A magnesite concrete with high sulfate erosion resistance and its preparation method

Abstract

This application relates to the field of magnesite concrete, and specifically discloses a magnesite concrete with high sulfate erosion resistance and a preparation method thereof. The magnesite concrete comprises the following components in parts by weight: 360 - 430 parts of cement, 1128.5 - 1146.6 parts of coarse aggregate, 663 - 689 parts of fine aggregate, 11.52 - 13.76 parts of silica fume, 160 - 185 parts of mixing water, 3.2 - 3.8 parts of water reducer, 17.28 - 20.64 parts of gneiss powder, and 6.12 - 7.36 parts of sulfate corrosion inhibitor; the preparation method is: first, mix and stir all raw materials except mixing water and water reducer, and then add mixing water and water reducer and continue to stir to obtain the magnesite concrete with high sulfate erosion resistance. The magnesite concrete of this application has strong mechanical properties and sulfate erosion resistance, and excellent durability.

Description

Technical Field

[0001] This application relates to the field of magnesite concrete, and more specifically, it relates to a magnesite concrete with high sulfate erosion resistance and a preparation method thereof. Background Art

[0002] China's magnesite resources are rich in reserves, accounting for about one-fourth of the world's total, ranking first in the world. Magnesite has excellent fire resistance and adhesiveness, and is widely used in the fields of metallurgy, chemical industry, light industry, construction, agriculture and animal husbandry. Magnesite cement produced from magnesite has the advantages of high mechanical strength, fast hardening speed, good bonding performance, strong resistance to brine, good flame retardant performance, low corrosiveness, etc., and can be mixed with various types of aggregates. In addition to traditional coarse and fine aggregates, some industrial wastes and crushed building materials can also be added, achieving the purpose of saving resources and protecting the environment.

[0003] At present, with the rapid development of the construction industry, the requirements for concrete in engineering construction are getting higher and higher. Concrete should not only have good physical and mechanical properties, but also have excellent durability, and be able to have a long service life under harsh environmental conditions. There are many factors affecting the durability of concrete, mainly including wet-dry cycles, carbonation, load effects, freeze-thaw cycles, alkali-aggregate reactions and salt erosion damage. Among them, sulfate erosion damage is one of the important reasons for the deterioration of concrete performance. During the erosion process, the damage of concrete will accumulate continuously. After reaching a certain level, the structure of concrete will be damaged, making it difficult to meet the design standards, which not only threatens the safety of people's work and life, but also reduces the service life of the project, causing huge waste of resources and economic losses. Summary of the Invention

[0004] To solve the above problems, this application provides a magnesite concrete with high sulfate erosion resistance and a preparation method thereof.

[0005] In the first aspect, a magnesite concrete with high sulfate erosion resistance provided by this application adopts the following technical scheme:

[0006] A magnesite concrete with high sulfate erosion resistance, the raw materials used include the following components in parts by weight:

[0007] Cement 360 - 430 parts;

[0008] Coarse aggregate 1128.5 - 1146.6 parts;

[0009] Fine aggregate 663 - 689 parts;

[0010] Silica fume 11.52 - 13.76 parts;

[0011] Mixing water: 160 - 185 parts;

[0012] Water reducing agent: 3.2 - 3.8 parts;

[0013] Gneiss rock powder: 17.28 - 20.64 parts;

[0014] Sulfate corrosion resistant agent: 6.12 - 7.36 parts.

[0015] By adopting the above technical solution, a certain amount of silica fume and gneiss rock powder are added to the magnesite concrete in this application, which can effectively fill the fine pores and cracks inside the magnesite concrete and strengthen the bonding performance of the interfacial transition zone, thereby improving and enhancing the mechanical properties and sulfate erosion resistance of the magnesite concrete.

[0016] Moreover, a certain amount of sulfate corrosion resistant agent is also added to the magnesite concrete in this application. The sulfate corrosion resistant agent can jointly improve and enhance the sulfate erosion resistance of the magnesite concrete with silica fume and gneiss rock powder, so that the magnesite concrete has excellent durability.

[0017] Preferably, by weight, the sulfate corrosion resistant agent includes 3.6 - 4.3 parts of an expansive agent, 0.72 - 0.86 parts of bentonite, and 1.8 - 2.2 parts of calcium phosphite.

[0018] By adopting the above technical solution, this application mixes the expansive agent, bentonite, and calcium phosphite to form a sulfate corrosion resistant agent and adds it to the magnesite concrete, giving full play to the synergistic effect among the three and jointly improving the sulfate erosion resistance of the magnesite concrete. Specifically, the expansive agent will expand in volume during the setting and hardening process of the magnesite concrete, and the generated expansive substances reduce the number of gaps and holes in the magnesite concrete and increase the compactness of the magnesite concrete, thereby enhancing the sulfate erosion resistance of the magnesite concrete. At the same time, bentonite has a water absorption effect and can absorb the excess water around it, increasing the water content in the magnesite concrete and further promoting the hydration of cement in the magnesite concrete to generate a large amount of hydration products, thus improving the compactness of the magnesite concrete. Calcium phosphite can not only enhance the strength of the already generated hydration products but also promote the hydration of unhydrated cement, thereby increasing the generation amount of calcium silicate precipitation and enhancing the sulfate erosion resistance of the magnesite concrete.

[0019] Preferably, the expansive agent includes a sulfoaluminate expansive agent and a magnesia expansive agent with a weight ratio of 1:(0.8 - 1.2).

[0020] By adopting the above technical solution, the present application uses a sulfoaluminate expansive agent and a magnesia expansive agent in a certain proportion in combination, giving full play to their synergistic effects with each other, reducing the number of cracks and pores in the magnesite concrete, making the structure of the magnesite concrete more dense, and thus improving the sulfuric acid erosion resistance of the magnesite concrete.

[0021] Preferably, the weight ratio of the gneiss powder and silica fume is (1.4 - 1.5):1.

[0022] By adopting the above technical solution, the gneiss powder and silica fume can give full play to their synergistic and complementary effects with each other to the greatest extent. Not only can the magnesite concrete obtain high sulfate erosion resistance, but also the dosage of the two can be significantly reduced, reducing the engineering cost.

[0023] Preferably, the raw materials further include 3.6 - 4.3 parts by weight of barium salt.

[0024] Preferably, the barium salt is barium carbonate and / or barium hydroxide.

[0025] By adopting the above technical solution, when the present application adds a barium salt to the magnesite concrete, barium ions in the barium salt can form insoluble barium sulfate with sulfate ions, solidifying the sulfate in the form of barium sulfate, reducing the sulfate concentration and porosity in the magnesite concrete, and thus improving the sulfuric acid erosion resistance of the magnesite concrete and enhancing the durability of the magnesite concrete.

[0026] Preferably, the raw materials further include 0.72 - 0.86 parts by weight of reinforcing fiber.

[0027] Preferably, the reinforcing fiber includes basalt fiber and polyvinyl alcohol fiber with a weight ratio of 1:(2 - 3).

[0028] By adopting the above technical solution, polyvinyl alcohol fiber can significantly inhibit the generation and development of internal microcracks in the magnesite concrete at the initial stage of sulfate erosion. However, as the sulfate erosion time prolongs, the cracks inside the magnesite concrete gradually increase, and the inhibition ability of the polyvinyl alcohol fiber reaches its limit. At this time, the basalt fiber plays a role in significantly inhibiting the generation and development of internal microcracks in the magnesite concrete.

[0029] The present application can give full play to the synergistic and complementary effects between the two to the greatest extent by further controlling the ratio of basalt fiber and polyvinyl alcohol fiber, thereby further improving the sulfate erosion resistance of the magnesite concrete.

[0030] In a second aspect, the present application provides a preparation method for a magnesite concrete with high sulfate erosion resistance, including the following steps:

[0031] First, mix all raw materials except mixing water and water reducer for 1 min - 3 min, then add mixing water and water reducer and continue to mix for 2 min - 5 min to obtain magnesite concrete with high sulfate erosion resistance.

[0032] By adopting the above technical solution to prepare magnesite concrete with high sulfate erosion resistance, the steps are simple, easy to operate, and suitable for large-scale industrial production.

[0033] Preferably, before mixing and stirring the magnesite in the raw materials with the remaining raw materials, soak it in water for 48 h - 50 h first, and then drain it for 10 min - 15 min.

[0034] By adopting the above technical solution, the water content of magnesite is 0.8%, and it is in a saturated surface dry state before mixing with other raw materials.

[0035] To sum up, this application has the following beneficial technical effects:

[0036] 1. The magnesite concrete of this application has strong mechanical properties and sulfate erosion resistance, excellent durability, and can have a long service life under harsh environmental conditions;

[0037] 2. The preparation method of the magnesite concrete of this application has simple steps, is easy to operate, the raw materials are extremely easy to obtain, and it is suitable for large-scale industrial production. Specific Embodiments

[0038] The following further elaborates on this application in combination with examples and comparative examples.

[0039] <Material Source>

[0040] The cement of this application is P.O42.5 grade portland cement, purchased from Liaoning, and the performance indicators of this cement are shown in Table 1;

[0041] Table 1

[0042]

[0043] The coarse aggregate of this application is low-grade magnesite crushed stone, which is industrial waste with a continuous gradation in the particle size range of 5 mm - 25 mm, produced in Liaoning. The component analysis of this magnesite crushed stone is shown in Table 2;

[0044] Table 2

[0045] Chemical Composition MgO CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> LOI Mass Fraction (%) 38.00 3.25 9.84 1.76 0.46 44.69

[0046] The fine aggregate of this application is natural sand, produced in Hebei, and the gradation is 0.31 mm - 0.63 mm;

[0047] The silica fume of this application is produced in Hebei, and the SiO2 content is about 94%;

[0048] The water reducing agent of this application is a naphthalene-based superplasticizer SNF-A, purchased from Shenyang Xingzhenghe Chemical Co., Ltd., and the water reducing rate is about 22%;

[0049] The gneiss powder of this application is the powder produced during the preparation of gneiss machine-made sand, with a particle size less than 0.0075mm, an apparent density of 2750kg / m 3 , and a specific surface area of 295m 2 / kg, and the methylene blue value is 1.5;

[0050] The sulfoaluminate expansive agent of this application is purchased from Chongqing Yuyuan Building Materials Co., Ltd., specifically a calcium sulfoaluminate-based expansive agent, model 402;

[0051] The magnesium oxide expansive agent of this application is purchased from Beijing Dechang Weiye Construction Engineering Technology Co., Ltd., model 1055;

[0052] The bentonite of this application is sodium-based bentonite, purchased from Heishan County Wancheng Bentonite Co., Ltd., with a mesh number of 200;

[0053] The calcium phosphite of this application is purchased from Hubei Jusheng Technology Co., Ltd.;

[0054] The barium carbonate of this application is purchased from Shandong Haoshun Chemical Co., Ltd., model HS-1250;

[0055] The barium hydroxide of this application is purchased from Jinan Century Tongda Chemical Co., Ltd.;

[0056] The basalt fiber of this application is purchased from Wuhan Qixing New Technology Research Institute, with a fiber diameter of 15μm - 25μm and a fiber length of 9mm;

[0057] The polyvinyl alcohol fiber of this application is purchased from Shandong Huibang New Material Technology Co., Ltd., with a length of 12mm.

[0058] <Example>

[0059] Example 1.1

[0060] A preparation method of magnesite concrete with high sulfate erosion resistance includes the following steps:

[0061] S1. First, soak the magnesite gravel in water for 48h, then take it out of the water and spread it out to drain for 10min;

[0062] S2. First, mix 360 kg of cement, 1146.6 kg of magnesite gravel, 663 kg of natural sand, 13.76 kg of silica fume, 17.28 kg of gneiss rock powder, and 7.36 kg of sulfate corrosion inhibitor in a concrete mixer and stir for 1 min. Then, add 160 kg of mixing water and 3.8 kg of naphthalene-based superplasticizer SNF-A and continue to stir for 5 min to obtain magnesite concrete with high sulfate erosion resistance;

[0063] Among them, the sulfate corrosion inhibitor includes 4.3 kg of expansive agent, 0.86 kg of sodium-based bentonite, and 2.2 kg of calcium phosphite. The expansive agent is specifically a calcium sulfoaluminate-based expansive agent.

[0064] Example 1.2

[0065] A preparation method of magnesite concrete with high sulfate erosion resistance includes the following steps:

[0066] S1. First, soak the magnesite gravel in water for 50 h, then take it out of the water and spread it out to drain for 15 min;

[0067] S2. First, mix 395 kg of cement, 1137.6 kg of magnesite gravel, 676 kg of natural sand, 12.64 kg of silica fume, 18.96 kg of gneiss rock powder, and 6.74 kg of sulfate corrosion inhibitor in a concrete mixer and stir for 3 min. Then, add 173 kg of mixing water and 3.5 kg of naphthalene-based superplasticizer SNF-A and continue to stir for 2 min to obtain magnesite concrete with high sulfate erosion resistance;

[0068] Among them, the sulfate corrosion inhibitor includes 4 kg of expansive agent, 0.79 kg of sodium-based bentonite, and 1.95 kg of calcium phosphite. The expansive agent is specifically a magnesia-based expansive agent.

[0069] Example 1.3

[0070] A preparation method of magnesite concrete with high sulfate erosion resistance includes the following steps:

[0071] S1. First, soak the magnesite gravel in water for 49 h, then take it out of the water and spread it out to drain for 13 min;

[0072] S2. First, mix 430 kg of cement, 1128.5 kg of magnesite gravel, 689 kg of natural sand, 11.52 kg of silica fume, 20.64 kg of gneiss rock powder, and 6.12 kg of sulfate corrosion inhibitor in a concrete mixer and stir for 2 min. Then, add 185 kg of mixing water and 3.2 kg of naphthalene-based superplasticizer SNF-A and continue to stir for 4 min to obtain magnesite concrete with high sulfate erosion resistance;

[0073] Among them, the anti-sulfate corrosion agent includes 3.6 kg of an expansive agent, 0.72 kg of sodium-based bentonite, and 1.8 kg of calcium phosphite. The expansive agent is specifically a calcium sulfoaluminate-based expansive agent.

[0074] Examples 2.1.1 - 2.1.3

[0075] A preparation method of magnesite concrete with high resistance to sulfate erosion, which is different from Example 1.1 in that: the 4.3 kg of expansive agent in the anti-sulfate corrosion agent includes a calcium sulfoaluminate-based expansive agent and a magnesium oxide expansive agent with a weight ratio of 1:(0.8 - 1.2). Specifically,

[0076] In Example 2.1.1, the weight ratio of the calcium sulfoaluminate-based expansive agent to the magnesium oxide expansive agent is 1:0.8, the calcium sulfoaluminate-based expansive agent is 2.39 kg, and the magnesium oxide expansive agent is 1.91 kg;

[0077] In Example 2.1.2, the weight ratio of the calcium sulfoaluminate-based expansive agent to the magnesium oxide expansive agent is 1:1, the calcium sulfoaluminate-based expansive agent is 2.15 kg, and the magnesium oxide expansive agent is 2.15 kg;

[0078] In Example 2.1.3, the weight ratio of the calcium sulfoaluminate-based expansive agent to the magnesium oxide expansive agent is 1:1.2, the calcium sulfoaluminate-based expansive agent is 1.95 kg, and the magnesium oxide expansive agent is 2.35 kg.

[0079] Examples 2.2.1 - 2.2.3

[0080] A preparation method of magnesite concrete with high resistance to sulfate erosion, which is different from Example 1.2 in that: the 4 kg of expansive agent in the anti-sulfate corrosion agent includes a calcium sulfoaluminate-based expansive agent and a magnesium oxide expansive agent with a weight ratio of 1:(0.8 - 1.2). Specifically,

[0081] In Example 2.2.1, the weight ratio of the calcium sulfoaluminate-based expansive agent to the magnesium oxide expansive agent is 1:0.8, the calcium sulfoaluminate-based expansive agent is 2.22 kg, and the magnesium oxide expansive agent is 1.78 kg;

[0082] In Example 2.2.2, the weight ratio of the calcium sulfoaluminate-based expansive agent to the magnesium oxide expansive agent is 1:1, the calcium sulfoaluminate-based expansive agent is 2 kg, and the magnesium oxide expansive agent is 2 kg;

[0083] In Example 2.2.3, the weight ratio of the calcium sulfoaluminate-based expansive agent to the magnesium oxide expansive agent is 1:1.2, the calcium sulfoaluminate-based expansive agent is 1.82 kg, and the magnesium oxide expansive agent is 2.18 kg.

[0084] Examples 2.3.1 - 2.3.3

[0085] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Example 1.3 in that: the 3.6 kg expansive agent in the sulfate corrosion inhibitor includes calcium sulfoaluminate expansive agent and magnesia expansive agent with a weight ratio of 1:(0.8 - 1.2). Specifically,

[0086] In Example 2.3.1, the weight ratio of calcium sulfoaluminate expansive agent to magnesia expansive agent is 1:0.8, the calcium sulfoaluminate expansive agent is 2 kg, and the magnesia expansive agent is 1.6 kg;

[0087] In Example 2.3.2, the weight ratio of calcium sulfoaluminate expansive agent to magnesia expansive agent is 1:1, the calcium sulfoaluminate expansive agent is 1.8 kg, and the magnesia expansive agent is 1.8 kg;

[0088] In Example 2.3.3, the weight ratio of calcium sulfoaluminate expansive agent to magnesia expansive agent is 1:1.2, the calcium sulfoaluminate expansive agent is 1.64 kg, and the magnesia expansive agent is 1.96 kg.

[0089] Examples 3.1.1 - 3.1.3

[0090] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Example 1.1 in that: the weight ratio of gneiss powder to silica fume is (1.4 - 1.5):1. Specifically,

[0091] In Example 3.1.1, the weight ratio of gneiss powder to silica fume is 1.4:1, the gneiss powder is 19.26 kg, and the silica fume is 13.76 kg;

[0092] In Example 3.1.2, the weight ratio of gneiss powder to silica fume is 1.45:1, the gneiss powder is 19.95 kg, and the silica fume is 13.76 kg;

[0093] In Example 3.1.3, the weight ratio of gneiss powder to silica fume is 1.5:1, the gneiss powder is 20.64 kg, and the silica fume is 13.76 kg.

[0094] Examples 3.2.1 - 3.2.3

[0095] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Example 1.2 in that: the weight ratio of gneiss powder to silica fume is (1.4 - 1.5):1. Specifically,

[0096] In Example 3.2.1, the weight ratio of gneiss powder to silica fume is 1.4:1, the gneiss powder is 17.70 kg, and the silica fume is 12.64 kg;

[0097] In Example 3.2.2, the weight ratio of gneiss powder to silica fume is 1.45:1, the gneiss powder is 18.33 kg, and the silica fume is 12.64 kg;

[0098] In Example 3.2.3, the weight ratio of gneiss powder to silica fume is 1.5:1, the gneiss powder is 18.96 kg, and the silica fume is 12.64 kg.

[0099] Examples 3.3.1 - 3.3.3

[0100] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Example 1.3 in that: in the weight ratio of gneiss powder to silica fume is (1.4 - 1.5):1, specifically,

[0101] In Example 3.3.1, the weight ratio of gneiss powder to silica fume is 1.4:1, the gneiss powder is 16.13 kg, and the silica fume is 11.52 kg;

[0102] In Example 3.3.2, the weight ratio of gneiss powder to silica fume is 1.45:1, the gneiss powder is 16.70 kg, and the silica fume is 11.52 kg;

[0103] In Example 3.3.3, the weight ratio of gneiss powder to silica fume is 1.5:1, the gneiss powder is 17.28 kg, and the silica fume is 11.52 kg.

[0104] Examples 4.1.1 - 4.1.3

[0105] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Example 1.1 in that: in step S2, the raw material mixed with cement, etc. also includes barium salt, specifically,

[0106] In Example 4.1.1, 3.6 kg of barium carbonate is added;

[0107] In Example 4.1.2, 3.95 kg of barium hydroxide is added;

[0108] In Example 4.1.3, 4.3 kg of barium carbonate and barium hydroxide are added, 2 kg of barium carbonate and 2.3 kg of barium hydroxide.

[0109] Examples 4.2.1 - 4.2.3

[0110] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Example 1.2 in that: in step S2, the raw material mixed with cement, etc. also includes barium salt, specifically, in Example 4.2.1, 3.6 kg of barium carbonate is added;

[0111] In Example 4.2.2, 3.95 kg of barium hydroxide was added;

[0112] In Example 4.2.3, 4.3 kg of barium carbonate and barium hydroxide were added, with 2 kg of barium carbonate and 2.3 kg of barium hydroxide.

[0113] Examples 4.3.1 - 4.3.3

[0114] A method for preparing magnesite concrete with high sulfate erosion resistance, which is different from Example 1.3 in that: in step S2, the raw materials mixed with cement, etc. also include barium salts. Specifically, in Example 4.3.1, 3.6 kg of barium carbonate was added;

[0115] In Example 4.3.2, 3.95 kg of barium hydroxide was added;

[0116] In Example 4.3.3, 4.3 kg of barium carbonate and barium hydroxide were added, with 2 kg of barium carbonate and 2.3 kg of barium hydroxide.

[0117] Examples 5.1.1 - 5.1.3

[0118] A method for preparing magnesite concrete with high sulfate erosion resistance, which is different from Example 1.1 in that: in step S2, the raw materials mixed with cement, etc. also include reinforcing fibers. Specifically,

[0119] In Example 5.1.1, 0.72 kg of basalt fiber was added;

[0120] In Example 5.1.2, 0.79 kg of polyvinyl alcohol fiber was added;

[0121] In Example 5.1.3, 0.86 kg of basalt fiber was added.

[0122] Examples 5.2.1 - 5.2.3

[0123] A method for preparing magnesite concrete with high sulfate erosion resistance, which is different from Example 1.2 in that: in step S2, the raw materials mixed with cement, etc. also include reinforcing fibers. Specifically,

[0124] In Example 5.2.1, 0.72 kg of basalt fiber was added;

[0125] In Example 5.2.2, 0.79 kg of polyvinyl alcohol fiber was added;

[0126] In Example 5.2.3, 0.86 kg of basalt fiber was added.

[0127] Examples 5.3.1 - 5.3.3

[0128] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from that of Example 1.3 in that: in step S2, the raw materials mixed with cement, etc. also include reinforcing fibers, specifically,

[0129] In Example 5.3.1, 0.72 kg of basalt fibers are added;

[0130] In Example 5.3.2, 0.79 kg of polyvinyl alcohol fibers are added;

[0131] In Example 5.3.3, 0.86 kg of basalt fibers are added.

[0132] Examples 6.1.1 - 6.1.3

[0133] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from that of Examples 5.1.1 - 5.1.3 in that: the reinforcing fibers include basalt fibers and polyvinyl alcohol fibers in a ratio of 1:(2 - 3), specifically,

[0134] In Example 6.1.1, the weight ratio of basalt fibers to polyvinyl alcohol fibers is 1:2, the basalt fibers are 0.24 kg, and the polyvinyl alcohol fibers are 0.48 kg;

[0135] In Example 6.1.2, the weight ratio of basalt fibers to polyvinyl alcohol fibers is 1:2.5, the basalt fibers are 0.226 kg, and the polyvinyl alcohol fibers are 0.564 kg;

[0136] In Example 6.1.3, the weight ratio of basalt fibers to polyvinyl alcohol fibers is 1:3, the basalt fibers are 0.215 kg, and the polyvinyl alcohol fibers are 0.645 kg.

[0137] Examples 6.2.1 - 6.2.3

[0138] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from that of Examples 5.2.1 - 5.2.3 in that: the reinforcing fibers include basalt fibers and polyvinyl alcohol fibers in a ratio of 1:(2 - 3), specifically,

[0139] In Example 6.2.1, the weight ratio of basalt fibers to polyvinyl alcohol fibers is 1:2, the basalt fibers are 0.24 kg, and the polyvinyl alcohol fibers are 0.48 kg;

[0140] In Example 6.2.2, the weight ratio of basalt fibers to polyvinyl alcohol fibers is 1:2.5, the basalt fibers are 0.226 kg, and the polyvinyl alcohol fibers are 0.564 kg;

[0141] In Example 6.2.3, the weight ratio of basalt fiber to polyvinyl alcohol fiber is 1:3, with 0.215 kg of basalt fiber and 0.645 kg of polyvinyl alcohol fiber.

[0142] Examples 6.3.1 - 6.3.3

[0143] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Examples 5.3.1 - 5.3.3 in that: the reinforcing fibers include basalt fiber and polyvinyl alcohol fiber with a ratio of 1:(2 - 3). Specifically,

[0144] In Example 6.3.1, the weight ratio of basalt fiber to polyvinyl alcohol fiber is 1:2, with 0.24 kg of basalt fiber and 0.48 kg of polyvinyl alcohol fiber;

[0145] In Example 6.3.2, the weight ratio of basalt fiber to polyvinyl alcohol fiber is 1:2.5, with 0.226 kg of basalt fiber and 0.564 kg of polyvinyl alcohol fiber;

[0146] In Example 6.3.3, the weight ratio of basalt fiber to polyvinyl alcohol fiber is 1:3, with 0.215 kg of basalt fiber and 0.645 kg of polyvinyl alcohol fiber.

[0147] Example 7.1

[0148] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Example 1.1 in that: among the sulfate corrosion inhibitors, the 4.3 kg of expansive agent includes a calcium sulfoaluminate - type expansive agent and a magnesia expansive agent with a weight ratio of 1:0.5. Specifically, the calcium sulfoaluminate - type expansive agent is 2.87 kg and the magnesia expansive agent is 1.43 kg.

[0149] Example 7.2

[0150] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Example 1.2 in that: among the sulfate corrosion inhibitors, the 4 kg of expansive agent includes a calcium sulfoaluminate - type expansive agent and a magnesia expansive agent with a weight ratio of 1:1.5. Specifically, the calcium sulfoaluminate - type expansive agent is 1.6 kg and the magnesia expansive agent is 2.4 kg.

[0151] Example 7.3

[0152] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Example 1.3 in that: among the sulfate corrosion inhibitors, the 3.6 kg of expansive agent includes a calcium sulfoaluminate - type expansive agent and a magnesia expansive agent with a weight ratio of 1:2. Specifically, the calcium sulfoaluminate - type expansive agent is 1.2 kg and the magnesia expansive agent is 2.4 kg.

[0153] Example 8.1

[0154] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Example 1.1 in that: in step S2, the raw materials mixed with cement, etc. also include 0.5 kg of basalt fiber.

[0155] Example 8.2

[0156] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Example 1.2 in that: in step S2, the raw materials mixed with cement, etc. also include 1 kg of polyvinyl alcohol fiber.

[0157] Example 8.3

[0158] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Example 1.3 in that: in step S2, the raw materials mixed with cement, etc. also include 1.2 kg of basalt fiber.

[0159] Examples 9.1.1 - 9.1.3

[0160] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Examples 5.1.1 - 5.1.3 in that: the reinforcing fibers include glass fiber and polypropylene fiber in a ratio of 1:(2 - 3). Specifically,

[0161] In Example 9.1.1, the weight ratio of glass fiber to polyvinyl alcohol fiber is 1:2, the glass fiber is 0.24 kg, and the polyvinyl alcohol fiber is 0.48 kg;

[0162] In Example 9.1.2, the weight ratio of glass fiber to polyvinyl alcohol fiber is 1:2.5, the glass fiber is 0.226 kg, and the polyvinyl alcohol fiber is 0.564 kg;

[0163] In Example 9.1.3, the weight ratio of glass fiber to polyvinyl alcohol fiber is 1:3, the glass fiber is 0.215 kg, and the polyvinyl alcohol fiber is 0.645 kg.

[0164] Examples 9.2.1 - 9.2.3

[0165] A preparation method of magnesite concrete with high sulfate erosion resistance, which is different from Examples 5.2.1 - 5.2.3 in that: the reinforcing fibers include basalt fiber and polypropylene fiber in a ratio of 1:(2 - 3). Specifically,

[0166] In Example 9.2.1, the weight ratio of basalt fiber to polypropylene fiber is 1:2, the basalt fiber is 0.24 kg, and the polypropylene fiber is 0.48 kg;

[0167] In Example 9.2.2, the weight ratio of basalt fiber to polypropylene fiber is 1:2.5, the basalt fiber is 0.226 kg, and the polypropylene fiber is 0.564 kg;

[0168] In Example 9.2.3, the weight ratio of basalt fiber to polypropylene fiber is 1:3, the basalt fiber is 0.215 kg, and the polypropylene fiber is 0.645 kg.

[0169] Examples 9.3.1 - 9.3.3

[0170] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Examples 5.3.1 - 5.3.3 in that: the reinforcing fiber comprises glass fiber and polypropylene fiber with a ratio of 1:(2 - 3). Specifically,

[0171] In Example 9.3.1, the weight ratio of glass fiber to polypropylene fiber is 1:2, the glass fiber is 0.24 kg, and the polypropylene fiber is 0.48 kg;

[0172] In Example 9.3.2, the weight ratio of glass fiber to polypropylene fiber is 1:2.5, the glass fiber is 0.226 kg, and the polypropylene fiber is 0.564 kg;

[0173] In Example 9.3.3, the weight ratio of glass fiber to polypropylene fiber is 1:3, the glass fiber is 0.215 kg, and the polypropylene fiber is 0.645 kg.

[0174] Examples 10.1.1 - 10.1.3

[0175] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Examples 5.1.1 - 5.1.3 in that: the reinforcing fiber comprises basalt fiber and polyvinyl alcohol fiber with a ratio of 1:1. Specifically,

[0176] In Example 10.1.1, the basalt fiber is 0.36 kg, and the polyvinyl alcohol fiber is 0.36 kg;

[0177] In Example 10.1.2, the basalt fiber is 0.395 kg, and the polyvinyl alcohol fiber is 0.395 kg;

[0178] In Example 10.1.3, the basalt fiber is 0.43 kg, and the polyvinyl alcohol fiber is 0.43 kg.

[0179] Examples 10.2.1 - 10.2.3

[0180] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Examples 5.2.1 - 5.2.3 in that: the reinforcing fibers include basalt fibers and polyvinyl alcohol fibers in a ratio of 1:5. Specifically,

[0181] In Example 10.2.1, the amount of basalt fibers is 0.12 kg, and the amount of polyvinyl alcohol fibers is 0.6 kg;

[0182] In Example 10.2.2, the amount of basalt fibers is 0.132 kg, and the amount of polyvinyl alcohol fibers is 0.658 kg;

[0183] In Example 10.2.3, the amount of basalt fibers is 0.14 kg, and the amount of polyvinyl alcohol fibers is 0.72 kg.

[0184] Examples 10.3.1 - 10.3.3

[0185] A preparation method of magnesite concrete with high sulfate erosion resistance, different from Examples 5.3.1 - 5.3.3 in that: the reinforcing fibers include basalt fibers and polyvinyl alcohol fibers in a ratio of 1:4. Specifically,

[0186] In Example 10.3.1, the amount of basalt fibers is 0.144 kg, and the amount of polyvinyl alcohol fibers is 0.576 kg;

[0187] In Example 10.3.2, the amount of basalt fibers is 0.158 kg, and the amount of polyvinyl alcohol fibers is 0.632 kg;

[0188] In Example 10.3.3, the amount of basalt fibers is 0.172 kg, and the amount of polyvinyl alcohol fibers is 0.688 kg.

[0189] <Comparative Example>

[0190] Comparative Example 1.1

[0191] Different from Example 1.1 in that: no silica fume is added, and the amount of gneiss powder is 31.04 kg.

[0192] Comparative Example 1.2

[0193] Different from Example 1.2 in that: no gneiss powder is added, and the amount of silica fume is 31.8 kg.

[0194] Comparative Example 1.3

[0195] Different from Example 1.3 in that: no silica fume is added, and the amount of gneiss powder is 32.36 kg.

[0196] Comparative Examples 2.1 - 2.3

[0197] It is different from Examples 1.1 - 1.3 in that no anti - sulfate corrosion inhibitor is added.

[0198] Comparative Examples 3.1.1 - 3.1.3

[0199] It is different from Example 1.1 in that no expansive agent, sodium - bentonite, and calcium phosphite are added respectively to the anti - sulfate corrosion inhibitor. Specifically,

[0200] In Comparative Example 3.1.1, the anti - sulfate corrosion inhibitor includes 3.01 kg of sodium - bentonite and 4.35 kg of calcium phosphite;

[0201] In Comparative Example 3.1.2, the anti - sulfate corrosion inhibitor includes 4.73 kg of calcium sulfoaluminate - type expansive agent and 2.63 kg of calcium phosphite;

[0202] In Comparative Example 3.1.3, the anti - sulfate corrosion inhibitor includes 5.4 kg of calcium sulfoaluminate - type expansive agent and 1.96 kg of sodium - bentonite.

[0203] Comparative Examples 3.2.1 - 3.2.3

[0204] It is different from Example 1.2 in that no expansive agent, sodium - bentonite, and calcium phosphite are added respectively to the anti - sulfate corrosion inhibitor. Specifically,

[0205] In Comparative Example 3.2.1, the anti - sulfate corrosion inhibitor includes 2.79 kg of sodium - bentonite and 3.95 kg of calcium phosphite;

[0206] In Comparative Example 3.2.2, the anti - sulfate corrosion inhibitor includes 4.395 kg of calcium sulfoaluminate - type expansive agent and 2.345 kg of calcium phosphite;

[0207] In Comparative Example 3.2.3, the anti - sulfate corrosion inhibitor includes 4.975 kg of calcium sulfoaluminate - type expansive agent and 1.765 kg of sodium - bentonite.

[0208] Comparative Examples 3.3.1 - 3.3.3

[0209] It is different from Example 1.3 in that no expansive agent, sodium - bentonite, and calcium phosphite are added respectively to the anti - sulfate corrosion inhibitor. Specifically,

[0210] In Comparative Example 3.3.1, the anti - sulfate corrosion inhibitor includes 2.52 kg of sodium - bentonite and 3.6 kg of calcium phosphite;

[0211] In Comparative Example 3.3.2, the anti - sulfate corrosion inhibitor includes 3.96 kg of calcium sulfoaluminate - type expansive agent and 1.62 kg of calcium phosphite;

[0212] In Comparative Example 3.3.3, the anti - sulfate corrosion inhibitor includes 4.5 kg of calcium sulfoaluminate - type expansive agent and 1.62 kg of sodium - bentonite.

[0213] <Performance Test>

[0214] Refer to the method in GB / T 50082-2009 "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete", and conduct dry-wet cycle resistance to sulfate erosion tests on the magnesite concrete specimens prepared in Examples 1-10 and Comparative Examples 1-3 after curing for 28 days under standard curing conditions. The size of the magnesite concrete specimens is 100mm×100mm×100mm, the concentration of sodium sulfate solution is 5%, the temperature of dry-wet cycle erosion is (23±2)°C, the number of dry-wet cycles is 150 times, and the total time of one dry-wet cycle is (24±2)h. Measure the compressive strength of the specimens after the dry-wet cycle ends; and adopt the penetration method, use the transmitting transducer to repeatedly emit ultrasonic pulse waves, let the ultrasonic waves propagate in the specimen, and then be received by the receiving transducer. Record the sound velocity of the ultrasonic waves according to the display on the ultrasonic instrument. Since there is no significant difference among multiple parallel samples under the third-level title, the average value of multiple parallel samples under the third-level title in this application is recorded in Table 3.

[0215] Table 3 Performance Test Results Table

[0216]

[0217]

[0218] As can be seen from Table 3, the ultrasonic wave propagation rate of the magnesite concrete specimens prepared in Examples 1.1-1.3 of this application is 7.4 km / s - 7.5 km / s, and the compressive strength can still reach 75.11 MPa - 76.03 MPa after 150 dry-wet cycles. This shows that the internal cracks and pores of the magnesite concrete prepared in Examples 1.1-1.3 of this application are less, the degree of compactness is higher, and it has strong resistance to sulfate erosion.

[0219] The difference between Examples 2.1-2.3 and Examples 1.1-1.3 is that in the sulfate corrosion inhibitor, the expansive agent is a mixture of calcium sulfoaluminate-based expansive agent and magnesia expansive agent. As can be seen from Table 3, the ultrasonic wave propagation rate of Examples 2.1-2.3 is 7.6 km / s - 7.7 km / s, and the compressive strength after 150 dry-wet cycles is 76.88 MPa - 77.09 MPa, which are respectively higher than those of Examples 1.1-1.3. The experimental results show that the mixed use of calcium sulfoaluminate-based expansive agent and magnesia expansive agent can further improve the anti-sulfuric acid erosion effect of the sulfate corrosion inhibitor in magnesite concrete.

[0220] Examples 3.1 - 3.3 are different from Examples 1.1 - 1.3 in that the weight ratio of gneiss powder and silica fume is further controlled. As can be seen from Table 3, the ultrasonic wave propagation rate of Examples 3.1 - 3.3 is 7.6 km / s - 7.7 km / s, and the compressive strength after 150 dry - wet cycles is 76.98 MPa - 77.54 MPa, both of which are higher than those of Examples 1.1 - 1.3 respectively. The experimental results show that gneiss powder and silica fume can maximize their synergistic and complementary effects at this weight ratio.

[0221] Examples 4.1 - 4.3 are different from Examples 1.1 - 1.3 in that barium salts are added to the magnesite concrete. As can be seen from Table 3, the ultrasonic wave propagation rate of Examples 4.1 - 4.3 is 7.8 km / s - 7.9 km / s, and the compressive strength after 150 dry - wet cycles is 78.86 MPa - 79.62 MPa, both of which are higher than those of Examples 1.1 - 1.3 respectively. The experimental results show that adding barium salts to the magnesite concrete can improve the compactness of the magnesite concrete, thereby improving the sulfuric acid erosion resistance of the magnesite concrete.

[0222] Examples 5.1 - 5.3 are different from Examples 1.1 - 1.3 in that reinforcing fibers are added to the magnesite concrete. As can be seen from Table 3, the ultrasonic wave propagation rate of Examples 5.1 - 5.3 is 7.9 km / s - 8.1 km / s, and the compressive strength after 150 dry - wet cycles is 79.88 MPa - 81.34 MPa, both of which are higher than those of Examples 1.1 - 1.3 respectively. The experimental results show that adding reinforcing fibers to the magnesite concrete can improve the compactness of the magnesite concrete, thereby improving the sulfuric acid erosion resistance of the magnesite concrete.

[0223] Examples 6.1 - 6.3 are different from Examples 5.1 - 5.3 in that basalt fibers and polyvinyl alcohol fibers are used in combination. As can be seen from Table 3, the ultrasonic wave propagation rate of Examples 6.1 - 6.3 is 8.1 km / s - 8.3 km / s, and the compressive strength after 150 dry - wet cycles is 81.09 MPa - 83.67 MPa, both of which are higher than those of Examples 5.1 - 5.3 respectively. The experimental results show that using basalt fibers and polyvinyl alcohol fibers in combination can further improve the compactness and sulfate erosion resistance of the magnesite concrete.

[0224] By comparing the data of Examples 7.1 - 7.3 with those of Examples 1.1 - 1.3 and Examples 2.1 - 2.3, it can be known that if the ratio between calcium sulfoaluminate - based expansive agent and magnesia - based expansive agent is not within the preferred range, the synergistic effect between the two cannot be maximized, thereby reducing the effect of the sulfate corrosion inhibitor in the magnesite concrete.

[0225] By comparing the data of Examples 8.1 - 8.3 with those of Examples 1.1 - 1.3 and Examples 5.1 - 5.3, it can be seen that if the dosage of the reinforcing fiber is not within the preferred range, the compactness and sulfate erosion resistance of the magnesite concrete will be reduced.

[0226] By comparing the data of Examples 9.1 - 9.3 with those of Examples 5.1 - 5.3 and Examples 6.1 - 6.3, it can be seen that the combined use of basalt fiber and polyvinyl alcohol fiber has the greatest effect on the sulfate erosion resistance of magnesite. Replacing either of them with other reinforcing fibers of the same type or using two other reinforcing fibers of the same type cannot achieve the effect of the combined use of basalt fiber and polyvinyl alcohol fiber.

[0227] By comparing the data of Examples 10.1 - 10.3 with those of Examples 5.1 - 5.3 and Examples 6.1 - 6.3, it can be seen that if the ratio of basalt fiber to polyvinyl alcohol fiber is not within the preferred range, the synergistic complementary effect will be reduced, thereby reducing the compactness and sulfate erosion resistance of the magnesite concrete.

[0228] The differences between Comparative Examples 1.1 - 1.3 and Examples 1.1 - 1.3 are that only one of silica fume or gneiss powder is used alone. As can be seen from Table 3, the ultrasonic wave propagation rate of Comparative Examples 1.1 - 1.3 is 6.7 km / s - 7.0 km / s, and the compressive strength after 150 wet-dry cycles is 66.47 MPa - 69.54 MPa. The experimental results show that using only one of silica fume or gneiss powder alone will not only increase the dosage of this substance, but also cannot achieve the effect of their combined use even if the dosage of this substance is increased.

[0229] The differences between Comparative Examples 2.1 - 2.3 and Examples 1.1 - 1.3 are that no sulfate corrosion inhibitor is added. As can be seen from Table 3, the ultrasonic wave propagation rate of Comparative Examples 2.1 - 2.3 is 4.4 km / s - 4.5 km / s, and the compressive strength after 150 wet-dry cycles is only 44.63 MPa - 54.12 MPa. The experimental results show that not adding a sulfate corrosion inhibitor will greatly reduce the sulfate erosion resistance of the magnesite concrete.

[0230] The differences between Comparative Examples 3.1 - 3.3 and Examples 1.1 - 1.3 are that in the sulfate corrosion inhibitor, the combined use of an expansive agent, sodium-based concrete, and calcium phosphite is not adopted. It can be seen from Table 3 that the ultrasonic propagation rate of Comparative Examples 3.1 - 3.3 is 7.1 km / s - 7.2 km / s, and the compressive strength after 150 dry-wet cycles is 72.78 MPa - 73.88 MPa. The experimental results show that the absence of any one of the expansive agent, sodium-based bentonite, and calcium phosphite will reduce the effect of the sulfate corrosion inhibitor in magnesite concrete.

[0231] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A magnesite concrete with high sulfate erosion resistance, characterized in that, The raw materials used include the following components in parts by weight: 360 - 430 parts of cement; 1128.5 - 1146.6 parts of coarse aggregate; 663 - 689 parts of fine aggregate; 11.52 - 13.76 parts of silica fume; 160 - 185 parts of mixing water; 3.2 - 3.8 parts of water reducing agent; 17.28 - 20.64 parts of gneiss rock powder; 6.12 - 7.36 parts of anti - sulfate corrosion agent; The coarse aggregate is low - grade magnesite crushed stone, which is industrial waste with a continuous gradation in the particle size range of 5mm - 25mm; The anti - sulfate corrosion agent includes 3.6 - 4.3 parts of expansive agent, 0.72 - 0.86 parts of bentonite and 1.8 - 2.2 parts of calcium phosphite; The expansive agent includes a sulfoaluminate expansive agent and a magnesia expansive agent with a weight ratio of 1:(0.8 - 1.2).

2. A magnesite concrete with high sulfate erosion resistance according to claim 1, characterized in that: The weight ratio of the gneiss rock powder to the silica fume is (1.4 - 1.5):

1.

3. A magnesite concrete with high sulfate erosion resistance according to claim 1, characterized in that: The raw materials also include 3.6 - 4.3 parts by weight of barium salt.

4. A magnesite concrete with high sulfate erosion resistance according to claim 3, characterized in that: The barium salt is barium carbonate and / or barium hydroxide.

5. A magnesite concrete with high sulfate erosion resistance according to claim 1, characterized in that: The raw materials also include 0.72 - 0.86 parts by weight of reinforcing fiber.

6. A magnesite concrete with high sulfate erosion resistance according to claim 5, characterized in that: The reinforcing fiber includes basalt fiber and polyvinyl alcohol fiber with a weight ratio of 1:(2 - 3).

7. A method for preparing magnesite concrete with high sulfate erosion resistance according to any one of claims 1-6, characterized in that, It includes the following steps: First, mix all the raw materials except the mixing water and the water reducing agent for 1min - 3min, and then add the mixing water and the water reducing agent and continue to stir for 2min - 5min to obtain magnesite concrete with high anti - sulfate erosion resistance.

8. The preparation method of a magnesite concrete with high sulfate erosion resistance according to claim 7, characterized in that: Before mixing and stirring the magnesite in the raw materials with the other raw materials, soak it in water for 48h - 50h first, and then drain it for 10min - 15min.

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