Foam concrete and long-life roadbed widening section construction method

Abstract

The invention discloses foam concrete and a construction method for a long-life roadbed widening section, belongs to the technical field of road engineering, and aims to solve the technical problems of how to improve the performance of desulfurization ash, save cement, improve the quality of the roadbed widening section, reduce the material cost and realize convenient and rapid silt new and old roadbed widening. According to the technical scheme, the foam concrete is mainly prepared from the following raw materials in parts by weight: 200-400 parts of desulfurized ash-steel slag powder; 4-9 parts of cement; 150 to 350 parts of water; 0.6 to 1.5 parts of an additive; 1-2 parts of a foaming agent; and 0.5-1 part of an activating agent. The method specifically comprises the following steps: S1, cleaning the surface of an old roadbed, and treating surface pits; s2, impacting and rolling; s3, a slope is brushed, and steps are excavated and compacted at the joint of the roadbed; s4, high-doped desulfurization ash-steel slag powder foam concrete is filled from bottom to top; and S5, measuring the strength after layer-by-layer maintenance.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, in particular to a foam concrete and long-life roadbed widening section construction method. Background Art

[0002] In highway reconstruction and expansion projects, the connection technology between the new and old embankments is a core technology, and ensuring the longevity of the roadbed during the widening section is paramount. Differences in settlement, deformation, and stiffness between the new and old embankments and foundations can lead to damage to the long-lived roadbed and pavement after the expansion and reconstruction, primarily in the form of longitudinal cracks. Therefore, the design must study the internal stress and strain states generated by these differences in embankment settlement, deformation, and stiffness to provide control indicators for engineering design and construction standards. Furthermore, insufficient compaction of the old embankment can be a common problem in reconstruction and expansion projects. These issues significantly determine the service life of the reconstructed highway. Effective treatment of the junction between the new and old roadbeds is crucial to the success of widening. This is especially true when dealing with subgrades in unfavorable geological conditions such as silt. Strengthening the extensive, easily liquefied silt foundation to improve its density and stability is a practical research direction.

[0003] Although traditional desulfurization ash backfill has the advantages of small volume, low cost, light material and small side pressure on the embankment, simple construction process, rapid embankment strength growth and effective shortening of construction period, it has problems such as strong water permeability, serious and irregular surface cracks, poor wear resistance and inability to form a plate body, poor flexural resistance and water stability. Therefore, there is an urgent need to find a low-cost, high-performance material that can significantly enhance the bonding strength of the joints and thus reduce uneven settlement.

[0004] Among the most challenging issues to address during highway renovations are abutment overturning and abutment derailment. These issues are primarily caused by uneven settlement between the abutment and backfill materials, stemming from the presence of a relatively soft soil foundation. These derailment and abutment instability are often attributed to the use of fillers such as gravel and graded gravel. Desulfurized ash offers distinct advantages over these fillers, making it suitable for use in place of crushed soil, graded gravel, and other fillers.

[0005] Currently, desulfurization ash utilization is low, with a large amount of it being used as landfill in mines and foundation pits. This not only occupies a significant amount of arable land but also pollutes the environment. Compared to foamed concrete backfill, desulfurization ash backfill is not as fast as foamed concrete, and foamed concrete is not affected by road conditions. Desulfurization ash is low-cost but has many disadvantages.

[0006] Therefore, how to improve the performance of desulfurization ash, save cement, improve the quality of the roadbed widening section and reduce material costs, and realize convenient and fast widening of the new and old silt roadbed is a technical problem that needs to be solved urgently. Summary of the Invention

[0007] The technical task of the present invention is to provide a foam concrete and long-life roadbed widening section construction method to solve the problem of how to improve the performance of desulfurization ash, save cement, improve the quality of the roadbed widening section and reduce material costs, and realize convenient and fast widening of new and old silt roadbeds.

[0008] The technical task of the present invention is achieved in the following manner: a foamed concrete, which is mainly prepared from the following raw materials in the following weight ratios:

[0009] Desulfurization ash-steel slag powder 200-400 parts;

[0010] 4-9 parts of cement;

[0011] 150-350 parts water;

[0012] 0.6-1.5 parts of admixture;

[0013] 1-2 parts of foaming agent;

[0014] 0.5 to 1 part of activator.

[0015] Preferably, the desulfurized ash-steel slag powder is mainly prepared from the following raw materials in the following weight ratios:

[0016] 85-90 parts of desulfurization ash;

[0017] 8-12 parts of steel slag powder;

[0018] 2-3 parts of silica fume;

[0019] Among them, the total content of SiO2 and Al2O3 in the desulfurization ash is not less than 70%. The desulfurization ash is a finely ground desulfurization slag obtained by grinding the original slag in a ball mill for 39 minutes and then passing it through an 80um square hole sieve; the desulfurization ash is selected from one or two of CFB desulfurization ash, FGD desulfurization ash, pellet desulfurization ash, and circulating desulfurization ash.

[0020] More preferably, the steel slag powder is steel slag aggregate with a diameter of 0 to 2.36 mm;

[0021] Silica fume as filler, with a bulk density of 600kg / m 3 The average particle size is 0.15um, and the 45μm sieve residue is less than 5%.

[0022] Preferably, the cement is prepared by mixing 42.5 grade ordinary Portland cement and 42.5 grade rapid hardening sulphoaluminate cement in a mass ratio of 2:1;

[0023] The water is hard water. When the mixture is mixed, the moisture content of the desulfurized ash-steel slag powder is tested so as to adjust the amount of water in time. The moisture content of the desulfurized ash-steel slag powder is controlled at 50% to 60%.

[0024] Preferably, the admixtures are water reducers and styrene acrylic emulsion. The water reducer has the function of activating the early activity of desulfurized ash, and has the functions of early strength, thickening and water reduction. The specific technical standards are as follows:

[0025] ① Fineness: Specific surface area shall not be less than 300m 2 / kg, the sieve residue (0.08mm) shall not exceed 8%;

[0026] ②Compressive strength: 2h compressive strength is 1MPA; 24h compressive strength is 3MPA; 7 days compressive strength is 4.5MPA; 28d compressive strength is 4.5MPA;

[0027] ③ Determine the reasonable initial setting time, which should not exceed 30 minutes in principle;

[0028] ④ Determine the reasonable pumpable time of single slurry, which should not be less than 24 hours in principle;

[0029] The styrene acrylic emulsion used is type GK-102, which is a bluish milky white liquid with a solid content of 48%, a viscosity of 1000-4000 mPa / s, an average particle size of 100 nm, a minimum film-forming temperature of 16°C, residual monomers of 0.4%-0.6%, and a pH of 7-8.

[0030] The foaming agent is Magna GX-7# magnesite-specific foaming agent, which is a slightly yellow transparent neutral liquid with a foaming multiple of 30 to 35 times, a foaming stability time of more than 3 hours, a solid content of about 35%, and a dilution multiple of 50 times when used.

[0031] Preferably, the foam concrete preparation steps are as follows:

[0032] (1) Mix desulfurized ash, cement and water in proportion using a 400L or higher slurry pump and a horizontal concrete mixer for 3 minutes.

[0033] (2) Add admixture and continue mixing for 1 minute;

[0034] (3) After stirring evenly, the foam generated by the foaming agent and water through the foaming machine is added to the cement slurry;

[0035] (4) When the foam cement slurry is mixed with the desulfurized ash, an activator of 1% to 5% of the cement dosage is added to obtain a highly desulfurized ash-steel slag powder foam concrete and then form it.

[0036] A long-life roadbed widening section construction method, the method is specifically as follows:

[0037] S1. Clear the old roadbed and deal with surface potholes;

[0038] S2, impact rolling;

[0039] S3, brush the slope, excavate the steps at the junction of the roadbed and compact them;

[0040] S4. Filling from bottom to top with the foamed concrete as described above;

[0041] S5. Measure the strength after curing each layer.

[0042] Preferably, the old roadbed clearing and surface pothole treatment in step S1 are as follows:

[0043] S101. The surveying team shall accurately measure the position and elevation of the center piles and the roadbed slope footing according to the construction drawings and clearly mark them with white lime;

[0044] S102. Use excavators, loaders, and dump trucks to clean up organic soil, planting soil walls, and garbage within the red line area;

[0045] S103: After removing tree roots from the dry section of the line, temporary drainage and water retaining works must be constructed before clearing the surface.

[0046] S104: Surface water must be drained and drainage measures must be taken during the rainy season. In areas with abundant water, earthen cofferdams should be built to a height of approximately 1 meter. Once this is completed, tree root removal can be carried out.

[0047] For general paddy fields and dry land, the surface clearing thickness is calculated from 30cm below the original ground surface;

[0048] For forest land, wasteland and orchard land, the measurement shall be from 10cm below the original ground surface;

[0049] S105. After cleaning the site, ensure that there is no loose debris, loose soil or accumulated water on the base, and compact and level it.

[0050] Preferably, during the impact rolling of the roadbed base in step S2, the rolling speed is controlled to be 10 km / h to 15 km / h. For general road sections with a fill height of less than 4 m, only the base impact rolling construction is performed;

[0051] If the fill height is over 4m, use a heavy-duty impact roller to perform 20 passes of compaction. When the fill reaches the lower roadbed elevation, perform another 20 passes. The overall settlement after compaction is required to be less than 3cm. The pit base and edge should be free of loose ballast, loose soil, or accumulated water, and should be compacted and leveled. The foundation compaction degree before filling should be greater than 93%. The thickness of each layer of edge soil should be in accordance with the "Technical Specifications for Highway Roadbed Construction". The edge soil serves as a template for pouring cement desulfurization ash mixture.

[0052] When brushing the slope and excavating the steps at the junction of the roadbed and compacting them in step S3, the old roadbed slope is brushed from the inner side (50 cm) of the old roadbed slope shoulder at a slope rate of 1:1.5, and the brushed soil is transported to the waste soil site; before filling, 2m wide steps are dug along the old embankment slope, the width of the bottom step is not less than 2.5m, and each step is inclined 4% toward the inner side of the embankment.

[0053] Preferably, the high-doped desulfurized ash-steel slag powder foam concrete as described above is filled from bottom to top in step S4. During filling, the free-fall height of the mixture is generally less than 2m. If it is >2m, a diversion trough is used. To ensure the construction progress, an excavator is used to assist in paving. When the on-site temperature is lower than 5°C, the filling is stopped. When pouring, the pouring is layered. When the pouring height is the same as the height of the adjacent roadbed step, the pouring height is 1m as a unit. The pouring thickness is consistent with the height of the adjacent roadbed step, in units of 100cm, to ensure that after pouring, the top of the mixture is level with the step.

[0054] In step S5, each layer is cured for 2 to 3 days, and the next layer is poured after the natural strength is formed. During the curing process, if cracks appear on the surface of the mixture, the mixture is used to fill the cracks.

[0055] The foamed concrete and long-life roadbed widening section construction method of the present invention have the following advantages:

[0056] (1) The foamed concrete of the present invention has the characteristics of light weight, high strength and low compressibility. It exerts low lateral pressure on the new roadbed soil during backfilling, reducing the impact on the stability of the old roadbed during backfilling. The flow characteristics during construction can effectively ensure that the corners can be effectively filled. At the same time, its self-compacting property can effectively ensure the compactness of the widened roadbed.

[0057] (2) The foam concrete construction process of the present invention is easy to control and has a fast construction speed. During summer construction, the pouring height is generally 1 meter, and the next step can be carried out after curing for 2 to 3 days. The project cost is low, and desulfurization ash is an industrial waste material from thermal power plants, which is high-quality, low-cost, and easy to obtain in various places.

[0058] (3) Compared with the traditional fly ash used to widen the roadbed, the foamed concrete of the present invention has poor flexural properties, poor water stability, and some cracks on the surface of the mixture during the curing process.

[0059] (4) The present invention solves the problem of difficulty in widening the new and old silt roadbeds by solidifying the junction of the new and old soft soil roadbeds with highly mixed desulfurized ash-steel slag powder foam concrete. Based on sufficient reference to existing technical information, a method and construction process for solidifying the junction of the new and old soft soil roadbeds using highly mixed desulfurized ash-steel slag powder foam concrete is provided.

[0060] (5) The present invention combines desulfurized ash with foamed concrete, resulting in a road and bridge backfill material with low cost and multiple advantages. Desulfurized ash, when used as an admixture in concrete, can improve performance, save cement, enhance construction quality, and reduce material costs. The highly desulfurized ash-steel slag powder foamed concrete of the present invention is used to improve desulfurized ash backfill materials, and is particularly suitable for reinforcing the junction of new and old silt roadbeds, which are prone to significant settlement. This will reduce costs while increasing competitiveness in road and bridge subgrade backfill materials.

[0061] (6) The synergistic effect of the desulfurization ash and steel slag powder of the present invention greatly improves the compressive and tensile properties of the matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The present invention will be further described below with reference to the accompanying drawings.

[0063] Attachment Figure 1 Schematic diagram of the process for preparing foam concrete. DETAILED DESCRIPTION

[0064] The following is a detailed description of a foamed concrete and a long-life roadbed widening section construction method of the present invention with reference to the accompanying drawings and specific embodiments.

[0065] Example 1: CFB desulfurization ash

[0066] The weight ratios of the raw materials of the CFB desulfurization ash-steel slag powder in this embodiment are shown in Table 1:

[0067] Table 1 Weight ratio of each raw material of CFB desulfurization ash-steel slag powder

[0068]

[0069] The total content of SiO2 and Al2O3 in the CFB desulfurization ash in this embodiment is not less than 70%. The CFB desulfurization ash is a fine desulfurization slag obtained by grinding the original slag in a ball mill for 39 minutes and then passing it through an 80um square hole sieve.

[0070] The steel slag powder in this embodiment is steel slag aggregate with a diameter of 0 to 2.36 mm, and its properties are shown in Table 2, Table 3 and Table 4:

[0071] Table 2 Basic performance indicators of steel slag powder

[0072]

[0073] Table 3 Steel slag powder pass rate

[0074]

[0075] Table 4 Basic mechanical properties of steel slag powder

[0076]

[0077] The silica fume in this embodiment is used as filler with a bulk density of 600 kg / m 3 The average particle size is 0.15um, and the 45μm sieve residue is less than 5%. Carry out the mix ratio test and strictly control the consistency of the desulfurization ash. Use a mortar consistency meter to test it, and it is generally controlled within 13-15s. Strictly control the use of admixtures and adjust the solution to the appropriate concentration before adding it to the mix.

[0078] The performance comparison of CFB desulfurization ash-steel slag powder and single CFB desulfurization ash is shown in Table 45 below:

[0079] Table 5 Performance comparison of CFB desulfurization ash-steel slag powder and single CFB desulfurization ash

[0080]

[0081] Example 2: FGD desulfurization ash

[0082] The weight ratios of the raw materials of the FGD desulfurization ash-steel slag powder in this embodiment are shown in Table 6:

[0083] Table 6 Weight ratio of each raw material of FGD desulfurization ash-steel slag powder

[0084]

[0085]

[0086] In this embodiment FGD The total content of SiO2 and Al2O3 in desulfurization ash is not less than 75%, FGD Desulfurized ash is obtained by grinding the raw slag in a ball mill for 39 minutes and then passing it through an 80 μm square mesh sieve to obtain finely ground desulfurized slag. The steel slag powder in this embodiment is steel slag aggregate with a size of 0 to 2.36 mm. The properties are shown in Tables 7, 8, and 9:

[0087] Table 7 Basic performance indicators of steel slag powder

[0088]

[0089] Table 8 Steel slag powder pass rate

[0090]

[0091] Table 9 Basic mechanical properties of steel slag powder

[0092]

[0093] The silica fume in this embodiment is used as filler with a bulk density of 600 kg / m3 The average particle size is 0.15um, and the 45μm sieve residue is less than 5%. Carry out the mix ratio test and strictly control the consistency of the desulfurization ash. Use a mortar consistency meter to test it, and it is generally controlled within 13-15s. Strictly control the use of admixtures and adjust the solution to the appropriate concentration before adding it to the mix.

[0094] The performance comparison of FGD desulfurization ash-steel slag powder and single FGD desulfurization ash is shown in Table 10 below:

[0095] Table 10 Performance comparison of FGD desulfurization ash-steel slag powder and single FGD desulfurization ash

[0096]

[0097] Example 3: Pellet desulfurization ash-circulating desulfurization ash (wherein the weight ratio of pellet desulfurization ash to circulating desulfurization ash is 3:2)

[0098] The weight ratios of the raw materials of pellet desulfurization ash, circulating desulfurization ash, and steel slag powder in this embodiment are shown in Table 11:

[0099] Table 11 Weight ratio of each raw material of pellet desulfurization ash-circulating desulfurization ash-steel slag powder

[0100]

[0101] The total content of SiO2 and Al2O3 in the pellet desulfurization ash-circulating desulfurization ash desulfurization ash in this embodiment is not less than 85%. The pellet desulfurization ash-circulating desulfurization ash desulfurization ash is made by grinding the raw slag in a ball mill for 39 minutes and then passing it through an 80μm square hole sieve to obtain a ground desulfurization slag. The steel slag powder in this embodiment is steel slag aggregate with a size of 0-2.36mm. The properties are shown in Tables 12, 13 and 14:

[0102] Table 12 Basic performance indicators of steel slag powder

[0103]

[0104] Table 13 Steel slag powder pass rate

[0105]

[0106] Table 14 Basic mechanical properties of steel slag powder

[0107]

[0108] The silica fume in this embodiment is used as filler with a bulk density of 600 kg / m 3The average particle size is 0.15um, and the 45μm sieve residue is less than 5%. Perform mix ratio tests and strictly control the consistency of desulfurization ash. Use a mortar consistency meter to test, and generally control it within 13s to 15s. Strictly control the use of admixtures, and first adjust the solution to the appropriate concentration before adding it to the mix.

[0109] The performance comparison of desulfurization ash from pellet desulfurization ash-circulating desulfurization ash-steel slag powder and single pellet desulfurization ash-circulating desulfurization ash is shown in Table 15:

[0110] Table 15 Performance comparison of pellet desulfurization ash-circulating desulfurization ash-steel slag powder and single pellet desulfurization ash-circulating desulfurization ash

[0111]

[0112] Example 4: CFB desulfurization ash-circulating desulfurization ash (wherein the weight ratio of CFB desulfurization ash to circulating desulfurization ash is 1:1)

[0113] The weight ratios of the raw materials of CFB desulfurization ash, circulating desulfurization ash, and steel slag powder in this embodiment are shown in Table 16:

[0114] Table 16 Weight ratio of each raw material of CFB desulfurization ash-circulating desulfurization ash-steel slag powder

[0115]

[0116] The total SiO₂ and Al₂O₃ content of the CFB desulfurization ash / circulating desulfurization ash in this embodiment is no less than 82%. The CFB desulfurization ash / circulating desulfurization ash is ground desulfurization slag obtained by ball milling raw slag for 39 minutes and then passing it through an 80 μm square mesh sieve. The steel slag powder in this embodiment is steel slag aggregate with a diameter of 0 to 2.36 mm. The properties are shown in Tables 17, 18, and 19:

[0117] Table 17 Basic performance indicators of steel slag powder

[0118]

[0119] Table 18 Steel slag powder pass rate

[0120]

[0121] Table 19 Basic mechanical properties of steel slag powder

[0122]

[0123] The silica fume in this embodiment is used as filler with a bulk density of 600 kg / m 3The average particle size is 0.15um, and the 45μm sieve residue is less than 5%. Carry out mix ratio tests and strictly control the consistency of desulfurization ash. Use a mortar consistency meter to test it, and it is generally controlled within 13Ss~15s. Strictly control the use of admixtures, and they should be adjusted to a solution of appropriate concentration before adding it to the mix.

[0124] The performance comparison of CFB desulfurization ash-circulating desulfurization ash-steel slag powder and single CFB desulfurization ash-circulating desulfurization ash is shown in Table 20:

[0125] Table 20 Comparison of desulfurization ash performance between CFB desulfurization ash-circulating desulfurization ash-steel slag powder and single CFB desulfurization ash-circulating desulfurization ash

[0126]

[0127] Example 5:

[0128] As attached Figure 1 As shown, the preparation method of the foamed concrete of this embodiment is as follows:

[0129] (1) Mix desulfurized ash, cement and water in proportion using a 400L or higher slurry pump and a horizontal concrete mixer for 3 minutes.

[0130] (2) Add admixture and continue mixing for 1 minute;

[0131] (3) After stirring evenly, the foam generated by the foaming agent and water through the foaming machine is added to the cement slurry;

[0132] (4) When the foam cement slurry is mixed with the desulfurized ash, an activator of 1% to 5% of the cement dosage is added to obtain a highly desulfurized ash-steel slag powder foam concrete and then form it.

[0133] The cement in this embodiment is prepared by mixing 42.5 grade ordinary Portland cement and 42.5 grade rapid hardening sulphoaluminate cement in a mass ratio of 2:1.

[0134] In this embodiment, hard water is used. When mixing the mixture, the moisture content of the desulfurization ash-steel slag powder is tested so that the amount of water can be adjusted in time. The moisture content of the desulfurization ash-steel slag powder is controlled at 50% to 60%.

[0135] The admixtures in this embodiment are water reducer and styrene acrylic emulsion. The water reducer has the function of activating the early activity of desulfurized ash, and has the functions of early strength, thickening and water reduction. The specific technical standards are as follows:

[0136] ① Fineness: Specific surface area shall not be less than 300m 2 / kg, the sieve residue (0.08mm) shall not exceed 8%;

[0137] ② Compressive strength: The compressive strength after 2 hours is 1 MPA; the compressive strength after 24 hours is 3 MPA; the compressive strength after 7 days is 4.5 MPA; and the compressive strength after 28 days is 4.5 MPA, as shown in Table 21:

[0138] Table 21 Compressive strength standards of admixtures

[0139] time Strength (MPA) 2h 1 24h 3 7d 4.5 28d 4.5

[0140] ③ Determine the reasonable initial setting time, which should not exceed 30 minutes in principle;

[0141] ④ Determine the reasonable pumpable time of single slurry, which should not be less than 24 hours in principle;

[0142] The styrene acrylic emulsion used is GK-102 type, which has the appearance of a bluish milky white liquid, a solid content of 48%, a viscosity of 1000-4000 m Pa / s, an average particle size of 100 nm, a minimum film-forming temperature of 16°C, 0.4%-0.6% residual monomers, and a pH value of 7-8.

[0143] The foaming agent in this embodiment is Magnesium Jiatu GX-7# magnesia special foaming agent, which is a slightly yellow transparent neutral liquid with a foaming multiple of 30 to 35 times, a stable foaming time of more than 3 hours, a solid content of about 35%, and a dilution multiple of 50 times when used.

[0144] Example 6:

[0145] The weight proportions of the raw materials of high-mix desulfurization ash-steel slag powder foam concrete are shown in Table 22, Table 23, Table 24 and Table 25:

[0146] Table 22 Weight ratio of high-added CFB desulfurization ash-steel slag powder foam concrete

[0147]

[0148] Table 23 Weight ratio of high-mix FGD desulfurization ash-steel slag powder foam concrete

[0149]

[0150] Table 24 Weight ratio of highly mixed pellet desulfurization ash-circulating desulfurization ash-steel slag powder foam concrete

[0151]

[0152]

[0153] Table 25 Weight ratio of high-doped CFB desulfurization ash-circulating desulfurization ash-steel slag powder foam concrete

[0154]

[0155] The performance data of high-mix CFB desulfurization ash foam concrete, high-mix FGD desulfurization ash-steel slag foam concrete, high-mix pellet desulfurization ash-circulating desulfurization ash-steel slag foam concrete, high-mix CFB desulfurization ash-circulating desulfurization ash-steel slag foam concrete and ordinary foam concrete are shown in Table 26:

[0156] Table 26 Performance data comparison of high-doped desulfurized ash foam concrete and ordinary foam concrete

[0157]

[0158] Example 7:

[0159] A long-life roadbed widening section construction method in this embodiment is as follows:

[0160] S1. Clear the old roadbed and deal with surface potholes;

[0161] S2, impact rolling;

[0162] S3, brush the slope, excavate the steps at the junction of the roadbed and compact them;

[0163] S4, filling from bottom to top with the foamed concrete as in Examples 1 to 6;

[0164] S5. Measure the strength after curing each layer.

[0165] In step S1 of this embodiment, the old roadbed is cleared and the surface potholes are processed as follows:

[0166] S101. The surveying team shall accurately measure the position and elevation of the center piles and the roadbed slope footing according to the construction drawings and clearly mark them with white lime;

[0167] S102. Use excavators, loaders, and dump trucks to clean up organic soil, planting soil walls, and garbage within the red line area;

[0168] S103: After removing tree roots from the dry section of the line, temporary drainage and water retaining works must be constructed before clearing the surface.

[0169] S104: Surface water must be drained and drainage measures must be taken during the rainy season. In areas with abundant water, earthen cofferdams should be built to a height of approximately 1 meter. Once this is completed, tree root removal can be carried out.

[0170] For general paddy fields and dry land, the surface clearing thickness is calculated from 30cm below the original ground surface;

[0171] For forest land, wasteland and orchard land, the measurement shall be from 10cm below the original ground surface;

[0172] S105. After cleaning the site, ensure that there is no loose debris, loose soil or accumulated water on the base, and compact and level it.

[0173] In step S2 of this embodiment, when impact-rolling the roadbed base, the rolling speed is controlled to be 10 km / h to 15 km / h. For general road sections with a fill height of less than 4 m, only the base impact rolling construction is performed;

[0174] If the fill height is above 4m, use a heavy impact roller to carry out 20 times of compaction first, and when the filling reaches the lower roadbed bottom elevation, it is rolled again 20 times; the overall settlement is required to be less than 3cm after the rolling construction; the pit bottom and edge should be free of loose slag, loose soil, and accumulated water, and should be rammed and leveled. The foundation compaction degree before filling should be greater than 93%; the thickness of each layer of edge soil shall be implemented in accordance with the "Technical Specifications for Highway Roadbed Construction", and the edge soil shall serve as a template for pouring cement desulfurization ash mixture.

[0175] In step S3 of this embodiment, when brushing the slope and excavating the steps at the junction of the roadbed and compacting them, the old roadbed slope is brushed from the inner side (50 cm) of the old roadbed slope shoulder at a slope ratio of 1:1.5, and the brushed soil is transported to the spoil site; before filling, 2m wide steps are dug along the old embankment slope, the width of the bottom step is not less than 2.5m, and each step is inclined 4% toward the inner side of the embankment.

[0176] In step S4 of this embodiment, the foam concrete is filled from bottom to top as in Examples 1 to 6. During filling, the free fall height of the mixture is generally less than 2m. If it is greater than 2m, a diversion trough is used. To ensure the construction progress, an excavator is used to assist in paving. When the temperature on site is lower than 5°C, the filling is stopped. When pouring, the mixture is layered. When the pouring height is the same as the height of the adjacent roadbed step, the pouring height is 1m as a unit. The pouring thickness is consistent with the height of the adjacent roadbed step, in units of 100cm, to ensure that the top of the mixture is level with the step after pouring.

[0177] In step S5 of this embodiment, each layer is cured for 2 to 3 days, and the next layer is poured after the natural strength is formed. During the curing process, if cracks appear on the surface of the mixture, the mixture is used to fill the cracks.

[0178] On the basis of this embodiment, the filling height should be 1m as a unit, and the two sides should be poured symmetrically. After each pouring, it should be naturally dried for 2d to 3d. After the natural strength is formed and cracks are formed, the cracks should be grouted with 1:2 cement slurry before the next pouring is allowed. During the pouring process, the same plane must be maintained and no steep slope should be formed. After each pouring, a scraper can be used to manually trim the slope to 2%. The strength of the material must also be tested, and at least 2 groups of test pieces should be made every day during the construction process. Before constructing the sealing layer of ash soil, the core strength should be measured, and the standard is the same as the test piece strength (28d strength is greater than 0.6MPa). If the strength does not meet the requirements, continue to maintain it until it meets the requirements.

[0179] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A foamed concrete, characterized in that: The foamed concrete is mainly prepared from the following raw materials in the following weight ratios: Desulfurization ash-steel slag powder 200-400 parts; 4-9 parts of cement; 150-350 parts water; 0.6-1.5 parts of admixture; 1-2 parts of foaming agent; 0.5 to 1 part of activator.

2. The foamed concrete according to claim 1, characterized in that Desulfurization ash-steel slag powder is mainly prepared from the following raw materials in the following weight ratios: 85-90 parts of desulfurization ash; 8-12 parts of steel slag powder; 2-3 parts of silica fume; Among them, the total content of SiO2 and Al2O3 in the desulfurization ash is not less than 70%. The desulfurization ash is a finely ground desulfurization slag obtained by grinding the original slag in a ball mill for 39 minutes and then passing it through an 80um square hole sieve. The desulfurization ash is selected from one or two of CFB desulfurization ash, FGD desulfurization ash, pellet desulfurization ash, and circulating desulfurization ash.

3. The foamed concrete according to claim 2, characterized in that The steel slag powder is steel slag aggregate with a diameter of 0 to 2.36 mm; Silica fume as filler, with a bulk density of 600kg / m 3 The average particle size is 0.15um, and the 45μm sieve residue is less than 5%.

4. The foamed concrete according to claim 1, characterized in that The cement is prepared by mixing 42.5 grade ordinary Portland cement and 42.5 grade rapid hardening sulphoaluminate cement in a mass ratio of 2:1; The water is hard water. When the mixture is mixed, the moisture content of the desulfurized ash-steel slag powder is tested so as to adjust the amount of water in time. The moisture content of the desulfurized ash-steel slag powder is controlled at 50% to 60%.

5. The foamed concrete according to claim 1, characterized in that The admixtures used are water reducer and styrene acrylic emulsion. The water reducer has the function of activating the early activity of desulfurized ash, and has the functions of early strength, thickening and water reduction. The specific technical standards are as follows: ① Fineness: Specific surface area shall not be less than 300m 2 / kg, the sieve residue shall not exceed 8%; ②Compressive strength: 2h compressive strength is 1MPA; 24h compressive strength is 3MPA; 7 days compressive strength is 4.5MPA; 28d compressive strength is 4.5MPA; ③ Determine the reasonable initial setting time, which should not exceed 30 minutes in principle; ④ Determine the reasonable pumpable time of single slurry, which should not be less than 24 hours in principle; The styrene acrylic emulsion used is type GK-102, which is a bluish milky white liquid with a solid content of 48%, a viscosity of 1000-4000 mPa / s, an average particle size of 100 nm, a minimum film-forming temperature of 16°C, residual monomers of 0.4%-0.6%, and a pH of 7-8. The foaming agent is Magna GX-7# magnesite-specific foaming agent, which is a slightly yellow transparent neutral liquid with a foaming multiple of 30 to 35 times, a foaming stability time of more than 3 hours, a solid content of about 35%, and a dilution multiple of 50 times when used.

6. The foamed concrete according to claim 1, characterized in that The foam concrete preparation steps are as follows: (1) Mix desulfurized ash, cement and water in proportion using a 400L or higher slurry pump and a horizontal concrete mixer for 3 minutes. (2) Add admixture and continue mixing for 1 minute; (3) After stirring evenly, the foam generated by the foaming agent and water through the foaming machine is added to the cement slurry; (4) When the foam cement slurry is mixed with the desulfurized ash, an activator of 1% to 5% of the cement dosage is added to obtain a highly desulfurized ash-steel slag powder foam concrete and then form it.

7. A long-life roadbed widening section construction method, characterized in that: The method is as follows: S1. Clear the old roadbed and deal with surface potholes; S2, impact rolling; S3, brush the slope, excavate the steps at the junction of the roadbed and compact them; S4. Filling from bottom to top with the foamed concrete according to any one of claims 1 to 6; S5. Measure the strength after curing each layer.

8. The long-life roadbed widening section construction method according to claim 7, characterized in that: The old roadbed clearing and surface pothole treatment in step S1 are as follows: S101. The surveying team shall accurately measure the position and elevation of the center piles and the roadbed slope footing according to the construction drawings and clearly mark them with white lime; S102. Use excavators, loaders, and dump trucks to clean up organic soil, planting soil walls, and garbage within the red line area; S103: After removing tree roots from the dry section of the line, build temporary drainage and water retaining works before clearing the surface; S104: First, drain the surface water in the water-rich areas and prepare for drainage during the rainy season. Build a water-retaining earthen cofferdam in the water-rich areas, keeping the height to approximately 1 meter. After this is completed, proceed with the excavation of tree roots. For paddy fields and dry land, the surface clearing thickness is calculated from 30cm below the original ground surface; For forest land, wasteland and orchard land, the measurement shall be from 10cm below the original ground surface; S105. After cleaning the site, ensure that there is no loose debris, loose soil or accumulated water on the base, and compact and level it.

9. The long-life roadbed widening section construction method according to claim 7, characterized in that: During the impact rolling of the roadbed base in step S2, the rolling speed is 10km / h to 15km / h. For general road sections with a fill height of less than 4m, only the base impact rolling construction is required; If the fill height is above 4m, a heavy-duty impact roller shall be used to perform 20 passes of compaction. When the fill reaches the lower roadbed elevation, another 20 passes of compaction shall be performed. The overall settlement after compaction shall be less than 3cm. The pit base and edge should be free of loose ballast, loose soil, or accumulated water, and should be compacted and leveled. The compaction degree of the foundation before filling should be greater than 93%. The thickness of each layer of edge soil should be in accordance with the "Technical Specifications for Highway Roadbed Construction". The edge serves as a template for pouring cement desulfurization ash mixture. When brushing the slope and excavating the steps at the junction of the roadbed and compacting them in step S3, the old roadbed slope is brushed from the inner side of the old roadbed slope shoulder at a slope rate of 1:1.5, and the brushed soil is transported to the waste soil site; before filling, 2m wide steps are dug along the old embankment slope, with the bottom step width not less than 2.5m, and each step is inclined 4% toward the inner side of the embankment.

10. The long-life roadbed widening section construction method according to claim 7, characterized in that: In step S4, the foam concrete according to any one of claims 1 to 6 is filled from bottom to top. During filling, the free fall height of the mixture is less than 2m. If it is greater than 2m, a diversion trough is used; to ensure the construction progress, an excavator is used to assist in paving; when the on-site temperature is lower than 5°C, the filling is stopped; during pouring, the pouring is layered, and when the pouring height is the same as the height of the adjacent roadbed step, the pouring height is 1m as a unit; the pouring thickness is consistent with the height of the adjacent roadbed step, in units of 100cm, to ensure that after pouring, the top of the mixture is level with the step. In step S5, each layer is cured for 2 to 3 days, and the next layer is poured after the natural strength is formed. During the curing process, if cracks appear on the surface of the mixture, the mixture is used to fill the cracks.

Images