Low-carbon concrete material containing solid waste and preparation method of low-carbon concrete material

Abstract

The invention discloses a low-carbon concrete material containing solid wastes and a preparation method of the low-carbon concrete material, and relates to the technical field of concrete materials. The concrete material is prepared from the following components in parts by weight: 520 to 660 parts of a cementing material, 1380 to 1650 parts of aggregate, 1.218 to 1.845 parts of an additive and 25 to 45 parts of other additives, specifically, the cementing material is prepared from 250 to 300 parts of cement, 120 to 150 parts of fly ash, 100 to 130 parts of slag powder, 20 to 30 parts of silica fume and 30 to 50 parts of metakaolin. A large amount of solid wastes are used in the formula, so that the pollution pressure on the environment is effectively reduced by utilizing the wastes; by reducing the use amount of the cement and replacing part of the cement with various solid wastes, the carbon emission in the concrete production process is effectively reduced, and the raw material cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete materials, in particular to a low-carbon concrete material containing solid waste and a preparation method thereof. Background Art

[0002] Concrete refers to a general term for engineering concrete materials composed of aggregates bonded together by cementitious materials. Concrete in Ningxia is severely impacted by environmental factors such as sulfate erosion and freeze-thaw damage. Furthermore, fly ash stockpiles in eastern Ningxia are substantial and their utilization rate is low. Furthermore, the high cement usage during production increases carbon emissions, placing a significant burden on the environment. To address these issues, the development of a low-carbon concrete material containing solid waste is necessary. Summary of the Invention

[0003] To solve the above problems, that is, to solve the problems raised by the above background technology, the present invention proposes a low-carbon concrete material containing solid waste and a preparation method thereof. The specific technical solutions are as follows: A low-carbon concrete material containing solid waste comprises 520-660 parts of cementitious materials, 1380-1650 parts of aggregates, 1.218-1.845 parts of admixtures, and 25-45 parts of other additives; specifically, the cementitious materials comprise 250-300 parts of cement, 120-150 parts of fly ash, 100-130 parts of slag powder, 20-30 parts of silica fume, and 30-50 parts of metakaolin.

[0004] Preferably, the aggregate specifically includes 800-900 parts of recycled coarse aggregate, 500-600 parts of recycled fine aggregate, 50-100 parts of waste glass particles, and 30-50 parts of waste rubber particles.

[0005] Preferably, the recycled coarse aggregate is demolished concrete with a particle size in the range of 5-31.5 mm, the recycled fine aggregate is demolished bricks with a particle size less than 5 mm, etc., and the waste rubber particles are tire processing waste.

[0006] Preferably, the admixture specifically includes 1.2-1.8 parts of high-efficiency water reducer, 0.01-0.03 parts of retarder, and 0.008-0.015 parts of air entraining agent.

[0007] Preferably, the high-efficiency water reducer is a polycarboxylic acid-based high-efficiency water reducer, the retarder is citric acid, tartaric acid and salts thereof, and the air entraining agent is a fatty alcohol sulfonate-based air entraining agent.

[0008] Preferably, the other additives specifically include 10-20 parts of nano-calcium carbonate and 15-25 parts of steel slag fibers, wherein the steel slag fibers are specifically processed from steelmaking waste slag with a length of 10-30 mm.

[0009] A method for preparing a low-carbon concrete material containing solid waste comprises the following steps: mixing the above-mentioned cementitious materials, stirring the mixture at a rotation speed of 1000-2000 r / min for 2-5 minutes, adding aggregate and water, stirring the mixture at a rotation speed of 1000-2000 r / min for 2-5 minutes, adding an admixture, stirring the mixture at a rotation speed of 1000-2000 r / min for 4-7 minutes, finally adding other additives, stirring the mixture at a rotation speed of 1000-2000 r / min for 4-7 minutes, placing the stirred mixture into a mold, compacting the mixture by shaking, and allowing the mixture to stand. After final setting, the surface of the mixture is covered with a wet cloth, and the mixture is allowed to stand for 1 day in an environment with a temperature of 20±2° C. and a relative humidity exceeding 50%, and then demolding the mixture. The demolded specimen is cured in an environment with a temperature of 23±2° C. and a relative humidity of 95±5% to obtain a concrete material.

[0010] The beneficial technical effects of the present invention are: A large amount of solid waste is used in the formula, and the utilization of these wastes effectively reduces the pollution pressure on the environment; by reducing the amount of cement and replacing part of the cement with a variety of solid waste, the carbon emissions in the concrete production process are effectively reduced and the raw material costs are reduced.

[0011] The addition of admixtures improves the fluidity of concrete, improves the workability, water retention and cohesion of concrete, makes the concrete more uniform, less prone to segregation and bleeding, and prolongs the setting time of concrete, ensuring that the concrete has enough time for transportation, pouring and vibration; the combined use of multiple cementitious materials can enable concrete to exert good strength properties at different stages, and the addition of waste rubber particles can effectively improve the toughness and impact resistance of concrete, enabling it to better withstand dynamic loads; the filling effect of silica fume and nano-calcium carbonate and the tiny bubbles introduced by the air entraining agent can effectively seal the pores inside the concrete, preventing moisture and organic matter from entering the concrete. The air-entraining agent can prevent the invasion of harmful chemicals, improve the impermeability of concrete, and thus extend the service life of concrete structures; the use of materials such as slag powder and fly ash can improve the chemical stability of concrete, making it more resistant to the erosion of chemicals such as sulfates and chlorides, and is suitable for building structures in harsh environmental conditions, such as coastal buildings and buildings near chemical facilities; the tiny bubbles introduced by the air-entraining agent form a buffer space inside the concrete. When the concrete is subjected to freeze-thaw cycles, the bubbles can relieve the pressure generated by the expansion of ice crystals, prevent the internal structure of the concrete from being damaged by freeze-thaw and resulting in strength reduction and surface spalling, and improve the freeze-thaw resistance of the concrete. DETAILED DESCRIPTION

[0012] The preferred embodiments of the present invention are described below. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0013] A low-carbon concrete material containing solid waste comprises 250-300 parts of cement, 120-150 parts of fly ash, 100-130 parts of slag powder, 20-30 parts of silica fume, 30-50 parts of metakaolin, 800-900 parts of demolished concrete with a particle size of 5-31.5 mm, 500-600 parts of demolished bricks with a particle size of less than 5 mm, 50-100 parts of waste glass particles, 30-50 parts of tire processing waste, 1.2-1.8 parts of a polycarboxylic acid-based high-efficiency water reducer, 0.01-0.03 parts of a retardant such as citric acid, tartaric acid and salts thereof, 0.008-0.015 parts of an air entraining agent such as a fatty alcohol sulfonate, 10-20 parts of nano-calcium carbonate, and 15-25 parts of steel slag fiber processed from steelmaking waste slag with a length of 10-30 mm.

[0014] The above-mentioned cementitious materials are mixed, stirred at a speed of 1000-2000 r / min for 2-5 minutes, and then aggregate and water are added, and stirred at a speed of 1000-2000 r / min for 2-5 minutes. Then, admixtures are added, and stirred at a speed of 1000-2000 r / min for 4-7 minutes. Finally, other additives are added, and stirred at a speed of 1000-2000 r / min for 4-7 minutes. The stirred mixture is placed in a mold, compacted by vibration, and allowed to stand. After final setting is completed, the surface is covered with a wet cloth, and the mixture is demolded after standing in an environment with a temperature of 20±2°C and a relative humidity of more than 50% for 1 day. The demolded specimen is cured in an environment with a temperature of 23±2°C and a relative humidity of 95±5% to obtain a concrete material. Example

[0015] During the preparation process, three groups of prismatic specimens with a size of 150mm*150mm*600mm were prepared. A 30mm deep incision was prefabricated at the mid-span position of the specimen, and the incision width was 3mm. The specimen was placed on the support of the universal testing machine with the incision located at the mid-span position. The displacement control method was adopted, and the loading rate was set to 0.05mm / min until the specimen was destroyed. The flexural strength performance of the concrete was calculated.

[0016] The experimental results are as follows: The average flexural strength of the three groups of specimens is 5.9 MPa. Example

[0017] During the preparation process, three groups of cubic specimens with a size of 100mm*100mm*100mm were prepared. After 28 days of curing, the three groups of specimens were taken out and the chloride ion migration coefficient of the specimens was tested according to the RCM method. The test results showed that the average chloride ion migration coefficient of the three groups of specimens was 2.2×10 -12 m 2 / s. Example

[0018] Prismatic specimens measuring 100mm x 100mm x 400mm were cured for 28 days before being removed from the specimens and placed in a testing machine with automated freeze-thaw cycles. The specimens were frozen at approximately -18°C for 5 hours and then thawed at approximately 5°C for 3 hours. After every 25 freeze-thaw cycles, the specimens were removed and their mass loss was measured. The experiment was terminated when the mass loss reached 5%.

[0019] The experimental results are as follows: The mass loss rate of the three specimens reached 5% when they were taken out for the 350th freeze-thaw cycle.

[0020] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, the various technical features described in the various embodiments may be combined in any manner as long as no structural conflicts exist. The present invention is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

[0021] Thus far, the technical solutions of the present invention have been described in conjunction with preferred embodiments. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is clearly not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A low-carbon concrete material containing solid waste, characterized in that: The concrete material includes 520-660 parts of cementitious materials, 1380-1650 parts of aggregates, 1.218-1.845 parts of admixtures, and 25-45 parts of other additives; specifically, the cementitious materials include 250-300 parts of cement, 120-150 parts of fly ash, 100-130 parts of slag powder, 20-30 parts of silica fume, and 30-50 parts of metakaolin.

2. The low-carbon concrete material containing solid waste according to claim 1, characterized in that: The aggregate specifically includes 800-900 parts of recycled coarse aggregate, 500-600 parts of recycled fine aggregate, 50-100 parts of waste glass particles, and 30-50 parts of waste rubber particles.

3. The low-carbon concrete material containing solid waste according to claim 2, characterized in that: The recycled coarse aggregate is demolished concrete with a particle size of 5-31.5 mm, the recycled fine aggregate is demolished bricks with a particle size of less than 5 mm, and the waste rubber particles are tire processing waste.

4. The low-carbon concrete material containing solid waste according to claim 1, characterized in that: The admixture specifically includes 1.2-1.8 parts of high-efficiency water reducing agent, 0.01-0.03 parts of retarder, and 0.008-0.015 parts of air entraining agent.

5. The low-carbon concrete material containing solid waste according to claim 4, characterized in that: The high-efficiency water reducing agent is specifically a polycarboxylic acid-based high-efficiency water reducing agent, the retarder is specifically a citric acid, tartaric acid and salt retarders, and the air entraining agent is specifically a fatty alcohol sulfonate-based air entraining agent.

6. The low-carbon concrete material containing solid waste according to claim 1, characterized in that: The other additives specifically include 10-20 parts of nano calcium carbonate and 15-25 parts of steel slag fibers, wherein the steel slag fibers are specifically processed from steelmaking waste slag with a length of 10-30 mm.

7. A method for preparing a low-carbon concrete material containing solid waste according to any one of claims 1 to 6, characterized in that: The above-mentioned cementitious materials are mixed, stirred at a speed of 1000-2000r / min for 2-5min, aggregate and water are added, stirred at a speed of 1000-2000r / min for 2-5min, admixtures are added, stirred at a speed of 1000-2000r / min for 4-7min, and other additives are added, stirred at a speed of 1000-2000r / min for 4-7min. The stirred mixture is loaded into a mold, compacted by vibration, and allowed to stand. After final setting, the surface is covered with a wet cloth, and the mixture is demolded after standing for 1d in an environment with a temperature of 20±2℃ and a relative humidity of more than 50%. The demolded specimen is cured in an environment with a temperature of 23±2℃ and a relative humidity of 95±5% to obtain a concrete material.