Red soil aggregate roadbed improvement method and construction method thereof

Abstract

The invention relates to the field of road engineering, and particularly discloses a laterite aggregate roadbed improvement method and a construction method thereof, the method comprises the following steps: S1, raw material preparation: preparing laterite aggregates, electrolytic manganese residue powder, sulphoaluminate cement, a composite activator and polymer rubber powder; s2, dry mixing: putting the red soil granules, the electrolytic manganese residue powder, the sulphoaluminate cement, the composite exciting agent and the polymer rubber powder in a mass ratio of (80-88): (10-15): (1.5-3): (0.5-1.5): (0.2-0.8) into mixing equipment, and carrying out dry mixing until the color of the mixture is uniform; through new material compatibility and fine process control, comprehensive improvement of the performance of the red soil aggregate roadbed is successfully realized, and the overall strength and bearing capacity of the red soil aggregate roadbed are remarkably improved, so that the red soil aggregate roadbed can meet the strict requirements of high-grade highways; the water stability of the roadbed material is greatly improved, water erosion and softening are effectively resisted, and the long-term service performance in a humid and rainy environment is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of road engineering, in particular to a laterite granular subgrade improvement method and a construction method thereof. BACKGROUND

[0002] Laterite, as a regional special soil widely distributed in tropical and subtropical regions, is a common filling material in highway subgrade engineering. Its mineral composition is mainly kaolinite, illite and hematite, usually with high strength and low plasticity, and good engineering properties in dry state. However, laterite granular material also has obvious engineering defects: its water stability is poor, and after seasonal dry-wet cycle or rainfall immersion, the cementing material between particles is easy to be softened and lost, resulting in significant strength attenuation, causing subgrade settlement, deformation and other diseases; at the same time, its shrinkage is large, and it is easy to produce dry shrinkage cracks when drying, which will damage the integrity of the subgrade and provide a channel for water intrusion, forming a vicious cycle, seriously affecting the long-term durability and stability of the subgrade.

[0003] In the practice of road engineering, inorganic cementitious materials such as cement and lime are often used to chemically improve laterite in order to improve its engineering performance. However, the traditional improvement method has certain limitations. For example, when using traditional cement improvement, although the strength can be improved to some extent, it is difficult to simultaneously and effectively solve the two core problems of insufficient water stability and significant dry shrinkage cracking of laterite granular material. The strength of cement improved soil is still greatly lost in water immersion environment (i.e. the softening coefficient is low), and its increased rigidity does not fundamentally improve its anti-shrinkage deformation capacity, and it is still easy to produce shrinkage cracks in dry environment, which cannot meet the stringent requirements of high-grade highways on the long-term performance of subgrade. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a laterite granular subgrade improvement method to solve the problem that the traditional improvement method in the prior art cannot simultaneously consider high strength, high water stability and low dry shrinkage, and cannot meet the long-term service requirements of high-grade subgrade.

[0005] A laterite granular subgrade improvement method, comprising the following steps:

[0006] S1, raw material preparation: preparing laterite granular material, electrolytic manganese residue powder, sulphoaluminate cement, composite activator and polymer powder;

[0007] S2, dry mixing: placing the laterite granular material, electrolytic manganese residue powder, sulphoaluminate cement, composite activator and polymer powder in the mixing equipment according to the mass ratio of (80-88):(10-15):(1.5-3):(0.5-1.5):(0.2-0.8), and carrying out dry mixing until the color of the mixture is uniform;

[0008] S3, moisture content adjustment and dampening: water is sprinkled on the dry mixture obtained in step S2 to adjust the moisture content to 92% to 96% of the moisture content corresponding to the maximum dry density determined by the standard compaction test, and then concentrated dampening is performed, with a dampening time of not less than 24 hours;

[0009] S4, secondary moisture content adjustment and mixing: after the dampening is completed, the moisture content of the mixture is detected, and water is added to accurately adjust the moisture content to 100% to 102% of the moisture content corresponding to the maximum dry density determined by the standard compaction test, and then wet mixing is performed until the water distribution is uniform.

[0010] Preferably, the electrolytic manganese residue powder is a powder after heat activation treatment at 500-600℃, with a specific surface area of not less than 500m² / kg, and a total content of active SiO2 and Al2O3 of not less than 60%; the composite activator is compounded by sodium sulfate and sodium metasilicate in a mass ratio of 2:1.

[0011] Preferably, the polymer powder is a redispersible latex powder, and the type is VAE or acrylate; the sulphoaluminate cement is a fast-hardening sulphoaluminate cement, with a specific surface area of not less than 380m² / kg.

[0012] Preferably, the dampening process in step S3 is specifically as follows: the mixture with the adjusted initial moisture content is filled into a sealed container in layers, 10-20kPa pressure is applied for preliminary compression every 20-30cm of filling, and finally the container is sealed for dampening; during the dampening, at least 2 times of pressure relief and turning are performed before re-pressurizing and sealing.

[0013] A laterite granular roadbed construction method, using the mixture prepared by the improved method, comprises the following steps:

[0014] T1, acceptance and measurement of the lower bearing layer: the lower bearing layer of the roadbed is accepted, and the center line and the side line are restored after passing the acceptance;

[0015] T2, mixture paving: the improved laterite granular mixture prepared in step S4 is transported to the construction site, and is paved according to a loose paving coefficient of 1.20-1.30 to form a uniform paving layer;

[0016] T3, vibration compaction: a vibrating road roller is used to compact the paving layer, with 1 pass of static compaction, 1 pass of weak vibration, and finally not less than 4 passes of strong vibration compaction until the compaction degree reaches more than 97% of the heavy compaction standard;

[0017] T4, moisture preservation and curing: after the compaction degree test is passed, spraying curing agent or covering high-molecular moisture preservation film is immediately used for curing, with a curing period of not less than 7 days.

[0018] Preferably, the strong vibration compaction in step T3 adopts a high-frequency low-amplitude vibration mode, the vibration frequency is 30-40 Hz, and the rolling speed is not more than 3 km / h.

[0019] Preferably, the improved laterite mixture has a 7-day unconfined compressive strength of not less than 2.0 MPa, a 28-day dry shrinkage coefficient of not more than 80*10 -6 , and a softening coefficient of not less than 0.90 after being soaked for 96 hours.

[0020] Preferably, the curing agent in step T4 is a water-based epoxy resin curing agent or an acrylic curing agent, and the spraying amount is controlled to be 0.8-1.2 kg / m².

[0021] Preferably, the paving in step T2 adopts a segmented continuous operation mode, and the paving length of each segment is not more than 50 m, so as to ensure that the paving and compaction are completed before the initial setting of the mixture.

[0022] Preferably, after the compaction operation in step T3 is completed, the thickness of the compacted layer is detected, and the thickness deviation should be controlled to be within ±5% of the design thickness.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] Through new material compatibility and fine process control, the performance of the laterite granular roadbed is comprehensively improved, and the overall strength and bearing capacity of the laterite granular roadbed are significantly improved, so that the laterite granular roadbed can meet the stringent requirements of high-grade highways.

[0025] The present application greatly improves the water stability of the roadbed material, effectively resists water erosion and softening, and ensures long-term service performance in humid and rainy environments.

[0026] The present method significantly inhibits the drying shrinkage of the improved soil body, greatly reduces the risk of base cracking, and thus improves the durability and long-term stability of the roadbed.

[0027] The present method ensures the uniformity and reliability of the performance in large-scale construction, and provides a technically advanced, economically reasonable and environmentally friendly solution for road construction in laterite areas BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The present application is a laterite granular roadbed improvement method flow chart.

[0029] Figure 2 The present application is a laterite granular roadbed construction method flow chart. DETAILED DESCRIPTION

[0030] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part 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 a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0031] As shown in Figure 1 and Figure 2 :

[0032] Embodiment one: a method for improving laterite granular roadbed, comprising the following steps:

[0033] S1, raw material preparation:

[0034] Laterite granular material: 800 kg, electrolytic manganese residue powder: 100 kg (heat-activated at 550 DEG C, specific surface area ≥ 500 m² / kg, active SiO2+Al2O3 content ≥ 60%), sulphoaluminate cement: 15 kg (fast-hardening type, specific surface area ≥ 380 m² / kg), composite activator: 5 kg (prepared by mixing 3.33 kg of sodium sulfate and 1.67 kg of sodium metasilicate at a mass ratio of 2:1), polymer powder: 2 kg (VAE type re-dispersible latex powder)

[0035] S2, dry mixing:

[0036] Put all the above raw materials into a forced mixer, and dry mix for 5-7 minutes until the color of the mixture is uniform and consistent, and there is no visible color difference and clumping.

[0037] S3, moisture content adjustment and material soaking:

[0038] According to the standard compaction test, the maximum dry density of the mixture is 2.10 g / cm³, and the optimum moisture content is 12.0%.

[0039] Calculate the target adjusted moisture content: 12.0% x 94% = 11.28%.

[0040] Sprinkle water on the dry mixture to accurately adjust its moisture content from the initial value to about 11.3%.

[0041] Material soaking: fill the mixture with adjusted moisture content into a large sealed soaking tank, and apply a pressure of 15 kPa for preliminary compression every 25 cm of thickness until the tank is filled. Seal the tank and soak the material for 24 hours. During the soaking, perform two pressure relief and turning over operations at the 8th hour and the 16th hour to break the particle agglomeration and make the water penetration more uniform, and then re-pressurize and seal.

[0042] S4, secondary moisture content adjustment and mixing:

[0043] After the curing process is completed, the moisture content of the mixture is tested, and it is assumed to be 11.2%.

[0044] The target final moisture content is calculated as: 12.0% × 101% = 12.12%. Water needs to be added to increase the moisture content from 11.2% to 12.12%.

[0045] After adding more water, put it back into the wet mixer and mix for 3-5 minutes until the moisture is evenly distributed in the mixture, so that it can be formed into a ball by hand and crumbles when dropped.

[0046] T1. Acceptance and surveying of the underlying subgrade:

[0047] The subgrade layer was inspected to ensure that the elevation, compaction, and flatness met the requirements. The centerline and edge lines of the subgrade were then restored and marked with stakes.

[0048] T2, Mixed material paving:

[0049] The improved mixture was quickly transported to the site. A paver was used to pave the mixture in sections with a loose paving coefficient of 1.20. The length of each section was controlled within 50 meters to form a uniform paving layer, ensuring that the section was completed before the mixture initially set.

[0050] T3, Vibratory compaction:

[0051] Static compaction: Use a vibratory roller to perform static compaction once to initially stabilize the paving layer.

[0052] Weak vibration: Turn on the weak vibration mode of the vibratory roller and compact it once.

[0053] Strong vibration: Adjust to high frequency low amplitude mode (vibration frequency 35Hz, rolling speed 2.5km / h), and perform strong vibration compaction 4 times.

[0054] Immediately after compaction, the compaction degree should be tested to achieve over 97% of the heavy compaction standard. The thickness of the compacted layer should be tested, and the deviation should be controlled within ±5% of the design thickness.

[0055] T4. Moisturizing and Nourishing:

[0056] After the compaction degree is qualified, immediately use a spraying device to evenly spray water-based epoxy resin curing agent, controlling the spraying amount to 0.8 kg / m². Curing is carried out for 7 days, during which traffic is closed to prevent moisture from evaporating too quickly.

[0057] Results: After improvement and construction using this method, the unconfined compressive strength of the roadbed mixture reaches more than 2.0 MPa after 7 days, the drying shrinkage coefficient after 28 days is no more than 80 × 10-6, and the softening coefficient after immersion in water for 96 hours is no less than 0.90.

[0058] Example 2: A method for improving red clay granular roadbed, comprising the following steps:

[0059] S1, raw material preparation:

[0060] Laterite granules: 840 kg, electrolytic manganese residue powder: 125 kg (heat-activated at 550°C, specific surface area ≥ 500 m² / kg, active SiO2+Al2O3 content ≥ 60%), sulphoaluminate cement: 22.5 kg (fast-hardening type, specific surface area ≥ 380 m² / kg), composite activator: 10 kg (prepared by mixing 6.67 kg of sodium sulfate and 3.33 kg of sodium metasilicate), polymer powder: 5 kg (acrylate type redispersible latex powder)

[0061] S2, dry mixing:

[0062] The raw materials were put into the mixer and dry mixed for 6-8 minutes until the color was uniform.

[0063] S3, moisture content adjustment and material soaking:

[0064] The optimum moisture content was 11.8% as determined by standard compaction test.

[0065] Initial target moisture content: 11.8% x 95% = 11.21%.

[0066] The mixture was adjusted to this value by watering.

[0067] The material was soaked for 24 hours, with a pressure of 10 kPa every 20 cm, and was turned over twice during the soaking.

[0068] S4, secondary moisture content adjustment and mixing:

[0069] The moisture content after soaking was 11.0%.

[0070] Final target moisture content: 11.8% x 101% = 11.92%. After additional watering, the mixture was wet mixed until the moisture was uniform.

[0071] T1, acceptance and measurement of sub-base:

[0072] The sub-base was accepted, ensuring that the elevation, compaction, and flatness were qualified. Then the centerline and side line of the roadbed were restored and marked.

[0073] T2, mixture paving:

[0074] The improved mixture was quickly transported to the site. The paving machine was used to segmentally pave at a loose laying coefficient of 1.25, with the single segment paving length controlled within 50 meters, forming a uniform paving layer, and ensuring that the segment work was completed before the mixture initial setting.

[0075] T3, vibration compaction:

[0076] Static pressure: static pressure 1 pass with vibrating roller, initial stabilization of the paving layer.

[0077] Strong vibration compaction 5 times (vibration frequency 38 Hz, speed 2.8 km / h).

[0078] Detect the compaction degree and thickness.

[0079] T4, moisture curing:

[0080] Spray acrylic ester curing agent, spraying amount 1.0 kg / m², curing for 7 days.

[0081] Effect: 7-day strength reaches 2.4 MPa, and other indicators are better than the specification requirements.

[0082] Example Three: A method for improving laterite granular subgrade, comprising the following steps:

[0083] S1, raw material preparation:

[0084] Laterite granules: 880 kg, electrolytic manganese residue powder: 150 kg (heat-activated at 550°C, specific surface area ≥500 m² / kg, active SiO2+Al2O3 content ≥60%), sulphoaluminate cement: 30 kg (fast-hardening type, specific surface area ≥380 m² / kg), composite activator: 15 kg (prepared by compounding 10 kg of sodium sulfate and 5 kg of sodium metasilicate), polymer powder: 8 kg (VAE type).

[0085] S2, dry mixing:

[0086] Put all the above raw materials into a forced mixer and dry mix for 7-9 minutes until the color of the mixture is uniform and there is no visible color difference and clumping.

[0087] S3, moisture content adjustment and material soaking:

[0088] The optimum moisture content measured by standard compaction test is 11.5%.

[0089] Initial target moisture content: 11.5% x 96% = 11.04%.

[0090] Sprinkle water to adjust the moisture content of the mixture to this value.

[0091] Soak the material for 26 hours, pressurize to 20 kPa every 30 cm of filling, and perform 3 times of pressure relief and turning during the period to ensure uniformity.

[0092] S4, secondary moisture content adjustment and mixing:

[0093] The moisture content after soaking is 10.8%.

[0094] Final target moisture content: 11.5% x 102% = 11.73%. After additional watering, mix well.

[0095] T1, Acceptance and measurement of the lower bearing layer:

[0096] Acceptance of the lower bearing layer of the roadbed to ensure that the elevation, compactness, and flatness are qualified. Then restore the roadbed centerline and side line and mark the piles.

[0097] T2, Mixture paving:

[0098] Use a paver to pave at a loose laying coefficient of 1.30, with a single segment length of 50 meters.

[0099] T3, Vibration compaction:

[0100] Static pressure: use a vibrating road roller for static pressure once to preliminarily stabilize the paving layer.

[0101] Strong vibration compaction 6 times (vibration frequency 40 Hz, speed 3.0 km / h).

[0102] Detect the compactness and thickness.

[0103] T4, Moisture preservation and maintenance:

[0104] Cover the polymer moisture film for maintenance, and maintain for 7 days.

[0105] Effect: The 7-day strength reaches more than 2.8 MPa, with extremely high water stability and extremely low dry shrinkage.

[0106] Experimental example: Key component role verification of laterite aggregate improvement method

[0107] 1. Experimental purpose

[0108] By designing different component omission comparison experiments, the key roles of electrolytic manganese residue powder, composite activator, and polymer powder in the improvement system are verified, and the influence on mechanical properties, water stability, and dry shrinkage characteristics is evaluated.

[0109] 2. Experimental design

[0110] This experiment sets up 5 groups:

[0111] Control group: completely according to the intermediate value of Example 2 and the process.

[0112] Comparative example 1: does not contain electrolytic manganese residue powder, and its mass is replaced with an equal amount of laterite aggregate.

[0113] Comparative example 2: does not contain a composite activator, and its mass is replaced with an equal amount of laterite aggregate.

[0114] Comparative example 3: does not contain polymer powder, and its mass is replaced with an equal amount of laterite aggregate.

[0115] Comparative Example 4: Ordinary Portland cement (P.O 42.5) was used to replace sulphoaluminate cement.

[0116] 3. Experimental materials and proportions

[0117] The total mass of all groups was kept at 1000 g, and the specific proportions are shown in the table below:

[0118] Group Red soil aggregate (g) Electrolytic manganese residue powder (g) Cement type and mass (g) Composite activator (g) Polymer powder (g) Note Control group 840 125 Fast hard sulphoaluminate cement 22.5 10 5 Followed the process of Example 2 completely Comparative Example 1 965 0 Fast hard sulphoaluminate cement 22.5 10 5 No electrolytic manganese residue powder Comparative Example 2 850 125 Fast hard sulphoaluminate cement 22.5 0 5 No composite activator Comparative Example 3 845 125 Fast hard sulphoaluminate cement 22.5 10 0 No polymer powder Comparative Example 4 840 125 Ordinary Portland cement 22.5 10 5 Cement type changed

[0119] 4. Preparation of test pieces and testing

[0120] Sample preparation: The modified mixture was prepared for each group according to the method (S2-S4 steps). Then, Φ50mm x 50mm standard cylindrical test pieces were prepared using the compaction method, with at least 9 parallel test pieces prepared for each group.

[0121] Curing: The test pieces were cured under standard curing conditions (temperature 20±2°C, humidity ≥95%) to the specified age.

[0122] Performance testing:

[0123] Unconfined compressive strength (UCS): The strength of test pieces cured for 7 days and 28 days was tested respectively (unit: MPa).

[0124] Dry shrinkage coefficient: The volume shrinkage rate of test pieces at 28 days of age in a dry environment was tested (unit: x10 -6 ).

[0125] Softening coefficient: The saturated strength of test pieces cured for 28 days was tested after being immersed in water for 96 hours, and the strength before immersion was compared to calculate the softening coefficient (saturated strength / dry strength).

[0126] Experimental results and data analysis

[0127] Table: Performance test results of each group

[0128] Group 7-day UCS (MPa) 28-day UCS (MPa) 28-day dry shrinkage factor (x 10 -6 ]) 0.0000 Softening coefficient Control group 2.45 3.20 75 0.93 Comparative Example 1 0.85 1.10 150 0.75 Comparative Example 2 1.52 2.05 110 0.82 Comparative Example 3 2.25 2.88 185 0.89 Comparative Example 4 1.60 2.80 95 0.90

[0129] Analysis of experimental results

[0130] Key role of electrolytic manganese residue powder (Comparative Example 1 vs. Control Group):

[0131] Phenomenon: The 7-day and 28-day strengths of Comparative Example 1 decreased significantly (by 65% and 66% respectively), the dry shrinkage increased sharply (100%), and the softening coefficient decreased significantly. This indicates that the structure is loose and the water stability is poor.

[0132] Analysis: The electrolytic manganese residue powder is the main source of active silica-alumina, which reacts with the cement hydration products under alkaline activation to form cementitious C-S-H and C-A-S-H gel with cementitious properties, which is the main component of the strength skeleton. Its absence leads to a serious shortage of total cementitious materials, and the structure cannot be effectively formed, so all performance indicators are deteriorated. Conclusion: The electrolytic manganese residue powder is the core material to provide strength and is indispensable.

[0133] Activation effect of composite activator (Comparative Example 2 vs. Control Group):

[0134] Phenomenon: The strength of Comparative Example 2 has a significant decrease (7-day and 28-day strengths decrease by 38% and 36%, respectively), the dry shrinkage increases, and the water stability becomes poor.

[0135] Analysis: The role of the composite activator (sodium sulfate + sodium metasilicate) is to destroy the glass structure of the electrolytic manganese residue and provide an alkaline environment to activate its activity and accelerate the pozzolanic reaction. Without the activator, the activity of the electrolytic manganese residue powder cannot be fully activated, the reaction rate and degree are reduced, resulting in a decrease in the generation of cementitious materials, and the strength and development speed are affected. Conclusion: The composite activator is crucial for fully activating the activity of the electrolytic manganese residue.

[0136] Toughening and anti-cracking effect of polymer powder (Comparative Example 3 vs. Control Group):

[0137] Phenomenon: The strength loss of Comparative Example 3 is small (about 10%), the softening coefficient decreases slightly, but the dry shrinkage coefficient abnormally increases (146%), which indicates that it is prone to cracking.

[0138] Analysis: The polymer powder forms a flexible network structure after film formation, effectively bridges microcracks, provides toughness, and significantly inhibits shrinkage caused by water evaporation. Its absence has little effect on peak strength, but makes the material brittle and has poor anti-shrinkage deformation ability. Conclusion: The main function of the polymer powder is to inhibit dry shrinkage and improve crack resistance, which is crucial for ensuring long-term durability.

[0139] Early strength characteristics of sulphoaluminate cement (Comparative Example 4 vs. Control Group):

[0140] Phenomenon: The early (7-day) strength of Comparative Example 4 is much lower than that of the control group (decreased by 35%), but the difference in late (28-day) strength is reduced. The dry shrinkage and water stability are also slightly worse.

[0141] Analysis: Fast-hardening sulphoaluminate cement is known for its fast early hydration speed and high strength, which can quickly provide a strength foundation for the system and create an alkaline environment to activate the activity of the manganese residue. The early strength development of ordinary Portland cement is slower, resulting in a lower early strength, which affects the optimization of overall performance. Conclusion: Sulphoaluminate cement has a clear advantage in achieving early high strength and is more suitable for this modified system.

[0142] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0143] Although the present application has been described in detail with reference to the foregoing embodiments, the skilled person in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for improving a lateritic granular subgrade, characterized in that, The method comprises the following steps: S1, raw material preparation: prepare laterite granules, electrolytic manganese residue powder, sulphoaluminate cement, composite activator and polymer glue powder; S2, dry mixing: place the laterite granules, electrolytic manganese residue powder, sulphoaluminate cement, composite activator and polymer glue powder in a mixing device according to a mass ratio of (80-88):(10-15):(1.5-3):(0.5-1.5):(0.2-0.8), and perform dry mixing until the color of the mixture is uniform; S3, moisture content adjustment and dampening: sprinkle water on the dry mixture obtained in step S2 to adjust the moisture content to 92% to 96% of the moisture content corresponding to the maximum dry density determined by a standard compaction test, and then perform concentrated dampening, with a dampening time of not less than 24 hours; S4, secondary moisture content adjustment and mixing: after the dampening is completed, detect the moisture content of the mixture, and supplement sprinkling of water to accurately adjust the moisture content to 100% to 102% of the moisture content corresponding to the maximum dry density determined by a standard compaction test, and then perform wet mixing until the water distribution is uniform.

2. The method for improving a lateritic granular subgrade according to claim 1, characterized in that, The electrolytic manganese residue powder is a powder after heat activation treatment at 500-600 DEG C, and has a specific surface area of not less than 500 m2 / kg, wherein the total content of active SiO2 and Al2O3 is not less than 60%; the composite activator is compounded by sodium sulfate and sodium metasilicate in a mass ratio of 2:

1.

3. The method for improving a lateritic granular subgrade according to claim 1, characterized in that, The polymer glue powder is a redispersible latex powder, and is of VAE type or acrylate type; the sulphoaluminate cement is a fast-hardening sulphoaluminate cement, and has a specific surface area of not less than 380 m2 / kg.

4. The method for improving a lateritic granular subgrade according to claim 1, characterized in that, The dampening process in step S3 is specifically as follows: the mixture with the adjusted initial moisture content is filled into a sealed container in layers, 10-20 kPa pressure is applied for preliminary compression every 20-30 cm of filling, and finally the container is sealed for dampening; during the dampening, at least 2 times of pressure relief and turning over are performed before re-pressurizing and sealing.

5. A method of construction of a lateritic granular subgrade, characterised in that, The mixture prepared by the improved method of any one of claims 1-4 comprises the following steps: T1, acceptance and measurement of the subbase layer: the subbase layer is accepted, and after being qualified, the center line and the side line are restored; T2, mixture paving: the improved laterite granule mixture prepared in step S4 is transported to the construction site, and is paved according to a loose paving coefficient of 1.20-1.30 to form a uniform paving layer; T3, vibration compaction: a vibrating road roller is used to compact the paving layer, 1 pass of static compaction, 1 pass of weak vibration, and finally not less than 4 passes of strong vibration compaction are performed until the compaction degree reaches more than 97% of the heavy compaction standard; T4, moisture preservation and curing: after the compaction degree test is qualified, a spraying curing agent or a high polymer moisture preservation film is used for curing immediately, and the curing period is not less than 7 days.

6. The construction method of claim 5, wherein The strong vibration compaction in step T3 adopts a high-frequency low-amplitude vibration mode, with a vibration frequency of 30-40 Hz and a rolling speed of not more than 3 km / h.

7. The construction method of claim 5, wherein the step of placing the subgrade is performed by placing the subgrade in a plurality of layers. The improved laterite mixture has 7-day unconfined compressive strength not less than 2.0 MPa, 28-day dry shrinkage coefficient not more than 80×10 -6 , and softening coefficient not less than 0.90 after 96 hours of immersion.

8. The construction method of claim 5, wherein the construction method is a construction method of a lateritic granular roadbed. The curing agent in step T4 is a water-based epoxy resin curing agent or an acrylate curing agent, and the spraying amount is controlled to be 0.8-1.2 kg / m2.

9. The construction method of claim 5, wherein the construction method is a construction method of a lateritic granular roadbed. The paving in step T2 is in the form of continuous operation in segments, each segment not exceeding 50 m in length, to ensure that the paving and compaction are completed before the initial setting of the mixture.

10. The construction method of claim 5, wherein the construction method is a construction method of a lateritic granular roadbed. After the compaction in step T3 is completed, the thickness of the compacted layer is detected, and the thickness deviation should be controlled within ± 5% of the design thickness.

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