Permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption and preparation method thereof

Abstract

The present invention provides a permeable concrete and a preparation method for the multi-solid waste synergistic and efficient carbon dioxide adsorption, wherein the permeable concrete contains: 600-900 parts of silicate cement, 240-450 parts of functional admixtures, 2100-4050 parts of crushed stone, and 180-360 parts of water. In the present invention, on the one hand, the carbon fixation effect is achieved through the alkaline wet grinding effect of solid waste materials; on the other hand, the layered double metal hydroxides (LDHs) with unique layered structure and anion adsorption function prepared from solid waste-based materials improve the effect of concrete adsorption and fixation of carbon dioxide; promote the sustainable development of low-carbon concrete materials, and provide a theoretical basis for achieving carbon neutrality in construction projects during the construction period.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to a permeable concrete capable of efficiently absorbing carbon dioxide through synergistic use of multiple solid wastes and a preparation method thereof. Background Art

[0002] Permeable concrete is an important material basis for the construction of "sponge cities". With the promotion and application of permeable concrete, many problems have also been exposed. Low strength is one of the main disadvantages of permeable concrete. Ordinary permeable concrete has low strength and is difficult to meet the strength requirements of daily vehicle parking and driving, which greatly limits its application area.

[0003] Pervious concrete mostly adopts single gradation or discontinuous gradation, with little or no fine aggregate, resulting in fewer contact points between aggregates, more pores, and easy stress concentration, which cannot bear the force normally like ordinary concrete. In addition, due to the characteristics of pervious concrete such as internal porosity and easy clogging, the freeze-thaw damage it suffers is even more serious than that of ordinary concrete, directly causing quality loss and internal structural damage. In addition, the complex mix ratio of pervious concrete and the unstable molding quality have always been a headache. Summary of the invention

[0004] In response to the above problems, a permeable concrete and a preparation method for the synergistic and efficient adsorption of carbon dioxide by multiple solid wastes are provided, aiming to prepare CaAl-LDHs under conditions such as wet grinding of solid wastes, thereby improving the carbon dioxide adsorption characteristics of the permeable concrete and enhancing the mechanical properties of the permeable concrete.

[0005] The beneficial effects of the above scheme are:

[0006] 1) In the present invention, CO 2 The synergistic wet grinding of steel slag and slag improves the grinding efficiency and dissolves Ca － , Cl － OH － Plasma promotes the formation of hydration products, effectively improving the chemical activity of steel slag and slag; wet grinding makes steel slag and slag particles ultra-fine, and the glass phase (active component) inside is broken up and peeled off from quartz, mullite and other crystal phases, which helps to improve their hydration activity. A large number of Si-O and Al-O bonds in the particles are broken, and some of them form Si-OH, Al-OH and alkaline ion OH in the liquid environment. － On the other hand, the silicon-aluminum phase groups dissolved in the liquid environment are more conducive to the secondary hydration reaction under the action of cement hydration, which solves the problem of low activity and low utilization rate of steel slag and slag. On the other hand, steel slag and slag are wet-milled to produce alkaline solution, and the ions dissolved in the wet-milling are dispersed in the liquid environment and react with CO 2After sufficient contact, a reaction occurs to generate stable carbonates, achieving a carbon fixation effect;

[0007] 2) In the present invention, fly ash (aluminum phase) and carbide slag (calcium phase) are used as the main raw materials, and Ca(OH) is extracted by wet grinding and high temperature conditions. 2 、Al(OH) 3 The powders were then wet-milled at high temperature under chemical reagents to form CaAl-LDHs (CaAl hydrotalcite) suspension, which increased the CO 2 Adsorption capacity (the adsorption mechanism of CaAl-LDHs is mainly the interlayer anion exchange reaction. The order of exchange capacity between the interlayer anions of CaAl-LDHs and other anion pairs in the solution is SO 4 2－ >CO 3 2－ >OH － , when the atmospheric CO 2 Entering the cement matrix, it reacts to produce CO 3 2－ , CO 3 2－ and SO 4 2－ It will destroy the structure of CaAl-LDHs and react to form CaCO 3 or CaSO 4 , achieving CO 2 Adsorption effect);

[0008] (3) CaAl-LDHs promote the early hydration and strength development of cement concrete through two forms: nucleation effect and change of pore solution composition. CaAl-LDHs can provide nucleation sites for cement hydration and adsorb excess free water and SO 4 2－ , which increases the hydration rate of silicate cement and promotes the hardening of paste; CaAl-LDHs can significantly accelerate the reaction of silicate cement, increase the content of early reaction products, and improve the early mechanical properties of permeable concrete; in addition, in CO 2 Under maintenance conditions, CO 2 After entering the cement matrix, it reacts with the calcium-containing phase and water to generate calcium carbonate, i.e., carbonization. Carbonization will cause the pH value of the pore solution to decrease. The CaAl-LDHs in the concrete will react with CO 3 2－ The adsorption of CO 3 2－ The probability of contact with calcium ions and other calcium-containing phases, and the OH released at the same time － It plays a buffering role on the pH value of the pore solution. The Ca(OH) 2The high content promotes the hydration of cement under alkaline conditions; it strengthens the connectivity between pores in permeable concrete and solves the problem of low strength of permeable concrete. DETAILED DESCRIPTION

[0009] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0010] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0011] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0012] In an embodiment of the present invention, a permeable concrete is provided for efficient carbon dioxide adsorption by synergistic use of multiple solid wastes, wherein the median particle size of fly ash used is D50=10 μm-20 μm, and the main chemical composition content thereof is: Al 2 O 3 ≥31.69%, CaO≤4.12%, SiO 2 ≤48.33%; the median particle size of carbide slag is D50 = 10μm ~ 20μm, and its main chemical composition content is: CaO ≥ 65.03%, Al 2 O 3 ≤1.34%; slag is ground granulated blast furnace slag, with a specific surface area of ​​≥410m 2 / kg, the main chemical composition content is: CaO ≥ 38.6%, SiO 2 ≥36.9%,Al 2 O 3 ≤12.3%; specific surface area of ​​silicate cement ≥419.7m 2 / kg, density ≥3.14g / cm 3 ; Crushed stone is crushed gravel, with an apparent density of ≥2903kg / m 3 , compact packing density ≥1628kg / m 3 The particle size is 4.75-9.50 mm; the grinding medium is formed by mixing small zirconia balls of 0.8-1.0 mm and large zirconia balls of 1.2-1.4 mm in a mass ratio of 1:2 or 2:5.

[0013] Example 1

[0014] A permeable concrete capable of efficiently absorbing carbon dioxide by synergistically using multiple solid wastes, the preparation of which comprises the following steps:

[0015] 1) 60 parts of fly ash, 60 parts of calcium carbide slag, 300 parts of grinding media, and 40 parts of water were put into a planetary ball mill, and wet-milled at a speed of 400 r / min for 60 min, and passed through a 30-mesh square hole sieve to obtain an alkaline slurry with a median particle size of 5 μm. The alkaline slurry was placed in an oven and dried at a temperature of 70° C. After being taken out, it was ground and passed through a 100-mesh square hole sieve to obtain 50 parts of powder A;

[0016] 2) Mix 50 parts of powder A, 40 parts of water, and 4 parts of 0.078 mol / L HNO 3 The solution and 300 parts of grinding media were put into a planetary ball mill, and wet-milled for 40 min at a speed of 400 r / min, and passed through a 30-mesh square hole sieve to obtain a slurry with a median particle size of 6 μm. The slurry was heated at 30° C. for 2 h to obtain a CaAl-LDHs crystal suspension B;

[0017] 3) Take 30 parts of slag, 30 parts of steel slag, 200 parts of grinding media, and 40 parts of water and put them into a vertical planetary ball mill. Then, CO2 was introduced from bottom to top at a rate of 0.5 L / min. 2 , wet-milled at a speed of 400 r / min for 60 min, passed through a 30-mesh square-hole sieve, and obtained an ultrafine slurry admixture C with a median particle size of 8 μm;

[0018] 4) The suspension B prepared above and the ultrafine slurry admixture C are mixed uniformly in a ratio of 1:1 to obtain 240 parts of functional admixture;

[0019] 5) Place 240 parts of functional admixture, 600 parts of Portland cement and 100 parts of water in a forced mixer and stir for 30 to 45 seconds. After fully stirring, take 2100 parts of crushed stone and place them in the mixer. Continue stirring for 120 seconds to make the slurry evenly adhere to the surface of the crushed stone aggregate. Finally, pour and cure the slurry and remove the mold to obtain a permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption.

[0020] Example 2

[0021] A permeable concrete capable of efficiently absorbing carbon dioxide by synergistically using multiple solid wastes, the preparation of which comprises the following steps:

[0022] 1) 80 parts of fly ash, 80 parts of calcium carbide slag, 350 parts of grinding media, and 60 parts of water were put into a planetary ball mill, and wet-milled at a speed of 425 r / min for 70 min, and passed through a 30-mesh square hole sieve to obtain an alkaline slurry with a median particle size of 4 μm. The alkaline slurry was placed in an oven and dried at 85° C. After being taken out, it was ground through a 100-mesh square hole sieve to obtain 60 parts of powder A;

[0023] 2) Mix 60 parts of powder A, 60 parts of water, and 5 parts of 0.078 mol / L HNO3 The solution and 350 parts of grinding media were put into a planetary ball mill, and wet-milled for 50 min at a speed of 425 r / min, and passed through a 30-mesh square-hole sieve to obtain a slurry with a median particle size of 5 μm. The slurry was heated at 35° C. for 2.5 h to obtain a CaAl-LDHs crystal suspension B;

[0024] 3) Take 50 parts of slag, 50 parts of steel slag, 250 parts of grinding media, and 60 parts of water and put them into a vertical planetary ball mill. Then, CO2 was introduced from bottom to top at a rate of 0.8 L / min. 2 , wet-milled at a speed of 425 r / min for 80 min, passed through a 30-mesh square-hole sieve, and obtained an ultrafine slurry admixture C with a median particle size of 7 μm;

[0025] 4) The suspension B prepared above and the ultrafine slurry admixture C are uniformly mixed in a ratio of 5:6 to obtain 300 parts of functional admixture;

[0026] 5) Place 300 parts of functional admixture, 800 parts of Portland cement and 120 parts of water in a forced mixer and stir for 30 to 45 seconds. After fully stirring, take 3000 parts of crushed stone and place them in the mixer. Continue stirring for 120 seconds to make the slurry evenly adhere to the surface of the crushed stone aggregate. Finally, pour the slurry, remove the mold after curing, and obtain a permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption.

[0027] Example 3

[0028] A permeable concrete capable of efficiently absorbing carbon dioxide by synergistically using multiple solid wastes, the preparation of which comprises the following steps:

[0029] 1) 80 parts of fly ash, 80 parts of calcium carbide slag, 350 parts of grinding media, and 80 parts of water were put into a planetary ball mill, and wet-milled at a speed of 450 r / min for 70 min, and passed through a 30-mesh square hole sieve to obtain an alkaline slurry with a median particle size of 3 μm. The alkaline slurry was put into an oven and dried at a temperature of 90° C. After being taken out, it was ground and passed through a 100-mesh square hole sieve to obtain 80 parts of powder A;

[0030] 2) Mix 80 parts of powder A, 80 parts of water, and 5 parts of 0.078 mol / L HNO 3 The solution and 350 parts of grinding media were put into a planetary ball mill, and wet-milled at a speed of 450 r / min for 50 min, and passed through a 30-mesh square hole sieve to obtain a slurry with a median particle size of 6 μm. The slurry was heated at 40° C. for 3 h to obtain a CaAl-LDHs crystal suspension B;

[0031] 3) Take 55 parts of slag, 55 parts of steel slag, 250 parts of grinding media, and 80 parts of water and put them into a vertical planetary ball mill. Then, CO2 was introduced from bottom to top at a rate of 1 L / min. 2, wet-milled at a speed of 450 r / min for 90 min, passed through a 30-mesh square-hole sieve, and obtained an ultrafine slurry admixture C with a median particle size of 6 μm;

[0032] 4) The suspension B prepared above and the ultrafine slurry admixture C are uniformly mixed in a ratio of 5:6 to obtain 350 parts of functional admixture;

[0033] 5) Place 350 parts of functional admixture, 800 parts of Portland cement and 100 parts of water in a forced mixer and stir for 30 to 45 seconds. After fully stirring, take 3500 parts of crushed stone and place them in the mixer. Continue stirring for 120 seconds to make the slurry evenly adhere to the surface of the crushed stone aggregate. Finally, pour and cure the slurry and remove the mold to obtain a permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption.

[0034] Example 4

[0035] A permeable concrete capable of efficiently absorbing carbon dioxide by synergistically using multiple solid wastes, the preparation of which comprises the following steps:

[0036] 1) 90 parts of fly ash, 90 parts of carbide slag, 400 parts of grinding media and 100 parts of water were put into a planetary ball mill, wet-milled at a speed of 450 r / min for 80 min, passed through a 30-mesh square hole sieve to obtain an alkaline slurry with a median particle size of 3 μm, and the alkaline slurry was put into an oven for drying at a temperature of 100° C. After being taken out, it was ground and passed through a 100-mesh square hole sieve to obtain 100 parts of powder A;

[0037] 2) Mix 100 parts of powder A, 100 parts of water, and 6 parts of 0.078 mol / L HNO 3 The solution and 400 parts of grinding media were placed in a planetary ball mill, wet-milled at a speed of 450 r / min for 60 min, passed through a 30-mesh square-hole sieve to obtain a slurry with a median particle size of 4 μm, and the slurry was heated at 40° C. for 3 h to obtain a CaAl-LDHs crystal suspension B;

[0038] 3) Take 60 parts of slag, 60 parts of steel slag, 300 parts of grinding media, and 160 parts of water and put them into a vertical planetary ball mill. Then, circulate CO from bottom to top at a rate of L / min. 2 , wet-milled at a speed of 450 r / min for 120 min, passed through a 30-mesh square-hole sieve, and obtained an ultrafine slurry admixture C with a median particle size of 5 μm;

[0039] 4) The suspension B prepared above and the ultrafine slurry admixture C are uniformly mixed in a ratio of 5:6 to obtain 450 parts of a functional admixture;

[0040] 5) Place 450 parts of functional admixture, 900 parts of Portland cement and 100 parts of water in a forced mixer and stir for 30 to 45 seconds. After fully stirring, take 4050 parts of crushed stone and place it in the mixer. Continue stirring for 120 seconds to make the slurry evenly adhere to the surface of the crushed stone aggregate. Finally, pour the slurry, remove the mold after curing, and obtain a permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption.

[0041] Comparative Example 1

[0042] A common permeable concrete comprises the following preparation methods: 600 parts of Portland cement PII52.5R, 72 parts of 920 grade silica fume, 1.8 parts of polycarboxylate water reducer and 180 parts of water are placed in a forced mixer and stirred for 45 seconds to be fully and evenly stirred; 2100 parts of crushed stone are placed in the mixer and stirred for 180 seconds to make the slurry evenly adhere to the surface of the crushed stone aggregate, and the slurry is poured, cured and demolded to form the common permeable concrete.

[0043] The performance of the permeable concrete prepared in Examples 1 to 4 and Comparative Example 1 was tested respectively, and the test results are shown in the following table.

[0044] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Compressive strength / 28d(MPa) 45.6 50.4 43.9 51.8 35.6 Flexural strength / 28d(MPa) 15.89 15.52 15.7 15.4 11.7 Water permeability / mm / s 0.64 0.65 0.64 0.63 0.52 Carbon dioxide consumption / kg / cubic meter 7.2 9.0 10.5 13.5 0 Water erosion resistance / % 95 96 95 96 91

[0045] It can be seen from the above table that the permeable concrete with multi-solid waste synergistically efficient carbon dioxide adsorption prepared in Examples 1 to 4 of the present invention is superior to the permeable concrete in Comparative Example 1 in terms of concrete mechanical properties, water permeability coefficient, and resistance to flowing water erosion.

[0046] In addition, compared with Comparative Example 1, the permeable concrete prepared by Examples 1 to 4 of the present invention with multi-solid waste synergistically and efficiently adsorbing carbon dioxide significantly improved the mechanical properties of the permeable concrete and solved the problem of low strength of the permeable concrete; in addition, the permeable concrete prepared by multi-solid waste synergistic wet grinding prepared by the present invention effectively adsorbed carbon dioxide by preparing CaAl-LDHs through solid waste synergistic wet grinding, and the carbon dioxide consumption increased. It can be seen that the permeable concrete prepared by multi-solid waste synergistic wet grinding in this application improves the effect of permeable concrete in adsorbing and fixing carbon dioxide, promotes the sustainable development of low-carbon concrete materials, and provides a theoretical basis for achieving carbon neutrality in construction projects during the construction period.

[0047] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption, characterized in that: The steps include: 1) 60-90 parts of fly ash, 60-90 parts of carbide slag, 300-400 parts of grinding media, and 40-100 parts of water are put into a planetary ball mill, wet-milled at a speed of 400-450 r / min for 60-80 min, passed through a 30-mesh square hole sieve to obtain an alkaline slurry with a median particle size of 3-5 μm, and the alkaline slurry is placed in an oven and dried at a temperature of 70-100° C., taken out, ground and passed through a 100-mesh square hole sieve to obtain 50-100 parts of powder A; 2) 50-100 parts of powder A, 40-100 parts of water, 4-6 parts of 0.078 mol / L HNO3 solution, and 300-400 parts of grinding media are placed in a planetary ball mill, wet-milled at a speed of 400-450 r / min for 40-60 min, passed through a 30-mesh square hole sieve to obtain a slurry with a median particle size of 4-6 μm, and the slurry is heated at 30-40° C. for 2-3 h to obtain a CaAl-LDHs crystal suspension B; 3) 30-60 parts of slag, 30-60 parts of steel slag, 200-300 parts of grinding media, and 40-100 parts of water are put into a vertical planetary ball mill, CO2 is introduced from bottom to top at a rate of 0.5-1 L / min, wet-milled at a speed of 400-450 r / min for 60-120 min, and passed through a 30-mesh square hole sieve to obtain an ultrafine slurry admixture C with a median particle size of 5-8 μm; 4) The suspension B and the ultrafine slurry admixture C are uniformly mixed in a mass ratio of 1:1 or 5:6 to obtain a functional admixture; 5) Place 240-450 parts of functional admixture, 600-900 parts of Portland cement and 180-360 parts of water in a forced mixer and stir for 30-45 seconds. After fully stirring, take 2100-4050 parts of crushed stone and place them in the mixer. Continue stirring for 120-180 seconds to make the slurry evenly adhere to the surface of the crushed stone aggregate. Finally, pour and cure the slurry and remove the mold to obtain a permeable concrete with multi-solid waste synergistic and efficient carbon dioxide adsorption.

2. The preparation method according to claim 1, characterized in that: The median particle size of the fly ash is D50=10 μm-20 μm, and the main chemical composition content thereof is: Al2O3≥31.69%, CaO≤4.12%, and SiO2≤48.33%.

3. The preparation method according to claim 1, characterized in that: The median particle size of the carbide slag is D50=10μm-20μm, and its main chemical composition content is: CaO≥65.03%, Al2O3≤1.34%.

4. The preparation method according to claim 1, characterized in that: The slag is ground granulated blast furnace slag, and its specific surface area is ≥410m 2 / kg, the main chemical composition content is: CaO ≥ 38.6%, SiO2 ≥ 36.9%, Al2O3 ≤ 12.3%.

5. The preparation method according to claim 1, characterized in that: The grinding medium is formed by mixing small zirconia balls with a size of 0.8 to 1.0 mm and large zirconia balls with a size of 1.2 to 1.4 mm in a mass ratio of 1:2 or 2:

5.

6. The preparation method according to claim 1, characterized in that: The specific surface area of ​​the silicate cement is ≥419.7m 2 / kg, density ≥3.14g / cm 3 .

7. The preparation method according to claim 1, characterized in that: The crushed stone is crushed gravel, and its apparent density is ≥2903kg / m 3 , compact packing density ≥1628kg / m 3 , particle size is 4.75~9.50mm.

8. A permeable concrete with multiple solid wastes for efficient carbon dioxide adsorption, characterized in that: Prepared according to the preparation method according to any one of claims 1-7.