CN113896493A - Chlorine salt corrosion resistant green concrete and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of building materials, and relates to a technology for preparing chlorine salt corrosion resistant green concrete by using industrial solid wastes, which has the technical scheme key points that: the composite material comprises the following components in percentage by mass: 20-25% of powder; 25-35% of fine aggregate; 35-45% of coarse aggregate; 8-12% of water; 0.3-0.6% of water reducing agent and 0.6-1.5% of basalt fiber, wherein the sum of the mass percentages of the components is 100%; wherein: the powder comprises the following components in percentage by mass: 50-60% of slag, 15-20% of gypsum, 15-25% of zeolite powder, 8-10% of sodium carbonate and 5.0-10.0% of hydrotalcite, wherein the sum of the mass percentages of the above powder components is 100%; the concrete fully utilizes industrial solid waste, does not add Portland cement, reduces carbon dioxide emission, and is suitable for being applied to areas with high chlorine salt content.

Description

Chlorine salt corrosion resistant green concrete and preparation method thereof

Technical Field

The invention belongs to the field of building materials, and relates to a method for preparing chlorine salt corrosion resistant green concrete by using industrial solid wastes.

Background

The concrete with silicate cement as basic cementing material is the most used artificial building material in civil engineering field. After more than 200 years of engineering practice, the system standards of concrete production process, manufacturing equipment, quality control and the like are very mature. Because the concrete has stable performance and low cost in the engineering field and meets the requirements of human beings on engineering construction, the concrete becomes one of the most important building materials of civil engineering.

However, the portland cement has inherent disadvantages that firstly, the energy consumption is large, the raw materials used in the production process need to be heated at 1450 ℃, and a large amount of fuel and electric energy are consumed; second, limestone (CaCO) is calcined in the production process₃) Producing carbon dioxide (CO)₂) And the like, and seriously pollutes the environment. It is calculated that approximately 0.9 tons of carbon dioxide gas are produced per ton of portland cement produced. The yield of concrete in China in 2019 is 27.38 billion cubic meters, the average cement consumption per cubic meter of concrete is 0.3 ton, the total amount of generated carbon dioxide is about 8.2 billion tons, and the huge carbon dioxide emission brings serious greenhouse effect to the earth, causes serious damage to the environment and ecology and restricts the sustainable development of human beings. Concrete has become a large household of human social resource consumption and environmental pollution. The search for suitable cementing materials to replace portland cement, in whole or in part, thereby reducing the usage amount of portland cement, reducing environmental pollution and reducing carbon emission is one of the problems to be solved urgently in the field.

Comprehensive utilization of industrial solid wastes is an important component of new energy-saving and environment-friendly strategic industries. According to statistics, the generation amount of the bulk industrial solid waste in 2019 in China is about 36.98 hundred million tons, wherein metallurgical slag accounts for 17.85%, and industrial byproduct gypsum accounts for 6.11%. A large amount of solid waste is piled up for a long time to form a tailing pond, so that the tailing pond occupies the land, harmful substances in the waste seep into the underground along with rainwater and snow water to cause environmental pollution, and the existence of the tailing pond seriously threatens the lives and properties of people around and forms an unstable factor to the society.

Chloride ions are the most dangerous corrosion medium in the service environment of the reinforced concrete structure. The source of chloride ions in the concrete is that sea wind, sea sand and sea fog in coastal areas all contain rich chloride ions; secondly, in northern areas of China, in winter snowing climate, deicing salt is sprayed on the road surface and the bridge for ensuring smooth traffic, and the deicing salt contains a large amount of chloride compounds; thirdly, in northwest and southwest China, a large amount of salt lakes and saline-alkali soil are available, and a large amount of abundant chlorine salt compounds are contained. The chloride salt causes corrosion and expansion of the steel bars in the concrete, cracks are generated, the service life of a building is influenced, and the engineering structure is seriously cracked or even damaged. The prepared concrete for resisting the corrosion of the chloride salt can effectively protect structural members, not only improve the durability and the safety of buildings, but also obtain economic benefits and protect the ecological environment.

Wuzhongwei academicians think that the green concrete should have three characteristics, namely, the industrial solid waste is used, the consumption of the portland cement is reduced, and the discharge of the solid waste is reduced; secondly, the green concrete has excellent mechanical property and durability; and thirdly, the device can be continuously used, low carbon emission is realized, and the environment is not damaged after the service life is finished.

Patent application publication No. CN 113045272A "Green and Environment-friendly concrete and preparation method thereof", discloses a mixture ratio of the Green and Environment-friendly concrete, and the mass parts of the components are: 265 portions of cementing material and 285 portions; 900 portions of coarse aggregate and 1100 portions of coarse aggregate; 35-35 parts of nano silicon carbide; 25-30 parts of potassium borate; 20-25 parts of calcium chloride; water 160 and 175; wherein the cementing material adopts 105 parts of cement 100, 75-85 parts of mineral powder and 90-95 parts of fly ash.

Patent application publication No. CN 112408927A "A chemical foaming low-density alkali slag foam concrete and preparation method" discloses an alkali slag foam concrete and preparation method, the technical scheme main points are: the weight percentage is composed of the following components: 56-58% of slag; 16-20% of water glass and 2-4% of sodium hydroxide; 1-2% of a chemical foaming agent; 0.057 to 0.082 percent of foam stabilizer; 2 to 18 percent of water; 1-1.2% of surfactant.

The currently adopted green concrete manufacturing technology utilizes solid waste on one hand, and adopts alkali-activated cementing materials on the other hand, so that the use of portland cement is reduced or even avoided. Because the amount of concrete used is huge, the emission of carbon dioxide and the environmental pollution caused by the concrete are also serious, so that more advanced technologies and methods are needed to reduce the environmental pollution and the greenhouse effect caused by the concrete production process; meanwhile, with the deep development of engineering construction, the corrosion of chloride in severe and complex engineering environments such as ocean engineering is inevitable in concrete engineering, and technical measures must be taken to endow concrete with more special properties to deal with severe service environments and ensure the safety and reliability of construction engineering.

Disclosure of Invention

In order to overcome the defects of the current green concrete manufacturing technology, the invention provides the green concrete for effectively utilizing industrial solid wastes to prevent chloride corrosion.

The technical purpose of the invention is realized by the following technical scheme:

the first aspect provides a chlorine salt corrosion resistant green concrete which comprises the following components in percentage by mass:

20-25% of powder; 25-35% of fine aggregate; 35-45% of coarse aggregate; 8-12% of water; 0.3-0.6% of water reducing agent and 0.6-1.5% of basalt fiber.

The sum of the mass percentages of the components is 100 percent.

Preferably, the powder material comprises the following components in percentage by mass:

50-60% of slag, 15-20% of gypsum, 15-25% of zeolite powder, 8-10% of sodium carbonate and 5.0-10% of hydrotalcite, wherein the sum of the mass percentages of the above powder components is 100%.

Preferably, the slag is water-quenched blast furnace slag, and the specific surface area of the slag is 450-600 m²Between/kg.

Preferably, the gypsum is dihydrate desulfurized gypsum with the molecular formula of CaSO₄‧2H₂O, the specific surface area is 400-500 m²Between/kg.

Preferably, the zeolite powder is natural zeolite powder, and the specific surface area is 450-550 m²Between/kg.

Preferably, the sodium carbonate of the invention is commercially pure.

Preferably, the hydrotalcite is magnesium-aluminum hydrotalcite with the molecular formula of Mg₂AI(OH)₆CI‧nH₂O。

Preferably, the fine aggregate is machine-made sand, and the fineness modulus is between 2.6 and 2.8.

Preferably, the coarse aggregate is crushed stone, and the particle size is 5-20 mm.

Preferably, the water of the present invention is locally drinkable tap water.

Preferably, the water reducing agent is a solid polycarboxylic acid high-efficiency water reducing agent.

Preferably, the basalt fiber provided by the invention has the diameter of 5-15 micrometers, the length of 6-10 millimeters and the tensile strength of 2600-3000 MPa.

In a second aspect, there is provided a method for preparing a chloride salt corrosion resistant green concrete according to any one of the first aspect, comprising the steps of:

s1: drying the hydrotalcite, heating to 500-;

s2: firstly putting the coarse aggregate into a stirrer, adding slag, gypsum, zeolite powder, roasted hydrotalcite and a polycarboxylic acid water reducing agent, then putting the fine aggregate, adding water with the total water consumption of 70% containing a sodium carbonate solution, stirring for 150 seconds, adding basalt fiber and the rest 30% of water, and stirring for 120-150 seconds;

s3: and pouring the stirred mixture into a mould, curing for 28 days under standard conditions, and demoulding to obtain the concrete.

Preferably, the preparation of the sodium carbonate solution is as follows: slowly pouring the sodium carbonate solid into a proper amount of water, stirring by using a glass rod while pouring, and cooling to room temperature for later use.

On the basis of referring to relevant literature data, the invention determines the material composition and the optimal material dosage through orthogonal tests in a laboratory, and compared with the prior art, the invention has the following beneficial effects:

the green concrete prepared by the invention fully utilizes the water-quenched blast furnace slag of the solid waste, reduces the stacking of the solid waste and saves the land;

in the production process of green concrete, Portland cement is not added, so that the carbon dioxide emission is reduced, and the greenhouse effect is reduced;

sodium carbonate and gypsum are used as composite excitant to excite the gelling property of slag; because sodium carbonate belongs to neutral salt, the generated environmental hazard and the harm to human bodies are far less than those of water glass and sodium hydroxide, so that the environment protection and the human health are facilitated, and the price of the sodium carbonate is lower, so that the mass use of concrete is facilitated;

the ecological environment is protected by adopting the machine-made sand, and the sustainable development requirement of concrete is met;

the green concrete prepared by the invention is doped with basalt fibers, so that the flexural strength and the splitting tensile strength of the concrete are enhanced, and the basalt fibers can be degraded in the environment after being discarded without generating harm;

the green concrete prepared by the invention is doped with the roasted hydrotalcite, so that the excellent function of adsorbing chloride ions is fully utilized, and the corrosion of the chloride ions to reinforcing steel bars in the concrete is greatly reduced.

Detailed Description

The following is a detailed description of embodiments of the invention: the present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, and the description of the embodiments is used for facilitating understanding of the present invention, and is not to be construed as limiting the present invention.

The test methods in the following examples are conventional methods unless otherwise specified, and the test materials used in the examples are commercially available from conventional sources.

Example 1:

the green concrete resisting the corrosion of chloride salt comprises 20 mass percent of powder, 30 mass percent of fine aggregate, 40 mass percent of coarse aggregate, 8 mass percent of water, 1.5 mass percent of basalt fiber and 0.5 mass percent of water reducing agent, wherein the mixing ratio of unit volume is shown in table 1;

the powder material comprises 50% of slag, 20% of desulfurized gypsum, 17% of zeolite powder, 8% of sodium carbonate and 5% of hydrotalcite by mass ratio;

wherein the specific surface area of the water-quenched blast furnace slag is 500m²The specific surface area of dihydrate desulfurized gypsum is 450 m/kg²Per kg, natural zeolite powder specific surface area 550m²Kg machineThe fineness modulus of the prepared sand is 2.6, the coarse aggregate is broken stone, and the particle size is 5-15 mm; the basalt fiber has the diameter of 15 microns, the length of 10 millimeters and the tensile strength of 3000 MPa.

The preparation method comprises the following steps:

s1: drying the hydrotalcite, heating to 500 ℃, preserving heat for 2 hours, cooling to obtain roasted hydrotalcite, and sealing for later use;

s2: placing coarse aggregate stones into a stirrer, adding slag, gypsum, zeolite powder, calcined hydrotalcite and a polycarboxylic acid water reducing agent, then placing the mixture into a fine aggregate machine to prepare sand, adding 5.6% of water containing a sodium carbonate solution, stirring for 150 seconds, then adding basalt fibers and 2.4% of water, and stirring for 120 seconds;

s3: and pouring the stirred mixture into a mould, curing for 28 days under standard conditions, and demoulding to obtain the concrete.

The preparation of the sodium carbonate solution is as follows: 5.6 percent of water is weighed, the sodium carbonate solid is slowly poured into the water, a glass rod is used for stirring while pouring, and the mixture is cooled to room temperature for standby.

Example 2:

the green concrete resisting the corrosion of chloride salt comprises 25 percent of powder, 25 percent of fine aggregate, 38.7 percent of coarse aggregate, 10 percent of water, 1.0 percent of basalt fiber and 0.3 percent of water reducing agent by mass percent, wherein the mixing ratio of unit volume is shown in table 1;

the powder material comprises 50% of slag, 18% of desulfurized gypsum, 15% of zeolite powder, 9% of sodium carbonate and 8% of hydrotalcite by mass ratio;

wherein the specific surface area of the water-quenched blast furnace slag is 500m²Specific surface area of dihydrate desulfurized gypsum of 450 m/kg²Per kg, the specific surface area of the natural zeolite powder is 550m²The machine-made sand has a fineness modulus of 2.8 and coarse aggregate of crushed stone and a particle size of 5-20 mm; the basalt fiber has the diameter of 15 micrometers, the length of 10 millimeters and the tensile strength of 3000 MPa.

The preparation method comprises the following steps:

s1: drying the hydrotalcite, heating to 500 ℃, preserving heat for 2 hours, cooling to obtain roasted hydrotalcite, and sealing for later use;

s2: placing coarse aggregate stones into a stirrer, adding slag, gypsum, zeolite powder, calcined hydrotalcite and a polycarboxylic acid water reducing agent, then placing the mixture into a fine aggregate machine to prepare sand, adding 7% of water containing a sodium carbonate solution, stirring for 150 seconds, adding basalt fibers and 3% of water, and stirring for 150 seconds;

s3: and pouring the stirred mixture into a mould, curing for 28 days under standard conditions, and demoulding to obtain the concrete.

The preparation of the sodium carbonate solution is as follows: weighing 7% of water, slowly pouring the sodium carbonate solid into the water while stirring by using a glass rod, and cooling to room temperature for later use.

Example 3:

the green concrete resisting the corrosion of chloride salt comprises 23 percent of powder, 31 percent of fine aggregate, 35.4 percent of coarse aggregate, 9 percent of water, 1.2 percent of basalt fiber and 0.4 percent of water reducing agent by mass percentage, and the mixing ratio of unit volume is shown in table 1;

the powder material comprises 55% of slag, 15% of desulfurized gypsum, 15% of zeolite powder, 10% of sodium carbonate and 10% of hydrotalcite by mass ratio;

wherein the specific surface area of the water-quenched blast furnace slag is 550m²The specific surface area of dihydrate desulfurized gypsum is 450 m/kg²Per kg, natural zeolite powder specific surface area 500m²The machine-made sand has a fineness modulus of 2.6 and coarse aggregate of crushed stone and a particle size of 5-15 mm; the diameter of the basalt fiber is 15 micrometers, the length of the basalt fiber is 10 millimeters, and the tensile strength of the basalt fiber is 3000 MPa.

The preparation method comprises the following steps:

s1: drying the hydrotalcite, heating to 550 ℃, preserving heat for 2 hours, cooling to obtain roasted hydrotalcite, and sealing for later use;

s2: placing coarse aggregate stones into a stirrer, adding slag, gypsum, zeolite powder, calcined hydrotalcite and a polycarboxylic acid water reducing agent, then placing the mixture into a fine aggregate machine to prepare sand, adding 6.3 percent of water containing a sodium carbonate solution, stirring for 150 seconds, then adding basalt fibers and 2.7 percent of water, and stirring for 120 seconds;

s3: and pouring the stirred mixture into a mould, curing for 28 days under standard conditions, and demoulding to obtain the concrete.

The preparation of the sodium carbonate solution is as follows: 6.3 percent of water is weighed, the sodium carbonate solid is slowly poured into the water, a glass rod is used for stirring while pouring, and the mixture is cooled to room temperature for standby.

TABLE 1 concrete unit volume mixing ratio (Kg/m) of examples³）

Comparative example 1

The components of a certain commercial C40 ordinary silicate concrete are as follows: P.O42.5 ordinary portland cement 270Kg/m³760Kg/m of medium sand³Fineness modulus of 2.6 and stones 1008Kg/m³Particle size of 5-20 mm, water 153Kg/m³6.16Kg/m of solid polycarboxylic acid water reducing agent³64Kg/m slag³Specific surface area 500m²/kg；

The preparation method comprises the following steps: the materials are mixed evenly, stirred for 120 seconds and placed under standard conditions for curing for 28 days.

Performance testing and analysis

The performance parameters of the concrete samples of examples 1 to 3 and comparative example 1 were tested according to GB/T50081-2019 test method Standard for physical and mechanical Properties of concrete, GB/T50082-2009 test method Standard for Long-term Performance and durability of ordinary concrete, GB/T50080-2016 test method Standard for Performance of ordinary concrete mixtures, issued by Ministry of housing and urban and rural construction, wherein test data of 28-day compressive strength, flexural strength, tensile strength at cleavage and diffusion coefficient of chloride ions are shown in Table 2, and the working properties of concrete are shown in Table 3:

table 2 test data for concrete examples and comparative examples

TABLE 3 working Properties of concrete of examples and comparative examples

As can be seen from Table 2, compared with the common silicate concrete of the comparative example, the chlorine salt corrosion resistant green concrete provided by the invention has the advantages that the diffusion coefficient of chlorine ions is obviously reduced, the chlorine ion corrosion resistance is excellent, the durability of the concrete in the chlorine salt-containing environment is improved, and the additional performance of slag is improved.

As can be seen from tables 2 and 3, the performance of the chlorine salt corrosion resistant green concrete provided by the invention meets the engineering construction requirements; the compressive strength is basically consistent with that of the common silicate concrete of the comparative example, but the breaking strength is improved by more than 50%, the splitting tensile strength is improved by more than 80%, and the crack resistance of the concrete is enhanced.

The present embodiment is only for explaining the present invention, and not for limiting the present invention, and the person skilled in the art will make modifications to the present embodiment without making invasive contributions as required after reading the present description, as long as they are protected by patent laws within the scope of the present invention.

Claims (9)

1. The green concrete capable of resisting chlorine salt corrosion comprises the following components in percentage by mass: 20-25% of powder; 25-35% of fine aggregate; 35-45% of coarse aggregate; 8-12% of water; 0.3-0.6% of water reducing agent and 0.6-1.5% of basalt fiber, wherein the sum of the mass percentages of the components is 100%; wherein: the powder comprises the following components in percentage by mass: 50-60% of slag, 15-20% of gypsum, 15-25% of zeolite powder, 8-10% of sodium carbonate and 5-10% of hydrotalcite, wherein the sum of the mass percentages of the above powder components is 100%.

2. The chloride corrosion-resistant green concrete according to claim 1, wherein the slag is water-quenched blast furnace slag and has a specific surface area of 450-600 m²Between/kg; the gypsum is dihydrate desulfurized gypsum with the molecular formula of CaSO₄‧2H₂O, the specific surface area is 400-500 m²Between/kg.

3. The chlorine salt corrosion resistant green concrete as claimed in claim 1, wherein the zeolite powder is natural zeolite powder, and the specific surface area is 450-550 m²Between the weight of the raw material and the weight of the raw material,the sodium carbonate is pure in industrial analysis.

4. The chloride corrosion resistant green concrete of claim 1, wherein the hydrotalcite is a magnesium aluminum hydrotalcite having the formula of Mg₂AI(OH)₆CI‧nH₂O。

5. The chloride corrosion-resistant green concrete according to claim 1, wherein the fine aggregate is machine-made sand, and the fineness modulus is 2.6-2.8; the coarse aggregate is broken stone with the particle size of 5-20 mm.

6. The chloride corrosion resistant green concrete according to claim 1, wherein the water is local tap water and the water reducing agent is a solid polycarboxylic acid high efficiency water reducing agent.

7. The chloride corrosion resistant green concrete according to claim 1, wherein the basalt fiber has a diameter of 5-15 microns, a length of 6-10 mm and a tensile strength of 2600-3000 MPa.

8. A method for preparing the chloride salt corrosion-resistant green concrete according to any one of claims 1 to 7, characterized by comprising the steps of:

s1: drying the hydrotalcite, heating to 500-600 ℃, preserving heat for 2 hours, cooling to obtain roasted hydrotalcite, and sealing for later use;

s2: firstly putting the coarse aggregate into a stirrer, adding slag, gypsum, zeolite powder, roasted hydrotalcite and a polycarboxylic acid water reducing agent, then putting the fine aggregate, adding water with the total water consumption of 70% containing a sodium carbonate solution, stirring for 150 seconds, adding basalt fiber and the rest 30% of water, and stirring for 120-150 seconds;

s3: and pouring the stirred mixture into a mould, curing for 28 days under standard conditions, and demoulding to obtain the concrete.

9. The method according to claim 8, wherein the sodium carbonate solution is prepared by: slowly pouring the sodium carbonate solid into a proper amount of water, stirring by using a glass rod while pouring, and cooling to room temperature for later use.