A cementitious material and a concrete and use thereof

Abstract

The application provides a cementing material and a concrete and application thereof, and belongs to the technical field of concrete. The cementing material provided by the application comprises the following components in percentage by mass: modified burned gypsum 55-85%, silicate 5-10%, magnesium type activated zeolite 5-10%, fuming sulfuric acid 3-4%, attapulgite 1.5-3.5% and active alumina 0.5-2%; the modified burned gypsum is obtained by mixing gypsum, potassium sulfate and anhydrous sodium sulfate after electromagnetic radiation and calcination in sequence. The application adopts the modified burned gypsum, the silicate, the magnesium type activated zeolite and the attapulgite as the base material, and the active alumina as the catalyst, and adopts the fuming sulfuric acid chemical excitation and the electromagnetic radiation physical excitation, so that the pH value of the concrete prepared from the cementing material is stabilized at 6.5-8.5.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to a cementitious material, a type of concrete, and their applications. Background Technology

[0002] Cementitious materials have good fluidity and permeability, enabling them to be evenly distributed in the complex underground environment of mines. They can penetrate into tiny cracks and pores, filling and sealing voids within the mine, preventing water and pollutants from further seeping or spreading. As a result, they have wide applications in mine pollution remediation and mine space grouting and filling.

[0003] Existing cementitious materials are generally cement or cement-water glass mixtures, which are used to prepare concrete for construction by combining cementitious materials with industrial solid waste. However, their initial pH value is generally greater than 12.5, and the pH value of leaching tests on slurry or concrete specimens after 28 days of setting is generally higher than 11.5, far exceeding the pH value requirement of 6.5~8.5 in the national standard GB / T 14848-2007, causing a certain degree of secondary environmental damage. Therefore, how to improve cementitious materials to make the pH value of the concrete prepared from them between 6.5 and 8.5 has become a difficult problem in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a cementitious material and a type of concrete, and their applications. The concrete prepared from the cementitious material provided by this invention has a pH value between 6.5 and 8.5.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a cementitious material comprising, by mass percentage: 55-85% modified calcined gypsum, 5-10% silicate, 5-10% magnesium-type activated zeolite, 3-4% fuming sulfuric acid, 1.5-3.5% attapulgite, and 0.5-2% activated alumina; wherein the modified calcined gypsum is obtained by mixing gypsum with potassium sulfate and sodium sulfate after sequentially subjecting it to electromagnetic radiation and calcination.

[0006] Preferably, the preparation method of the modified calcined gypsum includes: Plaster is subjected to electromagnetic radiation and calcination in sequence to obtain calcined plaster; The calcined gypsum was mixed with potassium sulfate and sodium sulfate to obtain modified calcined gypsum.

[0007] Preferably, the electromagnetic frequency of the electromagnetic radiation is 3~40GHz, and the duration of the electromagnetic radiation is ≥2.5min; the calcination temperature is 450~1250℃, and the calcination time is ≥2h.

[0008] Preferably, the mass ratio of potassium sulfate to gypsum is (0.008~0.035):1; and the mass ratio of sodium sulfate to gypsum is (0.006~0.015):1.

[0009] Preferably, the silicate comprises potassium silicate and / or sodium silicate; the modulus of the silicate is 0.8 to 3.2.

[0010] Preferably, the preparation method of the magnesium-type activated zeolite includes: Natural zeolite is calcined to obtain calcined zeolite; The calcined zeolite was soaked in acid solution and alkali solution in sequence to obtain alkali-treated zeolite; The alkali-treated zeolite was mixed with a magnesium salt solution to obtain magnesium-type activated zeolite.

[0011] Preferably, the calcination is performed by calcining at 300-400℃ for 0.5-1.5 hours, cooling to 100-200℃, and then heating to 400-500℃ for another 0.5-1.5 hours.

[0012] Preferably, the concentration of the magnesium salt solution is 1~1.5 mol / L, and the mixing time between the alkali-treated zeolite and the magnesium salt solution is 2~3 h.

[0013] The present invention also provides a concrete comprising the cementitious material, aggregate and water described in the above technical solution; wherein the cementitious material content in the concrete is 5~25wt%.

[0014] The present invention also provides the application of the cementitious materials or concrete described in the above technical solutions in mine pollution remediation and mine grouting and filling.

[0015] This invention provides a cementitious material comprising, by mass percentage: 55-85% modified calcined gypsum, 5-10% silicate, 5-10% magnesium-type activated zeolite, 3-4% fuming sulfuric acid, 1.5-3.5% attapulgite, and 0.5-2% activated alumina. The modified calcined gypsum is obtained by sequentially subjecting gypsum to electromagnetic radiation and calcination, followed by mixing with potassium sulfate and sodium sulfate. This invention uses modified calcined gypsum, silicate, magnesium-type activated zeolite, and attapulgite as base materials, and activated alumina as a catalyst. Fuming sulfuric acid is used for chemical activation, and electromagnetic radiation is used for physical activation of the gypsum, eliminating free calcium oxide in the gypsum. This results in a stable pH value of 6.5-8.5 in the concrete prepared by hydration of the cementitious material. Detailed Implementation

[0016] The present invention provides a cementitious material comprising, by mass percentage: 55-85% modified calcined gypsum, 5-10% silicate, 5-10% magnesium-type activated zeolite, 3-4% fuming sulfuric acid, 1.5-3.5% attapulgite, and 0.5-2% activated alumina.

[0017] Unless otherwise specified, the present invention does not have any special limitations on the source of each component, and commercially available products well known to those skilled in the art can be used.

[0018] The cementitious material provided by this invention comprises 55-85% modified calcined gypsum by weight percentage. As one embodiment, the content of the modified calcined gypsum may specifically be 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, or 85%.

[0019] In this invention, the modified calcined gypsum is obtained by sequentially subjecting gypsum to electromagnetic radiation and calcination, followed by mixing with potassium sulfate and sodium sulfate; the preferred method for preparing the modified calcined gypsum includes: Plaster is subjected to electromagnetic radiation and calcination in sequence to obtain calcined plaster; The calcined gypsum was mixed with potassium sulfate and sodium sulfate to obtain modified calcined gypsum.

[0020] The present invention preferably involves subjecting gypsum to electromagnetic radiation and calcination in sequence to obtain calcined gypsum.

[0021] In this invention, the gypsum is preferably dried and pulverized sequentially before use.

[0022] The present invention does not impose any special limitations on the drying operation; drying to constant weight can be achieved using drying techniques well known to those skilled in the art.

[0023] In this invention, the particle size of the pulverized gypsum is preferably 180-250 mesh. This invention does not impose any special limitations on the pulverization operation; any pulverization technique well-known to those skilled in the art can be used to ensure that the particle size of the pulverized gypsum is within the required range.

[0024] In this invention, the effective calcium sulfate content of the gypsum is preferably ≥85wt%.

[0025] In this invention, the electromagnetic frequency of the electromagnetic radiation is preferably 3~40 GHz; the duration of the electromagnetic radiation is preferably ≥2.5 min. As one embodiment, the electromagnetic frequency of the electromagnetic radiation can specifically be 3 GHz, 5 GHz, 10 GHz, 15 GHz, 20 GHz, 25 GHz, 30 GHz, 35 GHz, or 40 GHz; the duration of the electromagnetic radiation can specifically be 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, 5 min, 5.5 min, or 6 min.

[0026] In this invention, the electromagnetic radiation is preferably carried out in an electromagnetic rotary kiln; the rotational speed of the electromagnetic rotary kiln is preferably 30~45 r / min. As one embodiment, the rotational speed of the electromagnetic rotary kiln can specifically be 30 r / min, 32 r / min, 34 r / min, 36 r / min, 38 r / min, 40 r / min, 42 r / min, 44 r / min or 45 r / min.

[0027] In this invention, the calcination temperature is preferably 450~1250℃; the calcination time is preferably ≥2h. As one embodiment, the calcination temperature can specifically be 450℃, 500℃, 550℃, 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, or 1250℃; the calcination time can specifically be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h.

[0028] After calcination, the calcined product is preferably cooled. The cooling process is not particularly limited; any cooling technique well-known to those skilled in the art can be used to cool the product to room temperature.

[0029] After obtaining calcined gypsum, the present invention preferably mixes the calcined gypsum with potassium sulfate and sodium sulfate to obtain modified calcined gypsum.

[0030] In this invention, the purity of the potassium sulfate is preferably ≥96%.

[0031] In this invention, the preferred mass ratio of potassium sulfate to gypsum is (0.008~0.035):1. As one embodiment, the mass ratio of potassium sulfate to gypsum may specifically be 0.008:1, 0.010:1, 0.015:1, 0.020:1, 0.025:1, 0.030:1, or 0.035:1.

[0032] In this invention, the purity of the sodium sulfate is preferably ≥95%.

[0033] In this invention, the preferred mass ratio of sodium sulfate to gypsum is (0.006~0.015):1. As one embodiment, the mass ratio of sodium sulfate to gypsum can specifically be 0.006:1, 0.007:1, 0.008:1, 0.01:1, 0.011:1, 0.012:1, 0.013:1, 0.014:1, or 0.015:1.

[0034] The present invention does not have any special limitations on the operation of mixing the calcined gypsum with potassium sulfate and sodium sulfate. The three can be mixed evenly by means of mixing techniques known to those skilled in the art.

[0035] This invention uses potassium sulfate and sodium sulfate to modify calcined gypsum and controls the preparation parameters. Potassium sulfate and sodium sulfate are combined to synergistically activate gypsum, forming a ternary compound activator of potassium sulfate, sodium sulfate, and activated gypsum.

[0036] The cementitious material provided by the present invention further includes 5-10% silicate by weight percentage. As one embodiment, the silicate content may specifically be 5%, 6%, 7%, 8%, 9%, or 10%.

[0037] In this invention, the silicate preferably includes potassium silicate and / or sodium silicate; the sodium silicate preferably includes at least one of anhydrous sodium silicate, sodium silicate pentahydrate and sodium silicate nonahydrate.

[0038] In this invention, the modulus of the silicate is preferably 0.8 to 3.2. As one embodiment, the modulus of the silicate may specifically be 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, or 3.2.

[0039] The cementitious material provided by the present invention further includes 5-10% magnesium-type activated zeolite by weight percentage. As one embodiment, the content of the magnesium-type activated zeolite may specifically be 5%, 6%, 7%, 8%, 9%, or 10%.

[0040] In this invention, the preferred method for preparing the magnesium-type activated zeolite includes: Natural zeolite is calcined to obtain calcined zeolite; The calcined zeolite was soaked in acid solution and alkali solution in sequence to obtain alkali-treated zeolite; The alkali-treated zeolite was mixed with a magnesium salt solution to obtain magnesium-type activated zeolite.

[0041] The present invention preferably involves calcining natural zeolite to obtain calcined zeolite.

[0042] In this invention, the average fineness of the natural zeolite is preferably ≤0.5mm.

[0043] When the average fineness of the natural zeolite is not within the above-mentioned range, the present invention preferably pulverizes the natural zeolite. The present invention does not impose any special limitations on the pulverization operation; any pulverization technique well-known to those skilled in the art can be used to ensure that the average fineness of the natural zeolite is within the above-mentioned range.

[0044] In this invention, the calcination is preferably performed by calcining at 300-400°C for 0.5-1.5 hours, cooling down to 100-200°C, and then heating up to 400-500°C for calcination for 0.5-1.5 hours; more preferably, by calcining at 350°C for 1 hour, cooling down to 150°C, and then heating up to 450°C for calcination for 1 hour.

[0045] After calcination, the present invention preferably cools the calcined product to obtain calcined zeolite.

[0046] The present invention does not impose any particular limitation on the cooling operation; any cooling technique well known to those skilled in the art can be used to cool to room temperature. As one embodiment, the cooling is natural cooling.

[0047] After obtaining calcined zeolite, the present invention preferably soaks the calcined zeolite in acid solution and alkali solution in sequence to obtain alkali-treated zeolite.

[0048] In this invention, the acid solution is preferably a sulfuric acid solution; the mass concentration of the acid solution is preferably 10-15%. As one embodiment, the mass concentration of the acid solution may specifically be 10%, 11%, 12%, 13%, 14%, or 15%.

[0049] The present invention does not have a special limitation on the amount of acid solution used, as long as it can cover the calcined zeolite.

[0050] In this invention, the preferred temperature for soaking in the acid solution is 20-30°C; the preferred soaking time is 20-25 hours.

[0051] After soaking in the acid solution, the present invention preferably centrifuges the product after soaking in the acid solution to obtain a solid, and then soaks the solid in an alkaline solution.

[0052] The present invention does not impose any special limitations on the centrifugation operation; any centrifugation technique known to those skilled in the art can be used to obtain the solid.

[0053] In this invention, the alkaline solution is preferably an aqueous solution of slaked lime. The preferred method for preparing the aqueous solution of slaked lime in this invention is as follows: at room temperature, slaked lime and water are mixed at a mass ratio of (0.05~0.08):1, stirred until no more dissolves, and the supernatant is collected to obtain the aqueous solution of slaked lime.

[0054] The present invention does not have a special limitation on the amount of alkaline solution used, as long as it is sufficient to cover the solid.

[0055] In this invention, the preferred soaking temperature of the alkaline solution is 20-30°C. This invention does not impose a specific limitation on the soaking time of the alkaline solution, as long as the pH value of the zeolite treated with the alkaline solution is within the required range.

[0056] In this invention, the pH value of the alkali-treated zeolite is preferably 6 to 8. As one embodiment, the pH value of the alkali-treated zeolite may specifically be 6, 6.5, 7, 7.5, or 8.

[0057] After soaking in the alkaline solution, the present invention preferably dries the product soaked in the alkaline solution to obtain alkaline-treated zeolite.

[0058] This invention does not impose any special limitations on the drying operation; any drying technique well-known to those skilled in the art can be used to ensure that the moisture content of the alkali-treated zeolite is within the required range. In this invention, the moisture content of the alkali-treated zeolite is preferably ≤1%.

[0059] After obtaining the alkali-treated zeolite, the present invention preferably mixes the alkali-treated zeolite with a magnesium salt solution to obtain magnesium-type activated zeolite.

[0060] In this invention, the magnesium salt solution is preferably an aqueous solution of magnesium sulfate; the concentration of the magnesium salt solution is preferably 1~1.5 mol / L. As one embodiment, the concentration of the magnesium salt solution may specifically be 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, or 1.5 mol / L.

[0061] In this invention, the amount of magnesium salt solution used is preferably such that the liquid level of the magnesium salt solution is 10-50 cm higher than the surface of the alkali-treated zeolite.

[0062] In this invention, the preferred temperature for mixing the alkali-treated zeolite with the magnesium salt solution is 20-30°C; the preferred mixing time for mixing the alkali-treated zeolite with the magnesium salt solution is 20-30 hours.

[0063] In one embodiment, the mixing of the alkali-treated zeolite with the magnesium salt solution is carried out in a rotary shaker.

[0064] After mixing, the present invention preferably washes and dries the mixed product sequentially to obtain magnesium-type activated zeolite.

[0065] The present invention does not impose any special limitations on the water washing operation; any water washing technical solution known to those skilled in the art can be used.

[0066] This invention does not impose any special limitations on the drying operation; any drying technique well-known to those skilled in the art can be used to ensure that the moisture content of the magnesium-type activated zeolite is within the required range. In this invention, the moisture content of the magnesium-type activated zeolite is preferably ≤1%.

[0067] The method for preparing magnesium-type activated zeolite of the present invention can remove fluorine from the material system more efficiently than other zeolites, while reducing calcium ions, potassium and sodium ions in the material system, which is beneficial to reducing the pH value of the system.

[0068] The cementitious material provided by this invention further includes 3-4% fuming sulfuric acid by weight percentage. As one embodiment, the content of the fuming sulfuric acid may specifically be 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, or 4%. By adding fuming sulfuric acid and controlling its dosage, this invention uses fuming sulfuric acid for chemical activation, combined with physical activation via electromagnetic radiation, thereby ensuring that the pH value of the concrete prepared from the cementitious material is between 6.5 and 8.5.

[0069] The cementitious material provided by the present invention further includes 1.5-3.5% attapulgite by weight percentage. As one embodiment, the amount of attapulgite may specifically be 1.5%, 1.8%, 2.0%, 2.5%, 3.0%, or 3.5%.

[0070] In this invention, the attapulgite is preferably opal attapulgite; the opal content in the opal attapulgite is preferably ≥30wt%; and the total content of dolomite and montmorillonite in the opal attapulgite is preferably ≤5%.

[0071] The cementitious material provided by the present invention further includes 0.5-2% activated alumina by weight percentage. As one embodiment, the amount of activated alumina may be specifically 0.5%, 0.8%, 1.0%, 1.5%, or 2%.

[0072] This invention uses modified calcined gypsum, silicates, magnesium-type activated zeolite, and attapulgite as base materials, and activated alumina as a catalyst. It employs chemical activation with fuming sulfuric acid and physical activation with electromagnetic radiation to control the composition and dosage of each component, thereby stabilizing the pH value of concrete prepared from cementitious materials at 6.5~8.5. This invention has the advantages of protecting biodiversity and meeting the current national standard "Groundwater Quality Standard" (GB / T14848). In addition, the materials of this invention are readily available.

[0073] In this invention, the preferred method for preparing the cementitious material is as follows: mixing modified calcined gypsum, silicate, magnesium-type activated zeolite, fuming sulfuric acid, attapulgite, and activated alumina, and ball milling the mixture to obtain a mixture; aging the mixture to obtain the cementitious material.

[0074] In this invention, the average particle size of the mixture is preferably 45-60 μm. This invention does not impose any special limitations on the ball milling operation; any ball milling technique well-known to those skilled in the art can be used to ensure that the average particle size of the mixture is within the required range.

[0075] In this invention, the aging temperature is preferably 20~30℃; the aging time is preferably 7~10 days.

[0076] The preparation method provided by this invention is simple.

[0077] The present invention also provides a concrete comprising the cementitious material, aggregate and water described in the above technical solution.

[0078] The concrete provided by this invention includes cementitious materials.

[0079] In this invention, the content of cementitious materials in the concrete is 5-25 wt%. As one embodiment, the content of cementitious materials in the concrete may specifically be 5 wt%, 10 wt%, 15 wt%, 20 wt%, or 25 wt%.

[0080] The concrete provided by this invention also includes aggregates.

[0081] In this invention, the aggregate preferably includes one or more of the following: coal gangue, pyrite slag, fly ash, furnace bottom ash, desulfurization gypsum, coal slag, dust collector ash, and steel slag; the particle size of the aggregate is preferably ≤25mm.

[0082] The concrete provided by this invention also includes water.

[0083] In this invention, the water-to-solid ratio of the concrete is preferably (0.25~0.3):1.

[0084] Because the cementitious material provided by this invention is used, the pH value of the concrete prepared by the cementitious material is between 6.5 and 8.5, which can be used for filling and grouting underground mines to prevent ground subsidence and protect the groundwater environment.

[0085] The present invention does not impose any special limitation on the preparation method of the concrete; any preparation method well known to those skilled in the art can be used.

[0086] The present invention also provides the application of the cementitious materials or concrete described in the above technical solutions in mine pollution remediation and mine grouting and filling.

[0087] The present invention does not impose any special limitations on the operation of the application, and any technical solution known to those skilled in the art can be used.

[0088] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0089] Example 1 A cementitious material, by mass percentage, comprises the following components: 85% modified calcined gypsum, 5% silicate (anhydrous sodium silicate with a modulus of 0.8), 5% magnesium-type activated zeolite, 3% fuming sulfuric acid, 1.5% attapulgite (opal attapulgite, with an opal content of 34% and a total content of 5% for dolomite and montmorillonite), and 0.5% activated alumina; The modified calcined gypsum is prepared as follows: natural gypsum (with an effective calcium sulfate content of 85%) is dried and then pulverized (particle size of 180-250 mesh). It is then subjected to electromagnetic radiation in an electromagnetic rotary kiln at a frequency of 40 GHz for 2.5 min at a rotation speed of 45 r / min. After calcination at 1250℃ for 2 h, and cooling, potassium sulfate (98% purity) and sodium sulfate (95% purity) are added (the mass ratio of potassium sulfate to natural gypsum is 0.008:1, and the mass ratio of sodium sulfate to natural gypsum is 0.006:1). The mixture is then thoroughly mixed to obtain the modified calcined gypsum. The preparation method of the magnesium-type activated zeolite is as follows: natural zeolite is crushed (average fineness is 0.06 mm), heated to 350℃ and calcined for 1 hour, cooled to 150℃, then heated to 450℃ and calcined for 1 hour, and naturally cooled to room temperature to obtain calcined zeolite; the calcined zeolite is soaked in a 10% sulfuric acid solution for 24 hours, centrifuged to obtain a solid, and then soaked in a quicklime aqueous solution (at room temperature, quicklime and water are mixed at a mass ratio of 0.05:1, stirred until no more dissolves, and the supernatant is taken to obtain a quicklime aqueous solution) to adjust the pH value to 7.5, dried, to obtain alkali-treated zeolite with a water content of 1%; the alkali-treated zeolite is placed in a gyratory shaker, and a 1 mol / L magnesium sulfate aqueous solution is added, with the liquid level 50 cm above the surface of the alkali-treated zeolite, and treated for 24 hours, then washed and dried to obtain magnesium-type activated zeolite with a water content of 1%; The preparation method of the cementitious material is as follows: modified calcined gypsum, silicate, magnesium-type activated zeolite, fuming sulfuric acid, attapulgite and activated alumina are mixed and ball-milled to obtain a mixture (average particle size of 60 μm), and then aged for 7 days to obtain the cementitious material.

[0090] Example 2 A cementitious material, by mass percentage, comprises the following components: 82.5% modified calcined gypsum, 6% silicate (anhydrous sodium silicate with a modulus of 1.0), 5% magnesium-type activated zeolite, 3.3% fuming sulfuric acid, 2.2% attapulgite (opal attapulgite, with an opal content of 32% and a total content of 5% for dolomite and montmorillonite), and 1.0% activated alumina; The preparation method of the modified calcined gypsum is the same as in Example 1; The preparation method of the magnesium-type activated zeolite is the same as in Example 1; The preparation method of the gelling material is the same as in Example 1.

[0091] Example 3 A cementitious material, by mass percentage, comprises the following components: 75.9% modified calcined gypsum, 8% silicate (anhydrous sodium silicate with a modulus of 0.8), 8% magnesium-type activated zeolite, 3.6% fuming sulfuric acid, 3.0% attapulgite (opal attapulgite, with an opal content of 34% and a total content of dolomite and montmorillonite of 5%), and 1.5% activated alumina; The preparation method of the modified calcined gypsum is the same as in Example 1; The preparation method of the magnesium-type activated zeolite is the same as in Example 1; The preparation method of the gelling material is the same as in Example 1.

[0092] Example 4 A cementitious material, by mass percentage, comprises the following components: 70.5% modified calcined gypsum, 10% silicate (anhydrous sodium silicate with a modulus of 0.8), 10% magnesium-type activated zeolite, 4% fuming sulfuric acid, 3.5% attapulgite (opal attapulgite, with an opal content of 35% and a total content of dolomite and montmorillonite of 5%), and 2.0% activated alumina; The preparation method of the modified calcined gypsum is the same as in Example 1; The preparation method of the magnesium-type activated zeolite is the same as in Example 1; The preparation method of the gelling material is the same as in Example 1.

[0093] Application Example 1 A type of concrete is prepared from the cementitious material, aggregate and water of Example 1; the cementitious material content in the concrete is 25.64%, the aggregate is coal gangue with a particle size ≤15mm, and the water-to-solid ratio is 0.3. The concrete preparation method is as follows: 70g of cementitious material and 54g of water are put into a forced mixing tank and stirred evenly. 200g of aggregate is added and stirred evenly at 20r / min. Then, 36g of water and 30g of cementitious material are added and stirred evenly to obtain concrete.

[0094] In Application Example 1, the pH value of the concrete is 7.5.

[0095] Application Example 2 A type of concrete is prepared from the cementitious material, aggregate and water of Example 2; the cementitious material content in the concrete is 25.67%, the aggregate is coal gangue with a particle size ≤15mm, and the water-to-solid ratio is 0.3. The concrete preparation method is as follows: 78.5g of cementitious material and 60.5g of water are put into a forced mixing tank and mixed evenly. 224g of aggregate is added and mixed evenly at 20r / min. Then, 40g of water and 33.6g of cementitious material are added and mixed evenly to obtain concrete.

[0096] In Application Example 2, the pH value of the concrete is 7.56.

[0097] Application Example 3 A type of concrete is prepared from the cementitious material, aggregate and water of Example 3; the cementitious material content in the concrete is 25.65%, the aggregate is coal gangue with a particle size ≤15mm, and the water-to-solid ratio is 0.3. The concrete preparation method is as follows: 94g of cementitious material and 72.5g of water are put into a forced mixing tank and mixed evenly. 269g of aggregate is added and mixed evenly at 20r / min. Then, 48g of water and 40.4g of cementitious material are added and mixed evenly to obtain concrete.

[0098] In Application Example 3, the pH value of the concrete is 7.61.

[0099] Application Example 4 A type of concrete is prepared from the cementitious material, aggregate and water of Example 4; the cementitious material content in the concrete is 25.64%, the aggregate is coal gangue with a particle size ≤25mm, and the water-to-solid ratio is 0.3. The concrete preparation method is as follows: 104g of cementitious material and 80g of water are put into a forced mixing tank and stirred evenly. 298g of aggregate is added and stirred evenly at 20r / min. Then, 53g of water and 44.6g of cementitious material are added and stirred evenly to obtain concrete.

[0100] In Application Example 4, the pH value of the concrete is 7.54.

[0101] In summary, the pH value of concrete prepared from the cementitious material of this invention is between 6.5 and 8.5.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cementitious material, characterized in that, The product comprises the following components by mass percentage: 55-85% modified calcined gypsum, 5-10% silicate, 5-10% magnesium-type activated zeolite, 3-4% fuming sulfuric acid, 1.5-3.5% attapulgite, and 0.5-2% activated alumina; the modified calcined gypsum is obtained by mixing gypsum with potassium sulfate and sodium sulfate after it has been subjected to electromagnetic radiation and calcination in sequence.

2. The cementitious material according to claim 1, characterized in that, The preparation method of the modified calcined gypsum includes: Plaster is subjected to electromagnetic radiation and calcination in sequence to obtain calcined plaster; The calcined gypsum was mixed with potassium sulfate and sodium sulfate to obtain modified calcined gypsum.

3. The cementitious material according to claim 2, characterized in that, The electromagnetic radiation frequency is 3~40GHz, and the electromagnetic radiation time is ≥2.5min; the calcination temperature is 450~1250℃, and the calcination time is ≥2h.

4. The cementitious material according to claim 2, characterized in that, The mass ratio of potassium sulfate to gypsum is (0.008~0.035):1; the mass ratio of sodium sulfate to gypsum is (0.006~0.015):

1.

5. The cementitious material according to claim 1, characterized in that, The silicate includes potassium silicate and / or sodium silicate; the modulus of the silicate is 0.8 to 3.

2.

6. The cementitious material according to claim 1, characterized in that, The preparation method of the magnesium-type activated zeolite includes: Natural zeolite is calcined to obtain calcined zeolite; The calcined zeolite was soaked in acid solution and alkali solution in sequence to obtain alkali-treated zeolite; The alkali-treated zeolite was mixed with a magnesium salt solution to obtain magnesium-type activated zeolite.

7. The cementitious material according to claim 6, characterized in that, The calcination process involves calcining at 300-400℃ for 0.5-1.5 hours, cooling to 100-200℃, and then heating back to 400-500℃ for another 0.5-1.5 hours.

8. The cementitious material according to claim 6, characterized in that, The concentration of the magnesium salt solution is 1~1.5 mol / L, and the mixing time between the alkali-treated zeolite and the magnesium salt solution is 2~3 h.

9. A type of concrete, characterized in that, It includes the cementitious material, aggregate and water as described in any one of claims 1 to 8; the cementitious material content in the concrete is 5 to 25 wt%.

10. The application of the cementitious material according to any one of claims 1 to 8 or the concrete according to claim 9 in mine pollution remediation and mine grouting filling.