Artificial stone with high strength and saltpetering-resistant effect and preparation method of artificial stone

Abstract

The invention relates to the technical field of artificial stones, in particular to an artificial stone with high strength and alkali efflorescence resistance and a preparation method of the artificial stone. The artificial stone slurry is prepared from the following components in parts by mass: 60-80 parts of steel slag, 10-20 parts of red mud, 2-3 parts of gypsum, 40-70 parts of calcium magnesite, 1-1.5 parts of calcium carbonate whiskers, 1-2 parts of fibers and 12-15 parts of water. According to the artificial stone with the high strength and the saltpetering-resistant effect and the preparation method of the artificial stone, the strength and the saltpetering-resistant effect of the artificial stone can be improved on the premise that cement is not used and the production cost is greatly reduced, so that the defects in the prior art are overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial stone, and particularly relates to an artificial stone with high strength and alkali resistance and a preparation method thereof. BACKGROUND

[0002] Artificial stone is a decorative material made of cement, admixture, quartz sand, calcium carbonate and other raw materials through high temperature and high pressure compounding. It not only has the beautiful appearance of natural stone, but also has excellent properties such as wear resistance, high temperature resistance and corrosion resistance, and is widely used in home decoration, commercial places and medical facilities and other fields.

[0003] At the same time, steel slag produced in industrial production, as a solid waste, its large accumulation not only occupies valuable land resources, but also may cause environmental pollution and other problems. In order to promote resource recycling, reduce production cost and alleviate environmental pressure, researchers have begun to explore new ways to use steel slag to prepare artificial stone. The chemical composition of steel slag includes SiO2, MgO, Al2O3 and CaO. Among them, CaO mainly exists in the form of f-CaO (i.e. free calcium oxide), and MgO mainly exists in the form of f-MgO (i.e. free magnesium oxide). CaO can react with SiO2 to generate tricalcium silicate (C3S), beta-dicalcium silicate (β-C2S) and gamma-dicalcium silicate (γ-C2S), SiO2, Al2O3 and CaO can react to generate calcium aluminum yellow longite (CaO·Al2O3·2SiO2), and CaO and MgO can also form FeO-CaO-MgO-MnO solid solution (i.e. RO phase) with other components. Therefore, the mineral composition of steel slag mainly includes tricalcium silicate, beta-dicalcium silicate, gamma-dicalcium silicate, free calcium oxide, free magnesium oxide and RO phase. Because the tricalcium silicate and beta-dicalcium silicate in the steel slag have certain hydration activity, it is beneficial to promote the use of steel slag in the preparation of artificial stone.

[0004] However, the existing technology has the following defects in the preparation of artificial stone by using the hydration activity of steel slag: (1) the content of early hydration active tricalcium silicate (C3S) in the steel slag is extremely low, the activity of beta dicalcium silicate (beta-C2S) is limited, calcium aluminum yellow long stone and gamma dicalcium silicate (gamma-C2S) have no cementitious property, and the inert RO phase in the steel slag hardly reacts with water. In addition, the hydration process of free calcium oxide and free magnesium oxide is accompanied by the risk of volume expansion, and the dense mineral structure formed at high temperature further hinders the hydration reaction. The above factors together make the overall hydration activity of the steel slag significantly lower than that of Portland cement, resulting in that the strength of the artificial stone prepared by using the steel slag itself is easy to be insufficient; (2) the free calcium oxide and free magnesium oxide in the steel slag have low hydration activity and large content, and their slow and continuous hydration in the environment not only causes the delayed expansion and cracking of the artificial stone, thereby causing serious volume stability problems, but also causes the free calcium oxide and free magnesium oxide in the steel slag to be unable to be fully utilized, thereby affecting the strength of the artificial stone. That is, the artificial stone prepared by using the steel slag in the prior art has poor strength and is difficult to meet the actual use requirements. SUMMARY

[0005] The present application aims to provide an artificial stone with high strength and anti-efflorescence effect and a preparation method thereof, which can improve the strength and anti-efflorescence effect of the artificial stone without using cement, thereby overcoming the defects in the prior art.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] An artificial stone with high strength and anti-efflorescence effect is obtained by carbonation curing and solidification of an artificial stone slurry.

[0008] According to the mass fraction, the artificial stone slurry is composed of 60-80 parts of steel slag, 10-20 parts of red mud, 2-3 parts of gypsum, 40-70 parts of calcium magnesium sand, 1-1.5 parts of calcium carbonate whiskers, 1-2 parts of fibers, and 12-15 parts of water.

[0009] The chemical composition of the steel slag includes SiO2, Al2O3, MgO and CaO, and the mineral composition of the steel slag includes tricalcium silicate, beta dicalcium silicate, gamma dicalcium silicate, calcium aluminum yellow long stone, free calcium oxide, free magnesium oxide and RO phase.

[0010] The chemical composition of the red mud includes Fe2O3, CaO, Al2O3 and Na2O, and the content of Na2O in the red mud is 10-12% according to the mass percentage; the mineral composition of the red mud includes hematite, hydrated garnet, nepheline and gibbsite.

[0011] Further, the chemical composition of the steel slag includes, in percentage by mass, Al2O3 7.5-8%, SiO2 15-16%, Na2O 0.4-0.6%, MgO 4.1-4.3%, CaO 40-41%, TiO2 0.5-1%, MnO 3-4%, and Fe2O3 20-22%, with the remainder being loss on ignition;

[0012] The chemical composition of the red mud includes, in percentage by mass, Al2O3 16-18%, SiO2 11-14%, Na2O 10-12%, MgO 0.2-0.4%, CaO 14-16%, TiO2 6-8%, MnO 0.1-0.2%, and Fe2O3 30-35%, with the remainder being loss on ignition.

[0013] Further, the calcium-magnesium sand includes, in percentage by mass, 0-30% of a first type of sand having a mesh size of ≥26 mesh and <40 mesh, 40-60% of a second type of sand having a mesh size of ≥40 mesh and <70 mesh, 15-30% of a third type of sand having a mesh size of ≥70 mesh and <120 mesh, and 10-25% of a fourth type of sand having a mesh size of ≥120 mesh and <200 mesh.

[0014] Further, the steel slag includes, in percentage by mass, 8-12% of a first type of steel slag powder having a particle size of <0.76 μm, 35-45% of a second type of steel slag powder having a particle size of ≥0.76 μm and <5.48 μm, 35-45% of a third type of steel slag powder having a particle size of ≥5.48 μm and <40.91 μm, and 8-12% of a fourth type of steel slag powder having a particle size of ≥40.91 μm.

[0015] The red mud includes, in percentage by mass, 8-12% of a first type of red mud having a particle size of <0.76 μm, 35-45% of a second type of red mud having a particle size of ≥0.76 μm and <2.78 μm, 35-45% of a third type of red mud having a particle size of ≥2.78 μm and <84.82 μm, and 8-12% of a fourth type of red mud having a particle size of ≥84.82 μm.

[0016] Further, the calcium carbonate whisker has a length of 10-20 μm, and the fiber has a length of 6-12 mm.

[0017] Further, the fiber includes any one or a combination of polypropylene fiber, polyethylene fiber, polyformaldehyde fiber, and polyvinyl alcohol fiber.

[0018] Further, the artificial stone with high strength and anti-efflorescence effect has a compressive strength of ≥50 MPa and a flexural strength of ≥19 MPa.

[0019] The application discloses a preparation method of artificial stone with high strength and anti-efflorescence effect.

[0020] A. uniformly mixing formula amount of steel slag and red mud, and obtaining first mixture after drying;

[0021] B. uniformly mixing the first mixture with formula amount of gypsum, calcium carbonate whisker and fiber to obtain second mixture;

[0022] C. uniformly mixing the second mixture, formula amount of water and calcium-magnesium sand to obtain artificial stone slurry;

[0023] D. pouring the artificial stone slurry into a mold, and obtaining intermediate product after compression molding and demolding;

[0024] E. curing the intermediate product to obtain artificial stone with high strength and anti-efflorescence effect after carbonation curing.

[0025] Further, in step E, the curing temperature of the carbonation curing is 20-90 DEG C, the curing humidity is 70-90 % RH, the curing time is 24-72 h, the curing pressure is 0.1-0.4 MPa, and the purity of CO2 is 50-99.9 %.

[0026] Further, in step D, the pressure of the compression molding is 10-50 MPa.

[0027] The technical scheme provided by the application can have the following beneficial effects:

[0028] 1. In the carbonation curing, gaseous CO2 is quickly dissolved in the slurry to form carbonic acid, and then the carbonic acid is dissociated to generate bicarbonate ions and carbonate ions; calcium hydroxide generated in the aqueous environment reacts with the bicarbonate ions / carbonate ions to generate calcium carbonate crystals, and magnesium hydroxide generated in the aqueous environment reacts with the bicarbonate ions / carbonate ions to generate magnesium carbonate crystals, so that the free calcium oxide and the free magnesium oxide in the steel slag are quickly and largely eliminated, not only eliminating the delayed expansion and cracking hidden danger caused by the slow hydration of the free calcium oxide and the free magnesium oxide, but also improving the strength of the artificial stone by filling the pores and compacting the matrix through the generated calcium carbonate crystals and magnesium carbonate crystals.

[0029] 2. Na in sodium aluminum silicate minerals (such as nepheline and gibbsite) in the red mud is replaced by Ca in the calcium carbonate whisker and the calcium-magnesium sand, so that the anti-efflorescence effect of the artificial stone is improved. +CaO in the form of f-CaO in the steel slag, and releases soluble alkali NaOH with strong alkalinity, making the artificial stone slurry in a strong alkaline environment. At the same time, Na2O in the form of soluble salt (such as NaOH and Na2CO3) in the red mud immediately dissociates, which is conducive to enhancing the alkalinity of the artificial stone slurry and making it present in a strong alkaline environment.

[0030] 3. The mechanism of the strong alkaline environment improving the strength of the artificial stone is as follows: (1) OH - in the strong alkaline environment attacks the silicon-oxygen tetrahedral network structure of mineral components such as tricalcium silicate (C3S) and β-dicalcium silicate (β-C2S) in the steel slag, promotes the dissolution of Ca 2+ and the formation of [SiO4] 4- (namely, silicate) by breaking the ≡Si-O-Si≡ bond in the above mineral components. At the same time, OH - will preferentially erode the (001) crystal face of the dense crystal structure of γ-dicalcium silicate, so that the γ-dicalcium silicate is converted from the inert γ phase to a transition state component containing Ca(OH)2 and active silicate. In addition, OH 2+ in the strong alkaline environment attacks the ≡Si-O-Al≡ bond in the gehlenite, releasing Ca 4- , [SiO4] - and [Al(OH)4] 2+ . In addition, the strong alkaline environment can also dissolve the RO phase (FeO-CaO-MgO-MnO), so that it releases Mg 2+ and Ca 2+ . The dissolved Mg 2+ , Ca 4- , [SiO4] - and [Al(OH)4] - polymerize in the strong alkaline environment to form high-polymerization-degree calcium silicate gel (C-S-H), magnesium calcium silicate gel (M-S-H) and calcium aluminum silicate gel (C-A-S-H), which can well wrap and bond the calcium-magnesium sand aggregate in the artificial stone slurry formula, significantly improving the matrix bonding and density. (2) In the strong alkaline environment, FeO / MnO in the RO phase is converted into stable Fe2O3·nH2O and MnOOH, respectively, which improves the density through the micro-aggregate effect, thereby improving the strength of the artificial stone; (3) In the process of carbonation reaction, HCO3 2- and CO3 2+ generated by the dissolution of CO2 will combine with the dissolved Mg 2+ and Ca - to form calcium carbonate and magnesium carbonate passivation layers and cover the surfaces of mineral components such as tricalcium silicate (C3S) and β-dicalcium silicate (β-C2S), while the high concentration of OH -The soluble calcium carbonate passivation layer and the magnesium carbonate passivation layer are dissolved, thereby realizing continuous peeling of the passivation layer, exposing fresh reaction interface, maintaining Mg 2+ , Ca 2+ continuous dissolution of silicate, and finally realizing significant improvement of artificial stone strength through densification of the gel network; (4) the ion replacement reaction forms a negatively charged interface on the surface of the steel slag particles, promotes CO2 adsorption and reduces the nucleation potential barrier of calcium carbonate crystals and magnesium carbonate crystals. DETAILED DESCRIPTION

[0031] The technical solution provides the artificial stone with high strength and anti-alkali effect, which is obtained by carbonation curing and solidification of artificial stone slurry.

[0032] According to the mass fraction, the artificial stone slurry is composed of 60-80 parts of steel slag, 10-20 parts of red mud, 2-3 parts of gypsum, 40-70 parts of calcium-magnesium sand, 1-1.5 parts of calcium carbonate whisker, 1-2 parts of fiber and 12-15 parts of water.

[0033] The chemical composition of the steel slag includes SiO2, Al2O3, MgO and CaO, and the mineral composition of the steel slag includes tricalcium silicate, beta-dicalcium silicate, gamma-dicalcium silicate, calcium aluminum yellow long stone, free calcium oxide, free magnesium oxide and RO phase.

[0034] The chemical composition of the red mud includes Fe2O3, CaO, Al2O3 and Na2O, and the content of Na2O in the red mud is 10-12% according to the mass percentage; the mineral composition of the red mud includes hematite, hydrated garnet, calcium nepheline and gibbsite.

[0035] In view of the technical problem of poor strength of the artificial stone obtained by using the steel slag in the prior art, the technical solution provides the artificial stone with high strength and anti-alkali effect, through the proportioning design and raw material optimization of the artificial stone slurry, which is beneficial to improve the strength and anti-alkali effect of the artificial stone without using cement, greatly reduce the production cost, and meet the actual use requirement.

[0036] Specifically, steam curing is based on the hydration activity of steel slag, while the overall hydration activity of steel slag is low, and the free calcium oxide and free magnesium oxide in the steel slag have low hydration activity and large content, which can easily cause serious volume stability problems. Therefore, in order to overcome the above problems, the technical scheme discards steam curing and specially selects carbonation curing. In carbonation curing, gaseous CO2 is quickly dissolved in the slurry to form carbonic acid, and then the carbonic acid dissociates to generate bicarbonate ions and carbonate ions; the calcium hydroxide generated by the free calcium oxide in the aqueous environment reacts with the bicarbonate ions / carbonate ions to generate calcium carbonate crystals, and the magnesium hydroxide generated by the free magnesium oxide in the aqueous environment reacts with the bicarbonate ions / carbonate ions to generate magnesium carbonate crystals, so that the free calcium oxide and free magnesium oxide in the steel slag are quickly and largely eliminated, not only eliminating the delayed expansion and cracking risks caused by the slow hydration of free calcium oxide and free magnesium oxide, but also the generated calcium carbonate crystals and magnesium carbonate crystals can improve the strength of artificial stone by filling pores and compacting the matrix.

[0037] In addition, in the case of alkali-free activation, tricalcium silicate (chemical formula Ca3SiO5) and β-dicalcium silicate (Ca2SiO4) in the steel slag will undergo the following reactions during carbonation:

[0038] Ca3SiO5+3HCO3 - →3CaCO3+SiO2·nH2O+3OH - ;

[0039] Ca2SiO4+2HCO3 - →2CaCO3+SiO2·nH2O+2OH - .

[0040] That is, under the action of HCO3 - , the silicon-oxygen tetrahedron (≡Si-O-Si≡) of tricalcium silicate and β-dicalcium silicate is depolymerized, not only releasing soluble silicic acid ([SiO4] 4- ) and Ca 2+ , but also releasing OH - , so that the reaction environment is weakly alkaline with a pH of 8-10. In the weakly alkaline environment, Ca 2+ preferentially combines with CO3 2- to generate calcium carbonate, and the remaining [SiO4] 4- mainly forms amorphous SiO2·nH2O (silica gel) through a condensation reaction with a low degree of polymerization. However, this process has the following defects: (1) the depolymerization of tricalcium silicate and β-dicalcium silicate requires several hours to first depolymerize the silicon-oxygen network to release Ca 2+ , and Ca 2+ combines with CO3 2-The preferentially generated CaCO3 can easily nucleate directly on the surface of tricalcium silicate and β-type dicalcium silicate, forming a passivation layer, which hinders the internal Ca2+ of tricalcium silicate and β-type dicalcium silicate from 2+ and [SiO4] 4- The continuous dissolution of slag leads to insufficient reaction degree and low utilization rate of steel slag; (2) The silica gel generated in a weak alkaline environment is mainly short-chain structure, with poor mechanical properties and easy to pulverize; (3) γ-type dicalcium silicate and calcium aluminum feldspar hardly participate in the reaction due to their dense structure; RO phase hardly participates in the reaction due to its inertness. Therefore, it is difficult to fully stimulate the activity of steel slag by simply using the carbonation of steel slag, and the strength of the obtained artificial stone is limited, which is difficult to meet the actual use requirements. It should be noted that free calcium oxide and free magnesium oxide, as free oxides, react very quickly (seconds to minutes) to generate calcium carbonate and magnesium carbonate respectively during the carbonation process, and the generated calcium carbonate and magnesium carbonate are dispersed in the pores of the slurry and will not form a dense passivation layer.

[0041] The chemical composition of red mud mainly includes Fe2O3, CaO, Al2O3 and Na2O. Among them, the high content of Na2O in red mud exists in the form of NaOH, Na2CO3 and cancrinite (formed by the combination of Al2O3 and Na2O). At the same time, Al2O3 also exists in the form of gibbsite (Al(OH)3) and hydrated garnet (Ca3Al3(SiO4) 3-x (OH) 4x )(x=0~3) exists in the form of Fe2O3, and Fe2O3 exists in the form of hematite. In order to fully stimulate the activity of steel slag to improve the strength of artificial stone, this technical solution specifically adds red mud to the artificial stone slurry. The Na in the sodium aluminum silicate minerals (such as cancrinite and gibbsite) in the red mud + It can undergo a replacement reaction with CaO in the steel slag, which mainly exists in the form of f-CaO, to achieve the first dealkalization of the red mud and release the soluble alkali NaOH with strong alkalinity, making the artificial stone slurry present a strong alkaline environment. At the same time, the Na2O in the red mud that exists in the form of soluble salts (such as NaOH and Na2CO3) immediately dissociates, which is beneficial to enhance the alkalinity of the artificial stone slurry and make it present a strong alkaline environment. The mechanism by which the above-mentioned strong alkaline environment improves the strength of artificial stone is as follows: (1) OH in the strong alkaline environment - It will attack the silicon-oxygen tetrahedral network structure of mineral components in steel slag, such as tricalcium silicate (C3S) and β-dicalcium silicate (β-C2S), and promote the formation of Ca by breaking the ≡Si-O-Si≡ bond in the above mineral components. 2 + Dissolution and [SiO4] 4- At the same time, for the dense crystal structure of γ-type dicalcium silicate, OH -will preferentially attack its (001) plane, transforming the γ-dicalcium silicate from an inert γ-phase to a transition state component containing Ca(OH)2and active silicate groups. In addition, OH-in the strongly alkaline environment will attack the ≡Si-O-Al≡ bonds in the gehlenite, releasing Ca 2+ , [SiO4] 4- and [Al(OH)4] - . Furthermore, the strongly alkaline environment can also dissolve the RO phase (FeO-CaO-MgO-MnO), releasing Mg 2+ and Ca 2+ . The dissolved Mg 2+ , Ca 2+ , [SiO4] 4- , [Al(OH)4] - will then condense in the strongly alkaline environment to form high polymerization degree calcium silicate gel (C-S-H), magnesium calcium silicate gel (M-S-H) and calcium aluminum silicate gel (C-A-S-H), which can well coat and bond the calcium magnesium sand aggregate in the artificial stone slurry formulation, significantly improving the matrix bonding and compactness. (2) In the strongly alkaline environment, FeO / MnO in the RO phase are respectively transformed into stable Fe2O3·nH2O and MnOOH, which improve the compactness through micro-aggregate effect, thereby improving the strength of the artificial stone; (3) In the process of carbonation reaction, although HCO3 - and CO3 2- generated by the dissolution of CO2will combine with the dissolved Mg 2+ and Ca 2+ to form calcium carbonate and magnesium carbonate passivation layers and cover the surfaces of mineral components such as tricalcium silicate (C3S) and β-dicalcium silicate (β-C2S), the high concentration of OH - in the strongly alkaline environment can dissolve the calcium carbonate and magnesium carbonate passivation layers, and the corresponding reactions are as follows:

[0042] CaCO3+ OH - → Ca 2+ + HCO3 - ;

[0043] MgCO3+ OH - → Mg 2+ + HCO3 - .

[0044] Thus, the passivation layer is continuously stripped, exposing fresh reaction interfaces, maintaining Mg 2+ , Ca 2+The continuous dissolution of silicate and the final densification of the gel network finally achieve a significant increase in the strength of artificial stone; (4) The ion replacement reaction forms a negatively charged interface on the surface of the steel slag particles, promotes CO2 adsorption and reduces the nucleation potential barrier of calcium carbonate crystals and magnesium carbonate crystals. It should be noted that mineral composition refers to natural or industrial process formed inorganic solid material with a certain crystal structure and fixed chemical composition, and NaOH and Na2CO3 are not included in the mineral composition due to their high solubility, artificial synthesis and lack of stable crystal structure.

[0045] Further, the technical solution utilizes the interaction of steel slag and red mud to generate carbonate crystals (calcium carbonate crystals and magnesium carbonate crystals) and high polymerization degree gel (calcium aluminum silicate gel and magnesium aluminum silicate gel) in the system, and to improve the strength of artificial stone by the synergistic effect of the two. However, its strength is limited, and it is still difficult to meet the actual demand. Therefore, the technical solution adds gypsum to the formula, which can react with [Al(OH)4] - in the alkaline environment to generate needle-shaped ettringite (3CaO·Al2O3·3CaSO4·32H4O), and the interlayer channel (diameter of 0.8 nm) of the needle-shaped ettringite provides a fast penetration path for CO2 molecules (diameter of 0.33 nm). During carbonation, ettringite undergoes the following reaction:

[0046] 3CaO·Al2O3·3CaSO4·32H4O+3CO2→3CaCO3+2Al(OH)3+3SO4 2- +26H2O;

[0047] The generated nano-CaCO3 fills the space originally occupied by the needle-shaped ettringite, and the generated Al(OH)3 colloid is bonded by van der Waals force, thereby improving the strength of artificial stone. At the same time, the crystallization water channel of ettringite as a fast transport path makes CO2 directly reach the internal steel slag particles, combined with the H2O released by ettringite during decomposition to produce a microfluidic effect, carrying CO2 to diffuse around the steel slag, realizing the release of CO2 inside the artificial stone, making the steel slag undergo internal to external carbonation reaction, combined with the original external to internal carbonation reaction of steel slag, realizing double carbonation reaction, further improving the carbonation degree and enhancing the mechanical properties of artificial stone. It should be noted that the special layered structure of ettringite can quickly form a three-dimensional skeleton, greatly improving the early strength of artificial stone and solving the problem of easy damage during early demolding.

[0048] Secondly, although the carbonation of steel slag, alkali activation of red mud and the addition of gypsum are beneficial to improve the strength of artificial stone, when the strength is too high and the toughness is insufficient, it is easy to cause the rupture of artificial stone under the action of external force. Therefore, the technical scheme also adds fiber and calcium carbonate whisker in the artificial stone slurry raw material formula. The fiber itself has excellent flexibility, can form a network structure inside the artificial stone, effectively disperse and transfer stress, reduce the concentrated stress points caused by external force, thereby enhancing the flexibility and crack resistance of the artificial stone, and ensuring the overall strength of the artificial stone. As a small needle-shaped material, calcium carbonate whisker has a high aspect ratio and specific surface area. In the preparation process of artificial stone, it not only effectively prevents crack propagation and improves the crack resistance of artificial stone, but also provides growth sites for calcium carbonate crystals and magnesium carbonate crystals generated by steel slag carbonation, forming a dense skeleton structure, thereby also being beneficial to improve the overall strength of artificial stone.

[0049] Thirdly, when the artificial stone is exposed to a humid environment, the soluble Na + from NaOH / Na2CO3) is easy to migrate to the surface through capillary pores and react with CO2 in the air to generate white crystals (Na2CO3·10H2O), causing surface efflorescence and other problems. That is, the essence of red mud efflorescence is the dissolution-migration-crystallization process of Na + . The calcium silicate gel, magnesium calcium silicate gel and calcium aluminum silicate gel formed in the technical scheme can chemically bond or physically wrap the free Na + in a three-dimensional network, continuously solidify Na + , and reduce the occurrence of efflorescence caused by the migration of Na + . In addition, the calcium carbonate, magnesium carbonate and calcium carbonate whisker generated in the technical scheme can fully fill the fine pores in the artificial stone, physically block the migration path of Na + , reduce capillary action, and thus improve the anti-efflorescence effect.

[0050] Finally, the artificial stone slurry includes the following raw materials in mass fraction: steel slag 60-80 parts, red mud 10-20 parts, gypsum 2-3 parts, calcium magnesium sand 40-70 parts, calcium carbonate whisker 1-1.5 parts, fiber 1-2 parts and water 12-15 parts. By controlling the addition amount of each component in the artificial stone slurry within a more preferred range, the performance of the artificial stone is better, meeting the use requirements.

[0051] In summary, the technical scheme utilizes the alkali activation of the steel slag by the red mud and the carbonation of the steel slag, improves the utilization rate of the steel slag, fully and effectively utilizes the components in the steel slag, improves the strength and the alkali bleeding resistance of the artificial stone without using cement, greatly reduces the production cost, and meets the actual use requirements.

[0052] It should be noted that the OH - and the OH - generated by the first dealkalization can be quickly dissolved and dissociated to generate HCO3 - The above neutralization reaction can promote the secondary dealkalization of the red mud, realizes the deep reduction of the pH of the red mud to the environmental safety range, makes the final artificial stone close to neutral, and meets the actual use requirements.

[0053] Preferably, the mineral components of the steel slag include 15-35% of tricalcium silicate, 10-25% of beta dicalcium silicate, 5-10% of gamma dicalcium silicate, 5-15% of calcium aluminum yellow long stone, 5-15% of free calcium oxide, 5-15% of free magnesium oxide, 10-20% of RO phase, and 10-20% of glass phase, in terms of mass percentage.

[0054] The mineral components of the red mud include 10-30% of hematite, 20-50% of hydrated garnet, 5-20% of calcium nepheline, 5-15% of gibbsite, and 10-30% of calcite, in terms of mass percentage.

[0055] Further, the chemical components of the steel slag include 7.5-8% of Al2O3, 15-16% of SiO2, 0.4-0.6% of Na2O, 4.1-4.3% of MgO, 40-41% of CaO, 0.5-1% of TiO2, 3-4% of MnO, and 20-22% of Fe2O3, and the rest is loss on ignition, in terms of mass percentage.

[0056] The chemical components of the red mud include 16-18% of Al2O3, 11-14% of SiO2, 10-12% of Na2O, 0.2-0.4% of MgO, 14-16% of CaO, 6-8% of TiO2, 0.1-0.2% of MnO, and 30-35% of Fe2O3, and the rest is loss on ignition, in terms of mass percentage.

[0057] The steel slag with the Al2O3 content of 7.5-8%, the SiO2 content of 15-16%, the CaO content of 40-41% and the MgO content of 4.1-4.3% calculated in percentage by mass is preferably added into the artificial stone slurry formula, so that the total content of Al2O3, SiO2, CaO and MgO in the artificial stone slurry formula reaches 66.6-69.3%, which is beneficial to improve the carbonation degree of the steel slag and the alkali activation effect of the red mud on the steel slag, thereby promoting the improvement of the strength of the artificial stone.

[0058] Further, the red mud with the Al2O3 content of 16-18% and the Na2O content of 10-12% calculated in percentage by mass is preferably added into the artificial stone slurry formula, which is beneficial to improve the alkali activation effect of the red mud on the steel slag and promote the generation of more calcium aluminum silicate gel in the process of carbonation and solidification of the artificial stone slurry, thereby promoting the improvement of the strength of the artificial stone.

[0059] Preferably, the chemical composition of the steel slag includes Al2O3 7.96%, SiO2 15.36%, Na2O 0.51%, MgO 4.19%, CaO 40.97%, TiO2 0.95%, MnO 3.36%, Fe2O3 21.75% and the rest is loss on ignition, calculated in percentage by mass.

[0060] Preferably, the chemical composition of the red mud includes Al2O3 16.77%, SiO2 12.2%, Na2O 10.74%, MgO 0.33%, CaO 15.08%, TiO2 7.79%, MnO 0.12% and Fe2O3 34.11% and the rest is loss on ignition, calculated in percentage by mass.

[0061] Further, the calcium-magnesium sand includes 0-30% of a first type of sand material with a mesh number ≥ 26 mesh and < 40 mesh, 40-60% of a second type of sand material with a mesh number ≥ 40 mesh and < 70 mesh, 15-30% of a third type of sand material with a mesh number ≥ 70 mesh and < 120 mesh and 10-25% of a fourth type of sand material with a mesh number ≥ 120 mesh and < 200 mesh, calculated in percentage by mass.

[0062] In the technical solution, the mesh number and the ratio of the various types of sand materials are optimized, which is beneficial to improve the density of the artificial stone and thereby improve the strength of the artificial stone.

[0063] Further, the steel slag includes 8-12% of a first type of steel slag powder with a particle size < 0.76 μm, 35-45% of a second type of steel slag powder with a particle size ≥ 0.76 μm and < 5.48 μm, 35-45% of a third type of steel slag powder with a particle size ≥ 5.48 μm and < 40.91 μm and 8-12% of a fourth type of steel slag powder with a particle size ≥ 40.91 μm, calculated in percentage by mass.

[0064] The red mud comprises, in terms of mass percentage, 8-12% of a first type of red mud material with a particle size <0.76 μm, 35-45% of a second type of red mud material with a particle size ≥0.76 μm and <2.78 μm, 35-45% of a third type of red mud material with a particle size ≥2.78 μm and <84.82 μm, and 8-12% of a fourth type of red mud material with a particle size ≥84.82 μm.

[0065] The present technical solution optimizes the mesh number and the ratio of each type of steel slag powder in the steel slag and the mesh number and the ratio of each type of red mud in the red mud, so that the steel slag and the red mud have a large specific surface area, thereby fully exposing the active components in the steel slag and the red mud, which is conducive to fully activating the two, thereby improving the performance of the artificial stone.

[0066] Further, the length of the calcium carbonate whisker is 10-20 μm, and the length of the fiber is 6-12 mm.

[0067] In the present technical solution, the length of the calcium carbonate whisker and the fiber is optimized, so that they are uniformly dispersed in the artificial stone slurry, thereby facilitating the reinforcing and toughening effects of the two.

[0068] Further, the fiber comprises any one or a combination of polypropylene fiber, polyethylene fiber, polyformaldehyde fiber and polyvinyl alcohol fiber.

[0069] The polypropylene fiber, the polyethylene fiber, the polyformaldehyde fiber and the polyvinyl alcohol fiber all have high strength and high modulus, and the above raw materials can be effectively dispersed in the slurry to form a three-dimensional network structure, thereby improving the overall strength and toughness of the artificial stone. In addition, the polypropylene fiber and the polyvinyl alcohol fiber also have good acid and alkali resistance and corrosion resistance, and can be applied to various environments. Therefore, the fiber is preferably a combination of any one or more of polypropylene fiber, polyethylene fiber, polyformaldehyde fiber and polyvinyl alcohol fiber, which not only facilitates the improvement of the strength of the artificial stone, but also facilitates the improvement of its durability.

[0070] Further, the artificial stone with high strength and alkali bleeding resistance has a compressive strength ≥50 MPa and a flexural strength ≥19 MPa.

[0071] The present technical solution also proposes an artificial stone with high strength and alkali bleeding resistance, which has a compressive strength ≥50 MPa and a flexural strength ≥19 MPa, and has not only high strength but also alkali bleeding resistance.

[0072] A method for preparing an artificial stone with high strength and alkali bleeding resistance, for preparing the above artificial stone with high strength and alkali bleeding resistance, comprising the following steps:

[0073] A. Mix the steel slag and red mud in the formula amount uniformly, and after drying, a first mixture is obtained;

[0074] B. Mix the first mixture with the formula amount of gypsum, calcium carbonate whisker and fiber uniformly to obtain a second mixture;

[0075] C. Mix the second mixture, formula amount of water and calcium magnesium sand uniformly to obtain a stone artificial slurry;

[0076] D. Pour the stone artificial slurry into a mold, and after pressing and demolding, an intermediate product is obtained;

[0077] E. After carbonation curing, the intermediate product is solidified to obtain a stone artificial product with high strength and anti-efflorescence effect.

[0078] The technical solution also provides a preparation method of a stone artificial product with high strength and anti-efflorescence effect, which has simple steps, strong operability, and is beneficial to ensure the performance of the stone artificial product in the preparation process.

[0079] It should be noted that the carbonation curing refers to placing the green brick into a carbonation curing box with CO2 gas for curing.

[0080] Further, in step E, the curing temperature of the carbonation curing is 20-90℃, the curing humidity is 70-90% RH, the curing time is 24-72h, the curing pressure is 0.1-0.4MPa, and the purity of CO2 is 50-99.9%.

[0081] When the curing temperature, curing humidity, curing pressure and purity of CO2 are too high, the carbonation speed will be too fast, and the surface of the stone artificial product will be densified too early, thereby hindering the deep penetration of CO2; when the curing temperature, curing humidity, curing pressure and purity of CO2 are too low, the reaction rate will be too slow, thereby affecting the production efficiency. In the technical solution, the curing temperature, curing humidity, curing pressure and purity of CO2 of the carbonation curing are limited to ensure that CO2 can fully penetrate into the interior of the stone artificial product, improve the carbonation reaction degree, ensure the production efficiency under the premise of ensuring the strength of the stone artificial product, and reduce the production cost.

[0082] Further, when the curing time is insufficient, the carbonation degree will be reduced; when the curing time is too high, the carbonation degree will not be significantly improved, and the production efficiency will be easily reduced. Therefore, the curing time is limited to 1-72h, so that the production efficiency is improved under the premise of improving the carbonation degree and the strength of the stone artificial product.

[0083] Further, in step D, the pressing pressure of the pressing and molding is 10-50MPa.

[0084] When the pressure in the pressing process is too low, the artificial stone slurry cannot be fully compacted, resulting in a large number of voids and un-tightly combined areas in the artificial stone, affecting the overall strength of the artificial stone; when the pressure in the pressing process is too high, not only does it make the pores between the raw material particles too small during the carbonation process, hindering the diffusion of CO2 and reducing the degree of carbonation reaction, affecting the strength and density of the artificial stone, but also it requires higher production requirements, which is easy to increase the production cost. Therefore, by limiting the pressure in the pressing process, the technical scheme is beneficial to ensure the performance at a lower cost and a higher production efficiency.

[0085] The technical scheme of the present application will be further illustrated by the specific embodiments.

[0086] In the embodiments and comparative examples of the present application, the chemical composition of the steel slag includes Al2O3 7.96%, SiO2 15.36%, Na2O 0.51%, MgO 4.19%, CaO 40.97%, TiO2 0.95%, MnO 3.36%, Fe2O3 21.75% by mass, and the rest is loss on ignition; the mineral composition of the steel slag includes 3CaO·SiO2 20%, β2CaO·SiO2 15%, γ2CaO·SiO2 8%, CaAl2O4 10%, free CaO 10%, free MgO 10%, RO phase 15% and glass phase 12% by mass.

[0087] The chemical composition of the red mud includes Al2O3 16.77%, SiO2 12.2%, Na2O 10.74%, MgO 0.33%, CaO 15.08%, TiO2 7.79%, MnO 0.12% and Fe2O3 34.11% by mass, and the rest is loss on ignition; the mineral composition of the red mud includes hematite 20%, hydrated garnet 40%, cancrinite 10%, gibbsite 10% and calcite 20% by mass.

[0088] The steel slag includes 10% of a first steel slag powder with a particle size of <0.76 μm, 40% of a second steel slag powder with a particle size of ≥0.76 μm and <5.48 μm, 40% of a third steel slag powder with a particle size of ≥5.48 μm and <40.91 μm, and 10% of a fourth steel slag powder with a particle size of ≥40.91 μm by mass.

[0089] The red mud includes 10% of a first red mud with a particle size of <0.76 μm, 40% of a second red mud with a particle size of ≥0.76 μm and <2.78 μm, 40% of a third red mud with a particle size of ≥2.78 μm and <84.82 μm, and 10% of a fourth red mud with a particle size of ≥84.82 μm by mass.

[0090] The calcium-magnesium sand comprises 45% of a first sand material with a mesh size of ≥26 mesh and <40 mesh, 15% of a second sand material with a mesh size of ≥40 mesh and <70 mesh, and 40% of a third sand material with a mesh size of ≥70 mesh and <120 mesh, in terms of mass percentage.

[0091] Example 1

[0092] A. Steel slag 60 parts and red mud 20 parts are uniformly mixed to obtain a first mixture, which is dried;

[0093] B. The first mixture is uniformly mixed with gypsum 3 parts, calcium carbonate whiskers with a length of 10 μm 1.5 parts, and polypropylene fibers with a length of 8 mm 2 parts to obtain a second mixture;

[0094] C. The second mixture, water 12 parts, and calcium-magnesium sand 40 parts are uniformly mixed to obtain an artificial stone slurry;

[0095] D. The artificial stone slurry is poured into a mold, and after being pressed and formed under a pressure of 20 MPa, the intermediate product is obtained by demolding;

[0096] E. The intermediate product is carbonated and cured under the conditions of a curing temperature of 40°C, a curing humidity of 70% RH, a curing time of 24 h, a curing pressure of 0.1 MPa, and a purity of CO2 of 70%, to obtain an artificial stone with high strength and anti-efflorescence effect.

[0097] Example 2

[0098] A. Steel slag 75 parts and red mud 15 parts are uniformly mixed to obtain a first mixture, which is dried;

[0099] B. The first mixture is uniformly mixed with gypsum 2 parts, calcium carbonate whiskers with a length of 15 μm 1 part, and polyvinyl alcohol fibers with a length of 8 mm 2 parts to obtain a second mixture;

[0100] C. The second mixture, water 12 parts, and calcium-magnesium sand 50 parts are uniformly mixed to obtain an artificial stone slurry;

[0101] D. The artificial stone slurry is poured into a mold, and after being pressed and formed under a pressure of 20 MPa, the intermediate product is obtained by demolding;

[0102] E. The intermediate product is carbonated and cured under the conditions of a curing temperature of 50°C, a curing humidity of 80% RH, a curing time of 48 h, a curing pressure of 0.2 MPa, and a purity of CO2 of 99.9%, to obtain an artificial stone with high strength and anti-efflorescence effect.

[0103] Example 3

[0104] A. Steel slag 80 parts and red mud 20 parts are uniformly mixed to obtain a first mixture, which is dried;

[0105] B. The first mixture is mixed with gypsum 3 parts, calcium carbonate whisker 1.5 parts with a length of 20 μm, and polyformaldehyde fiber 1 part with a length of 10 mm to obtain a second mixture;

[0106] C. The second mixture, water 15 parts, and calcium-magnesium sand 60 parts are mixed uniformly to obtain an artificial stone slurry;

[0107] D. The artificial stone slurry is poured into a mold, and after compression molding under a pressure of 40 MPa, the intermediate product is obtained by demolding;

[0108] E. The intermediate product is carbonated and cured under the conditions of a curing temperature of 80 °C, a curing humidity of 90% RH, a curing time of 72 h, a curing pressure of 0.1 MPa, and a CO2 purity of 95%, to obtain an artificial stone with high strength and alkali bleeding resistance.

[0109] Comparative Example 1

[0110] Comparative Example 1 has the same preparation method and raw materials as Example 2, except that no steel slag is added to the artificial stone slurry formulation in Comparative Example 1.

[0111] Comparative Example 2

[0112] Comparative Example 2 has the same preparation method and raw materials as Example 2, except that no red mud is added to the artificial stone slurry formulation in Comparative Example 2.

[0113] The artificial stones obtained in the above examples and comparative examples are tested for bending strength and compressive strength according to the test standard of GB / T 35160 Synthetic Stone Test Methods. At the same time, the alkali bleeding resistant artificial stones obtained in the above examples and comparative examples are placed in a standard curing room with a temperature of 20±2 °C and a humidity of greater than 95% for 28 days, and the surface alkali bleeding phenomenon of the artificial stone products is observed and recorded. The specific test results are shown in Table 1.

[0114] Table 1: Test results of related properties of artificial stone

[0115]

[0116] As can be seen from the performance test results in Table 1, the artificial stone according to the technical solution has a compressive strength ≥ 50 MPa and a bending strength ≥ 19 MPa, and not only has high strength, but also has alkali bleeding resistance, to meet the use requirements.

[0117] Comparative Example 1 does not add steel slag, resulting in a decrease in the amount of gel, calcium carbonate, and magnesium carbonate generated during carbonation in the artificial stone slurry, leading to poor strength and obvious alkali bleeding of the obtained artificial stone.

[0118] The activity of the steel slag cannot be fully activated due to the absence of the red mud in Comparative Example 2, so that the amount of the gel generated in the system is reduced, and the FeO / MnO in the RO phase in the steel slag cannot be converted into stable Fe2O3·nH2O and MnOOH to play its micro aggregate effect, which not only affects the strength of the artificial stone, but also makes the artificial stone have poor resistance to Na + The fixing effect of the artificial stone on Na + The migration path is weakened, and the efflorescence phenomenon is easily caused.

[0119] The technical principles of the present application are described above in combination with specific examples. These descriptions are only for explaining the principles of the present application, and cannot be interpreted as limiting the protection scope of the present application in any way. Based on the explanations herein, other specific embodiments of the present application can be conceived by those skilled in the art without creative efforts, and these embodiments will all fall within the protection scope of the present application.

Claims

1. An artificial stone with both high strength and anti-efflorescence effect, characterized in that: Obtained by carbonation curing and solidification of artificial stone slurry; Calculated by weight, the artificial stone slurry consists of 60-80 parts of steel slag, 10-20 parts of red mud, 2-3 parts of gypsum, 40-70 parts of calcium magnesium sand, 1-1.5 parts of calcium carbonate whiskers, 1-2 parts of fiber and 12-15 parts of water; The chemical components of the steel slag include SiO2, Al2O3, MgO and CaO, and the mineral components of the steel slag include tricalcium silicate, beta-type dicalcium silicate, gamma-type dicalcium silicate, gehlenite, free calcium oxide, free magnesium oxide and RO phase; The chemical components of the red mud include Fe2O3, CaO, Al2O3 and Na2O, and the content of Na2O in the red mud is 10-12% calculated by mass percentage; the mineral components of the red mud include hematite, hydrated garnet, cancrinite and gibbsite.

2. The artificial stone with high strength and anti-efflorescence effect according to claim 1, characterized in that: Calculated by mass percentage, the chemical composition of the steel slag includes Al2O3 7.5-8%, SiO2 15-16%, Na2O 0.4-0.6%, MgO 4.1-4.3%, CaO 40-41%, TiO2 0.5-1%, MnO 3-4% and Fe2O3 20-22%, with the remainder being loss on ignition; Calculated by mass percentage, the chemical composition of the red mud includes Al2O3 16-18%, SiO2 11-14%, Na2O10-12%, MgO 0.2-0.4%, CaO 14-16%, TiO2 6-8%, MnO 0.1-0.2% and Fe2O3 30-35%, with the remainder being loss on ignition.

3. The artificial stone with high strength and anti-efflorescence effect according to claim 1, characterized in that: Calculated by mass percentage, the calcium magnesium sand includes 0-30% of Class I sand with a mesh size of ≥26 mesh and <40 mesh, 40-60% of Class II sand with a mesh size of ≥40 mesh and <70 mesh, 15-30% of Class III sand with a mesh size of ≥70 mesh and <120 mesh, and 10-25% of Class IV sand with a mesh size of ≥120 mesh and <200 mesh.

4. The artificial stone with high strength and anti-efflorescence effect according to claim 1, characterized in that: Calculated by mass percentage, the steel slag includes 8-12% of Class I steel slag powder with a particle size of less than 0.76 μm, 35-45% of Class II steel slag powder with a particle size of ≥0.76 μm and <5.48 μm, 35-45% of Class III steel slag powder with a particle size of ≥5.48 μm and <40.91 μm, and 8-12% of Class IV steel slag powder with a particle size of ≥40.91 μm; Calculated by mass percentage, the red mud includes 8-12% of Class I red mud material with a particle size of less than 0.76 μm, 35-45% of Class II red mud material with a particle size of ≥0.76 μm and <2.78 μm, 35-45% of Class III red mud material with a particle size of ≥2.78 μm and <84.82 μm, and 8-12% of Class IV red mud material with a particle size of ≥84.82 μm.

5. The artificial stone with high strength and anti-efflorescence effect according to claim 1, characterized in that: The length of the calcium carbonate whiskers is 10 to 20 μm, and the length of the fibers is 6 to 12 mm.

6. The artificial stone with high strength and anti-efflorescence effect according to claim 1, characterized in that: The fibers include any one or more combinations of polypropylene fibers, polyethylene fibers, polyoxymethylene fibers and polyvinyl alcohol fibers.

7. The artificial stone with high strength and anti-efflorescence effect according to claim 1, characterized in that: The artificial stone with both high strength and anti-efflorescence effect has a compressive strength of ≥50 MPa and a flexural strength of ≥19 MPa.

8. A method for preparing artificial stone with both high strength and anti-efflorescence effect, characterized in that: The method for preparing the artificial stone having high strength and anti-efflorescence effect as claimed in any one of claims 1 to 7 comprises the following steps: A. uniformly mixing the steel slag and red mud in a prescribed amount, and drying the mixture to obtain a first mixture; B. uniformly mixing the first mixture with a formulated amount of gypsum, calcium carbonate whiskers, and fiber to obtain a second mixture; C. uniformly mixing the second mixed material, the formulated amount of water and calcium magnesium sand to obtain an artificial stone slurry; D. Pour the artificial stone slurry into the mold, and obtain the intermediate product after pressing and demoulding; E. After the intermediate product is carbonated and cured, it is solidified to obtain artificial stone with high strength and anti-alkali effect.

9. The method for preparing an artificial stone having both high strength and anti-efflorescence effect according to claim 8, characterized in that: In step E, the carbonation curing temperature is 20-90° C., the curing humidity is 70-90% RH, the curing time is 24-72 hours, the curing pressure is 0.1-0.4 MPa, and the purity of CO 2 is 50-99.9%.

10. The method for preparing an artificial stone having both high strength and anti-efflorescence effect according to claim 8, characterized in that: In step D, the pressure of the compression molding is 10 to 50 MPa.

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