A novel type of confined brine recycled concrete pile and its construction method

Abstract

This invention discloses a novel type of confined brine recycled concrete pile and its construction method, belonging to the field of transportation engineering. The materials used to prepare the novel pile include a confining pipe, brine, recycled aggregate, curing agent, and admixtures. The confining pipe is a corrosion-resistant pipe with good mechanical properties. The brine is high-salinity brine from salt lakes or seawater left over from salt production. The recycled aggregate is derived from continuously graded aggregate obtained by crushing and screening construction waste. The curing agent consists of a cementing component and an expansion component. The expansion component is a material that reacts with chloride and sulfate ions in the brine to form expanding hydrates. The expansion component includes, but is not limited to, a mixture composed of aluminate cement, quicklime, and gypsum in a mass ratio ranging from 9~12:0-23:0~30. The cementing component consists of slag and an alkali activator. The brine, recycled aggregate, curing agent, and admixtures are mixed evenly in proportion and filled into the confining pipe, which has been pre-embedded in the foundation, and then vibrated to compact the mixture, forming a novel type of confined brine recycled concrete pile with high strength and good durability.

Description

Technical Field

[0001] This invention relates to a novel type of confined brine recycled concrete pile and its construction method, belonging to the field of transportation engineering. Background Technology

[0002] Brine is a byproduct of salt production and is classified into salt lake brine or seawater brine based on its formation process. my country's annual brine production exceeds 2 × 10⁻⁶ tons. 7 m 3 Currently, most brine treatment methods involve direct or indirect discharge into nature, which not only harms the ecological environment but also wastes brine resources. Furthermore, my country generates a large amount of construction waste annually, which is often left untreated in the open or simply landfilled, similarly threatening the ecological environment and wasting resources. Developing brine and construction waste into pile building materials is an effective way to achieve resource recycling, but the main challenges are: ① The large amounts of chloride and sulfate ions in the brine cause salt corrosion to silicate cement products; ② During the crushing of construction waste to produce recycled aggregate, damage accumulation easily leads to the formation of numerous microcracks in the aggregate, resulting in reduced aggregate strength and increased porosity.

[0003] Constrained solidified soil piles utilize a solidifying agent containing an expansive component, organically combined with a confinement tube, to achieve a significant strengthening effect. Under confinement conditions, the hydration of the expansive component causes volume expansion, which greatly reduces the porosity of the solidified soil, thus giving it dense and high-strength characteristics. Specific details can be found in patents "Construction Method of Solidified Soil Piles" (ZL201610183422.6) and "Treatment Method of Contaminated Soil" (201610184702.9). However, constrained solidified soil piles primarily use silicate cement as a binder, resulting in substantial carbon emissions. Furthermore, the large amounts of chloride and sulfate ions in the brine cause salt corrosion to silicate cement products, making this technology unsuitable for direct use in preparing brine-recycled concrete.

[0004] Based on this, the present invention proposes a novel type of confined brine recycled concrete pile and its construction method. Summary of the Invention

[0005] This invention proposes a novel type of confined brine recycled concrete pile and its construction method, which enables the resource utilization of chloride and sulfate ions in the brine and transforms them from harmful to beneficial. It achieves high-efficiency resource recycling of construction waste and forms high-strength and dense brine recycled concrete. At the same time, it realizes the complete replacement of silicate series cement with industrial waste residue as a binding material. This invention can significantly reduce carbon emissions and significantly save on the consumption and transportation of traditional building materials, and reduce engineering costs. The resulting novel confined brine recycled concrete pile has high strength and good durability.

[0006] This invention proposes a novel type of confined brine recycled concrete pile and its construction method. Specifically, the materials used to prepare the confined brine recycled concrete pile include a confining pipe, brine, recycled coarse aggregate, recycled fine aggregate, curing agent, and admixtures. A corrosion-resistant pipe with good mechanical properties is used as the confining pipe. The brine is high-salinity brine from salt lakes or seawater left over from salt production. Both the recycled coarse and fine aggregates are derived from continuously graded aggregates obtained by crushing and screening construction waste. The particle size range of the recycled coarse aggregate is 4.75~25mm, and the particle size range of the recycled fine aggregate is 0.075~4.75mm. Construction waste includes, but is not limited to, waste concrete, waste sintered bricks, waste ceramic tiles, waste granite, and waste sand and gravel. The curing agent consists of an expansion component and a cementing component. A material that rapidly hydrates and reacts with chloride and sulfate ions in the brine to form expanding hydrates is used as the expansion component of the curing agent. The expanding hydrates produced by its hydration include, but are not limited to, hydrated calcium aluminochloride and hydrated aluminum sulfide. Calcium silicate, an expanding component including but not limited to a mixture of aluminate cement, quicklime, and gypsum in a mass ratio ranging from 9 to 12: 0 to 23: 0 to 30; a cementing component using a material with a slow hydration rate as a curing agent, the cementitious hydrates produced by hydration including but not limited to calcium silicate hydrate, the cementing component consisting of slag and an alkali activator; admixtures including but not limited to water-reducing agents, pumping agents, air-entraining agents, waterproofing agents, rust inhibitors, antifreeze agents, etc.; curing agents, brine, and recycled coarse aggregate. The mass ratio of recycled fine aggregate and admixture is 1~6.4:0.5~5.8:0.3~8.8:0.2~6.8:0~0.6. The curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture are mixed evenly and filled into the confined pipe and vibrated to form a new type of confined brine recycled concrete pile. This can significantly improve the utilization efficiency of the curing agent. Both brine recycled concrete and confined brine recycled concrete piles have the characteristics of high density, high strength, and good durability.

[0007] The construction process of the novel confined brine recycled concrete pile described in this invention is as follows: First, indoor tests were conducted on the brine to determine the content of chloride and sulfate ions. Second, based on the strength of the brine-recycled concrete and the strength of the pile body in the design of the constrained brine-recycled concrete new type of pile, the mass ratio of curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture was determined. The material composition and proportion of the expansion component and cementing component in the curing agent, as well as the material composition and dimensions of the constraining tube, were also determined. Finally, the constraining tube was pre-installed in the foundation, and the curing agent, brine, recycled aggregate, and admixture were mixed evenly and filled into the constraining tube and compacted to form the constrained brine-recycled concrete new type of pile. The performance of the constrained brine-recycled concrete new type of pile was tested when it reached the curing age.

[0008] The confinement tube material of the novel confined brine recycled concrete pile of the present invention includes, but is not limited to, rigid materials, flexible materials, and combinations of the two types of materials. The rigid materials include, but are not limited to, polyvinyl chloride pipes, polyethylene pipes, reinforced high-density polyethylene pipes, polybutene pipes, polypropylene pipes, fiber braided pultruded pipes, etc., and the flexible materials include, but are not limited to, basalt fiber composite fabrics, glass fiber composite fabrics, carbon fiber composite fabrics, etc.

[0009] The mass ratio of slag and alkali activator in the cementing component of the present invention is 70~100:0~30; the alkali activator includes, but is not limited to, one or more combinations of quicklime, hydrated lime, active magnesium oxide, sodium hydroxide, hydrated sodium silicate, etc.

[0010] The curing agent described in this invention consists entirely of industrial-grade materials, all of which have a specific surface area greater than 150 m². 2 / kg of powder.

[0011] In this invention, the mass ratio of the expansion component and the cementing component in the curing agent is 15~70:30~85, respectively. The specific proportion of each component in the expansion component needs to be determined according to the content of chloride ions and sulfate ions in the brine and the chemical equation for the formation of expansion hydrates by hydration, using a known calculation method. The specific proportion of the cementing component and the cementing material needs to be determined by selecting the activator according to the designed hydration rate of the cementing component and by conducting preliminary experiments.

[0012] The novel confined brine recycled concrete pile of the present invention is formed by drilling holes in the foundation using a known method.

[0013] The application scope of the novel confined brine recycled concrete piles described in this invention includes, but is not limited to, airport engineering, road engineering, and industrial building engineering.

[0014] The ratio of the ultimate constraint stress provided by the constraint tube of the present invention to the strength of the brine recycled concrete is greater than 0.3.

[0015] The advantages of this invention are: 1. This invention solves the problem of completely replacing silicate cement with industrial waste residue as a binding material, which saves a lot of building materials, significantly reduces engineering costs, and greatly reduces carbon emissions.

[0016] 2. This invention uses a material that rapidly hydrates and forms expanding hydrates with chloride and sulfate ions in the brine as the expanding component of the curing agent, thereby transforming chloride and sulfate ions from harmful to beneficial, and realizing the efficient resource reuse of the brine.

[0017] 3. This invention organically combines constraint conditions with brine, recycled aggregate, and curing agent to form high-strength, dense brine recycled concrete, realizing the efficient resource reuse of construction waste. The resulting constrained brine recycled concrete new pile has good bearing capacity and durability. Detailed Implementation

[0018] The present invention provides a novel confined brine recycled concrete pile and its construction method in further detail below with specific embodiments. However, the application and scope of the novel confined brine recycled concrete pile and its construction method provided by the present invention are not limited to this.

[0019] Example 1 The foundation of a highway near a salt-producing area in a certain salt lake is to be reinforced using a novel type of confined brine recycled concrete pile and its construction method described in this invention. Indoor tests on the brine revealed chloride and sulfate ion contents of 20.22% and 5.72%, respectively. The reinforcement treatment using the novel confined brine recycled concrete pile and its construction method described in this invention forms a composite foundation with confined brine recycled concrete piles. The designed pile length is 12m, pile diameter is 280mm, and the strength of the recycled brine concrete and the strength of the confined brine recycled concrete pile body are 23MPa and 52MPa, respectively.

[0020] The recycled coarse and fine aggregates were determined to be waste bricks, and the admixture was an antifreeze agent. The mass ratio of curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture was 2.5:1.3:4.2:1.8:0.06. The curing agent composition, calculated by weight, was as follows: expansion component: 6.5 parts aluminate cement, 5.4 parts quicklime; binder component: 8.0 parts slag, 2.0 parts quicklime. The constraint pipe was selected as a combination of UPVC pipe and BFRP fabric, specifically a 10mm thick UPVC pipe with 5 layers of BFRP fabric adhered to its outer surface. The constraint pipe was pre-inserted into the foundation. The curing agent, brine, recycled aggregate, and admixture were mixed evenly and filled into the constraint pipe, then vibrated to compact, forming a new type of constrained brine-recycled concrete pile. Testing showed that the strength of the brine-recycled concrete and the strength of the constrained brine-recycled concrete pile both met the requirements at 28 days.

[0021] Example 2 The foundation of an airport project near a salt-producing area in a certain salt lake is to be reinforced using a novel type of confined brine recycled concrete pile and its construction method described in this invention. Indoor tests on the brine revealed chloride and sulfate ion contents of 4.13% and 5.25%, respectively. The reinforcement treatment using the novel confined brine recycled concrete pile and its construction method described in this invention will form a composite foundation with confined brine recycled concrete piles. The designed pile length is 18m, pile diameter is 350mm, and the strength of the recycled brine concrete and the strength of the confined brine recycled concrete pile body are 18MPa and 45MPa, respectively.

[0022] The recycled coarse and fine aggregates were determined to be waste sand and gravel, and the admixture was a pumping agent. The mass ratio of curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture was 1.5:1.1:3.3:1.2:0.08. The curing agent composition, calculated by weight, was as follows: expansion component: 4.5 parts aluminate cement, 6.8 parts quicklime, and 2.2 parts gypsum; binder component: 7.0 parts slag and 3.0 parts activated magnesium oxide. A 7mm thick GFRP pipe was selected as the confinement tube. The confinement tube was pre-inserted into the foundation. The curing agent, brine, recycled aggregate, and admixture were mixed evenly and filled into the confinement tube, then vibrated to compact, forming a new type of confined brine-recycled concrete pile. Testing showed that the strength of the brine-recycled concrete and the strength of the confined brine-recycled concrete pile both met the requirements at 28 days.

[0023] Example 3 The foundation of a high-speed railway near a coastal salt-producing area is to be reinforced using a novel type of confined brine-recycled concrete pile and its construction method described in this invention. Indoor tests on the brine revealed chloride and sulfate ion contents of 13.03% and 8.62%, respectively. The novel brine-recycled concrete piles described in this invention will be used to reinforce the foundation, forming a composite foundation. The designed pile length is 20m, pile diameter is 450mm, and the strength of the brine-recycled concrete and the strength of the confined brine-recycled concrete pile body are 42MPa and 85MPa, respectively.

[0024] The recycled coarse and fine aggregates were determined to be waste granite, and the admixture was a water-reducing agent. The mass ratio of curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture was 4.2:2.3:5.3:3.2:0.16. The curing agent composition, calculated by weight, was as follows: expansion component: 3.6 parts aluminate cement, 2.8 parts quicklime, and 1.1 parts gypsum; binder component: 8.8 parts slag and 1.2 parts quicklime. A 15mm thick CFRP pipe was selected as the confinement pipe. The confinement pipe was pre-inserted into the foundation. The curing agent, brine, recycled aggregate, and admixture were mixed evenly and filled into the confinement pipe, then vibrated to compact, forming a new type of confined brine-recycled concrete pile. Testing showed that the strength of the brine-recycled concrete and the strength of the confined brine-recycled concrete pile both met the requirements at 28 days of age.

[0025] Example 4 The foundation of an industrial building project near a coastal salt-producing area is to be reinforced using a novel type of confined brine recycled concrete pile and its construction method described in this invention. Indoor tests on the brine revealed chloride and sulfate ion contents of 9.25% and 13.54%, respectively. The novel brine recycled concrete pile described in this invention will be used to reinforce the foundation, forming a composite foundation. The designed pile length is 12m, the pile diameter is 300mm, and the strength of the brine recycled concrete and the strength of the confined brine recycled concrete pile body are 32MPa and 66MPa, respectively.

[0026] The recycled coarse and fine aggregates were determined to be waste concrete, and the admixture was a water-reducing agent. The mass ratio of curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture was 2.2:1.3:4.0:2.8:0.15. The curing agent composition, calculated by weight, was as follows: expansion component: 6.8 parts aluminate cement, 8.4 parts quicklime, and 0.6 parts gypsum; binder component: 8.5 parts slag and 1.5 parts quicklime. A 12mm thick HDPE pipe was selected as the confinement pipe, with three layers of BFRP fabric adhered to its outer surface. The confinement pipe was pre-inserted into the foundation. The curing agent, brine, recycled aggregate, and admixture were mixed evenly and filled into the confinement pipe, then vibrated to compact, forming a new type of confined brine-recycled concrete pile. Testing showed that the strength of the brine-recycled concrete and the strength of the confined brine-recycled concrete pile both met the requirements at 28 days.

Claims

1. A novel type of confined brine recycled concrete pile and its construction method, characterized in that: The materials used in the preparation of the new type of reinforced concrete piles made from confined brine include confining pipes, brine, recycled coarse aggregate, recycled fine aggregate, curing agent, and admixtures. Corrosion-resistant pipes with good mechanical properties are used as confining pipes, and the materials for these pipes include, but are not limited to, rigid materials, flexible materials, and combinations of both. The brine is high-salinity brine from salt lakes or seawater left over from salt production. Both the recycled coarse and fine aggregates are derived from continuously graded aggregates obtained by crushing and screening construction waste. The particle size range of the recycled coarse aggregate is 4.75~25mm, and the particle size range of the recycled fine aggregate is 0.075~4.75mm. Construction waste includes, but is not limited to, waste concrete, waste sintered bricks, waste ceramic tiles, waste granite, and waste sand and gravel. The curing agent consists of an expansion component and a cementing component. The expansion component is a material that rapidly hydrates with chloride and sulfate ions in the brine to generate expanding hydrates. The expansion component includes, but is not limited to, aluminate cement, quicklime, and gypsum in a mass ratio of 9:

1. The mixture consists of a mixture of ~12:0-23:0~30, and the expanding hydrates produced by its hydration include, but are not limited to, hydrated calcium aluminochloride and hydrated calcium sulfoaluminate; the cementing component is a material with a slow hydration rate, and the cementing component consists of cementing materials and activators, and the cementing hydrates produced by its hydration include, but are not limited to, hydrated calcium silicate; admixtures include, but are not limited to, water-reducing agents, pumping agents, air-entraining agents, waterproofing agents, rust inhibitors, antifreeze agents, etc.; curing agents, brine, recycled coarse aggregate, recycled fine aggregate, and admixtures. The mass ratio of the agent is 1~6.4:0.5~5.8:0.3~8.8:0.2~6.8:0~0.

6. The curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture are mixed evenly, filled into the confined pipe, and vibrated to compact, forming a new type of confined brine recycled concrete pile. Both brine recycled concrete and confined brine recycled concrete piles have the characteristics of high density, high strength, and good durability. The specific construction method for the new type of confined brine recycled concrete pile is as follows: First, indoor tests were conducted on the brine to determine the content of chloride and sulfate ions in the brine. Secondly, based on the strength of the brine recycled concrete and the strength of the brine recycled concrete pile body in the design of the new type of pile, the mass ratio of curing agent, brine, recycled coarse aggregate, recycled fine aggregate, and admixture is determined, as well as the material composition and proportion of the expansion component and cementing component in the curing agent, and the material composition and dimensions of the constraint tube are determined. Finally, the confinement tube is implanted into the foundation in advance, and the curing agent, brine, recycled aggregate and admixture are mixed evenly and filled into the confinement tube and compacted to form a new type of confinement brine recycled concrete pile. When the curing age is reached, the performance of the new type of confinement brine recycled concrete pile is tested.

2. The novel confined brine recycled concrete pile and its construction method according to claim 1, characterized in that: The rigid materials include, but are not limited to, polyvinyl chloride pipes, polyethylene pipes, reinforced high-density polyethylene pipes, polybutene pipes, polypropylene pipes, and fiber braided pultruded pipes; the flexible materials include, but are not limited to, basalt fiber composite fabrics, glass fiber composite fabrics, and carbon fiber composite fabrics.

3. The novel confined brine recycled concrete pile and its construction method according to claim 1, characterized in that: The mass ratio of the expansion component and the cementing component in the curing agent is 15~70:30~85, respectively. The specific proportion of each component in the expansion component needs to be determined according to the content of chloride ions and sulfate ions in the brine and the chemical equation for the formation of expansion hydrates by hydration, using a known calculation method.

4. The novel confined brine recycled concrete pile and its construction method according to claim 1, characterized in that: The mass ratio of slag and alkali activator in the cementing component is 70~100:0~30; the alkali activator includes, but is not limited to, one or more combinations of quicklime, hydrated lime, active magnesium oxide, sodium hydroxide, hydrated sodium silicate, etc.; the alkali activator needs to be selected according to the hydration rate of the cementing component and the specific proportion of cementing component materials needs to be determined through preliminary experiments.

5. The novel confined brine recycled concrete pile and its construction method according to claim 1, characterized in that: The ratio of the ultimate constraint stress provided by the constraint tube to the strength of the brine-recycled concrete is greater than 0.3; the constituent materials of the curing agent are all industrial grade, and all curing agent materials have a specific surface area greater than 150 m². 2 / kg of powder.

6. The novel confined brine recycled concrete pile and its construction method according to claim 1, characterized in that: The novel constrained brine recycled concrete piles are formed by drilling holes in the foundation using known methods. The application scope of the novel constrained brine recycled concrete piles includes, but is not limited to, airport engineering, road engineering, and industrial building engineering.