Carbonized reinforced steel slag concrete and preparation method thereof

Abstract

The present invention discloses a steel slag carbonization-reinforced concrete, the components and their weight percentages including: 250-350 parts of ordinary Portland cement, 50-150 parts of fly ash, 50-100 parts of mineral powder, 30-50 parts of silica fume, 650-850 parts of modified steel slag, 950-1100 parts of stone, 5-10 parts of a composite water reducer, and 140-170 parts of water; wherein the modified steel slag is obtained by adding steel slag to a culture medium containing iron-oxidizing bacteria, and carrying out oscillation culture and drying under the condition of introducing CO2. The present invention utilizes the metabolic mechanism and carbonization method of iron-oxidizing bacteria to modify steel slag, and combines it with a composite water reducer. While achieving the resource utilization of large amounts of steel slag, it can effectively take into account the stability, construction performance, and durability of steel slag concrete, etc., has significant economic and environmental benefits, and is suitable for promotion and application.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to steel slag carbonization reinforced concrete and a preparation method thereof. Background Art

[0002] With the widespread application of concrete in the construction field, sand and gravel resources, as natural aggregates of concrete, have become increasingly scarce, causing a series of environmental problems; it is urgent to further find suitable substitutes for coarse and fine aggregates in concrete.

[0003] The rapid development of industrialization has led to the widespread dumping of industrial waste. Industrial waste mainly includes steel slag, lithium slag, and mineral slag. Steel slag has a porous surface, high hardness, and good wear resistance, similar to sand and gravel aggregates. However, these steel slags are not currently being fully utilized, and some are even directly dumped in farmland, causing environmental pollution. Research into using steel slag to replace coarse and fine aggregates in concrete is imperative.

[0004] While steel slag aggregates and slag powder have been studied in the building materials industry, their widespread use is limited by their poor stability, which can easily damage concrete surfaces or structural damage. At room temperature, the f-CaO and f-MgO in steel slag readily hydrate, leading to volume expansion and severely impacting its application in building materials. Furthermore, steel slag concrete exhibits poor construction performance, making pumping difficult, resulting in significant shrinkage and the development of shrinkage cracks. Summary of the Invention

[0005] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a carbonized reinforced steel slag carbon concrete. While realizing the resource utilization of large amounts of steel slag, it can effectively take into account the stability, construction performance and durability of steel slag concrete, etc., has significant economic and environmental benefits, and is suitable for promotion and application.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A steel slag carbonization reinforced concrete comprises the following components and their weight proportions: 250-350 parts of ordinary Portland cement, 50-150 parts of fly ash, 50-100 parts of mineral powder, 30-50 parts of silica fume, 650-850 parts of modified steel slag, 950-1100 parts of stone, 5-10 parts of composite water reducer, and 140-170 parts of water; wherein the modified steel slag is obtained by adding steel slag to a culture solution containing iron-oxidizing bacteria, and performing oscillation culture and drying under the condition of introducing CO2.

[0008] Furthermore, the specific preparation steps of the modified steel slag include: taking 1.5-2 kg of steel slag, drying it, adding 11-15 L of culture solution containing iron-oxidizing bacteria, introducing CO2, performing shaking culture, and finally drying to obtain modified steel slag.

[0009] In the above solution, the flow rate of the CO2 is 1500-2500 sccm; the purity of the CO2 gas is 97-99.5 vol%.

[0010] In the above scheme, the drying temperature is 100-115° C. and the drying time is 1.5-2 hours.

[0011] In the above scheme, the shaking culture step adopts a temperature of 23-25° C., a shaking rate of 150-200 r / min, and a time of 10 d to 11 d.

[0012] Preferably, during the shaking culture process, an equal amount of the culture medium containing iron-oxidizing bacteria is replaced every 286 to 290 hours.

[0013] In the above scheme, the obtained modified steel slag is stored in an environment with a temperature of 20-25° C. and a humidity of not less than 50%.

[0014] In the above scheme, the steps of preparing the culture solution containing iron-oxidizing bacteria include:

[0015] 1) The main components of the culture medium and their weight percentages include: 0.2-1.5 parts of CaCl2·2H2O, 0.5-1.0 parts of KH2PO4·3H2O, 0.5-1.0 parts of NaNO3, 0.5-1.2 parts of (NH4)2SO4, 0.5-1.2 parts of MgSO4·7H2O, 10-15 parts of ammonium ferric citrate (FeC6H5O7·NH4OH), and 100-110 parts of water;

[0016] Dissolve the weighed components in water (100-110 parts), adjust the pH to 6.9-7.1 with NaOH solution, gradually add 20-30 parts of agar powder to the solution under heating conditions (95-100°C), and stir continuously to prevent the bottom from becoming sticky. When the agar is completely dissolved and the culture solution becomes viscous and solidifiable, sterilize it and cool it to room temperature (20-25°C) to obtain the culture medium.

[0017] 2) Soaking an iron block in water, breaking the rust layer with a glass rod after the rust layer falls off, applying the water sample to a culture medium, and inverting the culture medium in a constant temperature incubator until white filamentous colonies appear on the surface of the culture medium; picking a single white filamentous fungus and inoculating it into 50-60 mL of new selective culture medium and continuing to culture until a reddish-brown circular colony with a diameter of 1-3 mm is formed; picking a single reddish-brown circular colony and inoculating it again (50-60 mL of culture medium) until the morphology of the subsequently grown colonies remains unchanged, thereby obtaining a culture solution containing iron-oxidizing bacteria.

[0018] Furthermore, in the culture solution containing iron-oxidizing bacteria, the content of iron-oxidizing bacteria is 5 to 30 wt%.

[0019] In the above solution, the main chemical components of the steel slag and their mass percentages include: CaO 35-37%, iron oxide content 30-35%, SiO2 8-10%, and Al2O3 2-5%.

[0020] Furthermore, in the iron oxide, the content of FeO is 5 to 10 wt%.

[0021] Furthermore, the content of free calcium oxide in the steel slag is 4-6%.

[0022] In the above scheme, the preparation method of the composite water reducing agent includes:

[0023] 1) Weighing a polyether macromonomer and potassium methyl silicate and mixing them evenly to obtain a base liquid;

[0024] 2) Evenly mix acetic acid, thioglycolic acid, and water to obtain a mixed solution I; evenly mix hydroxypropionic acid and water to obtain a mixed solution II;

[0025] 3) The obtained mixed solution I and mixed solution II are added dropwise to the base liquid, and hydrogen peroxide and a stabilizer are added at the same time, and the mixture is stirred after the addition is completed to obtain the composite water reducing agent.

[0026] In the above solution, the polyether macromonomer can be selected from one or more of allyl polyoxyethylene ether, methallyl polyoxyethylene ether, etc.

[0027] Furthermore, the molecular weight of the polyether macromonomer is 1500-2400.

[0028] In the above scheme, the main raw materials of the composite water reducer and their weight proportions include: 20-35 parts of polyether macromonomer, 12-25 parts of potassium methyl silicate, 2-5 parts of acetic acid, 2-5 parts of thioglycolic acid, 2-5 parts of hydroxypropionic acid, 10-20 parts of hydrogen peroxide, and 2-8 parts of stabilizer.

[0029] Furthermore, the concentration of the hydrogen peroxide solution is 6 to 10 vol%.

[0030] Furthermore, the stabilizer may be ammonium persulfate or sodium persulfate, etc.; this can promote a continuous polymerization reaction and effectively improve the problem of slow reaction after the introduction of potassium methyl silicate.

[0031] In the above solution, the effective solid content of the composite water reducer is 11-14%.

[0032] In the above scheme, the mixed solution I and the mixed solution II are added using a peristaltic meter at a dropping rate of 1.5 to 3.0 g / min.

[0033] In the above scheme, the stirring treatment time in step 3) is 30 to 45 minutes.

[0034] The above-mentioned method for preparing steel slag carbonization-strengthened concrete comprises the following steps:

[0035] 1) Weigh the raw materials according to the proportions. The components and their weight percentages include: 250-350 parts of ordinary Portland cement, 50-150 parts of fly ash, 50-100 parts of mineral powder, 30-50 parts of silica fume, 650-850 parts of modified steel slag, 950-1100 parts of stone, 5-10 parts of composite water reducer, and 140-170 parts of water;

[0036] 2) First, ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone are added and stirred once, then part of the water is added and stirred twice, and the remaining water and composite water reducer are added and stirred three times to obtain a steel slag carbonization-strengthened concrete mixture;

[0037] 3) Forming and curing: pouring, vibrating, and forming; stopping, removing the formwork, and curing in a curing room to obtain the steel slag carbonization-strengthened concrete.

[0038] In the above scheme, in step 2), 1 / 3 to 1 / 2 of the amount of water is first added.

[0039] In the above scheme, the first stirring treatment time in step 2) is 20 to 30 seconds, the second stirring time is 30 to 50 seconds, and the third stirring time is 60 to 120 seconds.

[0040] In the above scheme, the vibration time is 30 to 90 seconds.

[0041] Preferably, before vibrating, manually tamp in a clockwise direction from the outside to the inside, and tap in all directions around with a rubber hammer.

[0042] In the above scheme, the static process conditions include: temperature of 20-25°C, humidity of more than 50%, and time of 24-32 hours.

[0043] The steel slag carbonization reinforced concrete prepared according to the above scheme has a concrete slump of 200-230 mm, an expansion of 580-630 mm, a 28-day compressive strength of 35-60 MPa, and a 3-day concrete shrinkage of 50-100×10 -6 , the carbonization depth at 28d is 0.1~0.9mm.

[0044] The principle of the present invention is:

[0045] The present invention utilizes the metabolic mechanism of iron-oxidizing bacteria to efficiently modify steel slag, oxidizing some of the +2-valent iron in the slag to +3-valent iron, thereby improving its CO2 adsorption capacity. Simultaneously, carbonization increases the surface hardness and strength of the slag, thereby enhancing the strength of the slag cementitious material, promoting the dissolution of calcium and magnesium ions in the slag, and reducing the f-CaO and f-MgO contents in the slag, thus providing suitable conditions for the mineralization reaction. Combining microbial modification technology with indirect carbon fixation technology through leaching of steel slag (carbonization by immersion in a carbon dioxide-containing solution) achieves the dual goals of modification and rapid carbon fixation.

[0046] The present invention uses polyether macromonomer and potassium methyl silicate as main raw materials to prepare a composite water-reducing agent, which is introduced into the preparation of steel slag concrete. On the basis of ensuring good water-reducing performance, the surface tension of steel slag can be effectively increased (the surface tension of steel slag-based aggregate can be enhanced when in contact with water, and the water absorption rate of aggregate can be reduced), the water absorption rate of steel slag-based aggregate can be reduced, the working performance of steel slag concrete can be optimized, and the effects of eliminating unstable factors of steel slag and improving gelling properties can be achieved, thereby realizing high-value-added utilization of steel slag waste.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1) The modified steel slag of the present invention can effectively reduce the content of f-CaO and f-MgO in the steel slag, eliminate the unstable factors of the steel slag, improve its stability, and can be carbonized and strengthened by CO2, achieving the dual effects of modification and carbon fixation;

[0049] 2) The composite water-reducing agent of the present invention can effectively improve the problems of high water absorption rate on the surface of steel slag and poor concrete workability, improve the concrete paste value, and increase the fluidity and encapsulation of concrete;

[0050] 3) The steel slag concrete obtained by the present invention has the advantages of low shrinkage, good stability, excellent surface performance, enhanced carbonation resistance, etc.; it can realize the high-value-added resource utilization of steel slag, and has significant environmental and economic benefits. DETAILED DESCRIPTION

[0051] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0052] In the following examples, the specific preparation steps of the modified steel slag used are: taking 2 kg of steel slag, drying it, introducing CO2 into 15 L of culture medium containing iron-oxidizing bacteria, performing oscillation culture, and finally drying to obtain the modified steel slag; the flow rate of the CO2 introduced is 20,000 sccm; the purity of the CO2 gas is 99.5 vol%; the drying temperature is 105°C and the time is 2 h; the temperature used in the oscillation culture step is 25°C, 200 r / min, and the time is 20 d.

[0053] The steel slag used was provided by Xinjiang Bayi Iron and Steel Co., Ltd. of Baosteel Group, and had a CaO content of 36% (of which free calcium oxide content was 5%), an iron oxide content of 34%, an SiO2 content of 8%, and an Al2O3 content of 3%.

[0054] In the following examples, the steps for preparing the culture solution containing iron-oxidizing bacteria include:

[0055] 1) Weigh each component according to the culture medium formula, wherein each component and its weight percentage are: 1.0 part CaCl2·2H2O, 0.5 part KH2PO4·3H2O, 0.5 part NaNO3, 1.2 parts (NH4)2SO4, 1.2 parts MgSO4·7H2O, 12 parts ferric ammonium citrate (FeC6H5O7·NH4OH), and 100 parts distilled water; add each weighed component to water and dissolve, adjust the pH value to 7.0 with NaOH solution, gradually add 30 parts agar powder to the culture medium under heating conditions of 100°C, and stir continuously to prevent the bottom from becoming sticky; when the agar is completely dissolved and the culture medium becomes viscous and solidifiable, sterilize it and cool it to room temperature of 20°C to obtain the culture medium;

[0056] 2) soaking an iron block in water, breaking the rust layer with a glass rod after the rust layer falls off, applying the water sample to a culture medium, and inverting the culture in a constant temperature incubator at 25° C. until white filamentous colonies appear on the surface of the culture medium; picking a single white filamentous fungus and inoculating it into a new culture medium and continuing to culture; after 2 days, the colony covers the entire surface of the culture medium and gradually grows into a reddish-brown circular colony; picking a single reddish-brown circular colony and inoculating it again into the new culture medium until the morphology of the subsequently grown colonies remains unchanged, thereby obtaining a culture solution containing iron-oxidizing bacteria, and the iron-oxidizing bacteria content is 20 wt%.

[0057] In the following examples, the preparation steps of the composite water reducer used are as follows: 30 parts of a polyether macromonomer (allyl polyoxyethylene ether, molecular weight 1800) are weighed and mixed with 20 parts of potassium methyl silicate to obtain a base liquid; 5 parts of acetic acid, 3 parts of thioglycolic acid and 100 parts of water are mixed to obtain a mixed solution I; 2 parts of hydroxypropionic acid and 50 parts of water are mixed to obtain a mixed solution II; the obtained mixed solution I and mixed solution II are added dropwise to the base liquid using a peristaltic meter at a drop rate of 2 g / min, and 15 parts of hydrogen peroxide (concentration 8%) and 5 parts of a stabilizer (ammonium persulfate) are added dropwise at the same time, and the mixture is stirred after the addition is completed. The stirring treatment time is 45 minutes to obtain the composite polycarboxylate water reducer.

[0058] Example 1

[0059] A steel slag carbonization reinforced concrete, the components and their weight percentages include: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 700 parts of modified steel slag, 980 parts of stone, 8 parts of composite water reducer, and 150 parts of water; the specific preparation method includes the following steps:

[0060] First, ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone were added and stirred for a first time for 30 seconds. Then, 1 / 2 of the amount of water was added and stirred for a second time for 50 seconds. Then, the remaining water and composite water reducer were added and stirred for a third time for 120 seconds to obtain a steel slag carbonization-strengthened concrete mixture. Molding and curing were performed by pouring, vibrating, molding, and standing for 24 hours. The mold was removed and placed in a curing room for curing to obtain the steel slag carbonization-strengthened concrete. The performance test results are shown in Table 1.

[0061] Table 1 Test results of concrete properties obtained in Example 1

[0062] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 58MPa 225mm 620mm <![CDATA[85×10 -6 ]]> 0.2mm

[0063] Example 2

[0064] A steel slag carbonization reinforced concrete, the components and their weight percentages include: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 850 parts of modified steel slag, 950 parts of stone, 10 parts of composite water reducer, and 150 parts of water; the preparation method thereof comprises the following steps:

[0065] First, ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone were added and stirred for 30 seconds. Half the amount of water was added and stirred for 50 seconds. The remaining water and composite water reducer were added and stirred for a third time for 120 seconds to obtain the steel slag carbonization-strengthened concrete mixture. Forming and curing: pouring, vibrating, forming, and stabilizing for 24 hours were performed. The concrete was then removed from the mold and placed in a curing room for curing to obtain the steel slag carbonization-strengthened concrete. Performance test results are shown in Table 2:

[0066] Table 2 Test results of concrete properties obtained in Example 2

[0067] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 52MPa 230mm 630mm <![CDATA[95×10 -6 ]]> 0.4mm

[0068] Example 3

[0069] A steel slag carbonization reinforced concrete, wherein the components and their weight percentages include: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 700 parts of modified steel slag, 980 parts of stone, 8 parts of composite water reducing agent, and 150 parts of water; and the preparation method thereof comprises the following steps:

[0070] First, ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone were added and stirred for 20 seconds. One-third of the water was added and stirred for 30 seconds. The remaining water and composite water reducer were added and stirred for a third time for 60 seconds to obtain the steel slag carbonization-strengthened concrete mixture. Forming and curing: pouring, vibrating, forming, and stabilizing for 24 hours were performed. The concrete was then removed from the mold and placed in a curing room for curing to obtain the steel slag carbonization-strengthened concrete. Performance test results are shown in Table 3:

[0071] Table 3 Test results of concrete properties obtained in Example 3

[0072] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 56MPa 210mm 585mm <![CDATA[80×10 -6 ]]> 0.5mm

[0073] Comparative Example 1

[0074] A steel slag concrete comprises the following components by weight: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 700 parts of steel slag, 980 parts of stone, 8 parts of a composite water reducer, and 150 parts of water; the steel slag is provided by East Hope Group Co., Ltd. and has a calcium oxide content of 35% (including 5.1% free calcium oxide), an iron oxide content of 35%, a silicon oxide content of 9%, and an aluminum oxide content of 3.2%. The preparation method comprises the following steps:

[0075] First, ordinary Portland cement, fly ash, mineral powder, silica fume, steel slag, and stone are added and stirred for a time of 30 seconds. Then, 1 / 2 of the amount of water is added and stirred for a second time of 50 seconds. Then, the remaining water and composite water reducer are added and stirred for a third time of 120 seconds to obtain a steel slag concrete mixture. Molding and curing: pouring, vibration, molding, and static suspension for 24 hours are carried out. After demolding, the mixture is placed in a curing room for curing to obtain steel slag concrete. The performance test results are shown in Table 4.

[0076] Table 4 Concrete performance test results obtained in Comparative Example 1

[0077] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 35MPa 160mm 570mm <![CDATA[-235×10 -6 ]]> 12mm

[0078] Comparative Example 2

[0079] A steel slag concrete, comprising the following components by weight: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 850 parts of modified steel slag, 830 parts of stone, 10 parts of an ordinary high-performance water reducer, and 150 parts of water; the water reducer used is a PCA-06 standard polycarboxylate water reducer provided by Urumqi Kehuida Chemical Building Materials Co., Ltd., having a solid content of 12.5% ​​and a water reduction rate of 25%. The preparation method of the steel slag concrete comprises the following steps:

[0080] First, ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone are added and stirred for a first time for 30 seconds. Then, 1 / 2 of the amount of water is added and stirred for a second time for 50 seconds. Then, the remaining water and composite water reducer are added and stirred for a third time for 120 seconds to obtain a steel slag concrete mixture. Molding and curing: pouring, vibrating, molding, and standing for 24 hours are performed. The steel slag concrete is then removed from the mold and placed in a curing room for curing to obtain the steel slag concrete. The performance test results are shown in Table 2:

[0081] Table 5 Concrete performance test results obtained in Comparative Example 2

[0082] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 45MPa 200mm 590mm <![CDATA[115×10 -6 ]]> 1.5mm

[0083] Comparative Example 3

[0084] A steel slag concrete, comprising the following components by weight: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 700 parts of oxidized / carbonized steel slag, 980 parts of stone, 8 parts of a composite water reducer, and 150 parts of water; wherein the oxidized / carbonized steel slag is prepared by: taking 500 g of the steel slag and treating it in a vacuum chamber at a negative pressure of -70 MPa for 1 hour, then adding 100 ml of hydrogen peroxide at normal atmospheric pressure, soaking it in a vacuum chamber for 6 hours, then removing the steel slag and placing it in water, introducing CO2 into the water at a flow rate of 20,000 sccm; the purity of the CO2 gas is 99.5 vol%, and the treatment time is 20 days, thereby obtaining the oxidized / carbonized steel slag;

[0085] The preparation method of the steel slag concrete comprises the following steps:

[0086] First, ordinary Portland cement, fly ash, mineral powder, silica fume, oxidized / carbonized steel slag, and stone were added and stirred for 20 seconds. One-third of the water was added and stirred for 30 seconds. The remaining water and composite water reducer were added and stirred for a third time for 60 seconds to obtain a steel slag carbonization-strengthened concrete mixture. Forming and curing: pouring, vibrating, forming, and stabilizing for 24 hours were performed. The mixture was then removed from the mold and placed in a curing room for curing to obtain the steel slag concrete. Performance test results are shown in Table 3:

[0087] Table 6 Test results of concrete properties obtained in Comparative Example 3

[0088] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 42MPa 180mm 565mm <![CDATA[102×10 -6 ]]> 5mm

[0089] Comparative Example 4

[0090] A steel slag concrete comprises the following components by weight: 350 parts of ordinary Portland cement, 120 parts of fly ash, 80 parts of mineral powder, 30 parts of silica fume, 850 parts of modified steel slag, 950 parts of stone, 150 parts of water, and 10 parts of a water reducer. The water reducer is prepared by the following steps: using 50 parts of a polyether macromonomer (allyl polyoxyethylene ether, molecular weight 1800) as a base liquid; uniformly mixing 5 parts of acetic acid, 3 parts of thioglycolic acid, and 100 parts of water to obtain a mixed solution I; and uniformly mixing 2 parts of hydroxypropionic acid and 50 parts of water to obtain a mixed solution II; dropwise adding the obtained mixed solution I and mixed solution II to the base liquid using a peristaltic instrument at a dropwise acceleration rate of 2.5 g / min, and simultaneously adding 15 parts of hydrogen peroxide (8% concentration) and stirring after the dropwise addition is complete for 45 minutes, thereby obtaining the polycarboxylate water reducer.

[0091] The concrete preparation method comprises the following steps:

[0092] First, ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone were added and stirred for 30 seconds. Half the amount of water was added and stirred for 50 seconds. The remaining water and composite water reducer were added and stirred for a third time for 120 seconds to obtain a steel slag carbonization-strengthened concrete mixture. Forming and curing were performed by pouring, vibrating, and forming. The mixture was allowed to stand for 24 hours, then removed from the mold and placed in a curing room for curing to obtain the steel slag concrete. Performance test results are shown in Table 2:

[0093] Table 2 Test results of concrete properties obtained in Example 2

[0094] 28d compressive strength Slump Scalability Shrinkage 28d carbonization depth 48MPa 185mm 550mm <![CDATA[325×10 -6 ]]> 6.5mm

[0095] Obviously, the above embodiments are merely examples for illustrative purposes and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. However, any obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A steel slag carbonization strengthened concrete, characterized in that: The components and their weight percentages include: 250-350 parts of ordinary Portland cement, 50-150 parts of fly ash, 50-100 parts of mineral powder, 30-50 parts of silica fume, 650-850 parts of modified steel slag, 950-1100 parts of stone, 5-10 parts of composite water reducer, and 140-170 parts of water; wherein the modified steel slag is obtained by adding steel slag to a culture solution containing iron-oxidizing bacteria, and performing shaking culture and drying under the condition of introducing CO2; The preparation method of the composite water reducing agent comprises: 1) Weigh polyether macromonomer and potassium methyl silicate and mix them evenly to obtain a base liquid; 2) Evenly mix acetic acid, thioglycolic acid, and water to obtain a mixture I; evenly mix hydroxypropionic acid and water to obtain a mixture II; 3) adding the obtained mixed solution I and mixed solution II dropwise to the base liquid, and adding hydrogen peroxide and stabilizer at the same time, stirring after the addition is completed, thereby obtaining the composite water reducing agent; The main raw materials of the composite water reducer and their weight percentages include: 20-35 parts of polyether macromonomer, 12-25 parts of potassium methyl silicate, 2-5 parts of acetic acid, 2-5 parts of thioglycolic acid, 2-5 parts of hydroxypropionic acid, 10-20 parts of hydrogen peroxide, and 2-8 parts of stabilizer; The droplet acceleration rate of the mixed solution I and the mixed solution II is 1.5-3.0 g / min.

2. The steel slag carbonization reinforced concrete according to claim 1, characterized in that: The main chemical components of the steel slag and their mass percentages include: CaO 35-37%, iron oxide content 30-35%, SiO2 8-10%, and Al2O3 2-5%.

3. The steel slag carbonization reinforced concrete according to claim 2, characterized in that: In the iron oxide, the content of FeO is 5-10wt%.

4. The steel slag carbonization reinforced concrete according to claim 1, characterized in that: In the culture solution containing iron-oxidizing bacteria, the content of iron-oxidizing bacteria is 5-30 wt%.

5. The steel slag carbonization reinforced concrete according to claim 1, characterized in that: The flow rate of the CO2 is 1500~2500sccm.

6. The method for preparing steel slag carbonization-strengthened concrete according to any one of claims 1 to 5, characterized in that: The steps include: 1) Weigh the raw materials according to the proportions. The components and their weight percentages include: 250-350 parts of ordinary Portland cement, 50-150 parts of fly ash, 50-100 parts of mineral powder, 30-50 parts of silica fume, 650-850 parts of modified steel slag, 950-1100 parts of stone, 5-10 parts of composite water reducer, and 140-170 parts of water. 2) First, add ordinary Portland cement, fly ash, mineral powder, silica fume, modified steel slag, and stone for a primary mixing process, add part of the water for a secondary mixing process, add the remaining water and composite water reducer for a third mixing process, and obtain a steel slag carbonization strengthened concrete mixture; 3) Forming and curing: pouring, vibrating, and forming are performed; the concrete is stopped, the formwork is removed, and the concrete is placed in a curing room for curing to obtain the steel slag carbonization-strengthened concrete.

7. The preparation method according to claim 6, characterized in that In step 2), add 1 / 3 to 1 / 2 of the required amount of water.