High-solidification backfill material for sealing slag pores with silt, and preparation method and application thereof

Abstract

The present invention provides a high-solidification backfill material with silt-sealed slag pores, as well as a preparation method and application thereof. The high-solidification backfill material comprises the following components by weight: 37-59 parts silt, 2-6 parts layered illite bentonite, 13-33 parts slag, 5-10 parts end-blocked isocyanate-based curing agent, and 19-27 parts water. The present invention uses high-strength slag of a certain particle size as the primary material, and uses slightly swollen silt to compensate for the slag's high porosity and water absorption. The end-blocked isocyanate curing agent is used as a cementing agent for curing, thereby producing a high-solidification backfill material with silt-sealed slag pores. The resulting high-solidification backfill material has high fluidity, self-compactness, and high curing properties. It not only meets the service requirements of high-load road and airport flight area backfill materials, but also recycles discarded construction waste, resulting in high economic value as well as social and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of road and airport geotechnical engineering, and in particular to a high-solidification backfill material based on silt to seal slag pore defects, and a preparation method and application thereof. Background Art

[0002] In recent years, the pace of airport renovation and expansion has accelerated across the country, leading to an increasing number of airfield pipeline corridors being installed. During the backfilling of trenches formed during excavation of foundation pits for underpasses, difficulties with compaction and insufficient compaction of the working surface of underpasses can significantly impact the mechanical properties of the upper concrete pavement structure. Due to the unique construction environment and complex structures, heavy machinery is often not available for backfilling underpass trenches. Instead, manual compaction is often performed using small-scale tools. This not only reduces construction efficiency but also fails to meet design expectations.

[0003] Backfilling the airfield with raw soil or ordinary solidified soil also struggles to meet the requirements. This is because aircraft loads on airfields are much greater than car loads, which in turn increases the stress transmitted to the subgrade. The soil is highly plastic and prone to plastic deformation. Under long-term, repeated loads and the effects of the natural environment, the foundation will experience excessive and differential settlement, resulting in excessive tensile stress at the bottom of the concrete slab and cracks, posing a safety hazard to aircraft takeoff and landing.

[0004] High-solidification backfill materials have high fluidity and strength, and are free of compaction and can backfill areas that heavy machinery cannot compact. At the same time, high solidification can increase sufficient strength to ensure the long-term stability of the foundation. However, due to the wide range of raw material sources for high-solidification backfill materials, their prices vary. Although aggregates can be used to prepare high-solidification materials with higher strength, the cost is expensive. There are also methods in the prior art that use waste slag to prepare high-solidification materials. For example, the Chinese invention patent with publication number CN112794682A discloses a premixed solidified soil mixed with high-silicon iron tailings and a preparation method thereof, wherein the raw materials of the solidified soil include lime, iron tailings powder, slag, water and grinding aids. Although the cost is reduced, the strength can only meet the use of ordinary road backfills and cannot meet the roadbed backfill requirements under the load of airport aircraft.

[0005] In addition, during the expansion of some airports, there is a large amount of construction waste generated by the demolition of residential houses, as well as a large amount of silt produced by foundation pit excavation.

[0006] In view of this, in order to respond to the core indicator of green in the four-type airports, based on the basic idea of ​​turning waste into treasure and being green and low-carbon, how to use construction waste mixed with silt to prepare a high-solidification backfill material that can be used for airports, and reduce the cost while ensuring the quality of the project, is a problem that needs to be solved urgently. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-solidification backfill material with silt-sealed construction slag pores, and a preparation method and application thereof. The material adopts construction slag with high strength and a certain particle size as the main material, and slightly swollen silt to make up for the defects of the construction slag having many pores and easy water absorption. At the same time, an end-blocked isocyanate curing agent is used as a gelling material for curing, thereby obtaining a high-solidification backfill material with silt-sealed construction slag pores. The obtained high-solidification backfill material has high fluidity, self-compactness and high curing performance. It can not only meet the service requirements of high-load roads and airport flight area backfill materials, but also recycles abandoned construction waste, and has high economic value as well as social and environmental benefits.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] One aspect of the present invention is to provide a high-solidification backfill material for sealing pores in construction waste with silt, comprising the following components in parts by weight: 37 to 59 parts of silt, 2 to 6 parts of layered illite bentonite, 13 to 33 parts of construction waste, 5 to 10 parts of an end-blocked isocyanate-based curing agent, and 19 to 27 parts of water; wherein the silt is micro-bentonite silt.

[0010] Optionally, the high-solidification backfill material comprises the following components in parts by weight: 40-54 parts of silt, 2-4 parts of layered illite bentonite, 15-30 parts of construction slag, 6-9 parts of end-blocked isocyanate-based curing agent, and 21-25 parts of water.

[0011] Optionally, the high-solidification backfill material includes the following components in parts by weight: 42 parts of silt, 2 parts of layered illite bentonite, 26 parts of construction slag, 8 parts of end-blocked isocyanate-based curing agent, and 24 parts of water.

[0012] Optionally, the weight percentage of sand particles in the silt is 30-35%, the weight percentage of silt particles is 65-70%, and the weight percentage of clay particles is 0-5%.

[0013] Optionally, the plastic limit index of the silt is 9.1 to 9.6, and the liquid limit index is 0.4 to 0.7.

[0014] Optionally, the compression modulus of the silt is 5.50-22.97 MPa, and the standard penetration number is 3.0-35.0 blows.

[0015] Optionally, the shear strength parameters of the silt are: cohesion of 11.0 to 45.0 KPa, and internal friction angle of 26.1 to 32.8°.

[0016] Optionally, the permeability coefficient k of the silt is 2.0E-04 to 3.5E-04 cm / s, and the gravity γ is 18.3 to 18.9 KN / m 3 .

[0017] Optionally, the silt can be natural silt in the site that meets the above indicators.

[0018] Optionally, the silt is mixed with silty clay in an amount less than or equal to 20% by weight.

[0019] Optionally, the plasticity index of the silty clay is 10.2 to 21.5, and the liquid index is 0.1 to 0.9.

[0020] Optionally, the silty clay has a compression modulus of 2.79 to 10.16 MPa and a standard penetration test number of 2.0 to 26.0 blows.

[0021] Optionally, the shear strength parameters of the silty clay are: cohesion of 22.0 to 44.0 KPa, and internal friction angle of 9.7 to 31.2°.

[0022] Optionally, the permeability coefficient k of the silty clay is 2.0E-04 to 3.5E-04 cm / s, and the gravity γ is 18.3 to 18.9 KN / m 3 .

[0023] Optionally, the silt may be replaced by silt sand, or may be a mixture of silt and silt sand or both.

[0024] Optionally, the silt sand has a compression modulus of 10.0 to 13.53 MPa and a standard penetration number of 3.0 to 43.0.

[0025] Optionally, the shear strength parameters of the silt sand are: cohesion of 7.5 KPa, and internal friction angle of 19.2°.

[0026] Optionally, the permeability coefficient k of the silt is 3.0E-02 cm / s, and the gravity γ is 18.9 KN / m 3 .

[0027] Optionally, the weight percentage of illite in the layered illite bentonite is 20-30%, and the weight percentage of montmorillonite is 7-12%.

[0028] Optionally, the layered illite bentonite has a plastic limit of 18.4% to 26.5% and a liquid limit of 43.6% to 61.3%.

[0029] Optionally, the layered illite bentonite has an expansion rate of 51.45% to 64.67% and a natural moisture content of 19.7% to 28.4%.

[0030] Optionally, the layered illite bentonite may be natural layered illite bentonite that meets the above indicators.

[0031] Optionally, the construction waste is brick-concrete construction waste or cement concrete construction waste.

[0032] Optionally, the particle size of the brick-concrete construction slag includes at least one of 0-5 mm, 5-10 mm, and 10-20 mm.

[0033] Optionally, the particle size of the brick-concrete slag is 0-5 mm, and its apparent density is not less than 2350 kg / m 3 , bulk density not less than 2350kg / m 3 , water absorption rate is not more than 5.63%, porosity is not more than 48%, and mud content is not more than 12.6%.

[0034] Optionally, the brick-concrete slag includes mixed slag of bricks and concrete, wherein the weight percentage of brick slag is 50-70% and the weight percentage of light matter is 0-1%.

[0035] Optionally, the construction slag can be recycled fine aggregate from brick-concrete construction waste within the site that meets the above indicators.

[0036] Optionally, the construction slag includes at least one of Class I construction waste recycled fine aggregate, Class II construction waste recycled fine aggregate, Class I construction waste recycled coarse aggregate, and Class II construction waste recycled coarse aggregate.

[0037] Optionally, the density of the end-blocked isocyanate-based curing agent is 1.23 g / cm 3 , viscosity is 620~700MPa·s, mass fraction is 85%, setting time is 50~1200s, and water retention is 45 times.

[0038] The fluidity of the high-solidification backfill material that seals the pores of the silt is controlled at 200-300 mm, the 7-day water immersion compressive strength is between 0.41 and 1.82 MPa, and the 28-day water immersion compressive strength is between 0.92 and 3.16 MPa, which can meet the strength requirements for the backfill of the flight area.

[0039] Another aspect of the present invention is to provide a preparation method of the high-solidification backfill material, comprising the following steps: S1, crushing and sieving silt, layered illite bentonite and construction slag, removing particles with a particle size of 4.75 mm or more, and obtaining a basic raw material for standby use; S2, weighing 37 to 59 parts of silt, 2 to 6 parts of layered illite bentonite, 13 to 33 parts of construction slag, 5 to 10 parts of end-blocked isocyanate-based curing agent and 19 to 27 parts of water by weight, adding the end-blocked isocyanate-based curing agent and water to the basic raw material comprising silt, layered illite bentonite and construction slag, and stirring thoroughly until the mixture is uniform, thereby obtaining the high-solidification backfill material.

[0040] Optionally, in step S1, during indoor testing, in order to control the amount of water used, the silt, layered illite bentonite, and construction slag with uneven moisture content can be cooled to a constant weight at a constant temperature of 105-110°C, and then the agglomerated soil lumps can be broken up with a wooden hammer and then sieved.

[0041] Optionally, in step S1 , a predetermined amount of silt may be cleaned first to remove plant roots and other organic impurities in the silt.

[0042] Optionally, in step S1 , the sieved silt, layered illite bentonite and construction slag may be placed in a ventilated place for air drying to obtain the basic raw material.

[0043] Optionally, in step S2, the construction slag and the blocked isocyanate-based curing agent may be first added to the silt and the layered illite bentonite and dry-mixed evenly, and then water may be added and mixed evenly.

[0044] Optionally, in step S2, a cement mortar mixer may be used for mixing; for example, a concrete mixer may be used for mixing in large-scale construction.

[0045] Another aspect of the present invention is to provide an application of the high-solidification backfill material in backfill projects of high-load roads and airport flight areas, especially airport flight area underpasses.

[0046] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects.

[0047] (1) The present invention uses natural silt, layered illite bentonite and construction slag in the site as basic raw materials, and evenly mixes the basic raw materials with a blocked isocyanate-based curing agent and water. At the same time, the dosage ratio of each component is regulated, and the synergistic effect between the components is utilized to prepare a high-solidification backfill material with silt-sealed construction slag pores. The obtained high-solidification backfill material is a backfill material with excellent performance. It not only has high fluidity, self-compactness, high curing properties, high strength, large compression modulus and uniform texture, but also can meet the service requirements of flight area backfill materials and has high economic value. It also has a certain early strength and can be backfilled with upper materials after 3 days, which can effectively shorten the construction period.

[0048] (2) The present invention can make full use of the abandoned soil generated during the excavation of the airport foundation pit and pipelines, as well as the construction waste such as houses demolished during the surrounding construction as raw materials, so as to maximize the use of on-site resources, obtain local materials, and process the raw materials, thereby greatly reducing the raw material and manufacturing costs.

[0049] (3) The present invention can utilize accumulated waste earth and construction waste as raw materials, which can not only effectively reduce the preparation cost of backfill materials and have high economic value; but also can recycle waste resources, in line with the principle of resource utilization and harmless utilization of waste earth, and has good environmental benefits and social impact.

[0050] (4) The preparation process of the high-solidification backfill material provided by the present invention is simple, and the construction only requires mixing with a concrete mixer, which can be mixed and cast on site, effectively speeding up the construction progress, shortening the construction period, saving labor costs, and greatly meeting the needs of on-site large-scale production and construction, and has high application value.

[0051] Compared with existing materials, the technical solution of the present invention has at least the following beneficial effects.

[0052] (1) The high-solidification backfill material prepared by the present invention is a new type of filling material formed by mixing soil, a curing agent and water. It has a short solidification time and has high density, strength and deformation resistance after solidification. It can solve the problem that the backfill soil and the backfill at the edge of the structure are not easy to be dense, and avoid the problem of excessive displacement of the retaining structure into the pit during construction and cracks in the upper structure due to uneven settlement.

[0053] (2) The selection of the high-solidification backfill material as the backfill material can not only effectively control the deformation of the deep foundation pit, but also the raw materials can use the abandoned soil excavated on site and the urban waste soil. The raw materials are widely available, which can reduce the consumption of soil and stone resources while shortening the construction period and reducing the overall cost. Therefore, the high-solidification backfill material has great application prospects in underground space backfill projects. It is a new material for sustainable development and has great significance for alleviating the pressure of urban abandoned soil and waste disposal and the construction of ecological civilization.

[0054] (3) The high-solidification backfill material prepared by the present invention not only has good self-compactness and high strength, and can effectively backfill areas subjected to high loads, but also has strength and rebound modulus that can meet the requirements of foundation bearing, and its long-term settlement is less than that of compacted silt (100% compaction degree).

[0055] (4) The present invention improves the working performance of the high-solidification backfill material by using construction slag. Since construction slag has a large particle size and a small specific surface area, and the water absorption rate of construction slag with a particle size of 0 to 5 mm is only 6.48%, its physical particle-water-electricity interaction system is weak. When the particles come into contact with water molecules, there is less water film formed, which has the effect of dispersing silt particles. Therefore, the addition of construction slag to replace part of the silt can reduce water consumption while maintaining the high fluidity of the high-solidification backfill material, thereby enabling the high-solidification backfill material to exhibit excellent working performance.

[0056] (5) The present invention improves the strength of the high-solidification backfill material and reduces its compression deformation by using slag. In addition, the application of slag of different particle sizes can improve the gradation of the material, so that the mixture forms an overall skeleton. According to the force chain theory, the coarse slag in the mixture acts as a strong force chain path in the force system, and the silt that closes the slag pores can also form more force chain paths to improve the strength, while the contact between fine particles of silt forms a weak force chain path. At the same time, a certain amount of cementitious material can make the skeleton stronger, so that the high-solidification backfill material forms a complete force system with a higher bearing capacity.

[0057] (6) The mineral components in the micro-bentonite used in the present invention swell when exposed to water and can fill and seal the pore defects between the slag particles. The reduced porosity of the mixture can enable the limited cementitious material to better bond the particles of each material to form a strong skeleton structure. At the same time, the layered illite bentonite incorporated into the micro-bentonite has a low montmorillonite content and a high illite content, and is weakly expansive. When the bentonite particles come into contact with water, the water molecules enter the illite crystal layers and expand slightly. Since it is a slight expansion, it will not impose excessive expansion stress on the skeleton structure, thereby effectively controlling the expansion scale. When it has a certain expansion scale, the expansive soil will contact the silt particles and the slag particles, further forming a new contact force chain. At this time, the skeleton changes from the original contact between the single coarse aggregate to the full contact between the large and small particles, forming a force chain network, thereby significantly improving the degree of solidification of the high-solidification backfill material, and making the high-solidification backfill material have higher strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 7d compression modulus curves of ordinary silt, comparative example, and backfill material obtained in Example;

[0059] Figure 2 7d compression deformation curves of ordinary silt, comparative example, and backfill materials obtained in Example;

[0060] Figure 3 7d porosity curves of the backfill materials obtained in the comparative example and the embodiment. DETAILED DESCRIPTION

[0061] To make the purpose, features and beneficial effects of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described below are only used to explain the present invention, rather than to limit the present invention.

[0062] Comparative Example 1 (non-micro-bent clay)

[0063] This comparative example provides a backfill material, wherein the silt is non-micro-expanded silt.

[0064] The preparation method of the backfill material comprises the following steps:

[0065] S11. During the indoor test, in order to control the water consumption, first, the silt (non-micro-bentonite silt), layered illite bentonite and construction slag with uneven moisture content were kept at a constant temperature of 105-110°C until they were constant weight; then, the agglomerated soil lumps were broken up with a wooden hammer and sieved to remove particles with a particle size of 4.75 mm or more, and set aside.

[0066] S12, weighing 3500g of silt, 1050g of construction slag, 410g of end-blocked isocyanate-based curing agent, and 1578g of water; before stirring, wipe and wet the stirring pot and stirring blade with a wet cloth, then add the silt, layered illite bentonite, and construction slag into the mixer, start the mixer, and dry mix for about 1 to 2 minutes at a stirring rate of 62±5r / min; then, mix the end-blocked isocyanate-based curing agent and water evenly and then slowly add it to the mixer and stir for no more than 2 minutes. After all the ingredients are added, continue stirring for about 2 minutes to obtain the backfill material.

[0067] Performance testing:

[0068] First, prepare a Φ100mm×200mm moist and smooth cylinder and place it on a work platform (metal or glass plate can be used), fill the cylinder with the mixture, slightly tamp it with a steel ruler, and smooth it out; slowly lift the cylinder vertically upward, and the lifting process takes about 2 to 4 seconds; immediately use a ruler to measure the collapse expansion diameter of the mixture. When measuring, two mutually perpendicular diameters need to be tested, and the experimental results are averaged; after the material mixing is completed, the entire process of filling, lifting, and measuring must be completed within 90 seconds, thereby measuring the fluidity of the backfill material.

[0069] The mixture was re-prepared according to the above method, and loaded into a cubic compressive strength test mold with a size of 70.7*70.7*70.7mm and a ring knife compression test mold with a size of Φ61.8×20mm (the casting was slightly higher than the test mold), and 3 parallel specimens; after being placed indoors for 1 hour, the surface was scraped flat; after pouring for 48 hours, the mold was removed and the specimens were placed in a standard curing box (20℃±1℃, 100% RH) and continued to cure until the age.

[0070] The compressive strength specimens need to be immersed in water for 1 day before reaching the age, and then tested with a pavement material strength comprehensive instrument at a loading rate of 1mm / min; the compression deformation under various pressures is tested with an oedometer; the 7d and 28d immersion compressive strength values ​​and the 7d compression modulus are calculated from this.

[0071] The fluidity test was conducted according to ASTM D6103, using a 100mm x 200mm cylinder. The unconfined compressive strength test mold was conducted according to the "Testing Procedure for Cement and Cement Concrete for Highway Engineering" JTG 3420-2020, and the test method was conducted according to the "Testing Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG E51-2009. The compression test was conducted according to the "Cement-Soil Mix Design Procedure" JGJ T233-2011.

[0072] Comparative Example 2 (non-micro-bent clay)

[0073] This comparative example provides a backfill material, wherein the silt is non-micro-expanded silt.

[0074] The preparation method of the backfill material is similar to that of Comparative Example 1, except that: 3500 g of silt, 1750 g of construction slag, 473 g of end-blocked isocyanate-based curing agent, and 1674 g of water are weighed.

[0075] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0076] Comparative Example 3 (non-micro-bent clay)

[0077] This comparative example provides a backfill material, wherein the silt is non-micro-expanded silt.

[0078] The preparation method of the backfill material is similar to that of Comparative Example 1, except that: 3500 g of silt, 2450 g of construction slag, 536 g of end-blocked isocyanate-based curing agent, and 1883 g of water are weighed.

[0079] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0080] Example 1:

[0081] This embodiment provides a high-solidification backfill material.

[0082] The preparation method of the high-solidification backfill material is similar to that of Comparative Example 1, except that: the silt uses micro-bentonite silt, and 3333g of silt, 167g of layered illite bentonite, 1050g of construction slag, 410g of end-blocked isocyanate-based curing agent, and 1621g of water are weighed.

[0083] Among them, the silt can be natural silt in the site that meets the following indicators:

[0084] The weight percentage of sand in silt is 30-35%, the weight percentage of silt is 65-70%, and the weight percentage of clay is 0-5%. The plastic limit index of silt is 9.1-9.6, and the liquid limit index is 0.4-0.7. The compression modulus of silt is 5.50-22.97 MPa, and the standard penetration number is 3.0-35.0 blows. The shear strength parameters of silt are: cohesion is 11.0-45.0 KPa, and the internal friction angle is 26.1-32.8°. The permeability coefficient k of silt is 2.0E-04-3.5E-04 cm / s, and the gravity γ is 18.3-18.9 KN / m 3 .

[0085] Furthermore, the silt may be mixed with silty clay in an amount of less than or equal to 20% by weight; and the plasticity index of the silty clay is 10.2 to 21.5, and the liquid index is 0.1 to 0.9; the compression modulus of the silty clay is 2.79 to 10.16 MPa, and the standard penetration number is 2.0 to 26.0 blows; the shear strength parameters of the silty clay are: cohesion is 22.0 to 44.0 KPa, and the internal friction angle is 9.7 to 31.2°; the permeability coefficient k of the silty clay is 2.0E-04 to 3.5E-04 cm / s, and the gravity γ is 18.3 to 18.9 KN / m 3 .

[0086] Furthermore, silt can be replaced by silt sand, or a mixture of silt and silt sand. The compression modulus of silt sand is 10.0-13.53 MPa, and the standard penetration number is 3.0-43.0. The shear strength parameters of silt sand are: cohesion is 7.5 KPa, internal friction angle is 19.2°, permeability coefficient k is 3.0E-02 cm / s, and gravity γ is 18.9 KN / m 3 .

[0087] Layered illite bentonite can be natural layered illite bentonite that meets the following indicators:

[0088] The weight percentage of illite in the layered illite bentonite is 20-30%, and the weight percentage of montmorillonite is 7-12%. The plastic limit of the layered illite bentonite is 18.4-26.5%, and the liquid limit is 43.6-61.3%. The expansion rate of the layered illite bentonite is 51.45-64.67%, and the natural water content is 19.7-28.4%.

[0089] The construction slag can be brick-concrete construction slag or cement concrete construction slag.

[0090] Furthermore, the construction slag can be made of recycled fine aggregates of brick-concrete construction waste that meets the following indicators: the particle size of the brick-concrete construction slag includes at least one of 0-5mm, 5-10mm, and 10-20mm; the particle size of the brick-concrete construction slag includes 0-5mm, and its apparent density is not less than 2350kg / m 3 , bulk density not less than 2350kg / m 3 , water absorption rate is not more than 5.63%, porosity is not more than 48%, and mud content is not more than 12.6%.

[0091] Furthermore, the brick-concrete construction slag includes mixed construction slag of bricks and concrete, wherein the weight percentage of brick slag is 50-70% and the weight percentage of light matter is 0-1%.

[0092] Furthermore, the construction slag includes at least one of Class I construction waste recycled fine aggregate, Class II construction waste recycled fine aggregate, Class I construction waste recycled coarse aggregate, and Class II construction waste recycled coarse aggregate.

[0093] The density of the blocked isocyanate curing agent is 1.23 g / cm 3 , viscosity is 620~700MPa·s, mass fraction is 85%, setting time is 50~1200s, and water retention is 45 times.

[0094] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0095] Example 2:

[0096] This embodiment provides a high-solidification backfill material.

[0097] The preparation method of the high-solidification backfill material is similar to that of Comparative Example 1, except that: the silt uses micro-bentonite silt, and 3333g of silt, 167g of layered illite bentonite, 1050g of construction slag, 592g of end-blocked isocyanate-based curing agent, and 1647g of water are weighed.

[0098] The selection of various raw materials is the same as in Example 1.

[0099] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0100] Example 3:

[0101] This embodiment provides a high-solidification backfill material.

[0102] The preparation method of the high-solidification backfill material is similar to that of Comparative Example 1, except that: the silt uses micro-bentonite silt, and 3333g of silt, 167g of layered illite bentonite, 1750g of construction slag, 473g of end-blocked isocyanate-based curing agent, and 1728g of water are weighed.

[0103] The selection of various raw materials is the same as in Example 1.

[0104] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0105] Example 4:

[0106] This embodiment provides a high-solidification backfill material.

[0107] The preparation method of the high-solidification backfill material is similar to that of Comparative Example 1, except that: the silt uses micro-bentonite silt, and 3333g of silt, 167g of layered illite bentonite, 1750g of construction slag, 683g of end-blocked isocyanate-based curing agent, and 1686g of water are weighed.

[0108] The selection of various raw materials is the same as in Example 1.

[0109] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0110] Example 5:

[0111] This embodiment provides a high-solidification backfill material.

[0112] The preparation method of the high-solidification backfill material is similar to that of Comparative Example 1, except that: the silt uses micro-bentonite silt, and 3333g of silt, 167g of layered illite bentonite, 2450g of construction slag, 536g of end-blocked isocyanate-based curing agent, and 1927g of water are weighed.

[0113] The selection of various raw materials is the same as in Example 1.

[0114] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0115] Example 6:

[0116] This embodiment provides a high-solidification backfill material.

[0117] The preparation method of the high-solidification backfill material is similar to that of Comparative Example 1, except that: the silt uses micro-bentonite silt, and 3333g of silt, 167g of layered illite bentonite, 2450g of construction slag, 774g of end-blocked isocyanate-based curing agent, and 1892g of water are weighed.

[0118] The selection of various raw materials is the same as in Example 1.

[0119] The subsequent preparation and testing of fluidity and strength specimens were the same as those in Comparative Example 1.

[0120] Component contents and performance test results of each embodiment and comparative example:

[0121] Table 1 Basic properties of high-curing backfill materials with different mix ratios

[0122]

[0123] It can be seen from Table 1 that, under the condition of controlling the same fluidity and the amount of the blocked isocyanate-based curing agent, the compressive strength of Examples 1 to 3 containing micro-bent clay is higher than that of Comparative Examples 1 to 3.

[0124] Table 2 Solidification performance test results of compacted silt, comparative examples and examples

[0125]

[0126]

[0127] According to Table 2 and Figure 1 It can be seen that the compression modulus of Example 2 and Example 3 at each level of pressure is greater than that of compacted silt (100% compaction degree), and the compression performance is better than that of compacted silt (100% compaction degree), showing high curing performance.

[0128] according to Figure 2 It can be seen that the total deformation curves of Examples 2 and 3 are generally below the deformation curve of compacted silt (100% compaction degree), that is, when the high-solidification backfill material provided by the present invention is used in foundation pit backfill, the compression deformation caused by the superstructure load and additional load is smaller than the compacted silt (100% compaction degree) used in the usual design, and therefore can meet the settlement deformation requirements of the foundation.

[0129] In contrast, the compression modulus of the backfill materials described in Comparative Examples 2 and 3 is smaller than that of compacted silt (100% compaction degree), the curing performance is poor, and the total deformation curve is generally above the deformation curve of the compacted silt (100% compaction degree) used in the usual design. The compression amount is large and does not meet the settlement deformation requirements of the foundation.

[0130] according to Figure 3 It can be seen that the porosity ratios of the high-curing backfill materials described in Examples 2 and 3 are respectively smaller than those of the backfill materials described in Comparative Examples 2 and 3, indicating that Examples 2 and 3 have fewer pores.

[0131] The above test results fully demonstrate that the use of micro-expanded silt in the present invention can effectively seal the void defects inside the construction slag, strengthen the material skeleton structure, and form a highly solidified material under the bonding of the cementitious material, so that the prepared highly solidified backfill material can obtain higher compressive strength and compression modulus while having good fluidity.

[0132] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in the present disclosure are intended to be illustrative, not limiting, unless otherwise stated. In specific implementations, the technical features of one or more dependent claims may be combined with the technical features of the independent claims, depending on actual needs and where technically feasible, and the technical features from the corresponding independent claims may be combined in any appropriate manner rather than solely through the specific combinations listed in the claims.

[0133] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A high-solidification backfill material for sealing slag pores with silt, characterized in that: The invention comprises the following components in parts by weight: 37-59 parts of silt, 2-6 parts of layered illite bentonite, 13-33 parts of construction waste, 5-10 parts of end-blocked isocyanate-based curing agent, and 19-27 parts of water; wherein the silt is slightly bentonite silt; the weight percentage of sand particles in the silt is 30-35%, the weight percentage of silt particles is 65-70%, and the weight percentage of clay particles is 0-5%; the plastic limit index of the silt is 9.1-9.6, the liquid limit index is 0.4-0.7; and the compression modulus of the silt is 5.50-22.

97. MPa, and the standard penetration number is 3.0-35.0 blows. The shear strength parameters of the silt are: cohesion is 11.0-45.0 kPa, the internal friction angle is 26.1-32.8 degrees; the permeability coefficient k of the silt is 2.0E-04-3.5E-04 cm / s, and the gravity γ is 18.3-18.9 kN / m 3 ; The preparation method of the high-solidification backfill material comprises the following steps: S1, crushing and sieving silt, layered illite bentonite, and construction slag to remove particles with a diameter of 4.75 mm or more to obtain basic raw materials for later use; S2, weighing 37 to 59 parts of silt, 2 to 6 parts of layered illite bentonite, 13 to 33 parts of construction slag, 5 to 10 parts of end-blocked isocyanate-based curing agent and 19 to 27 parts of water by weight, adding the end-blocked isocyanate-based curing agent and water to the basic raw materials comprising silt, layered illite bentonite and construction slag, and stirring thoroughly until the mixture is uniform, thereby obtaining the high-solidification backfill material.

2. The high-solidification backfill material according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 40-54 parts of silt, 2-4 parts of layered illite bentonite, 15-30 parts of construction slag, 6-9 parts of end-blocked isocyanate-based curing agent and 21-25 parts of water.

3. The high-curing backfill material according to claim 1 or 2, characterized in that: The silt is mixed with silty clay in an amount less than or equal to 20% by weight; or The silt is replaced by silt sand; or The silt is replaced by a mixture of silt and silt sand.

4. The high-solidification backfill material according to claim 1 or 2, characterized in that: The weight percentage of illite in the layered illite bentonite is 20-30%, and the weight percentage of montmorillonite is 7-12%.

5. The high-solidification backfill material according to claim 1 or 2, characterized in that: The construction slag includes brick-concrete construction slag; the particle size of the brick-concrete construction slag includes at least one of 0-5 mm, 5-10 mm, and 10-20 mm.

6. The high-solidification backfill material according to claim 1 or 2, characterized in that: The construction slag includes brick-concrete construction slag; the brick-concrete construction slag includes mixed construction slag of bricks and concrete, wherein the weight percentage of brick slag is 50-70% and the weight percentage of light matter is 0-1%.

7. The high-solidification backfill material according to claim 1 or 2, characterized in that: The construction slag includes at least one of Class I construction waste recycled fine aggregate, Class II construction waste recycled fine aggregate, Class I construction waste recycled coarse aggregate, and Class II construction waste recycled coarse aggregate.

8. A method for preparing a high-solidification backfill material according to any one of claims 1 to 7, characterized in that: The steps include: S1, crushing and sieving silt, layered illite bentonite, and construction slag to remove particles with a diameter of 4.75 mm or more to obtain basic raw materials for later use; S2, weighing 37 to 59 parts of silt, 2 to 6 parts of layered illite bentonite, 13 to 33 parts of construction slag, 5 to 10 parts of end-blocked isocyanate-based curing agent and 19 to 27 parts of water by weight, adding the end-blocked isocyanate-based curing agent and water to the basic raw materials comprising silt, layered illite bentonite and construction slag, and stirring thoroughly until the mixture is uniform, thereby obtaining the high-solidification backfill material.

9. Use of the high-solidification backfill material according to claim 8 in high-load road and airport flight area backfill projects.

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