Maritime work cement for offshore building component and preparation method of maritime work cement

Abstract

The invention provides maritime work cement for an offshore building component and a preparation method of the maritime work cement, and belongs to the technical field of offshore building materials. The maritime work cement comprises aggregate, a main material, an additive and reinforced fibers. The maritime work cement provided by the invention has the characteristics of high strength, durability, corrosion resistance, economy, rapid hardening and high fluidity, improves the safety, compactness, durability and strength of maritime work products, especially has excellent heat insulation property, strength and corrosion resistance, and has excellent crack restraining and crack resistance, so that the maritime work cement is particularly suitable for serving as a maritime building component material.

Description

Technical Field

[0001] This invention belongs to the field of marine construction materials technology, specifically relating to marine cement for marine construction components and its preparation method. Background Technology

[0002] The construction of offshore structures plays a positive role in the utilization of marine resources. Currently, most offshore floating structures and platforms are made of pure steel plates, which are not only costly and susceptible to corrosion, but also highly resource-intensive and carbon-emitting, and their excessive weight affects buoyancy. Developing lightweight, high-strength, and corrosion-resistant wall panels or floor slabs, referencing techniques used in land-based construction, as substrate materials for offshore building components has become a major research direction.

[0003] Precast reinforced concrete floor slabs are commonly used in land-based construction, and the properties of the cement in the concrete have a crucial impact on the performance of the final building components. However, to obtain building components more suitable for offshore construction, existing technologies mostly improve the component structure, such as the new integrated wall panel for floating offshore structures provided by patent CN115478648A, but rarely improve the component materials. Currently, the national standard GB / T 31289-2014 is relevant to marine engineering, but while it stipulates that marine silicate cement must have strong resistance to seawater erosion, it does not propose higher or more suitable requirements for other properties for offshore construction.

[0004] Since the practical application of cement industrial products, production has continuously expanded, processes and equipment have been constantly improved, and the variety and quality of cement have also greatly developed. However, there are significant differences in the performance between different types of cement. For example, silicate cement and sulfoaluminate cement are widely used. Ordinary silicate cement has a longer setting time and better strength development in the later stages, but its early strength development is slow. In actual production, except for pure operations, it is difficult to carry out heavy-duty moving or hoisting operations in a short period of time. Rapid-hardening sulfoaluminate cement has a very fast setting speed and high early strength, but poor durability and susceptibility to thermal cracking. Different types of cement are usually not mixed. For example, the application instructions for rapid-hardening sulfoaluminate cement state that it should not be mixed with other types of cement. In practice, it has been found that when sulfoaluminate cement is mixed with silicate cement, it easily leads to rapid setting or even flash setting, causing the cement volume to expand, resulting in reduced strength, or even expansion and collapse. Several studies have also reported that adding a portion of ordinary silicate cement to sulfoaluminate cement can cause severe shrinkage in later strength. Summary of the Invention

[0005] To address the aforementioned problems, this application aims to provide marine cement for offshore structural components, comprising main materials, additives, aggregates, and reinforcing fibers, by weight percentage,

[0006] The main materials include: composite cement composed of 65% to 95% silicate cement and 5% to 20% sulfoaluminate cement, 3% to 14% dihydrate gypsum, and fly ash accounting for 0.6% to 1% of the composite cement mass.

[0007] The additives include: a reinforcing agent comprising 3% to 7% of the composite cement mass, an expanding agent comprising 6% to 8% of the composite cement mass, plant cellulose comprising 0.2% to 0.3% of the composite cement mass, an air-entraining agent comprising (0.5-1.5) / 10000 of the composite cement mass, a polycarboxylate superplasticizer comprising 0.18% to 0.25% of the cement mass, a hydroxycarboxylate retarder comprising 0.1% to 0.25% of the cement mass, and a pumping retarder comprising 2% to 5% of the composite cement mass.

[0008] The aggregate comprises: fine sand at 2-2.5 times the weight of the composite cement;

[0009] The reinforcing fibers include: 0.15%-0.2% polypropylene chopped fibers by mass of the composite cement, and 3%-5% steel fibers by mass of the composite cement.

[0010] It is understood that in the marine cement provided in this application, the silicate cement in the main material can be selected from various types of ordinary silicate cement known in the art, such as ordinary silicate cement of grades 42.5, 42.5R, 52.5, and 52.5R; and the sulfoaluminate cement can be selected from various types of rapid-hardening sulfoaluminate cement known in the art, such as grade 42.5 and grade 52.5.

[0011] It is understood that in the marine cement provided in this application, the aggregate fine sand is known fine sand as conventionally understood in the art, such as sand and gravel with an average particle size of 0.125mm-0.25mm, and particles with a particle size greater than 0.075mm account for more than 85% of the total weight.

[0012] In one embodiment, the reinforcing agent is sodium silicate, potassium silicate, and lithium carbonate.

[0013] Preferably, the reinforcing agent is sodium silicate, potassium silicate and lithium carbonate in a mass ratio of 3:1:1.

[0014] In one embodiment, the molecular weight of plant cellulose is between 100,000 and 2 million.

[0015] In one embodiment, the expanding agent is prepared by the following method: 45-50 parts by weight of calcined phosphogypsum, 30-35 parts by weight of high-alumina clinker, and 18-25 parts by weight of fly ash are mixed and fed into a ball mill to produce a fineness of less than 12% and a specific surface area of ​​300-350 m². 3 / kg of powder. This expanding agent has properties such as compensating for shrinkage, introducing self-stress, rapid expansion and stabilization, and improving the density of marine engineering products, but compatibility needs to be considered when used in combination with other admixtures.

[0016] In one embodiment, the air-entraining agent is prepared by the following method: 10-30 parts by weight of 40wt% sodium hydroxide solution, 15-25 parts by weight of 30wt% hydrogen peroxide, 5-15 parts by weight of 10wt% potassium permanganate solution, 15-25 parts by weight of 20wt% sulfuric acid solution, and 80-100 parts by weight of water are mixed and heated to 70-90°C. Then, 20-50 parts by weight of rosin powder are added to obtain a solution. This air-entraining agent is diluted to 1% using (0.5-1.5) / 10000 parts of non-hard water. After addition, the gas content of marine engineering products is approximately 5%, workability is improved, there is no adverse effect on shrinkage, and there is no corrosion damage to reinforcing steel.

[0017] In the preparation of the marine cement provided in this application, all additives are first added to water and mixed before the main cement material is added. The stability and uniformity of the solid-liquid mixture formed after all additives dissolve in water have a significant impact on the appearance and various properties of the final marine cement components. For example, the powdered expansive agent in the above-mentioned additives undergoes volume expansion through hydration reaction, while the reinforcing agent, after dissolving in water, becomes a viscous liquid that focuses on sealing surface pores. There are significant differences between the two in reaction kinetics, hydrate density, and fluidity, which can lead to stratification and ultimately affect the quality of the marine cement product. In addition, the appropriate amount of plant cellulose and modified rosin powder as air-entraining agents in the additives, besides their own effects on cement (such as plant cellulose improving the crack resistance, impermeability, and durability of cement, and improving workability), can also significantly increase the suspension of materials and improve the dispersion effect of materials by utilizing highly active surface activity, thereby improving the uniformity and dispersibility of the additive mixture and the appearance quality of the final marine cement components.

[0018] In one embodiment, the polycarboxylate superplasticizer can be a common commercially available product, such as a high-performance superplasticizer with a water reduction rate of 25%-30%, which has the advantages of high water reduction rate, low dosage, good compatibility with cement, small slump loss, stable product performance, no corrosion to steel bars, and green environmental protection.

[0019] In one embodiment, the hydroxycarboxylate retarder can be a commercially available product that can effectively extend the setting time of concrete and gypsum products, reduce the rate of hydration heat rise, and has good compatibility with other components and cementitious main materials.

[0020] In one embodiment, the pumping retarder can be a commercially available product or prepared by the following method: Take 51-55 parts by weight of tetracalcium aluminosilicate, 21-25 parts by weight of calcium silicate, 3-6 parts by weight of tetracalcium aluminoferrite, 1.5-3 parts by weight of calcium titanate, and 8-11 parts by weight of boric acid, and mix thoroughly. This pumping retarder is particularly suitable for fast-setting, early-strength polymer-modified marine cement concrete. It allows adjustment of the setting time of the fast-setting, early-strength cement as needed, enabling the use of this concrete in large-scale mechanized pumping construction. This overcomes the limitation of fast-setting, early-strength polymer-modified marine concrete not being suitable for pumping, resulting in higher strength and a construction period 85% shorter than traditional ordinary concrete.

[0021] In one embodiment, the composite cement uses nanoscale raw materials with a particle size not exceeding 200 nm for a portion of the silicate cement and / or a portion of the sulfoaluminate cement.

[0022] Preferably, the proportion of the nanoscale raw materials is less than or equal to 50%. For example, silicate cement and sulfoaluminate cement can be used to make nanoscale materials in a 50 / 50 ratio. Smaller particle size is beneficial to improving the high adhesion between the components after hydration, and further improving strength and ductility.

[0023] In one embodiment, the additive further includes: an antifreeze agent at 4%-6% of the composite cement mass, a pumping agent at 1%-2% of the composite cement mass, and an interface treatment agent at 2-2.5 kg / m³. 2 Rust inhibitor 4-8 kg / m 3 Defoamer comprising 0.1%-0.2% of the composite cement mass, and curing agent comprising 1.52%-2.7% of the composite cement mass.

[0024] In one embodiment, the antifreeze agent can be a commercially available product, or a composite antifreeze agent can be prepared by mixing and grinding 25 parts sodium chloride, 16 parts sodium nitrite, 20 parts urea, and 39 parts grade II fly ash evenly by weight. This composite antifreeze agent has the effects of lowering the freezing point and good water reduction, resulting in a concrete antifreeze grade > D50. It also has no corrosive effect on reinforcing steel and is highly adaptable to different cement types. The dosage range is 4%-5%, and 6% can be added at -15℃, but trial mixing should be conducted based on actual production conditions.

[0025] In one embodiment, the pumping agent can be a commercially available product, or a composite pumping agent can be prepared using the following method: 22 parts by weight of NF naphthalene-based high-efficiency water-reducing agent, 7 parts by weight of AT retarding water-reducing agent, 2.5 parts by weight of calcium lignosulfonate, 0.8 parts by weight of sodium dodecylbenzenesulfonate, 0.8 parts by weight of citric acid, 2.5 parts by weight of sodium tripolyphosphate, 1.2 parts by weight of carboxyethyl methyl cellulose, 6 parts by weight of F-4 sodium polycarboxylate dispersant, and 57.2 parts by weight of water. The dosage range is 1%-2%, and the dosage can be adjusted within the recommended range according to cement adaptability, temperature, and slump requirements. It has advantages such as plasticizing, retarding, low air entrainment, low slump loss, and good pumpability.

[0026] In one embodiment, the interface treatment agent can be a commercially available product or prepared by the following method: By weight, take 350 parts of 425# silicate cement, 486 parts of fine sand aggregate with a particle size ≤0.01mm, 100 parts of fly ash, 40 parts of wollastonite powder, 15 parts of U-type expanding agent, 1.3 parts of MC methyl cellulose ether, 2 parts of sodium bentonite, 5 parts of redispersible latex powder RE5010N type, 2 parts of NF naphthalene-based high-efficiency water-reducing agent, and 220 parts of water. Mix with a water-cement ratio of 1:3 to form a paste. Dosage: 2-2.5 kg / m³ 2 Interface treatment agents, also known as marine interface adhesives, are used to enhance the surface properties and functions of marine engineering material wall panels. They can significantly enhance the adhesion between new and old cement and between marine engineering products and plaster mortar, preventing plaster from becoming hollow, peeling, or falling off.

[0027] In one embodiment, the rust inhibitor can be a commercially available product or prepared by the following method: Take 10 parts by weight of triethanolamine, 10 parts by weight of benzoic acid, 10 parts by weight of p-hydroxy-N-methylcyclohexylamine, 10 parts by weight of nitric acid, and 60 parts by weight of water, and mix thoroughly. This rust inhibitor can significantly mitigate the damage of chloride ions to the passivation film of steel bars, and has the characteristics of being environmentally friendly, alkali-free, requiring low dosage, and having good compatibility with cement.

[0028] In one embodiment, the curing agent can be a commercially available product or prepared by the following method: Take 40 parts by weight of 38wt% styrene-acrylic emulsion and 60 parts by weight of 4wt% acrylamide solution, and stir at low speed until homogeneous. Dosage: 5-7 kg per square meter using a sprayer. When this curing agent is sprayed onto the surface of marine engineering products, it forms a solidified film after the moisture evaporates or is absorbed by the products, thus preventing moisture evaporation and providing water retention and curing. This can replace burlap sack covering and watering for curing, saving on maintenance costs.

[0029] In one embodiment, the length of the chopped polypropylene fibers in the reinforcing fibers is 10-12 mm.

[0030] In one embodiment, the steel fiber has a diameter of 0.45-0.7 mm and an aspect ratio of 30-100.

[0031] On the other hand, this application provides a method for preparing marine cement for marine structural components, comprising the following steps:

[0032] Add additives to water, stir thoroughly, then add the main material, then add aggregates and reinforcing fibers, and stir thoroughly to obtain the marine cement.

[0033] In one embodiment, the amount of water used is 35%-48% of the total weight of the cementitious material.

[0034] In one embodiment, the stirring is performed using biaxial counter-current high-frequency stirring, and the stirring time is 2 to 10 minutes.

[0035] The dual-shaft counter-current high-frequency mixing can be achieved using existing production equipment, such as the SYN3000 / 2000 vertical shaft planetary mixer with a 30kW main motor. This method generates strong shear flow and counter-current material flow, resulting in strong convection. This allows the material to undergo multiple cross-mixing processes in a short time, breaking down material agglomeration structures. It is particularly suitable for dispersing and mixing high-viscosity materials.

[0036] In one embodiment, the finished marine cement has a flowability of 180-190 mm. This flowability is more suitable for the reaction time and performance of the production equipment in the production line.

[0037] On the other hand, this application provides a marine construction component, wherein the marine cement described above, or marine cement prepared by the method described above, is used as a raw material.

[0038] In one embodiment, the component further includes reinforcing bars, the type of which is selected from any one or more of HPB300, HRB400, HRB500, and HRB600, and the amount used is 20-30 kg per square meter of building.

[0039] This application has at least the following beneficial effects:

[0040] 1. The marine cement provided in this application has the characteristics of high strength, durability, corrosion resistance, economy, rapid hardening and high fluidity, which improves the safety, compactness, durability and strength of marine products, especially the excellent thermal insulation, strength and corrosion resistance, and restrains cracks and has excellent crack resistance, making it particularly suitable as a material for marine construction components.

[0041] 2. The marine cement provided in this application has significantly improved load-bearing capacity, thereby saving a large amount of steel when preparing marine structural components;

[0042] 3. The marine cement provided in this application optimizes the ratio of ordinary silicate cement and sulfoaluminate cement when using specific additives, resulting in high-strength cement with good workability, self-compacting without vibration, and significantly reduced production costs.

[0043] 4. The marine cement provided in this application, through the optimization of additive composition, results in marine cement components with small geometric dimensional deviations, good appearance and texture, uniform gloss, and dense surface with few air bubbles, which has a positive effect on improving its mechanical, thermal insulation, and durability properties. Attached Figure Description

[0044] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0045] Figure 1 Before and after comparison of the appearance of marine cement;

[0046] Figure 2 The image shows the results of the marine cement components provided in this application during the neutral salt spray test. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0049] The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention are not subject to any special restrictions on their source. Unless otherwise specified, they can all be obtained from conventional commercial channels or prepared in accordance with conventional methods known to those skilled in the art.

[0050] Unless otherwise specified, all raw materials used in the following examples are commercially available products. Specifically, ordinary silicate cement of type 42.5R is used, rapid-hardening sulfoaluminate cement of strength grade 42.5 is used, and fine sand is used as aggregate. A SYN3000 / 2000 vertical shaft planetary mixer with a 30kW main motor is used in the preparation process.

[0051] Some of the raw materials in the additives can be products obtained by the following methods:

[0052] Reinforcing agent: It is obtained by mixing sodium silicate, potassium silicate and lithium carbonate in a mass ratio of 3:1:1.

[0053] Expanding agent: By weight, take 48 parts of calcined phosphogypsum, 32 parts of high-alumina clinker, and 20 parts of fly ash, mix them, and grind them in a ball mill until the fineness is less than 12% (residue on a 0.8mm sieve) and the specific surface area is 300-350m². 3 / kg.

[0054] Air-entraining agent: Take 20 parts of 40wt% sodium hydroxide solution, 20 parts of 30wt% hydrogen peroxide, 10 parts of 10wt% potassium permanganate solution, 20 parts of 20% sulfuric acid solution, and 90 parts of water by mass. Mix them, heat to 80℃, add 30 parts of rosin powder, and stir for 30 minutes to obtain a solution.

[0055] Composite antifreeze: By weight, take 25 parts sodium chloride, 16 parts sodium nitrite, 20 parts urea, and 39 parts fly ash (grade 2), mix and grind them evenly to obtain the final product.

[0056] Composite pumping agent: By mass, take 22 parts of NF naphthalene-based high-efficiency water-reducing agent, 7 parts of AT retarding water-reducing agent, 2.5 parts of calcium lignosulfonate, 0.8 parts of sodium dodecylbenzyl sulfonate, 0.8 parts of citric acid, 2.5 parts of sodium tripolyphosphate, 1.2 parts of carboxyethyl methyl cellulose, 6 parts of F-4 sodium polycarboxylate dispersant, and 57.2 parts of water, and mix them evenly to obtain the final product.

[0057] Interface treatment agent: By weight, take 350 parts of 425# silicate cement (cement), 486 parts of fine sand (particle size ≤ 0.01mm) aggregate, 100 parts of fly ash (active filler), 40 parts of wollastonite powder (active filler), 15 parts of U-type expanding agent, 1.3 parts of MC methyl cellulose ether (water-retaining agent), 2 parts of sodium bentonite (thickening agent), 5 parts of redispersible latex powder RE5010N type (binder), 2 parts of NF naphthalene-based high-efficiency water-reducing agent (dispersant), and 220 parts of water. Mix the water and cement at a ratio of 1:3 to form a paste before use.

[0058] Pumping retarder: By weight, take 53 parts of tetracalcium aluminosilicate, 22 parts of calcium silicate, 5 parts of tetracalcium aluminoferrite, 2 parts of calcium titanate, and 9 parts of boric acid, and mix them evenly. Mix all components evenly according to the formula.

[0059] Rust inhibitor: Take 10 parts by weight of triethanolamine, 10 parts of benzoic acid, 10 parts of p-hydroxy-N-methylcyclohexylamine, 10 parts of nitric acid, and 60 parts of water, and mix them evenly to obtain the rust inhibitor.

[0060] Curing agent: Take 40 parts by weight of 38wt% styrene-acrylic emulsion and 60 parts by weight of 4wt% acrylamide solution, and stir evenly at low speed to obtain the product.

[0061] Example 1

[0062] This embodiment provides a marine cement, the raw materials of which include main materials, additives, aggregates and reinforcing fibers, wherein, by mass percentage,

[0063] The main materials include: composite cement composed of 70% to 90% silicate cement and 6% to 18% sulfoaluminate cement, 4% to 12% dihydrate gypsum, and fly ash accounting for 0.8% of the mass of the composite cement.

[0064] The additives include: 5% reinforcing agent (by mass of composite cement), 7% expanding agent (by mass of composite cement), 0.21% plant cellulose (by mass of composite cement), 1 / 10000 air-entraining agent (by mass of composite cement), 0.2% polycarboxylate superplasticizer (by mass of cement), 0.18% hydroxycarboxylate retarder (by mass of cement), 4% pumping retarder (by mass of composite cement), 5% composite antifreeze agent (by mass of composite cement), 1.5% composite pumping agent (by mass of composite cement), and 2 kg / m³ interface treatment agent. 2 Rust inhibitor 6kg / m 3 Defoamer accounting for 0.15% of the mass of composite cement, and curing agent accounting for 2% of the mass of composite cement;

[0065] Aggregates include: fine sand at 2.2 times the mass of the composite cement;

[0066] The reinforcing fibers include: 0.18% polypropylene chopped fibers by mass of the composite cement and 4% steel fibers by mass of the composite cement.

[0067] The above raw materials are processed into marine cement products according to the following steps:

[0068] Add additives to water at a dosage of 35%-48% of the total weight of cementitious materials, stir for 1 minute using a biaxial counter-current high-frequency mixer, then add the main materials, aggregates and reinforcing fibers in sequence, and stir for 4-5 minutes to obtain marine cement.

[0069] Example 2

[0070] This embodiment provides a marine cement, the raw materials of which include main materials, additives, aggregates and reinforcing fibers, wherein, by mass percentage,

[0071] The main materials include: composite cement composed of 70% to 90% silicate cement and 6% to 18% sulfoaluminate cement, 4% to 12% dihydrate gypsum, and fly ash accounting for 0.6% of the mass of composite cement.

[0072] The additives include: 5% reinforcing agent (by mass of composite cement), 6% expanding agent (by mass of composite cement), 0.2% plant cellulose (by mass of composite cement), 0.5 / 10000 air-entraining agent (by mass of composite cement), 0.18% polycarboxylate superplasticizer (by mass of cement), 0.1% hydroxycarboxylate retarder (by mass of cement), 2% pumping retarder (by mass of composite cement), 4% composite antifreeze agent (by mass of composite cement), 1% composite pumping agent (by mass of composite cement), and 2 kg / m³ interface treatment agent. 2 Rust inhibitor 4kg / m 3 Defoamer accounting for 0.1% of the mass of composite cement, and curing agent accounting for 1.52% of the mass of composite cement;

[0073] Aggregates include: fine sand at twice the mass of the composite cement;

[0074] The reinforcing fibers include: 0.15% polypropylene chopped fibers by mass of the composite cement and 3% steel fibers by mass of the composite cement.

[0075] The above raw materials are processed into marine cement products according to the following steps:

[0076] Add additives to water at a dosage of 35%-48% of the total weight of cementitious materials, stir for 1 minute using a biaxial counter-current high-frequency mixer, then add the main materials, aggregates and reinforcing fibers in sequence, and stir for 4-5 minutes to obtain marine cement.

[0077] Example 3

[0078] This embodiment provides a marine cement, the raw materials of which include main materials, additives, aggregates and reinforcing fibers, wherein, by mass percentage,

[0079] The main materials include: composite cement composed of 70% to 90% silicate cement and 6% to 18% sulfoaluminate cement, 4% to 12% dihydrate gypsum, and 1% fly ash by mass of composite cement.

[0080] The additives include: 5% reinforcing agent (by mass of composite cement), 8% expanding agent (by mass of composite cement), 0.23% plant cellulose (by mass of composite cement), 1.5 / 10000 air-entraining agent (by mass of composite cement), 0.25% polycarboxylate superplasticizer (by mass of cement), 0.25% hydroxycarboxylate retarder (by mass of cement), 5% pumping retarder (by mass of composite cement), 6% composite antifreeze agent (by mass of composite cement), 2% composite pumping agent (by mass of composite cement), and 2.5 kg / m³ interface treatment agent. 2 Rust inhibitor 8kg / m 3 Defoamer accounting for 0.2% of the mass of composite cement, and curing agent accounting for 2.7% of the mass of composite cement;

[0081] The aggregate consists of fine sand at a ratio of 2.4 times the mass of the composite cement.

[0082] The reinforcing fibers include: 0.2% polypropylene chopped fibers by mass of the composite cement and 5% steel fibers by mass of the composite cement.

[0083] The above raw materials are processed into marine cement products according to the following steps:

[0084] Add additives to water at a dosage of 35%-48% of the total weight of cementitious materials, stir for 1 minute using a biaxial counter-current high-frequency mixer, then add the main materials, aggregates and reinforcing fibers in sequence, and stir for 4-5 minutes to obtain marine cement.

[0085] This application also provides the optimized preparation process and performance test results of marine cement, as follows:

[0086] I. Optimization of the matching between setting time, fluidity and production process

[0087] Taking the marine cement provided in Example 3 as an example, the proportions of silicate cement, sulfoaluminate cement, and dihydrate gypsum in its main materials were adjusted, and the fluidity and setting time of the final product were tested according to the national standard method. The results are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] As shown in Table 1, the marine cement provided in this application has extremely strict requirements on the dosage of sulfoaluminate cement, silicate cement, and dihydrate gypsum when fixing the additive composition. The dosage will lead to poor setting time and stability, which will hinder actual production. Among them, the fluidity and setting time of test groups 2-6 are more suitable for the raw material state of this marine product in the production of automated production line, and are in line with the working frequency of mixer and paving machine. Therefore, they are the better main material proportions. In actual construction operations, the main material proportions of groups 2-6 can be selected according to different seasons, temperatures, and other conditions.

[0092] II. Optimization of Additive Composition

[0093] As shown in the experimental results above, the marine cement provided in this application embodiment has excellent workability. However, during the preparation of marine cement products using the preparation method provided in the embodiment, it was found that when all additives are added to water first, the uniformity and stability of the solid-liquid mixture system formed after the additives dissolve in water have a significant impact on the appearance, texture, gloss, and surface bubble distribution of the final marine cement product components. These properties, besides aesthetics, also affect other cement properties. For example, the powdered expansive agent in this application expands in volume through hydration, while the reinforcing agent, after dissolving in water, forms a viscous liquid that focuses on sealing surface pores. The significant differences between the two in reaction kinetics, hydrate density, and fluidity lead to stratification, ultimately affecting the quality of the marine cement product. In the additives provided in this application embodiment, taking the main material ratio of test group 5 as an example, before improvement, the air-entraining agent used commercially available sodium rosinate, and the suspending agent used lignin; after improvement, the air-entraining agent used modified rosin powder, and the suspending agent used plant cellulose. A comparison of the results before and after the improvement of the specific additive components is shown in Table 2 and... Figure 1 .

[0094] Table 2

[0095]

[0096] From Table 2 and Figure 1 The results show that the appropriate amount of plant cellulose and modified rosin powder as air-entraining agents in the additives provided in the examples, in addition to their own effects on cement, can also significantly increase the suspension of materials and improve the dispersion effect of materials by utilizing highly active surface activity, thereby improving the uniformity, dispersibility and final appearance quality of marine cement components.

[0097] III. Performance Testing

[0098] Taking marine cement from test group 5 as an example, performance tests were conducted. The test methods are detailed in GB / T1771-2007 "Determination of Neutral Salt Spray Resistance of Paints and Varnishes", GB / T 1766-2008 "Rating Method for Aging of Paint and Varnish Coatings", JG / T 350-2011 "Lightweight Concrete Panels", and JG / T169-2016 "General Technical Requirements for Lightweight Panels for Building Partitions". In the impact resistance test, the impact energy was ≥900 N·m, and the drop height was ≥2000 mm. The results of the neutral salt spray test are shown in the figure below. Figure 2 The test results are shown in Table 3:

[0099] Table 3

[0100] Test Project result Impact resistance (5 times) No damage observed Impact resistance (10 times) No damage observed Single-point hanging force ≥1200N neutral salt spray test Overall protective performance level 0

[0101] From Table 3 and Figure 2 The results show that the marine cement provided in this application has high mechanical properties and excellent corrosion resistance.

[0102] Taking marine cement from test group 5 as an example, it and traditional C40 fine aggregate concrete were respectively made into 12cm thick wall panel components according to national standard methods. The steel consumption was compared (unit: kg / m). 2 The results of the thermal insulation performance are shown in Table 4.

[0103] Table 4

[0104]

[0105] As shown in Table 4, the marine cement provided in this application embodiment has a higher load-bearing limit under the same steel consumption as traditional concrete materials, and can save steel consumption when a certain load-bearing limit is required. At the same time, the thermal conductivity of the wall made with the marine cement provided in this application embodiment is significantly reduced, and it has excellent thermal insulation performance, and can be used as a thermal insulation material.

[0106] In summary, the marine cement provided in this application has excellent economic advantages, durability, high strength, and high thermal insulation, making it suitable as a building material for marine construction components and possessing broad application prospects.

[0107] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A type of marine cement for marine structural components, characterized in that, include: Main ingredients, additives, aggregates, and reinforcing fibers, by weight percentage, The main materials include: composite cement composed of 65% to 95% silicate cement and 5% to 20% sulfoaluminate cement, 3% to 14% dihydrate gypsum, and fly ash accounting for 0.6% to 1% of the composite cement mass. The additives include: a reinforcing agent comprising 3% to 7% of the composite cement mass, an expanding agent comprising 6% to 8% of the composite cement mass, plant cellulose comprising 0.2% to 0.3% of the composite cement mass, an air-entraining agent comprising (0.5-1.5) / 10000 of the composite cement mass, a polycarboxylate superplasticizer comprising 0.18% to 0.25% of the cement mass, a hydroxycarboxylate retarder comprising 0.1% to 0.25% of the cement mass, and a pumping retarder comprising 2% to 5% of the composite cement mass. The aggregate comprises: fine sand at 2-2.5 times the weight of the composite cement; The reinforcing fibers include: 0.15%-0.2% polypropylene chopped fibers by mass of the composite cement, and 3%-5% steel fibers by mass of the composite cement.

2. The marine cement for marine structural components according to claim 1, characterized in that, The reinforcing agent is sodium silicate, potassium silicate, and lithium carbonate; And / or, the molecular weight of the plant cellulose is 100,000 to 2,000,000; And / or, the expanding agent is prepared by the following method: 45-50 parts by mass of calcined phosphogypsum, 30-35 parts by mass of high-alumina clinker, and 18-25 parts by mass of fly ash are mixed and fed into a ball mill to produce an aggregate with a fineness of less than 12% and a specific surface area of ​​300-350 m². 3 / kg of powder; And / or, the air-entraining agent is prepared by the following method: by mass, take 10-30 parts of 40wt% sodium hydroxide solution, 15-25 parts of 30wt% hydrogen peroxide, 5-15 parts of 10wt% potassium permanganate solution, 15-25 parts of 20wt% sulfuric acid solution, and 80-100 parts of water, mix them, heat to 70-90℃, and then add 20-50 parts of rosin powder to obtain a solution.

3. The marine cement for marine structural components according to claim 1, characterized in that, In the composite cement, part of the silicate cement and / or part of the sulfoaluminate cement uses nanoscale raw materials with a particle size not exceeding 200 nm.

4. The marine cement for marine structural components according to claim 1, characterized in that, The additives also include: Antifreeze agent (4%-6% of composite cement mass), pumping agent (1%-2% of composite cement mass), and interface treatment agent (2-2.5 kg / m³). 2 Rust inhibitor 4-8 kg / m 3 Defoamer comprising 0.1%-0.2% of the composite cement mass, and curing agent comprising 1.52%-2.7% of the composite cement mass.

5. The marine cement for marine structural components according to claim 1, characterized in that, In the reinforcing fibers, the length of the chopped polypropylene fibers is 10-12 mm; and / or, the diameter of the steel fibers is 0.45-0.7 mm, and the aspect ratio is 30-100.

6. The method for preparing marine cement for marine structural components as described in any one of claims 1-5, characterized in that, Includes the following steps: Add additives to water, stir thoroughly, then add the main material, then add aggregates and reinforcing fibers, and stir thoroughly to obtain the marine cement.

7. The preparation method according to claim 6, characterized in that, The amount of water used is 35%-48% of the total weight of the cementitious material.

8. The preparation method according to claim 6, characterized in that, The stirring is carried out using a dual-shaft counter-current stirring method, and the stirring time is 2 to 10 minutes. And / or, the finished product flowability of the marine cement is 180-190 mm.

9. A marine structural component, characterized in that, The component uses marine cement as a raw material, as described in any one of claims 1-5 or marine cement prepared by any one of claims 6-8.

10. The marine structural component according to claim 9, characterized in that, The component also includes reinforcing bars, the type of which is selected from any one or more of HPB300, HRB400, HRB500, and HRB600, and the amount used is 20-30 kg per square meter of building.

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