A new type of sea water and sea sand recycled concrete base and a construction method thereof

Abstract

This invention discloses a novel seawater and sea sand recycled concrete base course and its construction method, belonging to the field of transportation engineering. Its characteristics are as follows: the preparation material of the novel base course is a mixture composed of a curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures in a mass ratio ranging from 1~8:0.4~4.2:0.2~6.8:0.4~8.8:0~0.6; the sea sand is a continuously graded fine aggregate such as marine sand and gravel, coral fragments, and shell fragments; the recycled coarse aggregate is a continuously graded coarse aggregate such as waste coral; the curing agent consists of a slowly hydrated cementing component and a rapidly hydrated expansion component that reacts with chloride and sulfate ions in the seawater and sea sand to form expanding hydrates; based on the design strength value of the novel base course, specific compaction machinery, compaction rate, number of compaction passes, and constraint load value are selected; the curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures are mixed evenly in a certain proportion, spread, compacted using a compaction machine, and cured under constraint load for 7 days before the constraint is removed to obtain the novel seawater and sea sand recycled concrete base course.

Description

Technical Field

[0001] This invention relates to a novel base course of seawater sand recycled concrete and its construction method, belonging to the field of transportation engineering. Background Technology

[0002] my country has numerous islands, numbering approximately 11,000, with a total coastline of about 32,000 kilometers. The coastline and surrounding islands possess abundant resources such as seawater, sea sand, and discarded shells and corals. Currently, the base materials for infrastructure projects in coastal and island areas, including roads, airports, parking lots, sports fields, and large-scale storage yards, primarily use traditional building materials such as ordinary silicate cement, crushed stone, and gravel. However, the production of silicate cement generates significant carbon emissions, and the large-scale mining of crushed stone and gravel damages natural resources and the ecological environment. River sand and freshwater resources are increasingly scarce, while seawater, sea sand, and discarded shells and corals are abundant, readily available, and can replace freshwater and river sand as building materials. However, chloride and sulfate ions in seawater and sea sand often corrode silicate cement products. Currently, the main method for using sea sand as a building material is by washing it with freshwater, which wastes a large amount of freshwater and incurs enormous engineering workload and costs. Therefore, the efficient reuse of resources such as seawater and sea sand, and the development of a new type of low-carbon, environmentally friendly, and economical base layer, are of great value and significance for infrastructure construction such as road engineering, airport engineering, parking lots, sports fields, and large-area storage yards.

[0003] Based on this, the present invention proposes a novel base course of seawater sand recycled concrete and its construction method. Summary of the Invention

[0004] This invention proposes a novel seawater and sea sand recycled concrete base course and its construction method, aiming to solve the technical problem of efficient resource recycling of seawater, sea sand, and construction waste. At the same time, it achieves the technical effect of using industrial waste residue as a cementing material to completely replace silicate cement and improve the utilization efficiency of curing agents. It provides a low-carbon, environmentally friendly, economical, and durable new base course for infrastructure construction such as road engineering, airport engineering, parking lots, sports fields, and large-area storage yards in China, which can significantly save carbon emissions, building material consumption, and engineering costs of the base course.

[0005] This invention proposes a novel seawater sand recycled concrete base course and its construction method. Specifically, the materials used to prepare the novel seawater sand recycled concrete base course include: seawater, sea sand, recycled coarse aggregate, curing agent, and admixtures. The sea sand consists of continuously graded fine aggregates such as marine sand and gravel, coral fragments, and shell fragments, with a particle size range of 0.075~4.75mm. The shell fragments are shell fragments from marine mollusks. The recycled coarse aggregate consists of continuously graded coarse aggregates such as waste coral, with a particle size range of 4.75~25mm. The curing agent is composed of a cementing component and an expansion component. A material with a slow hydration rate is used as the cementing component of the curing agent, while a material that hydrates rapidly and forms expanding hydrates with chloride and sulfate ions in the seawater sand is used as the expansion component. The mass ratio of the cementing component to the expansion component in the curing agent is 35~85:1. 5~65; admixtures include, but are not limited to, water-reducing agents, pumping agents, air-entraining agents, waterproofing agents, rust inhibitors, antifreeze agents, etc.; the mass ratio range of curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures is 1~8:0.4~4.2:0~6.8:0~8.8:0~0.6; select specific compaction machinery, compaction rate, number of compaction passes, and constraint load value according to the strength design value of the new base course of seawater and sea sand recycled concrete; mix the curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures evenly according to the ratio, spread them, compact them with compaction machinery, and cure them under constraint load for 7 days before removing the constraint to obtain the new base course of seawater and sea sand recycled concrete; this invention can realize the efficient resource utilization of seawater and construction waste and the low-carbon preparation of the base course, significantly reducing the cost of base course engineering; the obtained new base course of seawater and sea sand recycled concrete has good load-bearing performance, water stability, and durability.

[0006] The specific construction process of the new type of seawater sand recycled concrete base layer described in this invention is as follows: First, based on the content of chloride ions and sulfate ions in seawater and sea sand and the design value of the 7-day unconfined compressive strength of the new base course of seawater and sea sand recycled concrete, the mass ratio of curing agent, seawater, sea sand, recycled coarse aggregate and admixture is determined. The material composition and proportion of the cementing component and expansion component in the curing agent are determined. The compaction machinery, compaction rate, number of compaction passes and constraint load are determined. Secondly, the curing agent, seawater, sea sand, recycled coarse aggregate, and admixture are mixed evenly in proportion, spread, and compacted using rolling machinery according to the set compaction rate and number of compaction passes. The restraint load is set on the surface of the compacted seawater and sea sand recycled concrete. After curing the seawater and sea sand recycled concrete under restraint conditions for 7 days, the restraint load is removed to obtain the new base layer of seawater and sea sand recycled concrete. Finally, the performance of the new base course made from recycled seawater and sea sand was tested.

[0007] The mechanical compaction rate range of the present invention is 1-8 km / h; the curing under constrained load refers to setting a constrained load on the surface of the recycled seawater sand concrete after compaction. The method of setting the constrained load includes, but is not limited to, laying a flexible geotextile on the surface of the compacted recycled seawater sand concrete and covering it with a soil load of equal thickness, or laying a sheet sandbag load of equal thickness on the surface of the compacted recycled seawater sand concrete.

[0008] The expansion component of this invention is a rapidly hydrating material, consisting of part 1 and part 2. Part 1 is a material that rapidly hydrates with chloride and sulfate ions in seawater and sea sand to generate expanded hydrates. The expanded hydrates generated by its hydration include, but are not limited to, hydrated calcium chloroaluminate and hydrated calcium sulfoaluminate. Part 2 is a material that rapidly hydrates itself to generate expanded hydrates. The expanded hydrates generated by its hydration include, but are not limited to, hydrated calcium sulfoaluminate. The mass ratio of part 1 and part 2 in the expansion component is 20-100:0-80, respectively.

[0009] Part 1 of the present invention includes, but is not limited to, a mixture composed of aluminum-containing waste residue, alkaline waste residue, etc. When a combination of aluminate cement and quicklime is used, the corresponding mass ratio of the two is in the range of 9~12:0-23.

[0010] Part 2 of the present invention includes, but is not limited to, a mixture composed of aluminum-containing waste residue, gypsum-based waste residue, sulfate waste residue, alkaline waste residue, etc. When a combination of aluminate cement, quicklime, and gypsum is used, the corresponding mass ratio of the three is in the range of 9~12:6-8:24~30.

[0011] The cementing component of this invention is a material with a slow hydration rate, and the cementitious hydrates produced by its hydration include, but are not limited to, hydrated calcium silicate. The cementing component is composed of cementing materials and activators, with the mass ratio of cementing materials and activators in the cementing component being 70~100:0~30, respectively. The cementing materials include, but are not limited to, one or more combinations of slag, copper slag, phosphorus slag, coal gangue, bottom ash, rice husk ash, kiln ash, etc. The activator is an alkaline activator, including, but not limited to, quicklime, hydrated lime, active magnesium oxide, sodium hydroxide, sodium silicate hydrate, etc., one or more combinations.

[0012] 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.

[0013] The expansion component described in this invention needs to be determined according to the content of chloride ions and sulfate ions in seawater and sea sand, as well as the chemical equation for the formation of expansion hydrates, and the specific proportion of each component material in the expansion component needs to be determined according to known calculation methods.

[0014] The curing agent described in this invention comprises industrial-grade materials, all of which have a specific surface area greater than 150 m². 2 / kg of powder.

[0015] The application scope of the new type of seawater sand recycled concrete base layer described in this invention includes, but is not limited to, road engineering, airport engineering, parking lots, sports fields, large-area storage yards, etc.

[0016] The advantages of this invention are: ①This invention uses seawater sand as a new type of base material, which can realize the resource utilization of seawater sand, and transform the chloride ions and sulfate ions in seawater sand from harmful to beneficial, thus saving a large amount of freshwater and river sand resources. ② The dense, high-strength seawater sand recycled concrete formed by this invention saves a lot of crushed stone resources, realizes the use of industrial waste residue as a cementing material to completely replace silicate series cement, and greatly saves carbon emissions. ③ The resulting seawater and sand recycled concrete new base course has good load-bearing capacity, water stability and durability, providing a low-carbon, environmentally friendly and economical new base course for infrastructure construction such as road engineering, airport engineering, parking lots, sports fields and large-area storage yards in my country. It saves the consumption and transportation of traditional building materials and reduces project costs. Detailed Implementation

[0017] The following detailed description of the new type of seawater sand recycled concrete base layer and its construction method according to the present invention is based on specific embodiments. However, the application forms and scope of the new type of seawater sand recycled concrete base layer provided by the present invention are not limited to this.

[0018] Example 1 A parking lot plans to use the new type of seawater sand recycled concrete base course and its construction method described in this invention. Tests show that the chloride and sulfate ion contents in seawater are 1.95% and 0.12%, respectively, while the chloride and sulfate ion contents in sea sand are 0.12% and 0.009%, respectively. The design value for the 7-day unconfined compressive strength of the new type of seawater sand recycled concrete base course is 5 MPa.

[0019] The recycled coarse aggregate was determined to be waste coral, and the admixture was a water-reducing agent. The mass ratio of the curing agent, seawater, sea sand, recycled coarse aggregate, and admixture was 4.0:2.3:5.4:6.5:0.01. The curing agent composition by weight was as follows: 7.0 parts copper slag and 3.0 parts active magnesium oxide as the cementing component; and 4.5 parts aluminum-containing waste slag, 3.7 parts alkaline waste slag, and 2.3 parts sulfate waste slag as the expansion component. A 13-ton vibratory roller was selected for compaction, with a compaction rate of 5 km / h, 4 passes, and a constraint load of 15 kPa. The curing agent, seawater, sea sand, recycled coarse aggregate, and admixture were mixed evenly according to the ratio, spread evenly, and compacted using the roller at the set compaction rate and number of passes. A constraint load was applied to the compacted seawater and sea sand recycled concrete surface. After curing the seawater and sea sand recycled concrete under constraint conditions for 7 days, the constraint load was removed to obtain a new type of seawater and sea sand recycled concrete base course. Tests have shown that the performance of the new type of seawater and sea sand recycled concrete base layer meets the requirements.

[0020] Example 2 A highway project plans to adopt the novel seawater and sea sand recycled concrete base course and its construction method described in this invention. Tests revealed that the chloride and sulfate ion contents in seawater are 2% and 0.1%, respectively, while the chloride and sulfate ion contents in sea sand are 0.1% and 0.01%, respectively. The design value for the 7-day unconfined compressive strength of the novel seawater and sea sand recycled concrete base course is 11 MPa.

[0021] The recycled coarse aggregate was determined to be waste coral, and the admixture was an antifreeze agent. The mass ratio of the curing agent, seawater, sea sand, recycled coarse aggregate, and admixture was 2.6:1.1:2.9:6.5:0.03. The curing agent composition by weight was as follows: cementing component: 9.0 parts slag, 1.0 part quicklime; expansion component: 2.9 parts aluminum-containing waste residue, 3.3 parts alkaline waste residue, and 5.8 parts gypsum-based waste residue. A 22-ton vibratory roller was selected for compaction, with a compaction rate of 2 km / h, 5 passes, and a constraint load of 23 kPa. The curing agent, seawater, sea sand, recycled coarse aggregate, and admixture were mixed evenly according to the ratio, spread evenly, and compacted using the roller at the set compaction rate and number of passes. A constraint load was applied to the compacted seawater and sea sand recycled concrete surface. After curing the seawater and sea sand recycled concrete under constraint conditions for 7 days, the constraint load was removed to obtain a new type of seawater and sea sand recycled concrete base course. Tests have shown that the performance of the new type of seawater and sea sand recycled concrete base layer meets the requirements.

[0022] Example 3 An airport project plans to use the new type of seawater and sea sand recycled concrete base course and its construction method described in this invention. Tests show that the chloride and sulfate ion contents in seawater are 1.98% and 0.09%, respectively, while the chloride and sulfate ion contents in sea sand are 0.13% and 0.008%, respectively. The design value for the 7-day unconfined compressive strength of the new type of seawater and sea sand recycled concrete base course is 15 MPa.

[0023] The recycled coarse aggregate was determined to be waste sand and gravel. The mass ratio of admixtures, pumping agents, curing agents, seawater, sea sand, recycled coarse aggregate, and admixtures was 5.6:2.6:6.3:8.5:0.12. The curing agent composition, calculated by weight, was as follows: cementing component: 6.0 parts rice husk ash, 3.5 parts kiln ash, 0.5 parts slaked lime; expansion component: 4.2 parts aluminum-containing waste residue, 3.1 parts alkaline waste residue, and 4.8 parts gypsum-based waste residue. The compaction equipment was determined to be a 32-ton vibratory roller with a compaction rate of 2 km / h, 6 compaction passes, and a constraint load of 35 kPa. The curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures were mixed evenly in proportion, spread, and compacted using a rolling mill at the set rolling speed and number of passes. A restraint load was then applied to the compacted seawater and sea sand recycled concrete surface. After curing the seawater and sea sand recycled concrete under restraint conditions for 7 days, the restraint load was removed, resulting in a new type of seawater and sea sand recycled concrete base course. Testing showed that the performance of this new base course met the requirements.

[0024] Example 4 A certain stockpile plans to adopt the new type of seawater sand recycled concrete base course and its construction method described in this invention. Tests show that the chloride and sulfate ion contents in seawater are 1.99% and 0.08%, respectively, while the chloride and sulfate ion contents in sea sand are 0.13% and 0.008%, respectively. The design value of the 7-day unconfined compressive strength of the new type of seawater sand recycled concrete base course is 6 MPa.

[0025] The recycled coarse aggregate was determined to be waste sand and gravel. The mass ratio of curing agent, seawater, sea sand, recycled coarse aggregate, and admixture was 6.2:3.3:6.9:8.8:0. The curing agent composition, calculated by weight, was as follows: cementing component: 5.5 parts slag, 3.5 parts rice husk ash, 1.0 part sodium hydroxide; expansion component: 12.5 parts aluminum-containing waste residue, 6.2 parts alkaline waste residue. An 18-ton vibratory roller was selected for compaction, with a compaction rate of 5 km / h, 4 passes, and a constraint load of 16 kPa. The curing agent, seawater, sea sand, recycled coarse aggregate, and admixture were mixed evenly according to the ratio, spread, and compacted using the roller at the set compaction rate and number of passes. A constraint load was applied to the compacted seawater and sea sand recycled concrete surface. After curing under constraint conditions for 7 days, the constraint load was removed to obtain a new type of seawater and sea sand recycled concrete base course. Tests have shown that the performance of the new type of seawater and sea sand recycled concrete base layer meets the requirements.

Claims

1. A novel base course for recycled seawater sand concrete and its construction method, characterized in that: The materials used to prepare the new base course of seawater and sea sand recycled concrete include: seawater, sea sand, recycled coarse aggregate, curing agent, and admixtures. The sea sand consists of continuously graded fine aggregates such as marine sand and gravel, coral fragments, and shell fragments, with a particle size range of 0.075~4.75mm. The shell fragments are shell fragments from marine mollusks. The recycled coarse aggregate consists of continuously graded coarse aggregates such as waste coral, with a particle size range of 4.75~25mm. The curing agent is composed of a cementing component and an expansion component. A material with a slow hydration rate is used as the cementing component, while a material that hydrates rapidly and forms expanding hydrates with chloride and sulfate ions in the seawater and sea sand is used as the expansion component. The mass ratio of the cementing component to the expansion component in the curing agent is 35~85:15~65, respectively. Admixtures include, but are not limited to, water-reducing agents. The additives include pumping agents, air-entraining agents, waterproofing agents, rust inhibitors, and antifreeze agents; the mass ratio of curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures is 1~8:0.4~4.2:0.2~6.8:0.4~8.8:0~0.6; based on the design strength value of the new base course of seawater and sea sand recycled concrete, select specific compaction machinery, compaction rate, number of compaction passes, and constraint load value; mix the curing agent, seawater, sea sand, recycled coarse aggregate, and admixtures evenly according to the ratio, spread them, compact them with compaction machinery, and cure them under constraint load for 7 days before removing the constraint to obtain the new base course of seawater and sea sand recycled concrete; this invention can realize the efficient resource utilization of seawater and sea sand and the low-carbon preparation of the base course, significantly reducing the cost of base course engineering; the obtained new base course of seawater and sea sand recycled concrete has good load-bearing performance, water stability, and durability; The specific construction method for the new type of seawater sand recycled concrete base course is as follows: First, based on the content of chloride ions and sulfate ions in seawater and sea sand and the design value of the 7-day unconfined compressive strength of the new base course of seawater and sea sand recycled concrete, the mass ratio of curing agent, seawater, sea sand, recycled coarse aggregate and admixture is determined. The material composition and proportion of the cementing component and expansion component in the curing agent are determined. The compaction machinery, compaction rate, number of compaction passes and constraint load are determined. Secondly, the curing agent, seawater, sea sand, recycled coarse aggregate, and admixture are mixed evenly in proportion, spread, and compacted using rolling machinery according to the set compaction rate and number of compaction passes. The restraint load is set on the surface of the compacted seawater and sea sand recycled concrete. After curing the seawater and sea sand recycled concrete under restraint conditions for 7 days, the restraint load is removed to obtain the new base layer of seawater and sea sand recycled concrete. Finally, the performance of the new base course made of recycled seawater and sea sand was tested.

2. The novel base course of seawater sand recycled concrete and its construction method according to claim 1, characterized in that: The expansion component is a rapidly hydrating material, consisting of part 1 and part 2. Part 1 is a material that rapidly hydrates with chloride and sulfate ions in seawater and sea sand to generate expanding hydrates, including but not limited to hydrated calcium chloroaluminate and hydrated calcium sulfoaluminate. Part 2 is a material that rapidly hydrates itself to generate expanding hydrates, including but not limited to hydrated calcium sulfoaluminate. The mass ratio of part 1 and part 2 in the expansion component is 20-100:0-80, respectively. Part 1 includes, but is not limited to, a mixture composed of aluminum-containing waste residue, alkaline waste residue, etc. When using a combination of aluminate cement and quicklime, the corresponding mass ratio range of the two is 9~12:0-23. Part 2 includes, but is not limited to, a mixture composed of aluminum-containing waste residue, gypsum waste residue, sulfate waste residue, alkaline waste residue, etc. When using a combination of aluminate cement, quicklime, and gypsum, the corresponding mass ratio range of the three is 9~12:6-8:24~30.

3. The novel base course of seawater sand recycled concrete and its construction method according to claim 1, characterized in that: The mechanical compaction rate ranges from 1 to 8 km / h; the curing under constrained load refers to setting a constrained load on the surface of the seawater sand recycled concrete after compaction. The methods for setting the constrained load include, but are not limited to, laying a flexible geotextile on the surface of the compacted seawater sand recycled concrete and covering it with a soil load of equal thickness, or laying sheet sandbags of equal thickness on the surface of the compacted seawater sand recycled concrete.

4. The novel base course of seawater sand recycled concrete and its construction method according to claim 1, characterized in that: The cementing component is a material with a slow hydration rate, and the cementing hydrates produced by its hydration include, but are not limited to, hydrated calcium silicate. The cementing component is composed of cementing materials and activators, with the mass ratio of cementing materials and activators in the cementing component being 70~100:0~30, respectively. The cementing materials include, but are not limited to, one or more combinations of slag, copper slag, phosphorus slag, coal gangue, bottom ash, rice husk ash, kiln ash, etc. The activator is an alkaline activator, including, but not limited to, one or more combinations of quicklime, hydrated lime, active magnesium oxide, sodium hydroxide, hydrated sodium silicate, etc.

5. The novel base course of seawater sand recycled concrete and its construction method according to claim 1, characterized in that: The cementing component requires the selection of an activator based on the designed hydration rate, and the specific ratio of cementing material and activator in the cementing component must be determined through preliminary experiments. The expansion component requires the specific ratio of each component to be determined according to known calculation methods based on the chloride and sulfate ion content in the seawater and sea sand, and the chemical equation for the formation of expanded hydrates. All components of the curing agent are industrial grade, and all components have a specific surface area greater than 150 m². 2 / kg of powder.

6. The novel base course of seawater sand recycled concrete and its construction method according to claim 1, characterized in that: The application scope of the new type of seawater sand recycled concrete base course includes, but is not limited to, road engineering, airport engineering, parking lots, sports fields, large-area storage yards, etc.