can reach a minimum air temperature of 5 DEG C, and the normal reaction of the material at low temperature is realized by preheating the aggregate and heating the activator.

[0092] The rapid-setting anti-freezing geopolymer pavement base material is cured by the following method:

[0093] The initial curing is performed by covering with heat insulation cloth or felt cloth, and the construction environment temperature is ensured to be higher than 5 DEG C, and the humidity is maintained to be greater than or equal to 85%, so as to prevent water evaporation and early freezing damage. Demolding is performed after 24 hours, and the material enters the later curing stage, and the natural curing, greenhouse curing or low-temperature steam assisted curing method can be selected according to the site conditions, the recommended temperature range is 10-30 DEG C, the relative humidity is greater than or equal to 85%, and the curing period is suggested to be 7-28 days.

[0094] The curing method fully ensures the continuous progress of the gelation reaction in the material and the perfect generation of the gel structure, and is a key guarantee measure for realizing the anti-freezing durability.

[0095] Example 1

[0096] The example provides a rapid-setting anti-freezing geopolymer pavement base material, and the total amount of the cementing material is 600 kg / m 3 , wherein the amount of the red mud is 180 kg / m 3 (accounting for 30%), the amount of the titanium white waste residue is 240 kg / m 3 (accounting for 40%), the amount of the calcium carbide slag is 90 kg / m 3 (accounting for 15%), and the remaining 150 kg / m 3 is composed of white mud, ceramic powder and brick powder, and each of the three accounts for 30 kg / m 3 . The water-binder ratio is controlled to be 0.38, and the water amount used per cubic meter of the material is 228 kg.

[0097] The red mud used was ground to a particle size of 70 pm or less after drying at 105°C, and XRF (X-ray diffraction) showed that it mainly contained Si02(16.2%), Al203(14.8%), Fe203(36.5%), Na20(5.3%), and CaO (3.7%) and other components. The titanium white waste residue came from the sulfuric acid method titanium dioxide process, was dried and ground to 75 pm or less, and XRF showed that after calcination, the main chemical components were Fe203(17.6%), Si02(21.4%), Al203(8.9%), CaS04(28.7%), and Ti02(6.2%), with potential activity and stable sources of silicon and aluminum. The activator carbide slag was an acetylene gas by-product, containing more than 70% Ca(OH)2, with sufficient alkalinity and a specific surface area of 420 m 2 / kg, which could effectively activate the potential active components in the red mud and titanium white residue.

[0098] First, the red mud, titanium white residue, carbide slag, white mud, ceramic powder, and brick powder were dry mixed according to the ratio, with a stirring time of 60 seconds to ensure uniform distribution of the components. Then, the prepared carbide slag solution was slowly added, with a water-binder ratio of 0.38, and the mixture was continuously stirred in the mixer for 90 to 120 seconds to ensure that the components were in full contact and began to polymerize. After stirring, the material should be poured and initially rolled within 30 minutes, which is suitable for rapid construction in cold regions. The material was immediately covered with a thermal insulation film after shaping to prevent early water loss, and was left to stand in a natural environment at 10-15°C for 24 hours to complete the initial setting and early reaction. After demolding, the material was placed in a curing room for steam-assisted curing, with a curing temperature of 25-30°C and a relative humidity of not less than 90%. The mechanical and durability performance tests were conducted at 6 hours, 1 day, 3 days, 7 days, and 28 days, respectively.

[0099] Combining SEM and XRF tests showed that the silicon and aluminum activity of the red mud and titanium white residue was rapidly released under the activation of the carbide slag, generating dense C-A-S-H and N-A-S-H gels, and the freeze-thaw resistant components further filled the pores, effectively blocking the ice crystal expansion path.

[0100] According to the standard test procedures, the results showed that the material had an initial setting time of 42 minutes in a 10°C environment, a 6-hour compressive strength of 8.2 MPa, and 1-day, 3-day, 7-day, and 28-day compressive strengths of 15.6 MPa, 26.7 MPa, 34.8 MPa, and 46.1 MPa, respectively, showing excellent early strength performance. After 300 freeze-thaw cycles, the mass loss of the test specimen was only 1.3%, the relative dynamic elastic modulus retention rate was 91.5%, and the compressive strength retention rate was as high as 95.2%. The above data fully demonstrate that the material has the combined advantages of rapid hardening, early load bearing, and long-term durability in high-cold environments, making it extremely suitable for use as a pavement base for border roads, mountainous roads, and urban roads in cold regions.

[0101] Example 2

[0102] This example provides a low dosage scheme. The total amount of cementitious material is 600 kg / m 3 , in which the dosage of red mud is 120 kg / m 3 (20%), the dosage of titanium white waste residue is 180 kg / m 3 (30%), the dosage of calcium carbide slag is 60 kg / m 3 (10%), and the remaining 240 kg / m 3 is frost-resistant reinforcing material (white mud, ceramic powder, and brick powder each accounts for 80 kg / m³). The water-binder ratio is controlled at 0.40, and the water consumption is 240 kg.

[0103] The material mixing and curing method is the same as that of Example 1. The test results show that the initial setting time is 44 minutes under the environment of 10°C, the 6-hour compressive strength is 6.5 MPa, and the 28-day strength is 41.3 MPa. After 300 freeze-thaw cycles, the mass loss rate is 1.6%, the compressive strength retention rate is 92.8%, and the relative dynamic elastic modulus retention rate is 90.2%, which meets the durability requirements of the base in cold regions.

[0104] Example 3

[0105] This example provides a high dosage scheme. The total amount of cementitious material is 600 kg / m 3 , in which the dosage of red mud is 240 kg / m 3 (40%), the dosage of titanium white waste residue is 300 kg / m 3 (50%), the dosage of calcium carbide slag is 120 kg / m 3 (20%), and the frost-resistant reinforcing material is 30 kg / m 3 (white mud, ceramic powder, and brick powder each accounts for 10 kg / m 3 ). The water-binder ratio is 0.35, and the water consumption is 210 kg.

[0106] The material mixing and curing method is the same as that of Example 1. The test results show that the initial setting time is 38 minutes under the environment of 10°C, the 6-hour compressive strength is 9.3 MPa, and the 28-day strength is 49.7 MPa. After 300 freeze-thaw cycles, the mass loss rate is 1.1%, the compressive strength retention rate is 96.4%, and the relative dynamic elastic modulus retention rate is 93.7%, which has the best comprehensive performance.

[0107] Comparative Example

[0108] In order to verify the performance advantages of the material, ordinary cement-based layer material (P.O42.5 cement + sand aggregate, water-binder ratio 0.40) is used as a control to test under the same specimen size and curing conditions. The results show that the initial setting time of the control group is 140 minutes at 10 DEG C, the 6-hour strength is less than 3 MPa, and the 28-day strength is about 36.5 MPa; after 300 freeze-thaw cycles, the mass loss rate is 4.8%, the compressive strength retention rate is only 76.3%, and the relative dynamic elastic modulus is reduced to 72.5%; compared with the control group, the early strength of the material is increased by 2-3 times, and the frost resistance is significantly better than that of the traditional cement-based layer.

[0109] The above describes the embodiments of the present application, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative but not restrictive, and those skilled in the art can make many forms without departing from the scope of the present application under the inspiration of the present application, which are all within the protection of the present application.

Claims

1. A fast-setting, freeze-resistant polymer pavement base material, characterized in that, The material includes a gelling material and an antifreeze reinforcing material. The gelling material comprises the following components by weight percentage: 20-40 parts red mud, 30-50 parts titanium dioxide slag, and 10-20 parts carbide slag. The antifreeze reinforcing material is added at 5%-10% of the total amount of the gelling material. The antifreeze reinforcing material is a compound of white mud, ceramic powder, and brick powder. The titanium dioxide slag is a solid waste generated from the production of titanium dioxide using the sulfuric acid process, and its ferrous sulfate content is above 50%. The white mud is a solid waste generated from the alkali recovery process in papermaking, with a calcium carbonate content of over 60%.

2. The rapid-setting, frost-resistant geopolymer pavement base material according to claim 1, characterized in that, The red mud is a solid waste produced after the extraction of aluminum oxides from bauxite using the Bayer process. It has a particle size of less than 75 μm, an aluminum oxide content of 10%-20%, and an iron oxide content of 30%-60%. The calcium carbide slag is a solid waste generated during the acetylene gas preparation process, with a calcium hydroxide content of over 70%. The total content of silicon dioxide and aluminum oxide in the ceramic powder is above 60%; The brick powder consists of silicon dioxide, aluminum oxide, iron oxide, and less than 5% of alkali metal and alkaline earth metal oxides in total.

3. The rapid-setting, frost-resistant geopolymer pavement base material according to claim 1, characterized in that, The red mud and titanium dioxide slag are dried and ground to a particle size ≤75μm before use; the carbide slag and antifreeze reinforcing material are ground to a specific surface area ≥400m². 2 / kg.

4. The rapid-setting, freeze-resistant geopolymer pavement base material according to claim 1, characterized in that, The mass ratio of white clay, ceramic powder, and brick powder in the antifreeze reinforcing material is 1:1:1 to 2:1:

1.

5. The rapid-setting, frost-resistant geopolymer pavement base material according to claim 1, characterized in that, The water-cement ratio of the rapid-setting, frost-resistant polymer pavement base material is 0.35-0.

40.

6. The rapid-setting, freeze-resistant geopolymer pavement base material according to claim 1, characterized in that, The fast-setting antifreeze geopolymer pavement base material has a freeze-thaw cycle count of ≥300 times, an initial setting time of ≤45 minutes, a 6-hour compressive strength of ≥8MPa, a 28-day compressive strength of not less than 40MPa, a compressive strength retention rate of ≥95%, and a relative dynamic modulus of elasticity retention rate of ≥90%.

7. A method for preparing a rapid-setting, frost-resistant geopolymer pavement base material as described in any one of claims 1-6, characterized in that, Includes the following steps: Step S1: After drying, the red mud and titanium dioxide slag are sieved to control the particle size to below 75 μm; the carbide slag is dried and then ground to a specific surface area ≥ 400 m². 2 / kg; the antifreeze reinforcing material is dried and then ground to within 90μm; Step S2: Dry mix red mud, titanium dioxide slag and antifreeze reinforcing material for 60 seconds to pre-disperse the raw materials and form a dry mixture; Step S3: Provide water according to the preset water-cement ratio, mix carbide slag and water in proportion to form an activating liquid, slowly pour it into the dry mixture and stir for 90-120 seconds to form a uniform slurry; Step S4 involves spreading, leveling, and compacting the slurry to ensure that the geopolymer completes its molding process before initial setting.

8. The preparation method according to claim 7, characterized in that, In step S3, the ambient temperature during the stirring process is controlled to be no lower than 5℃, and the stirring speed is 60-80 rpm.

9. The preparation method according to claim 7, characterized in that, During the molding process in step S4, the compaction degree is ≥95%.

10. The preparation method according to claim 7, characterized in that, The rapid-setting, frost-resistant polymer pavement base material is maintained in the following manner: During the initial curing period of 0-24 hours, cover the area with insulating cloth or felt, and ensure that the ambient temperature is above 5℃ and the humidity is ≥85%. Demolding is carried out 24 hours later, and the later curing stage begins. Depending on the site conditions, natural curing, greenhouse curing, or low-temperature steam-assisted curing methods are selected. The curing temperature is 10-30℃, the relative humidity is ≥85%, and the curing cycle is 7-28 days.