A steel slag-based concrete carbon sequestration protective coating, its preparation method and application

Abstract

The present invention belongs to the technical field of concrete, and particularly relates to a steel slag-based concrete carbon sequestration protective coating, a preparation method thereof, and an application. The steel slag-based concrete carbon sequestration protective coating provided by the present invention, in terms of parts by mass, the preparation raw materials include the following components: 40-50 parts of steel slag micropowder, 30-40 parts of quartz sand, 5-10 parts of quick-setting and quick-hardening cement, 9-15 parts of calcium supplement, 0.1-0.5 parts of defoaming agent, 1-1.5 parts of thickening agent, 1-2 parts of binder, 1-5 parts of water-reducing agent, and 30-40 parts of water; the total mass parts of the steel slag micropowder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoaming agent, thickening agent, binder, and water-reducing agent are 100 parts. It has a strong adhesion force with the base concrete, is not easy to age, has excellent durability, a long service life, and uses steel slag micropowder as the main raw material, expanding a new way for comprehensive utilization of steel slag, with low price and simple preparation method.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and particularly relates to a steel slag-based concrete carbon sequestration protective coating, a preparation method thereof, and an application thereof. Background Art

[0002] In some coastal, northwest, and southwest regions, the groundwater and soil contain a large amount of corrosive ions, such as chlorides, sulfates, magnesium salts, etc. These corrosive ions will erode reinforced concrete. On the one hand, they will harden the concrete, thus changing the cement composition, affecting the strength of the concrete, and even causing the failure of concrete structures; on the other hand, the water containing corrosive ions will enter the interior of the concrete, causing the internal steel bars to rust. At the same time, in a cold environment, porous and hydrophilic concrete is easily wetted by water. The water enters the interior of the concrete through these hydrophilic pores and freezes inside the concrete, resulting in volume expansion and causing freeze-thaw, which causes cracking damage to the concrete. Therefore, taking corresponding protective measures to improve the reliability and durability of concrete structures is of great significance.

[0003] In recent years, researchers have developed a variety of concrete surface coatings to improve the durability of concrete. Functionally, they are mainly divided into four categories: surface treatment, hydrophobic modification, pore blocking treatment, and composite surface treatment. Surface treatment is to form a protective layer on the surface of the cement base material to prevent the penetration of corrosive substances, such as epoxy resin, acrylic acid, polyethylene copolymer, polyurethane, and polymer-modified mortar. Hydrophobic modification is to penetrate the concrete pores with hydrophobic compounds (including silanes and siloxane-based materials, etc.), thereby producing a hydrophobic pore surface. Pore blocking treatment is to fill the capillary pores on the concrete surface, thereby improving the impermeability of the concrete. Silicate-based materials have been proven to be good pore-blocking treatment agents, and sodium silicate is the most commonly used one. Composite surface treatment is a combination of at least the aforementioned two technologies, such as hydrophobic modification and pore blocking. However, the traditional organic polymer coatings used in surface treatment have relatively weak interfacial bonding with the concrete surface and are easily aged due to various external physical damages, resulting in poor durability and short service life. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a steel slag-based concrete carbon sequestration protective coating, a preparation method thereof, and an application thereof. The steel slag-based concrete carbon sequestration protective coating provided by the present invention has strong adhesion to the base concrete, is not easily aged, has excellent durability, a long service life, and uses steel slag fine powder as the main raw material, expanding a new way for the comprehensive utilization of steel slag, with a low price and a simple preparation method.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a carbon sequestration protective coating for steel slag-based concrete. In terms of parts by mass, the raw materials for its preparation include the following components:

[0007] 40 - 50 parts of steel slag powder, 30 - 40 parts of quartz sand, 5 - 10 parts of quick-setting and quick-hardening cement, 9 - 15 parts of calcium supplement, 0.1 - 0.5 parts of defoamer, 1 - 1.5 parts of thickener, 1 - 2 parts of binder, 1 - 5 parts of water reducer, and 30 - 40 parts of water;

[0008] The total mass parts of the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder, and water reducer is 100 parts.

[0009] Preferably, the specific surface area of the steel slag powder is 450 - 500 m 2 / kg; the particle size of the steel slag powder is 25 - 75 μm; the basicity of the steel slag powder ≥ 2.4, and the mass percentage content of C 2 S in the steel slag powder is 15 - 25%, and the mass percentage content of C 3 S is 35 - 45%.

[0010] Preferably, the particle size of the quartz sand is 0.6 - 2 mm.

[0011] Preferably, the calcium supplement is one or more of calcium hydroxide, calcium carbonate, and calcium oxide; the particle size of the calcium supplement ≤ 32 μm; the mass percentage content of calcium element in the calcium supplement > 95%.

[0012] Preferably, the pH value of the defoamer is 6.0 - 7.5, and the solid content is 99.5%.

[0013] Preferably, the thickener is hydroxypropyl methylcellulose and / or hydroxyethyl cellulose.

[0014] Preferably, the binder is one or more of polyvinyl alcohol, hydroxypropyl guar gum, and resin powder.

[0015] Preferably, the water reducer is a polycarboxylate-based superplasticizer; the water reduction rate of the water reducer ≥ 30%.

[0016] The present invention also provides a preparation method for the carbon sequestration protective coating for steel slag-based concrete according to the above technical solution, including the following steps:

[0017] Mix the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder, water reducer, and water to obtain a mixture;

[0018] After applying the mixture to the concrete surface, place it in a sealed environment and introduce CO 2 , and carry out carbonation curing to obtain a carbon sequestration protective coating for steel slag-based concrete.

[0019] The present invention also provides an application of the steel slag-based concrete carbon sequestration protective coating described in the above technical solution or the steel slag-based concrete carbon sequestration protective coating prepared by the preparation method described in the above technical solution in concrete protection.

[0020] The present invention provides a steel slag-based concrete carbon sequestration protective coating. Calculated by mass parts, its preparation raw materials include the following components: 40-50 parts of steel slag powder, 30-40 parts of quartz sand, 5-10 parts of quick-setting and quick-hardening cement, 9-15 parts of calcium supplement, 0.1-0.5 parts of defoaming agent, 1-1.5 parts of thickening agent, 1-2 parts of binder, 1-5 parts of water-reducing agent, and 30-40 parts of water; the total mass parts of the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoaming agent, thickening agent, binder and water-reducing agent are 100 parts.

[0021] The steel slag-based concrete carbon sequestration protective coating provided by the present invention uses steel slag powder as the main material. Compared with cementitious materials, steel slag powder is green and environmentally friendly, does not produce carbon dioxide during the production process, and has certain cementitious properties. Through hydration reaction, a protective layer with a certain strength can be formed on the surface of concrete structures. On the other hand, because steel slag contains rich γ-C 2 S, f-CaO, f-MgO, it shows high carbonation reaction activity. By reacting with carbon dioxide in the air to generate calcium carbonate, using the stability of calcium carbonate, a carbonation layer is formed on the surface of existing concrete. The protective layer and the carbonation layer act together to fill the external pores of the concrete and improve the durability of the concrete; the added calcium supplement can, on the one hand, stimulate the cementitious activity of the steel slag, and on the other hand, provide an external calcium source for the carbonation reaction of the steel slag powder. At the same time, thickening agent and binder are added, and organic and inorganic are compounded, which not only improves the adhesion between the protective coating and the base concrete, greatly extends the service life of the coating, but also reduces the shrinkage rate and rigidity during the hardening process of the coating slurry, making it not easy to age and having a long service life. This steel slag-based concrete carbon sequestration protective coating can, on the one hand, effectively improve the durability of concrete structures, and on the other hand, the coating slurry is inexpensive, the preparation process is simple, and the construction is convenient. Using steel slag powder as the main raw material also expands new ways for comprehensive utilization of steel slag. At the same time, the carbonation reaction of steel slag consumes carbon dioxide, which can effectively reduce carbon dioxide emissions, and has good economic, social and environmental benefits. Specific embodiments

[0022] The present invention provides a steel slag-based concrete carbon sequestration protective coating. Calculated by mass parts, its preparation raw materials include the following components:

[0023] 40 - 50 parts of steel slag powder, 30 - 40 parts of quartz sand, 5 - 10 parts of quick-setting and quick-hardening cement, 9 - 15 parts of calcium supplement, 0.1 - 0.5 parts of defoamer, 1 - 1.5 parts of thickener, 1 - 2 parts of binder, 1 - 5 parts of water reducer and 30 - 40 parts of water;

[0024] The total mass parts of the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder and water reducer are 100 parts.

[0025] Unless otherwise specified, the present invention has no special requirements for the sources of the raw materials used in the preparation, and commercially available products well-known to those skilled in the art can be used.

[0026] The raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention include 40 - 50 parts by mass of steel slag powder, preferably 43 - 45 parts.

[0027] In the present invention, the specific surface area of the steel slag powder is preferably 450 - 500 m 2 / kg, more preferably 480 - 500 m 2 / kg; the particle size of the steel slag powder is preferably 25 - 75 μm, more preferably 40 - 60 μm; the basicity of the steel slag powder is preferably ≥2.4, more preferably ≥2.6; the mass percentage content of C 2 S in the steel slag powder is preferably 15 - 25%, more preferably 18 - 22%, and the mass percentage content of C 3 S is preferably 35 - 45%, more preferably 40 - 42%.

[0028] In the present invention, the preparation method of the steel slag powder is preferably to remove iron from the steel slag tailings and then carry out crushing and screening in sequence to obtain the steel slag powder; the equipment for crushing is preferably a roller mill and a vertical mill; the equipment for screening is preferably a separator.

[0029] The main reason for the present invention to select steel slag powder as a component of the concrete carbon sequestration protective coating is that on the one hand, due to its gelling properties, a protective layer with a certain strength can be formed on the surface of the existing concrete structure through hydration reaction, and on the other hand, the steel slag powder contains rich γ-C 2 S, f-CaO, f-MgO, showing high carbonation reaction activity, and generating calcium carbonate by reacting with carbon dioxide in the air to form a carbonated layer on the surface of the existing concrete.

[0030] Although the mineral composition of steel slag is similar to that of Portland cement clinker, steel slag has experienced high-temperature effects, and its mineral activity is much lower than that of cement. By using mechanical grinding equipment to grind steel slag finely, as the specific surface area increases, the contact area between steel slag powder and mixing water increases, accelerating the hydration rate of steel slag and effectively improving the activity of steel slag. From a microscopic perspective, during the grinding process of steel slag, part of the energy is converted into the internal energy and surface energy of new steel slag particles. The reduction of lattice energy leads to lattice dislocation, defect secondary crystallization, etc., resulting in an amorphous structure that is easily soluble in water on the surface of steel slag powder. Water molecules around it are more likely to enter the interior of steel slag particles, accelerating the hydration reaction rate and greatly improving the activity of steel slag.

[0031] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating include 30 - 40 parts by mass of quartz sand, preferably 33 - 36 parts by mass.

[0032] In the present invention, the particle size of the quartz sand is preferably 0.6 - 2 mm, more preferably 0.6 - 1.18 mm. In the examples of the present invention, the quartz sand is purchased from LingShou HaoFan Mineral Products Co., Ltd.

[0033] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating include 5 - 10 parts by mass of quick-setting and quick-hardening cement, preferably 5 - 8 parts by mass.

[0034] In the examples of the present invention, the quick-setting and quick-hardening cement is 52.5 quick-hardening sulphoaluminate cement produced by Tangshan Polar Bear Building Materials Co., Ltd., with a 1-day compressive strength of 59.5 MPa and a 28-day compressive strength of 67.1 MPa.

[0035] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating include 9 - 15 parts by mass of calcium supplement, preferably 11 - 13 parts by mass.

[0036] In the present invention, the calcium supplement is preferably one or more of calcium hydroxide, calcium carbonate, and calcium oxide, more preferably calcium hydroxide; when the calcium supplement is several of the above, the present invention has no special limitation on the ratio of different types of calcium supplements, and any ratio is acceptable; the particle size of the calcium supplement is preferably ≤ 32 μm, more preferably ≤ 25 μm; the mass percentage content of calcium element in the calcium supplement is preferably > 95%, more preferably ≥ 98%.

[0037] The incorporation of calcium supplement in the present invention is beneficial to the formation of ettringite and C 3 S, C2 The hydration rate of S is increased, thereby activating the activity of steel slag and playing an alkali activation role; on the other hand, it can provide an external calcium source for the carbonation reaction, form stable calcium carbonate to fill the pores, improve the pore structure, reduce the connectivity of the pores, and make the concrete surface coating more dense.

[0038] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration and protection coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration and protection coating include 0.1 - 0.5 parts by mass of defoamer, preferably 0.2 - 0.4 parts by mass.

[0039] In the present invention, the defoamer is preferably a polyether-modified silicone defoamer; the pH value of the defoamer is preferably 6.0 - 7.5, more preferably 6.5 - 7.5, and the solid content is preferably 99.5%. In the examples of the present invention, the defoamer is the 902 solid powder defoamer produced by Foshan Jingqi Chemical Technology Co., Ltd., which is a non-ionic defoamer.

[0040] After the steel slag-based concrete carbon sequestration and protection coating solidifies, many tiny pores will be generated inside it. The existence of pores will have an adverse impact on the strength and durability of the coating structure. After using the defoamer to eliminate uneven bubbles in the present invention, the coating structure itself can be made more compact, improving its strength and durability. The advantages of the polyether-modified silicone defoamer selected in the present invention are strong defoaming and foam suppression ability, small dosage, no influence on the basic properties of the foaming system, good heat resistance, and stable chemical properties.

[0041] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration and protection coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration and protection coating include 1 - 1.5 parts by mass of thickener, preferably 1.2 - 1.4 parts by mass.

[0042] In the present invention, the thickener is preferably hydroxypropyl methylcellulose and / or hydroxyethyl cellulose, more preferably hydroxypropyl methylcellulose; when the thickener is hydroxypropyl methylcellulose and hydroxyethyl cellulose, the present invention has no special limitation on the ratio of hydroxypropyl methylcellulose and hydroxyethyl cellulose, and any ratio is acceptable.

[0043] In the present invention, both hydroxypropyl methylcellulose and hydroxyethyl cellulose are preferably white powders; the particle size of hydroxypropyl methylcellulose and hydroxyethyl cellulose is preferably that the passing rate through 100 - mesh sieve > 98.5% and the passing rate through 80 - mesh sieve > 100%; the pH value of hydroxypropyl methylcellulose and hydroxyethyl cellulose is preferably 5 - 8.5, more preferably 6 - 8; the viscosity of the cellulose solution with a mass concentration of 2% formed by hydroxypropyl methylcellulose and hydroxyethyl cellulose at 20°C is preferably 100,000 mPa·s.

[0044] The thickener selected in the present invention has excellent water retention and thickening properties, and can greatly improve the working performance of the coating slurry. The added calcium supplement, thickener and binder are compounded organically and inorganically, which not only improves the adhesion between the protective coating and the base concrete, greatly extends the service life of the coating, but also reduces the shrinkage rate and rigidity during the hardening process of the coating slurry, making it not easy to age and having a long service life.

[0045] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating include 1 to 2 parts by mass of binder, preferably 1.5 to 1.7 parts by mass.

[0046] In the present invention, the binder is preferably one or more of polyvinyl alcohol, hydroxypropyl guar gum and resin powder, more preferably polyvinyl alcohol; when the binder is the above several kinds, the present invention has no special limitation on the ratio of different kinds of binders, and any ratio can be used.

[0047] The binder selected in the present invention has a good toughening and crack resistance effect, making the coating slurry have good anti-drooping and anti-sagging properties. The hydroxyl group of polyvinyl alcohol associates with the oxygen atom of the ether bond in the cellulose ether to form a hydrogen bond with a network structure. The synergistic effect of the two makes the free water in the coating slurry become bound water, giving it good water retention performance and effectively preventing the slurry from segregation.

[0048] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating include 1 to 5 parts by mass of water reducing agent, preferably 1 to 3 parts by mass.

[0049] In the present invention, the water reducing agent is preferably a polycarboxylate-based high-efficiency water reducing agent; the water reducing rate of the water reducing agent is preferably ≥30%, more preferably ≥32%; the pH value of the aqueous solution with a mass concentration of 20% formed by the water reducing agent at 23°C is preferably 7.5 ± 0.5.

[0050] In the present invention, the total mass parts of the steel slag powder, quartz sand, rapid hardening cement, calcium supplement, defoaming agent, thickener, binder and water reducing agent are 100 parts.

[0051] Based on 1 part by mass of steel slag powder in the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating provided by the present invention, the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating include 30 to 40 parts by mass of water, preferably 30 to 35 parts by mass.

[0052] The present invention also provides a method for preparing the steel slag-based concrete carbon sequestration protective coating according to the above technical solution, including the following steps:

[0053] Mix steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder, water reducer and water to obtain a mixture.

[0054] After applying the mixture on the concrete surface, place it in a sealed environment and introduce CO 2 for carbonation curing to obtain a steel slag-based concrete carbon sequestration protective coating.

[0055] In the present invention, steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder, water reducer and water are mixed to obtain a mixture.

[0056] In the present invention, the mixing is preferably carried out by first mixing steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder and water reducer to obtain a dry powder mixture; and then mixing the dry powder mixture and water for the second time to obtain a mixture.

[0057] In the present invention, the first mixing is preferably carried out under stirring conditions; the stirring rate is preferably 200 - 400 r / min, more preferably 350 - 400 r / min; the temperature of the first mixing is preferably 20 - 40 °C, more preferably 25 - 35 °C; the time of the first mixing is preferably 3 - 5 min, more preferably 5 min.

[0058] In the present invention, the second mixing is preferably carried out under stirring conditions; the stirring rate is preferably 200 - 350 r / min, more preferably 300 - 350 r / min; the temperature of the second mixing is preferably 20 - 30 °C, more preferably 20 - 25 °C; the time of the second mixing is preferably ≥2 min, more preferably ≥3 min.

[0059] After obtaining the mixture, in the present invention, the mixture is applied on the concrete surface and then placed in a sealed environment and introduced CO 2 for carbonation curing to obtain a steel slag-based concrete carbon sequestration protective coating.

[0060] In the present invention, the concrete is preferably a precast concrete member. Before coating, the surface of the concrete is preferably polished until the natural rough pores of the concrete are exposed; there are no special limitations on the polishing treatment in the present invention, and the well-known polishing treatment in the art can be used. In the present invention, the floating slurry and impurities on the concrete surface are removed by polishing, making its surface clean, oil-free, dust-free and free of residual chemical corrosion media.

[0061] In the present invention, the coating is preferably spraying or roller coating; the equipment for spraying is preferably a mortar spraying machine; the equipment for roller coating is preferably an ordinary roller brush.

[0062] In the present invention, the thickness of the steel slag-based concrete carbon sequestration protective coating is preferably 3 - 5 mm, more preferably 4 mm.

[0063] In the present invention, the sealed environment is preferably to seal the concrete with a flexible material; the flexible material is preferably canvas or plastic sheeting; before introducing CO 2 In the present invention, the concrete placed in the sealed environment is preferably left standing; the temperature for standing is preferably 25 ± 1 °C; the humidity for standing is preferably 50 ± 2% RH; the time for standing is preferably 30 min; the volume concentration of CO 2 in the sealed environment is preferably 55 ± 5%; the time for carbonation curing is preferably 1 - 3 d, more preferably 2 d; the temperature for carbonation curing is preferably 25 ± 1 °C, more preferably 25 °C; the humidity for carbonation curing is preferably 55% RH. In the present invention, it is preferred to monitor the CO 2 concentration in the sealed environment during the carbonation curing process, and as CO 2 is consumed in the carbonation reaction, high-concentration CO 2 is replenished in a timely manner.

[0064] The present invention also provides the application of the steel slag-based concrete carbon sequestration protective coating described in the above technical solution or the steel slag-based concrete carbon sequestration protective coating prepared by the preparation method described in the above technical solution in concrete protection.

[0065] The present invention does not have any special limitations on the application method of the steel slag-based concrete carbon sequestration protective coating in concrete protection, and any well-known application method in the art can be adopted.

[0066] Next, the technical solutions in the present invention will be clearly and completely described in combination with the examples in the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0067] The sources of the raw materials for preparing the steel slag-based concrete carbon sequestration protective coating in Examples 1 - 5 are as follows:

[0068] The steel slag powder was purchased from Hebei Yanxi Mineral Products Processing;

[0069] The quartz sand was purchased from LingShou HaoFan Mineral Products Co., Ltd.;

[0070] The 52.5 rapid hardening sulphoaluminate cement was purchased from Tangshan Polar Bear Building Materials Co., Ltd.;

[0071] Calcium hydroxide, calcium oxide, and calcium carbonate were purchased from Hebei Hongze New Material Technology Co., Ltd.;

[0072] The defoaming agent was purchased from Foshan Jingqi Chemical Technology Co., Ltd.;

[0073] Hydroxyethyl cellulose and hydroxymethyl cellulose were purchased from Hebei Hehao Cellulose Co., Ltd.;

[0074] Polyvinyl alcohol, hydroxypropyl guar gum, and resin powder were purchased from Shijiazhuang Yaguan New Material Technology Co., Ltd.;

[0075] The polycarboxylate superplasticizer powder was purchased from Zhongyan Building Materials Technology Co., Ltd.

[0076] Example 1

[0077] Taking the preparation of 100 g of the product as an example, 45 g of steel slag powder, 33 g of quartz sand, 5 g of 52.5 rapid hardening sulphoaluminate cement, 12 g of calcium hydroxide, 0.3 g of 902 solid powder defoamer, 0.6 g of hydroxypropyl methylcellulose, 0.4 g of hydroxyethyl cellulose, 1 g of polyvinyl alcohol, 0.7 g of hydroxypropyl guar gum, and 2 g of polycarboxylate superplasticizer were taken; the total amount of the above raw materials was 100 g;

[0078] The specific surface area of the above steel slag powder was 500 m 2 / kg, the alkalinity was 2.6, and the mass percentage content of C 2 S was 20%, and the mass percentage content of C 3 S was 41%;

[0079] The above quick-setting and rapid-hardening cement was 52.5 rapid hardening sulphoaluminate cement, with a 1-day compressive strength of 59.5 MPa and a 28-day compressive strength of 67.1 MPa;

[0080] The particle size distribution of the above quartz sand was 0.85 - 2 mm;

[0081] The particle size of the above calcium hydroxide was ≤25 μm, and the mass percentage content of calcium element was 98%;

[0082] The pH value of the above 902 solid powder defoamer was 7.1, and the solid content was 99.5%;

[0083] The 100-mesh passing rate of the above hydroxypropyl methylcellulose was >99.5% and the 80-mesh passing rate was >100%, the pH value was 7.2, and the viscosity of the cellulose solution with a mass concentration of 2% formed by hydroxypropyl methylcellulose at 20°C was 100,000 mPa·s;

[0084] The 100-mesh passing rate of the above hydroxyethyl cellulose was 99.0%, the 80-mesh passing rate was >100%, the pH value was 7.2, and the viscosity of the cellulose solution with a mass concentration of 2% formed by hydroxyethyl cellulose at 20°C was 100,000 mPa·s;

[0085] The above binder was polyvinyl alcohol and hydroxypropyl guar gum, and the mass ratio was 1:0.7;

[0086] The superplasticizer described above is a polycarboxylate superplasticizer powder, with a water reduction rate of 35%. The pH value of the aqueous solution with a mass concentration of 20% formed by the superplasticizer at 23°C is 7.2.

[0087] Mix each raw material by weight at 25°C with a stirring speed of 350 r / min for 5 min to obtain a dry powder. Then, mix the dry powder and water at a mass ratio of 1:0.35 at 25°C with a stirring speed of 300 r / min for 3 min to obtain a mixture.

[0088] Grind and clean the floating slurry and impurities on the surface of the precast concrete member until the natural pore roughness of the concrete is exposed. Spray the above mixture on the surface of the precast concrete member using a mortar spraying machine, and control the coating thickness at 4 mm. Then, seal the concrete structure with plastic sheeting. After maintaining for 30 min at 25°C and 50% RH, then introduce CO 2 , until the volume concentration of CO 2 in the sealed environment is 55%, the carbonation curing time is 2 d, the temperature of carbonation curing is 25°C, and the humidity is 55% RH. At the same time, monitor the CO 2 in the sealed environment. As CO 2 is consumed in the carbonation reaction, replenish high-concentration CO 2 in a timely manner to obtain a steel slag-based concrete carbon sequestration protective coating.

[0089] Example 2

[0090] The difference from Example 1 is that, taking the preparation of 100 g of the product as an example, 45 g of steel slag powder, 35 g of quartz sand, 6 g of 52.5 rapid hardening sulphoaluminate cement, 6 g of calcium hydroxide, 4 g of calcium oxide, 0.25 g of 902 solid powder defoamer, 1 g of hydroxypropyl methylcellulose, 1 g of polyvinyl alcohol, 0.25 g of hydroxypropyl guar gum, and 1.5 g of polycarboxylate superplasticizer are taken. The total amount of the above raw materials is 100 g. The specific surface area of the above steel slag powder is 480 m 2 / kg, and the mass percentage content of C 2 S is 25%, and the mass percentage content of C 3 S is 10%. The particle size of the above calcium hydroxide and calcium oxide is ≤28 μm, and the mass percentage content of calcium element is 98%. The above binder is polyvinyl alcohol and hydroxypropyl guar gum with a mass ratio of 1:0.25, and the rest is the same as in Example 1.

[0091] Example 3

[0092] The difference from Example 1 is that, taking the preparation of 100 g of the product as an example, 40 g of steel slag micro-powder, 30 g of quartz sand, 9 g of 52.5 rapid hardening sulphoaluminate cement, 15 g of calcium hydroxide, 0.5 g of 902 solid powder defoamer, 1 g of hydroxypropyl methylcellulose, 0.5 g of hydroxyethyl cellulose, 1 g of polyvinyl alcohol, 1 g of hydroxypropyl guar gum, and 2 g of polycarboxylate superplasticizer are taken. The total amount of the above raw materials is 100 g; the specific surface area of the above steel slag micro-powder is 450 m 2 / kg, and the mass percentage content of C 2 S is 15%, and the mass percentage content of C 3 S is 5%; the above binder is polyvinyl alcohol and hydroxypropyl guar gum with a mass ratio of 1:1; the particle size of the above calcium hydroxide is ≤30 μm, and the mass percentage content of calcium element is 98%. The rest is the same as in Example 1.

[0093] Example 4

[0094] The difference from Example 1 is that, taking the preparation of 100 g of the product as an example, 50 g of steel slag micro-powder, 30 g of quartz sand, 5 g of 52.5 rapid hardening sulphoaluminate cement, 5 g of calcium hydroxide, 4 g of calcium oxide, 0.5 g of 902 solid powder defoamer, 0.6 g of hydroxypropyl methylcellulose, 0.4 g of hydroxyethyl cellulose, 1 g of polyvinyl alcohol, 0.5 g of hydroxypropyl guar gum, and 3 g of polycarboxylate superplasticizer are taken. The total amount of the above raw materials is 100 g; the particle sizes of the above calcium hydroxide and calcium oxide are ≤25 μm, and the mass percentage content of calcium element is 98%; the above binder is polyvinyl alcohol and hydroxypropyl guar gum with a mass ratio of 1:0.5. The rest is the same as in Example 1.

[0095] Example 5

[0096] The difference from Example 1 is that, taking the preparation of 100 g of the product as an example, 40 g of steel slag micro-powder, 40 g of quartz sand, 5 g of 52.5 rapid hardening sulphoaluminate cement, 6 g of calcium hydroxide, 4 g of calcium oxide, 0.2 g of 902 solid powder defoamer, 0.7 g of hydroxypropyl methylcellulose, 0.3 g of hydroxyethyl cellulose, 1 g of polyvinyl alcohol, 0.8 g of resin powder, and 2 g of polycarboxylate superplasticizer are taken. The total amount of the above raw materials is 100 g; the particle sizes of the above calcium hydroxide and calcium oxide are ≤25 μm, and the mass percentage content of calcium element is 98%; the above binder is polyvinyl alcohol and resin powder with a mass ratio of 1:0.8. The rest is the same as in Example 1.

[0097] Comparative Example 1

[0098] The difference from Example 1 is that the specific surface area of the steel slag micro-powder is 380 m 2 / kg, and the mass percentage content of C 2 S is 20%, and the mass percentage content of C 3The mass percentage content of S is 8%, and the rest is the same as in Example 1.

[0099] Comparative Example 2

[0100] The difference from Example 1 is that 52.5 ordinary Portland cement is used to replace 52.5 quick-setting sulphoaluminate cement, and the rest is the same as in Example 1.

[0101] Comparative Example 3

[0102] The difference from Example 1 is that natural sand with the same particle size distribution of 0.85 - 2 mm is used to replace quartz sand (river sand), and the rest is the same as in Example 1.

[0103] Comparative Example 4

[0104] The difference from Example 1 is that calcium hydroxide is not added, and the rest is the same as in Example 1.

[0105] Comparative Example 5

[0106] The difference from Example 1 is that polyvinyl alcohol is not added, and the rest is the same as in Example 1.

[0107] Performance Test

[0108] Refer to the experimental methods and requirements in JC / T 984 - 2011 "Polymer Cement Waterproof Mortar" and JC / T 2381 - 2016 "Repair Mortar" to measure the steel slag-based concrete carbon sequestration protective coatings obtained in Examples 1 - 5 and Comparative Examples 1 - 5, and the results are shown in Tables 1 - 3.

[0109] Table 1 Performance Measurement Table of Steel Slag-based Concrete Carbon Sequestration Protective Coating

[0110]

[0111]

[0112] Table 2 Performance Test Results of Steel Slag-based Concrete Carbon Sequestration Protective Coatings Obtained in Examples 1 - 5

[0113]

[0114] Table 3 Performance Test Results of Steel Slag-based Concrete Carbon Sequestration Protective Coatings Obtained in Comparative Examples 1 - 5

[0115]

[0116]

[0117] As can be seen from Table 2 and Table 3, compared with Comparative Examples 1 to 5, the steel slag-based concrete carbon sequestration protective coatings obtained in Examples 1 to 5 of the present invention have excellent compressive strength, flexural strength and bond strength, and are a steel slag-based concrete carbon sequestration protective coating with excellent effects, low cost and convenient construction.

[0118] Although the above embodiments have made a detailed description of the present invention, they are only a part of the embodiments of the present invention rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A steel slag-based concrete carbon sequestration and protection coating, characterized in that, by mass parts, its preparation raw materials include the following components: 40-50 parts of steel slag powder, 30-40 parts of quartz sand, 5-10 parts of quick-setting and quick-hardening cement, 9-15 parts of calcium supplement, 0.1-0.5 parts of defoamer, 1-1.5 parts of thickener, 1-2 parts of binder, 1-5 parts of water reducer, and 30-40 parts of water; The total mass parts of the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder and water reducer are 100 parts; The specific surface area of the steel slag fine powder is 450 - 500 m 2 / kg; the basicity of the steel slag fine powder ≥ 2.4; the mass percentage content of C 2 S in the steel slag fine powder is 15 - 25%, and the mass percentage content of C 3 S is 35 - 45%; The quick-setting and quick-hardening cement is 52.5 quick-hardening sulphoaluminate cement; The calcium supplement is one or more of calcium hydroxide, calcium carbonate and calcium oxide; the particle size of the calcium supplement is ≤32 µm; The preparation method of the steel slag-based concrete carbon sequestration and protection coating includes the following steps: Mix the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder, water reducer and water to obtain a mixture; After applying the mixture to the concrete surface, place it in a sealed environment and introduce CO 2 , and carry out carbonation curing to obtain a steel slag-based concrete carbon sequestration protective coating; The volume concentration of CO in the sealed environment 2 is 55 ± 5%.

2. The steel slag-based concrete carbon sequestration and protection coating according to claim 1, characterized in that, The particle size of the steel slag powder is 25-75 µm.

3. The steel slag-based concrete carbon sequestration and protection coating according to claim 1, characterized in that, The particle size of the quartz sand is 0.6-2 mm.

4. The steel slag-based concrete carbon sequestration and protection coating according to claim 1, characterized in that, The pH value of the defoamer is 6.0-7.5, and the solid content is 99.5%.

5. The steel slag-based concrete carbon sequestration and protection coating according to claim 1, characterized in that, The thickener is hydroxypropyl methylcellulose and / or hydroxyethyl cellulose.

6. The steel slag-based concrete carbon sequestration and protection coating according to claim 1, characterized in that, The binder is one or more of polyvinyl alcohol, hydroxypropyl guar gum and resin powder.

7. The steel slag-based concrete carbon sequestration and protection coating according to claim 1, characterized in that, The water reducer is a polycarboxylate-based superplasticizer; the water reduction rate of the water reducer is ≥30%.

8. The preparation method of the steel slag-based concrete carbon sequestration and protection coating according to any one of claims 1-7, including the following steps: Mix the steel slag powder, quartz sand, quick-setting and quick-hardening cement, calcium supplement, defoamer, thickener, binder, water reducer and water to obtain a mixture; After applying the mixture to the concrete surface, place it in a sealed environment and introduce CO 2 , and carry out carbonation curing to obtain a steel slag-based concrete carbon sequestration protective coating.

9. The application of the steel slag-based concrete carbon sequestration and protection coating according to any one of claims 1-7 or the steel slag-based concrete carbon sequestration and protection coating prepared by the preparation method according to claim 8 in concrete protection.

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