A high-efficiency solidified soil base layer prepared by using the expansion energy of a solidifying agent and a constraint process

Abstract

The application discloses a kind of solidified soil base prepared by efficiently using curing agent expansion energy and constraint process, belongs to traffic engineering field.Its characteristics are: the preparation material of solidified soil base includes soil body, solidified agent, water;Slow hydration rate type material is used as the cementing component of solidified agent, and the cementing hydrate generated by hydration includes but is not limited to hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium silicate-aluminate;Fast hydration expansion type material is used as the expansion component of solidified agent, and the expansion hydrate generated by hydration includes but is not limited to ettringite, single-sulfur type calcium sulphoaluminate;According to the specific rolling mechanical, rolling speed, rolling number and constraint load value selected according to the property of solidified soil and the design value of solidified soil base strength, solidified agent is uniformly mixed with soil body near optimum moisture content with fixed water-cement ratio, and after compaction and densification using rolling mechanical and curing under constraint load for 7 days, constraint is removed to obtain solidified soil base with good bearing performance, water stability and durability.

Description

Technical Field

[0001] This invention relates to a solidified soil base course that utilizes the expansion energy of a curing agent and a constraint process to prepare a high-efficiency solidified soil base course, belonging to the field of transportation engineering. Background Technology

[0002] Developing a new type of low-carbon, environmentally friendly, and economical base layer for the efficient resource utilization of industrial solid waste such as tailings for use in road, airport, and parking lot construction projects will have significant engineering value and social significance.

[0003] Constrained solidification technology utilizes a solidifying agent containing an expansive component, organically combined with the constrained body. Under constrained conditions, the expansive component undergoes hydration and volume expansion, significantly reducing the porosity of the solidified soil and substantially increasing its strength. This also enables the resource utilization of the soil, as detailed in patents "Construction Method for Solidified Soil Piles" (ZL201610183422.6) and "Treatment Method for Contaminated Soil" (201610184702.9). However, constrained solidification technology still uses silicate-based cement as the main binding component, resulting in significant carbon emissions. Furthermore, the compressive stress on the core solidified soil generated within the constrained body persists throughout the entire service life, and the limited value of this stress restricts further improvement in the solidified soil's strength.

[0004] Based on this, the present invention proposes a solidified soil base course that efficiently utilizes the expansion energy of the curing agent and the constraint process. Summary of the Invention

[0005] This invention proposes a solidified soil base course that efficiently utilizes the expansion energy of the curing agent and a constrained process. This course can provide a low-carbon, environmentally friendly, and economical solidified soil base course for roads, airports, and other applications. The resulting solidified soil base course has the characteristics of high strength, good water stability, and good durability. By completely replacing silicate-based cement with industrial waste residue as the binding component, the utilization rate of solid waste such as tailings can be effectively improved. At the same time, the carbon reduction of the base course is achieved, and construction materials and engineering costs are saved.

[0006] This invention proposes a highly efficient method for preparing a solidified soil base course using the expansion energy of a curing agent and a constraint process. Specifically, the preparation materials for the solidified soil base course include soil, a curing agent, and water. The curing agent consists of a cementing component and an expansion component, with the mass ratio of the cementing component to the expansion component in the curing agent being 30-80:20-70, respectively. A material with a slow hydration rate is used as the cementing component of the curing agent, and the cementitious hydrates produced by its hydration include, but are not limited to, hydrated calcium silicate, hydrated calcium aluminate, and hydrated calcium aluminosilicate. Simultaneously, a material with a rapid hydration and expansion rate is used as the expansion component of the curing agent, and its hydration produces… The expanding hydrates include, but are not limited to, ettringite and monosulfide calcium sulfoaluminate. Based on the soil's properties and the design strength of the solidified soil base course, specific compaction machinery, compaction rate, number of compaction passes, and constraint load values ​​are selected. The water-cement ratio of the curing agent and the soil moisture content are controlled. The curing agent is mixed evenly with soil near its optimum moisture content at a fixed water-cement ratio, compacted using compaction machinery, and cured under constraint load for 7 days before the constraint is removed to obtain the solidified soil base course. The solidified soil base course has good bearing capacity, water stability, and durability, enabling the resource utilization of soil and reducing carbon emissions in the base course, while significantly saving base course costs.

[0007] The rolling rate range of the present invention is 1-6 km / h; the curing under the constraint load refers to setting a constraint load on the surface of the solidified soil after rolling. The method of setting the constraint load includes, but is not limited to, laying a flexible geotextile on the surface of the rolled solidified soil and covering the geotextile with a soil load of equal thickness, or laying a sheet sandbag load of equal thickness on the surface of the rolled solidified soil.

[0008] The cementing component of this invention is a material with a slow hydration rate. The cementing component is composed of cementing material and activator, with the mass ratio of cementing material and activator in the cementing component being 75~100:0~25, respectively. The cementing material includes, but is not limited to, one or more combinations of slag, copper slag, steel slag, phosphorus slag, fly ash, coal gangue, silica fume, red mud, bottom ash, rice husk ash, calcined ash, kiln ash, and desulfurization slag. The activator is an alkaline activator, including, but not limited to, one or more combinations of quicklime, hydrated lime, activated magnesium oxide, carbide slag, sodium hydroxide, and hydrated sodium silicate.

[0009] The expansion component of this invention is a rapid hydration expansion type material. The expansion component includes, but is not limited to, a mixture composed of aluminum-containing waste residue, alkaline waste residue, gypsum-based waste residue, or sulfate waste residue. The gypsum-based waste residue includes, but is not limited to, industrial waste gypsum such as phosphogypsum, titanium gypsum, flue gas desulfurization gypsum, organic gypsum, soda gypsum, salt gypsum, fluorogypsum, yellow gypsum, and boron gypsum.

[0010] The cementing component described in this invention requires the selection of an activator based on the hydration rate of the cementing component design, and the specific ratio of cementing material and activator in the cementing component is determined through preliminary experiments.

[0011] The expansion component described in this invention needs to be determined according to the chemical equation for the formation of expansion hydrates and the known calculation method to determine the specific proportion of each component material in the expansion component.

[0012] The curing agent described in this invention comprises industrial-grade materials, all of which have a specific surface area greater than 200 m². 2 / kg of powder; the dosage of the curing agent is 10~100% of the total dry weight of the curing agent and the soil.

[0013] The water referred to in this invention refers to drinking water that meets the "Standards for Drinking Water Quality" (GB 5749-2022). When non-drinking water is used, a comparative test should be conducted with drinking water.

[0014] The water-cement ratio control of the curing agent described in this invention refers to determining the water-cement ratio based on the composition of the curing agent to meet the minimum water consumption required for all curing agent materials to complete hydration.

[0015] The near-optimal moisture content mentioned in this invention refers to the soil moisture content. w The optimum moisture content obtained from the compaction test according to the "Standard for Geotechnical Testing Methods" (GB / T50123-2019) is compared with that obtained from the compaction test. satisfy .

[0016] The soil described in this invention includes, but is not limited to, sandy soil, silty soil, and clay soil; the application scope of the solidified soil base includes, but is not limited to, road engineering, airport engineering, parking lots, etc.

[0017] The specific construction process of the solidified soil base layer described in this invention is as follows: First, indoor tests were conducted on the soil to understand its physical properties. Second, based on the design value of the 7-day unconfined compressive strength of the solidified soil base, the material composition of the cementing and expansion components in the curing agent, the curing agent dosage, and the water-cement ratio were determined, as well as the compaction machinery, compaction rate, number of compaction passes, and constraint load values. Finally, the soil moisture content was controlled. w Make it satisfy The curing agent is mixed evenly with the soil near the optimum moisture content at a fixed water-cement ratio. The soil is then compacted using a rolling machine at a set rolling rate and number of rolling passes. A constraint load is set on the surface of the compacted soil. After curing the soil under constraint conditions for 7 days, the constraint load is removed to obtain the solidified soil base course. The performance of the solidified soil base course is then tested.

[0018] The advantages of this invention are as follows: This invention breaks through the technical bottleneck of the limited compressive stress value of the core solidified soil formed in the constrained body and lasting throughout the entire service life. The solidifying agent material used is all industrial waste residue, which completely replaces the traditional solidifying agent with high carbon emission. It provides a low-carbon, environmentally friendly and economical solidified soil base for roads, airports and other facilities. The solidified soil base has the characteristics of high strength, good water stability and good durability. Detailed Implementation

[0019] The following detailed description, using specific embodiments, illustrates the present invention's method for efficiently preparing a solidified soil base layer by utilizing the expansion energy of a curing agent and a constraint process. However, the application forms and scope of the solidified soil base layer provided by the present invention are not limited to this.

[0020] Example 1 A highway project plans to use a solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention. Indoor tests on the soil in the highway construction section revealed the following particle size distribution (mass fraction): sand 27%, silt 25%, clay 48%, and soil moisture content 25%. The solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention has a design value of 12 MPa for its 7-day unconfined compressive strength.

[0021] The composition of the curing agent, calculated by weight, is as follows: cementing component: 5.0 parts slag, 2.0 parts copper slag, 2.0 parts steel slag, 1.0 part quicklime; expansion component: 2.4 parts aluminum-containing waste residue, 1.2 parts alkaline waste residue, 5.6 parts phosphogypsum. The curing agent dosage is 30% of the total dry weight of the curing agent and soil, and the water-cement ratio of the curing agent is 0.50. The compaction machinery selected is a 20-ton vibratory roller, a compaction speed of 3 km / h, 4 compaction passes, and a constraint load of 22 kPa. The soil moisture content w is controlled to meet the following requirements. The curing agent was mixed evenly with the soil near its optimum moisture content at a fixed water-cement ratio. The mixture was then compacted using a rolling mill at the set rolling speed and number of passes. A constraint load was applied to the compacted soil surface. After curing the soil under constraint conditions for 7 days, the constraint load was removed to obtain the solidified soil base course. Testing showed that the performance of the solidified soil base course met the requirements.

[0022] Example 2 A certain Class I highway is proposed to use a solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention. Indoor tests on the soil in the construction section of the Class I highway revealed that the soil particle size distribution (mass fraction) was: sand 38%, silt 30%, clay 32%, and the soil moisture content was 36%. The solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention has a design value of 5 MPa for its 7-day unconfined compressive strength.

[0023] The composition of the curing agent, calculated by weight, is as follows: The cementing component consists of 6.0 parts fly ash, 2.2 parts desulfurization slag, and 1.8 parts carbide slag; the expansion component consists of 4.2 parts aluminum-containing waste residue, 2.6 parts alkaline waste residue, and 9.8 parts salt gypsum. The curing agent dosage is 15% of the total dry weight of the curing agent and the soil, and the water-cement ratio of the curing agent is 0.45. The compaction machinery selected is a 15-ton vibratory roller, a compaction rate of 4 km / h, 3 compaction passes, and a constraint load of 12 kPa. The soil moisture content w is controlled to meet the following requirements. The curing agent was mixed evenly with the soil near its optimum moisture content at a fixed water-cement ratio. The mixture was then compacted using a rolling mill at the set rolling speed and number of passes. A constraint load was applied to the compacted soil surface. After curing the soil under constraint conditions for 7 days, the constraint load was removed to obtain the solidified soil base course. Testing showed that the performance of the solidified soil base course met the requirements.

[0024] Example 3 A service area parking lot plans to use a solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention. Indoor tests on the surrounding soil revealed a particle size distribution (mass fraction) of 40% sand, 20% silt, and 40% clay, with a moisture content of 28%. The solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention has a design value of 3 MPa for its 7-day unconfined compressive strength.

[0025] The composition of the curing agent, calculated by weight, is as follows: The cementing component consists of 4.0 parts phosphorus slag, 2.0 parts red mud, 2.0 parts furnace bottom ash, and 2.0 parts activated magnesium oxide; the expanding component consists of 3.2 parts aluminum-containing waste residue, 2.3 parts alkaline waste residue, and 6.3 parts soda gypsum. The curing agent dosage is 10% of the total dry weight of the curing agent and soil, and the water-cement ratio of the curing agent is 0.43. The compaction machinery selected is a 12-ton vibratory roller, with a compaction speed of 6 km / h, 2 passes, and a constraint load of 8 kPa. The soil moisture content w is controlled to meet the following requirements. The curing agent was mixed evenly with the soil near its optimum moisture content at a fixed water-cement ratio. The mixture was then compacted using a rolling mill at the set rolling speed and number of passes. A constraint load was applied to the compacted soil surface. After curing the soil under constraint conditions for 7 days, the constraint load was removed to obtain the solidified soil base course. Testing showed that the performance of the solidified soil base course met the requirements.

[0026] Example 4 An airport project plans to use a solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention. Indoor tests on the soil surrounding the airport project revealed the following particle size distribution (mass fraction): sand 35%, silt 22%, clay 43%, and moisture content 42%. The solidified soil base course prepared using the efficient expansion energy and constraint process of the curing agent described in this invention has a design value of 10 MPa for its 7-day unconfined compressive strength.

[0027] The curing agent composition, calculated by weight, is as follows: The binding component consists of 3.0 parts rice husk ash, 3.0 parts silica fume, 1.5 parts kiln ash, and 2.5 parts hydrated sodium silicate; the expansion component consists of 5.6 parts aluminum-containing waste residue, 3.5 parts alkaline waste residue, and 8.8 parts sulfate waste residue. The curing agent dosage is 25% of the total dry weight of the curing agent and soil, and the water-cement ratio of the curing agent is 0.48. A 20-ton vibratory roller was selected for compaction, with a compaction speed of 2 km / h, 3 passes, and a constraint load of 18 kPa. The soil moisture content w was controlled to meet the following requirements. The curing agent was mixed evenly with the soil near its optimum moisture content at a fixed water-cement ratio. The mixture was then compacted using a rolling mill at the set rolling speed and number of passes. A constraint load was applied to the compacted soil surface. After curing the soil under constraint conditions for 7 days, the constraint load was removed to obtain the solidified soil base course. Testing showed that the performance of the solidified soil base course met the requirements.

Claims

1. A solidified soil base course that efficiently utilizes the expansion energy of a curing agent and a constraint process, characterized in that: The materials for preparing a solidified soil base course include soil, a hardener, and water. The hardener consists of a cementing component and an expansion component, with the mass ratio of the cementing component to the expansion component in the hardener being 30-80:20-70, respectively. When a material with a slow hydration rate is used as the cementing component of the hardener, the resulting cementitious hydrates include, but are not limited to, hydrated calcium silicate, hydrated calcium aluminate, etc. Alternatively, when a material with a rapid hydration and expansion rate is used as the expansion component of the hardener, the resulting expansion hydrates include, but are not limited to, ettringite, monosulfide, etc. Calcium aluminate; based on the soil's own properties and the design value of the solidified soil base strength, select specific compaction machinery, compaction rate, number of compaction passes, and constraint load value, control the water-cement ratio of the curing agent and the soil moisture content, mix the curing agent with the soil near the optimum moisture content at a fixed water-cement ratio, compact it with compaction machinery, and cure it under constraint load for 7 days before removing the constraint to obtain the solidified soil base; the solidified soil base has good bearing capacity, water stability, and durability, can realize the efficient resource utilization of soil and the reduction of carbon in the base, and significantly save the cost of the base; The range of the compaction rate is 1-6 km / h; the curing under the constraint load refers to setting a constraint load on the surface of the solidified soil after compaction. The method of setting the constraint load includes, but is not limited to, laying a flexible geotextile on the surface of the compacted solidified soil and covering the geotextile with a soil load of equal thickness, or laying a sheet sandbag load of equal thickness on the surface of the compacted solidified soil. The cementing component is composed of cementing materials and activators, with the mass ratio of cementing materials and activators in the cementing component being 75~100:0~25, respectively. The cementing materials include, but are not limited to, one or more combinations of slag, copper slag, steel slag, phosphorus slag, fly ash, coal gangue, silica fume, red mud, bottom ash, rice husk ash, calcined ash, kiln ash, and desulfurization slag. The activator is an alkaline activator, including, but not limited to, one or more combinations of quicklime, hydrated lime, activated magnesium oxide, carbide slag, sodium hydroxide, and hydrated sodium silicate. The expansion component includes, but is not limited to, a mixture composed of aluminum-containing waste residue, alkaline waste residue, gypsum-based waste residue, or sulfate-based waste residue. The gypsum-based waste residue includes, but is not limited to, industrial waste gypsum such as phosphogypsum, titanium gypsum, flue gas desulfurization gypsum, organic gypsum, soda gypsum, salt gypsum, fluorogypsum, yellow gypsum, and borosilicate gypsum.

2. The solidified soil base course prepared by efficiently utilizing the expansion energy of the curing agent and the constraint process according to claim 1, characterized in that: The cementing component requires the selection of an activator based on the designed hydration rate and the determination of the specific ratio of cementing material and activator in the cementing component through preliminary experiments; the expansion component requires the determination of the specific ratio of each component material in the expansion component based on the chemical equation for the formation of expanded hydrates and according to known calculation methods; the curing agent consists of industrial-grade materials, all with a specific surface area greater than 200 m². 2 / kg of powder; the dosage of the curing agent is 10~100% of the total dry weight of the curing agent and the soil.

3. The solidified soil base course prepared by efficiently utilizing the expansion energy of the curing agent and the constraint process according to claim 1, characterized in that: The water referred to is drinking water that meets the "Standards for Drinking Water Quality" (GB 5749-2022). When using non-drinking water, a comparative test with drinking water should be conducted. The control of the water-cement ratio of the curing agent refers to determining the water-cement ratio based on the composition of the curing agent to meet the minimum water requirement for complete hydration of all curing agent materials. The near-optimal moisture content refers to the soil moisture content. w The optimum moisture content obtained from the compaction test according to the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019) is compared with that obtained from the compaction test. satisfy .

4. The solidified soil base course prepared by efficiently utilizing the expansion energy of the curing agent and the constraint process according to claim 1, characterized in that: The soil includes, but is not limited to, sandy soil, silty soil, and clay soil; the application scope of the solidified soil base includes, but is not limited to, road engineering, airport engineering, parking lot, etc.

5. A solidified soil base course prepared by efficiently utilizing the expansion energy of a curing agent and a constraint process according to claim 1, characterized in that: The specific construction process for solidified soil base courses is as follows: ① Conduct indoor tests on the soil to understand its physical properties; ② Based on the design value of the 7-day unconfined compressive strength of the solidified soil base course, determine the material composition of the cementing and expansion components in the curing agent, the dosage of the curing agent, the water-cement ratio, and determine the compaction machinery, compaction rate, number of compaction passes, and constraint load value; ③ Control the soil moisture content. w Make it satisfy The curing agent is mixed evenly with the soil near the optimum moisture content at a fixed water-cement ratio. The soil is then compacted using a rolling machine at a set rolling rate and number of rolling passes. A constraint load is set on the surface of the compacted soil. After curing the soil under constraint conditions for 7 days, the constraint load is removed to obtain the solidified soil base course. The performance of the solidified soil base course is then tested.