A high performance portland cement and a method for making the same

Abstract

The application relates to the field of building materials, and particularly discloses high-performance portland cement and a preparation method thereof. The high-performance portland cement comprises the following components in parts by weight: cement clinker 30-40 parts, mixed material 8-16 parts, gypsum 8-10 parts, modified coal gangue 10-20 parts, water reducing agent 0.2-0.4 parts, waterproof agent 0.03-0.05 parts and grinding aid 0.05-0.1 parts. The preparation method comprises the following steps: drying the mixed material, adding the cement clinker, gypsum, modified coal gangue and grinding aid, grinding, adding the water reducing agent and waterproof agent, and homogenizing treatment to obtain the high-performance portland cement. The high-performance portland cement has the advantages of high toughness, small brittleness, no easy cracking, recycling of coal gangue and high impermeability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, more particularly, it relates to a high-performance Portland cement and a preparation method thereof. BACKGROUND

[0002] Cement is a kind of paste after stirring with water, which can harden in air or water and can firmly cement sand, stone and other materials together, and is widely used in civil construction, water conservancy construction, national defense construction and other engineering. At present, the most widely used cement in the world is Portland cement, which has the advantages of low cost and maintenance cost, good integrity and high compressive strength.

[0003] Portland cement is mainly made of cement clinker, mixed materials and a proper amount of gypsum and other components by grinding. Due to the brittleness of cement, it is easy to shrink and crack seriously in early stage after hardening.

[0004] Coal gangue is an industrial waste generated in the process of mining and washing in coal mines. Long-term accumulation and gradual disposal not only occupy a large amount of land, but also pollute the atmosphere and groundwater under suitable conditions. At present, the existing coal gangue reserves in China are huge and increasing year by year. If not used reasonably, it will cause huge social, economic and environmental losses.

[0005] According to the related technology in the above, the inventors believe that it is an urgent problem to be solved to use coal gangue to solve the problem of large brittleness, easy shrinkage and serious early cracking of Portland cement in practical application. SUMMARY

[0006] In order to improve the toughness of Portland cement, reduce its shrinkage and early cracking, and recycle coal gangue, the present application provides a high-performance Portland cement and a preparation method thereof.

[0007] In the first aspect, the present application provides a high-performance Portland cement, which adopts the following technical scheme:

[0008] A high-performance Portland cement, comprising the following components by weight: cement clinker 30-40 parts, mixed material 8-16 parts, gypsum 8-10 parts, modified coal gangue 10-20 parts, water reducing agent 0.2-0.4 parts, waterproof agent 0.03-0.05 parts, grinding aid 0.05-0.1 parts;

[0009] The preparation method of the modified coal gangue is as follows:

[0010] (1) The coal gangue is crushed and ball milled, and then mixed with silane coupling agent KH550 to obtain pretreated coal gangue, and the mass ratio of coal gangue to silane coupling agent KH550 is 0.2-0.4:1;

[0011] (2) 10-15 parts by weight of the pretreated coal gangue is mixed with 5-10 parts by weight of the silicone-modified alkyd resin, 3-5 parts by weight of the poly-p-xylene and 2-4 parts by weight of the silicon oxynitride to form a master batch by melting and extruding;

[0012] (3) The pore-forming agent is atomized and deposited on the surface of the master batch, and then calcined at 200-250°C for 3-5h to form a porous master batch, the mass ratio of the pore-forming agent to the master batch being 0.04-0.1:1;

[0013] (4) 5-10 parts by weight of the porous master batch is mixed with 1-3 parts by weight of the hydroxyapatite and 0.6-1.2 parts by weight of the carbon nanotube, and a gelatin solution is sprayed while stirring, and then dried at 105-110°C to form the modified coal gangue, the mass ratio of the gelatin solution to the porous master batch being 0.03-0.05:1.

[0014] By using the above technical scheme, since the gypsum and the modified coal gangue are used to prepare the Portland cement, the gypsum can play a role in setting and early strength of the cement, increase the workability of the cement mixture, reduce the water consumption, reduce the opportunity of formation of monosulfide type calcium aluminate sulfate, avoid the volume expansion caused by the transformation of monosulfide type sulphoaluminate into trisulfide type hydrated sulphoaluminate, reduce the dry shrinkage and prevent the cement from cracking during hardening; when the coal gangue is modified, the silane coupling agent KH550 is used to pretreat the coal gangue, the silane coupling agent KH550 as an amphiphilic molecule is firmly combined with the coal gangue to form organic groups which can covalently react with the silicone-modified alkyd resin and the like, these organic groups improve the compatibility of the coal gangue with the organic modified alkyd resin and the dispersibility of the coal gangue with the organic modified alkyd resin, the poly-p-xylene and the silicon oxynitride, greatly improve the bonding force of the coal gangue with the silicone-modified alkyd resin, the organic modified alkyd resin has strong hydrophobicity and can increase the waterproof and anti-permeability effect of the cement, and the silicone-modified alkyd resin has strong adhesion and great toughness and has good wear resistance, can be firmly combined with the coal gangue and increase the tensile strength of the coal gangue; the silicone-modified alkyd resin, the poly-p-xylene and the silicon oxynitride are coated on the coal gangue to form a master batch, the pore-forming agent is sprayed on the master batch, the pore-forming agent is decomposed after being heated to form pores on the surface of the master batch, and then the gelatin solution is used to load the hydroxyapatite and the carbon nanotube in the pores and on the surface of the master batch, the hydroxyapatite and the carbon nanotube have great toughness and good tensile resistance, thereby further enhancing the tensile resistance of the modified coal gangue, improving the toughness of the Portland cement and preventing the cement from being brittle and cracking.

[0015] Preferably, the mixed material comprises the following components by weight: 3.4-5 parts by weight of fly ash, 0.5-1 part by weight of blast furnace slag powder and 1.6-3 parts by weight of chromium slag.

[0016] The chromium residue is the residue left after production of chromium compounds from chromite in the chromium salt industry, and the hexavalent chromium contained in the chromium residue has the characteristics of strong migration and easy diffusion. After soaking in rainwater, a large amount of hexavalent chromium in the untreated and stacked chromium residue migrates to the soil and underground water, causing serious environmental pollution. The blast furnace slag powder and fly ash are used to fix the chromium in the chromium residue to prepare the mixed material for cement, which can reduce the leaching concentration of total chromium and hexavalent chromium, so as to achieve the purpose of recycling the chromium residue and preventing it from polluting the environment. The fly ash has the spherical particle shape, and together with the blast furnace slag, plays a lubricating role in the cement, improves the fluidity of the cement mixture, reduces the water demand, and the addition of the fly ash and the blast furnace slag replaces part of the cement clinker, reduces the hydration heat of the cementitious material, and improves the dimensional stability of the cement. In addition, the fly ash and the blast furnace slag also play the role of micro aggregate, and improve the density of the cement.

[0017] Preferably, the preparation method of the mixed material is as follows: the chromium residue and the blast furnace slag powder are mixed, dried, ball milled, the fly ash and the alkali activator are added, and the ball milling is continued, and then the mixture is placed at 70-80 DEG C for 20-24 hours of steam curing. The amount of the alkali activator is 20-30% of the amount of the fly ash.

[0018] By using the above technical scheme, first, the drying and the ball milling are used to make the chromium residue and the blast furnace slag powder be subjected to severe impact under the mechanical action, so that the particle size is reduced, the internal structure is damaged, the crystal lattice is distorted, the crystallinity is reduced, and the activity is improved. The addition of the alkali activator and the fly ash makes the activity of the blast furnace slag powder and the fly ash increase under the excitation of the alkali activator, and the blast furnace slag powder and the fly ash are coated on the surface of the chromium residue as gel materials, and quickly react with calcium hydroxide in the cement slurry to accelerate the hydration process and the pozzolanic reaction, so that the mortar strength stably increases.

[0019] Preferably, the alkali activator is one or a combination of calcium hydroxide, calcium sulfate and calcium carbonate.

[0020] By using the above technical scheme, the calcium hydroxide, the phosphogypsum and the calcium carbonate as the alkali activator can excite the activity of the fly ash, improve the surface performance of the fly ash particles, and improve the compressive strength of the cement, so as to stabilize and solidify the chromium residue.

[0021] Preferably, the specific surface area of the mixed material is 400-450 m 2 / kg.

[0022] By using the above technical scheme, the fineness of the mixed material is smaller than that of the cement clinker, so that the mixed material can be fully filled between the cement particles to improve the strength of the mixed material and the cement, improve the fluidity of the cement mixture, and play a water-reducing role.

[0023] Preferably, the cement clinker is prepared by mixing 8-10 parts by weight of limestone and 2-4 parts by weight of iron tailings, ball milling to 80um residue of 15-18%, calcining at 1300-1400℃ for 30-60min, cooling, to obtain the clinker; mixing 1-2 parts by weight of water glass with 0.15-0.2 parts by weight of sodium polyacrylate, heating to 80-90℃, adding 2-3 parts by weight of sodium polyphosphate, keeping warm for 1.5-3h, cooling to room temperature, then adding the clinker and mixing uniformly to obtain the cement clinker.

[0024] By adopting the technical scheme, the hydration products of the cement clinker prepared by taking iron tailings and limestone as main raw materials are ettringite, calcium hydroxide and C-S-H, and with continuous hydration of silicate minerals, the cement slurry is more and more compact, and the cement strength is higher; in addition, the iron tailings are industrial solid waste, which can be effectively recycled and used for the preparation of cement clinker, thereby improving the comprehensive utilization rate of the iron tailings; the amide group in the sodium polyacrylate can crosslink with the silicon-oxygen bond in the water glass, and is used as a dispersant, which promotes the dissolution of sodium polyphosphate in the water glass, accelerates the polymerization reaction of sodium polyacrylate and water glass, promotes the adsorption of sodium polyacrylate on the water glass colloidal particles, and hinders the coalescence and growth of the water glass colloidal particles, so that the water glass is fine and has strong adhesion, the limestone has strong reaction capacity with the modified water glass, and the reaction product has high cementing strength, thereby increasing the compressive strength and flexural strength of the cement.

[0025] Preferably, the water reducing agent is one or a combination of several of polycarboxylic acid water reducing agent and naphthalene series water reducing agent.

[0026] The grinding aid is one or a combination of several of triethanolamine, sodium tripolyphosphate and sodium pyrophosphate.

[0027] By adopting the technical scheme, the polycarboxylic acid water reducing agent and the naphthalene series water reducing agent can reduce the amount of mixing water, improve the strength of the hardened cement, and the grinding aid can weaken the ball coating and paste grinding phenomenon during cement grinding, reduce the classic adsorption phenomenon in the grinding process, and improve the grinding efficiency.

[0028] Preferably, the pore-forming agent is one of PVA, ammonium bicarbonate and n-heptane.

[0029] By adopting the technical scheme, the thermal decomposition temperature of PVA, ammonium bicarbonate and n-heptane is low, all within 250℃, and pores can be formed on the surface of the master batch during calcination.

[0030] Preferably, the waterproof agent is prepared by mixing 3-hydroxyoctadecenoic acid, methyl triethoxysilane and anhydrous ethanol, and the mass ratio of 3-hydroxyoctadecenoic acid, methyl triethoxysilane and anhydrous ethanol is 1:0.2-1:10-20.

[0031] By adopting the technical scheme, the 3-hydroxyoctadecenoic acid belongs to a long-chain fatty acid with hydrophobicity, is complexed with methyl triethoxysilane through hydrolysis to form a waterproof agent, and the waterproof and anti-permeability of the silicate cement are increased.

[0032] In a second aspect, the application provides a preparation method of high-performance silicate cement, which adopts the following technical scheme:

[0033] The preparation method of high-performance silicate cement comprises the following steps: after drying the mixed material, cement clinker, gypsum, modified coal gangue and grinding aid are added, grinding is performed, water reducing agent and waterproof agent are added, and homogenization treatment is performed to obtain high-performance silicate cement.

[0034] By adopting the technical scheme, the preparation method is simple and easy to operate.

[0035] In summary, the application has the following beneficial effects:

[0036] 1. Since the silicate cement is prepared by using the modified coal gangue, the compatibility of the coal gangue with the organosilicon modified alkyd resin and the poly-p-xylene is increased by the silane coupling agent KH550, so that the organosilicon modified alkyd resin and the poly-p-xylene and the silicon oxynitride are coated on the surface of the coal gangue to form a master batch with good waterproofness and high toughness, and after the pores are formed on the master batch by using a porogen, the hydroxyapatite and the carbon nanotube with high elastic modulus and strength and excellent hydrophobicity are filled in the pores, so that the toughness and the anti-permeability of the modified coal gangue are further improved, and the environmental pollution caused by the stacking of the coal gangue is solved.

[0037] 2. In the application, the mixed material is preferably prepared by using fly ash, blast furnace slag powder and chromium residue, since the toxic hexavalent chromium is easily leached out of the chromium residue, the fly ash and the blast furnace slag powder are activated by using an alkali activator, so that the fly ash and the blast furnace slag powder with improved activity are coated on the surface of the chromium residue to accelerate the reaction with calcium hydroxide in the cement, thereby ensuring the stable growth of the strength of the mortar system.

[0038] 3. In the application, the cement clinker is preferably prepared by using iron tailings, limestone, water glass and other raw materials, the iron tailings are industrial solid waste, and the cement clinker is prepared by using the iron tailings, so that the density of the prepared cement clinker is increased, and in addition, the iron tailings and the limestone are mixed with the water glass, sodium polyacrylate and sodium polyphosphate to increase the cementing strength of the cement clinker, thereby improving the flexural strength of the silicate cement and making it less prone to cracking. DETAILED DESCRIPTION

[0039] Preparation examples 1-3 of modified coal gangue

[0040] Silane coupling agent KH550 is selected from Zhengzhou Longxin Chemical Product Co., Ltd., organic silicon modified alkyd resin is selected from Anhui Mingyi Silicon Industry Co., Ltd., model is MY330C, parylene is selected from Baite Technology (Suzhou) Co., Ltd., model is PTP-5V, silicon oxynitride, PVA is selected from Guangzhou Shenchuang Chemical Co., Ltd., model is BP-24, hydroxyapatite is selected from Xi'an Zebang Biological Technology Co., Ltd., model is ZB6556, carbon nanotube is selected from Zibo Yuxing New Material Technology Co., Ltd., model is 001.

[0041] Preparation example 1: the preparation method of the modified coal gangue is as follows:

[0042] (1) after the coal gangue is crushed and ball milled for 30 min, the coal gangue is mixed with silane coupling agent KH550 to prepare pretreated coal gangue, the mass ratio of coal gangue to silane coupling agent KH550 is 0.2:1, and the chemical composition of the coal gangue is shown in table 1;

[0043] (2) 10 kg of pretreated coal gangue is mixed with 5 kg of organic silicon modified alkyd resin, 3 kg of parylene and 2 kg of silicon oxynitride, melted at 350 DEG C, extruded to prepare a master batch with a particle size of 30 um, and the solid content of the organic silicon modified alkyd resin is 50%;

[0044] (3) the pore-forming agent is atomized and deposited on the surface of the master batch, and then calcined at 200 DEG C for 5 h to prepare a porous master batch, the mass ratio of the pore-forming agent to the master batch is 0.04:1, and the pore-forming agent is PVA;

[0045] (4) 5 kg of the porous master batch is mixed with 1 kg of hydroxyapatite and 0.6 kg of carbon nanotube, stirred, and sprayed with a gelatin solution while stirring, and dried at 105 DEG C to prepare a modified coal gangue, the mass ratio of the gelatin solution to the porous master batch is 0.03:1.

[0046] Table 1 chemical composition of coal gangue

[0047] Component / % SiO2 Al2O3 Fe2O3 CaO MgO Coal gangue 63.07 22.80 6.51 4.32 0.61

[0048] Preparation example 2: (1) after the coal gangue is crushed and ball milled for 40 min, the coal gangue is mixed with silane coupling agent KH550 to prepare pretreated coal gangue, the mass ratio of coal gangue to silane coupling agent KH550 is 0.3:1, and the chemical composition of the coal gangue is shown in table 1;

[0049] (2) 13 kg of pretreated coal gangue is mixed with 8 kg of organic silicon modified alkyd resin, 4 kg of parylene and 3 kg of silicon oxynitride, melted at 400 DEG C, extruded to prepare a master batch with a particle size of 35 um, and the solid content of the organic silicon modified alkyd resin is 51%;

[0050] (3) The pore-forming agent is atomized and deposited on the surface of the master batch, and then calcined at 230℃ for 4h to prepare the porous master batch, the mass ratio of the pore-forming agent to the master batch is 0.07:1, and the pore-forming agent is ammonium bicarbonate;

[0051] (4) 8kg of the porous master batch is mixed with 2kg of hydroxyapatite and 0.9kg of carbon nanotubes, and a gelatin solution is sprayed while stirring, and then dried at 110℃ to prepare the modified coal gangue, the mass ratio of the gelatin solution to the porous master batch is 0.04:1.

[0052] Preparation Example 3: (1) The coal gangue is crushed and ball milled for 50min, and then mixed with a silane coupling agent KH550 to prepare the pretreated coal gangue, the mass ratio of the coal gangue to the silane coupling agent KH550 is 0.4:1, and the chemical composition of the coal gangue is shown in Table 1;

[0053] (2) 15kg of the pretreated coal gangue is mixed with 10kg of a silicone-modified alkyd resin, 5kg of poly-p-xylene and 4kg of silicon oxynitride, melted at 450℃, and extruded to prepare a master batch with a particle size of 40um, and the solid content of the silicone-modified alkyd resin is 52%;

[0054] (3) The pore-forming agent is atomized and deposited on the surface of the master batch, and then calcined at 250℃ for 3h to prepare the porous master batch, the mass ratio of the pore-forming agent to the master batch is 0.1:1, and the pore-forming agent is n-heptane;

[0055] (4) 10kg of the porous master batch is mixed with 3kg of hydroxyapatite and 1.2kg of carbon nanotubes, and a gelatin solution is sprayed while stirring, and then dried at 110℃ to prepare the modified coal gangue, the mass ratio of the gelatin solution to the porous master batch is 0.05:1.

[0056] Example

[0057] In the following examples, the blast furnace slag powder is selected from Qiangdongchuang Product Processing Factory in Lingshou County, the model number is qd094, the polycarboxylate superplasticizer is selected from Rongtai Chemical Product Co., Ltd. in Jinshui District of Zhengzhou, the model number is S-1217, the naphthalene-based superplasticizer is selected from Jinan Wei Zhen Chemical Co., Ltd., the model number is 015, the waterproof agent is selected from Shandong Jingfeng New Building Material Co., Ltd., the article number is 1001, the cement clinker is selected from Yanxing Mineral Product Processing Factory in Lingshou County, the article number is 25, the triethanolamine is selected from Guangzhou Changhong Chemical Technology Co., Ltd., the model number is TEA, the sodium tripolyphosphate is selected from Wujiang Puhua Chemical Light Industry Co., Ltd., the article number is 0122, and the sodium pyrophosphate is selected from Lianyungang Guansu Industry Co., Ltd., the model number is GS-31.

[0058] Example 1: A high-performance Portland cement, the raw material usage is shown in Table 2, the preparation method of the high-performance Portland cement comprises the following steps:

[0059] 8 kg of mixed materials were dried to a moisture content of 3%, 30 kg of cement clinker, 8 kg of gypsum, 10 kg of modified coal gangue and 0.05 kg of grinding aid were added, and grinding was performed for 30 min, 0.2 kg of water reducing agent and 0.03 kg of waterproofing agent were added, and homogenization treatment was performed, to obtain high-performance Portland cement, the mixed materials were prepared by mixing 3.4 kg of fly ash and 0.5 kg of blast furnace slag powder, the fly ash was grade III fly ash, the cement clinker was selected from commercially available products, the content of calcium oxide in the gypsum was 38%, the content of silicon oxide was 2.8%, the modified coal gangue was selected from the preparation example 1 of modified coal gangue, the water reducing agent was a polycarboxylic acid water reducing agent, the grinding aid was triethanolamine, and the waterproofing agent was selected from commercially available products.

[0060] Table 2: Raw material usage in high-performance Portland cement in examples 1-5

[0061]

[0062] Example 2: A high-performance Portland cement, which is different from example 1 in that the raw material usage is shown in table 2, the water reducing agent is a naphthalene-based water reducing agent, and the grinding aid is triethanolamine and sodium pyrophosphate in a mass ratio of 1:1.

[0063] Example 3: A high-performance Portland cement, which is different from example 1 in that the raw material usage is shown in table 2, the water reducing agent is a mixture of polycarboxylic acid water reducing agent and naphthalene-based water reducing agent in a mass ratio of 1:1, and the grinding aid is sodium tripolyphosphate.

[0064] Examples 4-5: A high-performance Portland cement, which is different from example 1 in that the raw material usage is shown in table 2.

[0065] Example 6: A high-performance Portland cement, which is different from example 1 in that the modified coal gangue is prepared by the preparation example 2 of modified coal gangue.

[0066] Example 7: A high-performance Portland cement, which is different from example 1 in that the modified coal gangue is prepared by the preparation example 3 of modified coal gangue.

[0067] Example 8: A high-performance Portland cement, which is different from example 1 in that the mixed materials are prepared by the following method: 1.6 kg of chromium slag and 0.5 kg of blast furnace slag powder are mixed, dried at 80°C for 30 min, ball milled for 40 min, 3.4 kg of fly ash and 0.68 kg of alkali activator are added, and ball milling is continued until the specific surface area of the mixed materials is 400 m 2 / kg, and then placed in a steam curing oven at 80°C for 20 h, the alkali activator is calcium hydroxide, and the fly ash is grade III fly ash.

[0068] Example 9: A high performance Portland cement, which is different from Example 1 in that the mixed material is made by the following method: 2.3 kg of chromium residue and 0.8 kg of blast furnace slag powder are mixed, then dried at 70 °C for 40 min, ball milled for 50 min, 4.2 kg of fly ash and 1.05 kg of alkali activator are added, and the ball milling is continued until the specific surface area of the mixed material is 430 m2 / kg, and then placed at 75 °C for 22 h, the alkali activator is calcium sulfate, and the fly ash is Grade III fly ash. 2

[0069] Example 10: A high performance Portland cement, which is different from Example 1 in that the mixed material is made by the following method: 3 kg of chromium residue and 1 kg of blast furnace slag powder are mixed, then dried at 80 °C for 40 min, ball milled for 60 min, 5 kg of fly ash and 1.5 kg of alkali activator are added, and the ball milling is continued until the specific surface area of the mixed material is 450 m2 / kg, and then placed at 70 °C for 24 h, the alkali activator is calcium carbonate, and the fly ash is Grade III fly ash. 2

[0070] Example 11: A high performance Portland cement, which is different from Example 8 in that no alkali activator is added.

[0071] Example 12: A high performance Portland cement, which is different from Example 1 in that the preparation method of the cement clinker is as follows: 8 kg of limestone and 2 kg of iron tailings are mixed and ball milled to a 80 um residue of 15%, calcined at 1300 °C for 60 min, and cooled to obtain the clinker; 1 kg of water glass is mixed with 0.15 kg of sodium polyacrylate, heated to 80 °C, 2 kg of sodium polyphosphate is added, and heated for 1.5 h, then cooled to room temperature, and the clinker is added and mixed uniformly to obtain the cement clinker, the chemical composition of the limestone and iron ore is shown in Table 3.

[0072] Table 3 Main chemical composition of limestone and iron ore

[0073] w / ％ CaO Al2O3 SiO2 Fe2O3 MgO SO3 Loss on ignition Limestone 50.32 2.83 10.22 2.36 1.35 0.12 32.76 Iron tailings 12.41 19.07 45.41 10.86 7.23 0.44 1.22

[0074] Example 13: A high performance Portland cement, which is different from Example 1 in that the preparation method of the cement clinker is as follows: 9 kg of limestone and 3 kg of iron tailings are mixed and ball milled to a 80 um residue of 16%, calcined at 1350 °C for 50 min, and cooled to obtain the clinker; 1.5 kg of water glass is mixed with 0.18 kg of sodium polyacrylate, heated to 85 °C, 2.5 kg of sodium polyphosphate is added, and heated for 2 h, then cooled to room temperature, and the clinker is added and mixed uniformly to obtain the cement clinker, the chemical composition of the limestone and iron ore is shown in Table 3.

[0075] ​​Example 14: A high-performance Portland cement, which differs from Example 1 in that the cement clinker is prepared as follows: 10 kg of limestone and 4 kg of iron tailings are mixed and ball milled to a residue on an 80 um sieve of 18%, calcined at 1400°C for 30 min, and cooled to produce the clinker; 2 kg of water glass is mixed with 0.2 kg of sodium polyacrylate, heated to 90°C, 3 kg of sodium polyphosphate is added, and held at temperature for 2 h, and after cooling to room temperature, the clinker is added and mixed uniformly to produce the cement clinker. The chemical compositions of the limestone and iron tailings are shown in Table 3.

[0076] Example 15: A high-performance Portland cement, which differs from Example 12 in that the cement clinker is prepared by mixing 9 kg of limestone and 3 kg of iron tailings, ball milling to a residue on an 80 um sieve of 16%, and calcining at 1350°C for 50 min, and cooling to produce the clinker.

[0077] Example 16: A high-performance Portland cement, which differs from Example 12 in that no sodium polyacrylate is added.

[0078] Example 17: A high-performance Portland cement, which differs from Example 12 in that no sodium polyphosphate is added.

[0079] Example 18: A high-performance Portland cement, which differs from Example 1 in that the water repellent agent is prepared by mixing 3-hydroxyoctadecenoic acid, methyl triethoxysilane, and anhydrous ethanol in a mass ratio of 1:0.2:10.

[0080] Example 19: A high-performance Portland cement, which differs from Example 1 in that the water repellent agent is prepared by mixing 3-hydroxyoctadecenoic acid, methyl triethoxysilane, and anhydrous ethanol in a mass ratio of 1:0.5:15.

[0081] Example 20: A high-performance Portland cement, which differs from Example 1 in that the water repellent agent is prepared by mixing 3-hydroxyoctadecenoic acid, methyl triethoxysilane, and anhydrous ethanol in a mass ratio of 1:1:20.

[0082] Example 21: A high-performance Portland cement, which differs from Example 18 in that the mixed material is prepared as follows: 1.6 kg of chromium slag and 0.5 kg of blast furnace slag micro-powder are mixed and dried at 80°C for 30 min, ball milled for 40 min, 3.4 kg of fly ash and 0.68 kg of alkali activator are added, and the ball milling is continued until the specific surface area of the mixed material is 400 m 2 / kg, and then placed at 80℃ for 20h, and the alkali activator was calcium hydroxide; the preparation method of the cement clinker was as follows: 8kg of limestone and 2kg of iron tailings were mixed, ball-milled to 80um of 15% of the residue, calcined at 1300℃ for 60min, and cooled to obtain the clinker; 1kg of water glass was mixed with 0.15kg of sodium polyacrylate, heated to 80℃, 2kg of sodium polyphosphate was added, and kept for 1.5h, and then cooled to room temperature, and then the clinker was added and uniformly mixed to obtain the cement clinker, and the chemical compositions of the limestone and the iron tailings were shown in Table 3.

[0083] Comparative Example

[0084] Comparative Example 1: A high-performance Portland cement, which was different from Example 1 in that the modified coal gangue was replaced by unmodified coal gangue.

[0085] Comparative Example 2: A high-performance Portland cement, which was different from Example 1 in that the coal gangue was not pretreated by silane coupling agent KH550 in step (1).

[0086] Comparative Example 3: A high-performance Portland cement, which was different from Example 1 in that the organic silicon modified alkyd resin was not added in step (2).

[0087] Comparative Example 4: A high-performance Portland cement, which was different from Example 1 in that the poly-p-xylylene was not added in step (2).

[0088] Comparative Example 5: A high-performance Portland cement, which was different from Example 1 in that the silicon oxynitride was not added in step (2).

[0089] Comparative Example 6: A high-performance Portland cement, which was different from Example 1 in that step (3) was not performed.

[0090] Comparative Example 7: A high-performance Portland cement, which was different from Example 1 in that the hydroxyapatite was not added in step (4).

[0091] Comparative Example 8: A high-performance Portland cement, which was different from Example 1 in that the carbon nanotube was not added in step (4).

[0092] Comparative Example 9: A preparation method of a composite Portland cement: (1) 70 parts by weight of Portland cement clinker and 6 parts by weight of dihydrate gypsum were crushed to a particle size of 5-6mm; (2) 7 parts by weight of steel slag was crushed and placed in a ball mill for grinding to obtain a ground steel slag powder with a particle size of 18-20μm; (3) 15 parts by weight of fly ash was placed in a superfine grinder for grinding to obtain a fly ash powder with a specific surface area of 900-1000m 2 / kg of superfine fly ash; (4) grinding and mixing the broken silicate cement clinker, dihydrate gypsum, ground steel slag powder, superfine fly ash, 1.5 parts by weight of activator and 0.5 parts by weight of grinding aid for 3 hours to obtain composite portland cement with a specific surface area of 600-700 m 2 / kg of composite portland cement; the portland cement clinker contains 65 parts by weight of CaO, 20 parts by weight of SiO2, 5 parts by weight of Al2O3, 5 parts by weight of Fe2O3 and 5 parts by weight of MgO; the steel slag contains 55 parts by weight of CaO, 17 parts by weight of SiO2, 4 parts by weight of Al2O3, 6 parts by weight of Fe2O3, 8 parts by weight of FeO, 5 parts by weight of MgO, 3 parts by weight of MnO and 2 parts by weight of P2O5; the activator is a mixture of sodium aluminate and sodium aluminosilicate; the chemical components of the grinding aid include triethanolamine, ethylene glycol, sodium chloride and aluminum sulfate.

[0093] Performance test

[0094] I. The mixed materials were prepared according to the methods in Examples 8-10, and the leaching amounts of hexavalent chromium and total chromium in the chromium slag were detected by using the sulfuric acid-nitric acid method and TCLP toxicity leaching method, and the detection results were recorded in Table 4.

[0095] Table 4 Concentrations of chromium in the mixed materials prepared in Examples 8-10.

[0096]

[0097] As can be seen from the data in Table 4, the leaching concentrations of total chromium and hexavalent chromium in the mixed materials prepared by using fly ash, blast furnace slag powder and alkali activator to treat the chromium slag are low, which meets the standard (total chromium concentration is less than 0.3 mg / L, and hexavalent chromium concentration is less than 0.1 mg / L) for producing bricks or blocks by using chromium slag in the “Technical Code for Chromium Slag Pollution Control and Environmental Protection (Provisional)” (HJ / T 301-2007), and thus the mixed materials can be used to prepare cement without causing pollution.

[0098] II. The high-performance portland cement was prepared according to the methods in the examples and comparative examples, and the performance of the portland cement was detected by using the following methods, and the detection results were recorded in Table 5.

[0099] 1. Compressive strength: detected according to GB / T 17671-1999 “Cement-Determination of Strength Properties of Hardened Cement Mortar and Concrete”;

[0100] 2. Flexural strength: detected according to GB / T 17671-1999 “Cement-Determination of Strength Properties of Hardened Cement Mortar and Concrete”;

[0101] 3. 28d dry shrinkage rate: detected according to JC / T 603-2004 “Cement-Determination of Shrinkage of Hardened Cement Mortar”;

[0102] 4. Hydration heat: According to GB / T 12959-2008 "Standard Test Method for Determination of Hydration Heat of Cement";

[0103] 5. Anti-permeability pressure: According to GB 18445-2001 "Cementitious Capillary Crystalline Waterproofing Material".

[0104] Table 5. Performance test results of high-performance Portland cement

[0105]

[0106]

[0107] From the data in Examples 1-7 and Table 5, it can be seen that the high-performance Portland cement prepared by replacing part of the Portland cement clinker with the modified coal gangue prepared in the present application in Examples 1-7 has high compressive strength, large flexural strength, small hydration heat, and low dry shrinkage, which improves the toughness of the cement and reduces the brittleness, so that the cement is not easy to crack when hardened.

[0108] In Examples 8-10, the mixed material prepared in the present application is added to the high-performance Portland cement on the basis of adding the modified coal gangue prepared in the present application. The mixed material in Examples 1-6 is prepared by mixing blast furnace slag powder and fly ash, while the mixed material in Examples 8-10 is prepared by mixing blast furnace slag powder, fly ash, chromium slag, and alkali activator. The cement prepared in Examples 8-10 has reduced hydration heat and dry shrinkage.

[0109] Compared with Example 8, Example 11 does not add alkali activator, and fails to activate the activity of fly ash and chromium slag. The hydration heat of the high-performance Portland cement increases, the dry shrinkage increases, and the compressive strength decreases, which indicates that the alkali activator can effectively reduce the hydration heat and dry shrinkage of the cement and improve the compressive strength.

[0110] In Examples 12-14, the cement clinker prepared in the present application is added to the high-performance Portland cement on the basis of adding the modified coal gangue prepared in the present application. From the results in Table 5, it can be seen that the flexural strength of the Portland cement prepared in Examples 12-14 significantly increases, and the dry shrinkage decreases, which indicates that the cement clinker prepared in the present application can significantly improve the toughness of the Portland cement and reduce its dry shrinkage.

[0111] The cement clinker in Example 15 is prepared by calcining iron tailings and limestone, no sodium polyacrylate is added in preparing the cement clinker in Example 16, and no sodium polyphosphate is added in preparing the cement clinker in Example 17. As can be seen from the data in Table 5, the high-performance Portland cement prepared in Examples 15-17 has a significantly decreased flexural strength and an increased dry shrinkage as compared with Example 12, indicating that the cement clinker prepared in the application can significantly increase the toughness of the Portland cement, reduce the dry shrinkage, and prevent cracking during hardening.

[0112] In Examples 18-20, the waterproofing agent prepared in the application is added on the basis of Example 1. As can be seen from the data in Table 5, the 28-day impermeable pressure of the Portland cement prepared in Examples 18-20 is significantly increased as compared with Example 1, and the impermeability is improved.

[0113] In Example 21, the cement clinker and the mixed material prepared in the application are further added as compared with Example 18. As can be seen from Table 5, the high-performance Portland cement prepared in Example 21 has a large flexural strength and a strong impermeability, and is the optimal example.

[0114] In Comparative Example 1, unmodified coal gangue is used instead of modified coal gangue. As compared with Example 1, the Portland cement prepared in Comparative Example 1 has a decreased compressive strength and flexural strength, an increased dry shrinkage and hydration heat, and poor toughness, and is prone to cracking, indicating that the modified coal gangue prepared in the application can effectively increase the toughness of the Portland cement and improve the anti-cracking performance.

[0115] In Comparative Example 2, the coal gangue is not pretreated with the silane coupling agent KH550. The data in Table 5 show that the flexural strength of the Portland cement prepared in Comparative Example 2 is decreased, and the dry shrinkage is increased, indicating that the silane coupling agent KH550 can increase the compatibility of the organosilicon-modified alkyd resin and poly-p-xylylene with the coal gangue, thereby improving the toughness of the Portland cement.

[0116] In Comparative Example 3, the organosilicon-modified alkyd resin is not used for melt extrusion with the pretreated coal gangue, and in Comparative Example 4, the poly-p-xylylene is not used for melt extrusion with the pretreated coal gangue. As can be seen from the data in Table 5, the flexural strength of the Portland cement prepared in Comparative Examples 3 and 4 is significantly decreased as compared with Example 1, indicating that the melt extrusion of the organosilicon-modified alkyd resin and the poly-p-xylylene with the pretreated coal gangue can effectively improve the toughness of the Portland cement and prevent cracking during hardening.

[0117] In Comparative Example 5, the silicon oxynitride is not used for melt extrusion with the pretreated coal gangue. The compressive strength of the Portland cement prepared in Comparative Example 5 is decreased as compared with Example 1, and the flexural strength changes little, indicating that the silicon oxynitride can increase the compressive strength of the concrete.

[0118] The data in Table 5 shows that the compressive strength of the portland cement prepared in Comparative Example 6 is increased compared with Example 1, and the flexural strength is decreased, which indicates that the pore-forming on the master batch can increase the toughness of the portland cement and prevent the hardened cement from cracking.

[0119] The data in Table 5 shows that the toughness of the portland cement prepared in Comparative Example 7 and Comparative Example 8 is decreased, and the shrinkage is increased, which indicates that the hydroxyapatite and the carbon nanotube can increase the toughness of the portland cement and prevent the hardened cement from cracking.

[0120] Comparative Example 9 is a composite portland cement prepared by the prior art, which has a high compressive strength, but a low flexural strength and a poor impermeability compared with the present application.

[0121] The embodiments are only illustrative of the present application, and are not intended to limit the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high performance Portland cement, characterized in that, The cement clinker comprises the following components in parts by weight: cement clinker 30-40 parts, mixed material 8-16 parts, gypsum 8-10 parts, modified coal gangue 10-20 parts, water reducing agent 0.2-0.4 parts, waterproof agent 0.03-0.05 parts, grinding aid 0.05-0.1 parts; The preparation method of the modified coal gangue is as follows: (1) the coal gangue is mixed with silane coupling agent KH550 after being crushed and ball milled to obtain pretreated coal gangue, and the mass ratio of the coal gangue to the silane coupling agent KH550 is 0.2-0.4:1; (2) 10-15 parts by weight of the pretreated coal gangue is mixed with 5-10 parts by weight of silicone modified alkyd resin, 3-5 parts by weight of poly-p-xylene and 2-4 parts by weight of silicon oxynitride, and then is melted, extruded to obtain master batch; (3) the pore-forming agent is atomized and deposited on the surface of the master batch, and then is calcined at 200-250 DEG C for 3-5 h to obtain porous master batch, and the mass ratio of the pore-forming agent to the master batch is 0.04-0.1:1; (4) 5-10 parts by weight of the porous master batch is mixed with 1-3 parts by weight of hydroxyapatite and 0.6-1.2 parts by weight of carbon nanotube, and then is stirred and sprayed with gelatin solution, and is dried at 105-110 DEG C to obtain modified coal gangue, and the mass ratio of the gelatin solution to the porous master batch is 0.03-0.05:

1.

2. The high-performance Portland cement according to claim 1, characterized in that: The mixed material comprises the following components in parts by weight: fly ash 3.4-5 parts, blast furnace slag powder 0.5-1 part and chromium slag 1.6-3 parts.

3. The high-performance Portland cement according to claim 2, characterized in that: The preparation method of the mixed material is as follows: the chromium slag and the blast furnace slag powder are mixed, dried, ball milled, and then the fly ash and alkali activator are added and ball milled, and then the mixture is steamed at 70-80 DEG C for 20-24 h, and the amount of the alkali activator is 20-30% of the amount of the fly ash.

4. The high-performance Portland cement according to claim 3, characterized in that, The alkali activator is one or a combination of calcium hydroxide, calcium sulfate and calcium carbonate.

5. The high-performance Portland cement according to claim 1, characterized in that, The specific surface area of the mixed material is 400-450 m 2 / kg.

6. The high-performance Portland cement according to claim 1, characterized in that, The preparation method of the cement clinker is as follows: 8-10 parts by weight of limestone and 2-4 parts by weight of iron tailings are mixed, ball milled to 80 um residue on sieve of 15-18%, and then are calcined at 1300-1400 DEG C for 30-60 min, and then are cooled to obtain clinker; 1-2 parts by weight of water glass is mixed with 0.15-0.2 parts by weight of sodium polyacrylate, heated to 80-90 DEG C, 2-3 parts by weight of sodium polyphosphate is added, and then is kept warm for 1.5-3 h, and then is cooled to room temperature, and then the clinker is added and mixed uniformly to obtain cement clinker.

7. The high-performance Portland cement according to claim 1, characterized in that, The water reducing agent is one or a combination of polycarboxylic acid water reducing agent and naphthalene series water reducing agent; The grinding aid is one or a combination of triethanolamine, sodium tripolyphosphate and sodium pyrophosphate.

8. The high-performance Portland cement according to claim 1, characterized in that, The pore-forming agent is one of PVA, ammonium bicarbonate and n-heptane.

9. The high-performance Portland cement according to claim 1, characterized in that, The waterproof agent is prepared by mixing 3-hydroxyoctadecenoic acid, methyl triethoxysilane and anhydrous ethanol, and the mass ratio of the 3-hydroxyoctadecenoic acid, the methyl triethoxysilane and the anhydrous ethanol is 1:0.2-1:10-20.

10. Process for the production of a high-performance Portland cement according to any one of claims 1 to 9, characterized in that, The method comprises the following steps: After the mixed material is dried, the cement clinker, the gypsum, the modified coal gangue and the grinding aid are added and ground, and then the water reducing agent and the waterproof agent are added and homogenized to obtain high-performance portland cement.

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