A Low-Temperature Autoclaved Concrete and Its Preparation Method

Abstract

This invention discloses a low-temperature, non-steam-cured concrete and its preparation method. By adding different proportions of quicklime powder to a semi-finished concrete product under varying construction ambient temperatures, and simultaneously introducing carbon dioxide gas into the mixture of the semi-finished concrete and quicklime powder, the mixture is stirred and mixed to produce a carbonized low-temperature concrete product. This invention can produce concrete with rapid setting and early strength properties, suitable for use in various low-temperature construction environments. Furthermore, the preparation steps are simple, on-site construction is easy, and carbon dioxide can be recycled, which is beneficial to environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to a low-temperature steam-free curing concrete and a preparation method thereof. BACKGROUND

[0002] Concrete is a widely used building material. Concrete has high strength and good durability, which can meet the needs of various construction projects. However, there are some problems when using concrete in low-temperature environments. In low-temperature environments, the water in the concrete will freeze, causing the concrete to expand in volume, decrease in strength, and even crack and peel off. This seriously affects the use effect and service life of the concrete. Generally, in order to overcome the defects of concrete in low-temperature environments, steam curing is required during the production process. Steam curing is a way of curing concrete, which provides a suitable temperature and humidity environment to promote the hydration reaction of concrete, so that it can obtain better strength and durability.

[0003] However, steam curing has some inconveniences. First, steam curing requires a large amount of energy input and high equipment cost, and requires a certain amount of space. Second, the steam curing process requires several days to several weeks of time, which will prolong the construction period. Finally, the steam curing equipment needs regular maintenance and maintenance, which increases the construction cost and difficulty. SUMMARY

[0004] The main purpose of the present application is to provide a low-temperature steam-free curing concrete and a preparation method thereof, which solves the problem of insufficient performance of concrete in low-temperature environments.

[0005] A low-temperature steam-free curing concrete, the ingredients of which include a concrete semi-finished product, lime powder, and carbon dioxide gas.

[0006] The amount of lime powder mixed in different low-temperature construction environments is different, specifically:

[0007] When the construction environment temperature is 0 to -5℃, the amount of lime powder mixed is 1.0% to 3.0% of the mass of the concrete semi-finished product;

[0008] When the construction environment temperature is -5 to -10℃, the amount of lime powder mixed is 3.0% to 5.0% of the mass of the concrete semi-finished product;

[0009] When the construction environment temperature is -10 to -15℃, the amount of lime powder mixed is 5.0% to 7.0% of the mass of the concrete semi-finished product.

[0010] Preferably, the semi-finished concrete product, when constructed in a low-temperature environment of 0 to -15℃, comprises, by weight, 320-380 parts cement, 30-45 parts mineral powder, 50-75 parts fly ash, 1040-1100 parts crushed stone, 720-780 parts medium sand, 3.0-4.0 parts water-reducing agent, and 120-160 parts water.

[0011] Preferably, the cement is silicate cement 52.5, the mineral powder is mineral powder S95, the particle size range of the crushed stone is 5-31.5 mm, and the water-reducing agent is polycarboxylate water-reducing agent.

[0012] A method for preparing low-temperature, non-steam-cured concrete includes the following steps:

[0013] Step 1: According to the construction needs, use the raw materials of the required weight of concrete semi-finished product. In an environment with a temperature of 0-10℃, pour cement, mineral powder, fly ash, crushed stone, medium sand and water-reducing agent into the mixer truck, add water and mix to prepare the required weight of concrete semi-finished product.

[0014] Step 2: Based on different construction environment temperatures and the weight of the semi-finished concrete, select the appropriate weight ratio of quicklime powder and mix it into the semi-finished concrete.

[0015] Step 3: Introduce carbon dioxide gas into the mixture of quicklime powder and semi-finished concrete. During the gas introduction process, the three are mixed and stirred to prepare carbonized low-temperature concrete.

[0016] Preferably, in each cubic meter of the semi-finished concrete, the concentration of carbon dioxide gas introduced is 50%-60%, the aeration rate is 2-8 L / min, the aeration time is 30-60 min, and the stirring rate is 40-80 rpm.

[0017] Preferably, when the ambient temperature during construction is 0 to -5℃, quicklime powder can be poured into water and carbon dioxide gas can be introduced at the same time. During the gas introduction process, the three are mixed and stirred to form a carbonized quicklime solution. This solution is then poured into the semi-finished concrete and stirred to prepare the finished carbonized low-temperature concrete.

[0018] Preferably, the ratio of quicklime powder to water is 1:3.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are:

[0020] 1. This invention adjusts the dosage of quicklime powder according to the quality of the semi-finished concrete under different low-temperature construction environments. The quicklime powder reacts with water to generate calcium hydroxide, regulating the pH value of the concrete and maintaining a certain alkaline environment inside. This prevents acidic substances from chemically reacting with the reinforcing steel, causing corrosion, volume expansion, and structural damage, thus improving the durability of the concrete. Furthermore, the addition of quicklime powder promotes the generation of hydroxide ions, which helps enrich the formation of CSH (calcium silicate hydrate) gel, thereby accelerating the cement hardening process and improving the density, strength, and durability of the concrete. Simultaneously, the exothermic properties of quicklime powder help shorten the curing time of the concrete and reduce fluctuations in the expansion rate caused by temperature changes, effectively reducing concrete shrinkage and further improving its durability. Introducing carbon dioxide gas further enhances the concrete's strength and durability. When the concrete surface is exposed to air, the carbon dioxide reacts with water to form calcium carbonate, promoting the reaction of unreacted calcium hydroxide and aluminum hydroxide (and other alkaline substances) with carbon dioxide to form stronger calcified cement stone. Therefore, concrete with rapid setting and early strength properties can be prepared without steam curing, and it can be used in different low-temperature construction environments. Moreover, the preparation steps are simple and the on-site construction difficulty is low.

[0021] 2. This invention improves the performance of concrete by introducing carbon dioxide into it, while also recovering and utilizing the carbon dioxide produced by burning fossil fuels such as coal, oil, and natural gas in industrial production, which is beneficial to the environment. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the concrete production process according to an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Example 1

[0025] This embodiment describes a low-temperature, autoclaved concrete and its preparation method. The components include semi-finished concrete, quicklime powder, and carbon dioxide gas. The dosage of quicklime powder varies depending on the low-temperature construction environment: 1.0%-3.0% of the semi-finished concrete mass when the ambient temperature is 0 to -5℃; 3.0%-5.0% when the ambient temperature is -5 to -10℃; and 5.0%-7.0% when the ambient temperature is -10 to -15℃.

[0026] This invention produces carbonized low-temperature concrete by adding quicklime powder to semi-finished concrete and introducing carbon dioxide gas. This finished product has rapid setting and early strength properties without steam curing and can be used in low-temperature environments. By adjusting the amount of quicklime powder added under different low-temperature construction environments, the carbonized low-temperature concrete product can be made more adaptable to different low-temperature construction environments.

[0027] Specifically, in this embodiment, the semi-finished concrete, under a low-temperature construction environment of 0 to -15℃, comprises the following components by weight: 320-380 parts cement, 30-45 parts mineral powder, 50-75 parts fly ash, 1040-1100 parts crushed stone, 720-780 parts medium sand, 3.0-4.0 parts water-reducing agent, and 120-160 parts water. Among these, the cement is silicate cement 52.5, the mineral powder is mineral powder S95, the particle size range of the crushed stone is 5-31.5 mm, and the water-reducing agent is polycarboxylate water-reducing agent.

[0028] A method for preparing low-temperature, non-steam-cured concrete includes the following steps:

[0029] Step 1: According to the construction needs, use the raw materials of the required weight of concrete semi-finished product. In an environment with a temperature of 0-10℃, pour cement, mineral powder, fly ash, crushed stone, medium sand and water-reducing agent into the mixer truck, add water and mix to prepare the required weight of concrete semi-finished product.

[0030] Step 2: Based on different construction environment temperatures and the weight of the semi-finished concrete, select the appropriate weight ratio of quicklime powder and mix it into the semi-finished concrete.

[0031] Step 3: Introduce carbon dioxide gas into the mixture of quicklime powder and semi-finished concrete. The concentration of carbon dioxide gas in each cubic meter of semi-finished concrete is 50%-60%, the gas introduction rate is 2-8 L / min, the gas introduction time is 30-60 min, and the stirring rate is 40-80 rpm. During the gas introduction process, the three are mixed and blended to prepare carbonized low-temperature concrete.

[0032] Furthermore, when the ambient temperature during construction is 0 to -5℃, quicklime powder can be poured into water at a ratio of 1:3, and carbon dioxide gas can be introduced simultaneously. During the gas introduction process, the three are mixed and stirred to form a carbonized quicklime solution. This solution is then poured into the semi-finished concrete and stirred continuously to prepare the finished carbonized low-temperature concrete.

[0033] Example 2

[0034] This embodiment describes autoclaved concrete that is not steam-cured when the ambient temperature is -5 to -10℃. The autoclaved concrete in this embodiment consists of semi-finished concrete, quicklime powder, and carbon dioxide gas. The amount of quicklime powder is 4% of the mass of the semi-finished concrete. The components of the semi-finished concrete, by weight, include: 345 parts silicate cement 52.5, 35 parts mineral powder S95, 50 parts fly ash, 1040 parts crushed stone (particle size range 5-31.5mm), 755 parts medium sand, 3.6 parts polycarboxylate superplasticizer, and 160 parts water.

[0035] The preparation process of the autoclaved concrete in this embodiment is as follows:

[0036] Step 1: In an environment with a temperature of 0-10℃, pour silicate cement 52.5, mineral powder S95, fly ash, crushed stone (particle size range 5-31.5mm), medium sand, polycarboxylate superplasticizer and water into a mixer truck and mix them to prepare a semi-finished concrete product.

[0037] Step 2: Take out quicklime powder at a dosage of 2% of the mass of the semi-finished concrete and add it to the semi-finished concrete.

[0038] Step 3: Introduce carbon dioxide gas into the mixture of quicklime powder and semi-finished concrete. The concentration of carbon dioxide gas in each cubic meter of semi-finished concrete is 50%-60%, the gas introduction rate is 3L / min, the gas introduction time is 45min, and the stirring rate is 50rpm. During the gas introduction process, the three are mixed and blended to prepare carbonized low-temperature concrete.

[0039] Comparative Example 1

[0040] This comparative example examines the effect of not introducing carbon dioxide gas on the performance of concrete. The concrete semi-finished product of Example 2 is used as the basis for this comparative example. Except for not introducing carbon dioxide gas, the other components and dosages are the same as those in Example 2.

[0041] Comparative Example 2

[0042] This comparative example examines the effect of not adding quicklime powder and carbon dioxide on the performance of concrete. The concrete semi-finished product of Example 2 is used as the basis for this comparative example.

[0043] Comparative Example 3

[0044] This comparative example examines the performance of ordinary antifreeze concrete made by adding an antifreeze agent. The concrete semi-finished product of Example 2 is used as the basis for this comparative example, and HZ-6 concrete antifreeze agent with a dosage of 5% of the total mass of silicate cement 52.5, mineral powder S95 and fly ash is added to it.

[0045] Table 1 shows the concrete fluidity, setting time, and 1-day, 7-day, and 28-day strengths of Examples 2, Comparative Examples 1, 2, and 3.

[0046] Table 1

[0047]

[0048] As shown in Table 1, the carbonized low-temperature concrete product prepared by this application has lower fluidity, shorter setting time, faster early strength development, and higher strength.

[0049] The freeze-thaw resistance of concrete in Examples 2, 1, 2 and 3 is shown in Table 2.

[0050] Table 2

[0051]

[0052] As shown in Table 2, the carbonized low-temperature concrete product prepared by this application has better freeze-thaw resistance.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A low temperature steam-free concrete, characterized by: The components include concrete semi-product, lime powder and carbon dioxide gas; The carbon dioxide gas is introduced when the lime powder and the concrete semi-product are mixed and stirred; The mixing amount of the lime powder is different in different low-temperature construction environments, and specifically: When the construction environment temperature is 0~ -5℃, the mixing amount of the lime powder is 1.0%-3.0% of the mass of the concrete semi-product; When the construction environment temperature is -5~ -10℃, the mixing amount of the lime powder is 3.0%-5.0% of the mass of the concrete semi-product; When the construction environment temperature is -10~ -15℃, the mixing amount of the lime powder is 5.0%-7.0% of the mass of the concrete semi-product.

2. A cold curing concrete according to claim 1, characterized in that: The components of the concrete semi-product in the low-temperature construction environment of 0~ -15℃ include, by weight: cement 320-380 parts, mineral powder 30-45 parts, fly ash 50-75 parts, gravel 1040-1100 parts, medium sand 720-780 parts, water reducing agent 3.0-4.0 parts, and water 120-160 parts.

3. A cold curing concrete according to claim 2, wherein: The cement is Portland cement 52.5, the mineral powder is mineral powder S95, the particle size range of the gravel is 5~31.5mm, and the water reducing agent is polycarboxylic acid water reducing agent.

4. A method of producing the low-temperature non-autoclaved concrete according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: Step 1: according to the construction needs, using the required weight of raw materials of the concrete semi-product, in an environment with a temperature of 0~10℃, the cement, mineral powder, fly ash, gravel, medium sand and water reducing agent are poured into a mixer truck and stirred with water to prepare the concrete semi-product with the required weight; Step 2: according to the weight of the concrete semi-product and the different construction environment temperatures, the corresponding weight of the lime powder is selected and mixed into the concrete semi-product; Step 3: carbon dioxide gas is introduced into the mixture of the lime powder and the concrete semi-product, and the three are mixed and stirred during the aeration process to prepare the carbonated low-temperature concrete product.

5. A method of producing a low temperature steam-free concrete according to claim 4, characterized in that: In the concrete semi-product per cubic meter, the carbon dioxide gas is introduced at a concentration of 50%-60%, an aeration rate of 2-8L / min, an aeration time of 30~60min, and a stirring rate of 40-80rpm.

6. A method of producing a low temperature steam-free concrete according to claim 4, characterized in that: When the construction environment temperature is 0~ -5℃, the lime powder is first poured into water, and carbon dioxide gas is introduced, and the three are mixed and stirred during the aeration process to prepare a carbonated lime solution, which is then poured into the concrete semi-product and continuously stirred to prepare the carbonated low-temperature concrete product.

7. A method of producing a low temperature steam-free concrete according to claim 6, characterized in that: The ratio of the lime powder to water is 1:3.

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