Modifying agents, modifying methods and modified coral aggregates

Abstract

The present application provides a modifier for coral aggregate, a modification method and modified coral aggregate. The modifier comprises at least a composite powder rust inhibitor, which comprises: inorganic salt, carboxylic acid compound and inorganic nanomaterial. The modification method comprises: placing the coral aggregate into a solution of the composite powder rust inhibitor for soaking, then wrapping with a wrapping agent, and then curing to obtain the modified coral aggregate. The present application can improve the cylinder compressive strength, crushing index and control free chloride ion content of the coral aggregate.

Description

Technical Field

[0001] This invention relates to modifiers, modification methods, and modified coral aggregates, belonging to the field of building materials technology. Background Technology

[0002] With the active advancement of marine engineering construction, concrete, as a basic material in the marine engineering construction process, has received widespread attention and importance regarding the availability of raw materials and its service performance in harsh environments.

[0003] Aggregate constitutes approximately 70%-80% of the volume of concrete. In offshore island and reef construction projects, the demand for sand and gravel aggregates, a crucial component, is enormous. Transporting aggregates by sea would significantly increase project costs. To meet the needs of the rapidly developing marine engineering industry, it is urgent to find alternative materials that satisfy engineering requirements. Fully utilizing marine resources while protecting the marine ecological environment can greatly reduce the initial construction and subsequent maintenance costs of island and reef projects. Therefore, without damaging the original ecological environment, using coral sand and gravel from islands as concrete aggregates can effectively reduce construction costs and accelerate construction progress in island and reef projects.

[0004] Unlike ordinary lightweight aggregates, coral aggregates are porous materials with basic characteristics such as lightweight, porousness, high water absorption, and low strength. Researchers have primarily focused on single-modification methods to enhance the performance of coral aggregates. These methods mainly include inorganic modification, organic modification, and biological modification. Examples include soaking coral aggregates in water glass solution, soaking them in PVA (polyvinyl alcohol) solution, and using bacterial culture tubes to cultivate microorganisms in coral aggregates. Currently, the performance of coral aggregates is mainly measured by three indicators: cylinder compressive strength, crushing index, and free chloride ion content. Currently, the main method used is cement coating to modify and improve coral aggregates, but cement modification alone cannot fully penetrate the interior of the coral aggregate and does not effectively reduce the free chloride ion content.

[0005] CN109354431B discloses a method for incorporating a rust inhibitor to improve the durability of coral concrete structures. This method involves mixing the rust inhibitor with seawater and pouring it into crushed coral aggregate for pre-absorption treatment. Based on the "water absorption and return" characteristics of coral aggregate, the rust inhibitor inside the coral aggregate is released, thereby increasing the resistance to chloride ion movement. CN110981255B discloses a method for reinforcing porous coral aggregate. This method treats the coral aggregate with a water glass solution and a calcium ion solution, utilizing a chemical reaction to generate calcium silicate precipitate to fill the pores. A reinforcing agent slurry is then used to further improve density and strength, and finally, modified coral aggregate is obtained through curing. CN111943546A discloses a coral aggregate and its low-cost modification method. This method involves immersing the coral aggregate in a slag solution and stirring the water glass solution, effectively reducing its porosity and water absorption rate through corresponding chemical reactions, thereby improving its mechanical properties. Huang Long explored the application of nanomaterials in coral aggregate concrete. He prepared a suspension using three nanomaterials: nano-SiO2, nano-TiO2, and nano-CaCO3. The suspension was then used to soak the coral aggregate in a vacuum environment to fill its pores (Huang Long. Experimental Study on Basic Mechanical Properties and Impermeability of Modified Coral Aggregate Concrete [D], 2022).

[0006] Most of the rust inhibitors used in existing technologies are liquid rust inhibitors, and their compositions are mostly relatively simple, making it difficult to simultaneously fill aggregate pores and reduce the content of free chloride ions. Furthermore, the modification methods in existing technologies cannot simultaneously improve the cylinder compressive strength, crushing index, and free chloride ion content of coral aggregates. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a modifier for coral aggregate, a method for modifying coral aggregate, and a modified coral aggregate. The present invention can improve the cylinder compressive strength, crushing index, and control the free chloride ion content of coral aggregate.

[0008] To achieve the above objectives, the first aspect of the present invention provides a modifier for coral aggregate, comprising at least: a composite powder rust inhibitor, wherein, based on 100% of the total weight of the composite powder rust inhibitor, it comprises: 30-40% inorganic salt, 10-30% carboxylic acid compound, and 20-35% inorganic nanomaterial; wherein the carboxylic acid compound comprises one or more of aminocarboxylate and unsaturated carboxylic acid.

[0009] According to a specific embodiment of the present invention, preferably, the inorganic salt includes zinc sulfate and / or calcium sulfate, etc. More preferably, the inorganic salt includes a combination of zinc sulfate and calcium sulfate, and the content of zinc sulfate is 15-20% and the content of calcium sulfate is 15-25% based on 100% of the total weight of the composite powder rust inhibitor.

[0010] According to a specific embodiment of the present invention, preferably, the aminocarboxylate includes glycine salt, etc., and the unsaturated carboxylic acid includes acrylic acid, etc.

[0011] According to a specific embodiment of the present invention, preferably, the inorganic nanomaterial includes nano-titanium dioxide and / or nano-zinc oxide, etc.

[0012] According to a specific embodiment of the present invention, preferably, the composite powder rust inhibitor, based on 100% of its total weight, further comprises: 5-10% stabilizer, wherein the stabilizer includes surfactant.

[0013] According to a specific embodiment of the present invention, preferably, the composite powder rust inhibitor, based on 100% of its total weight, further comprises: 5-10% pH adjuster.

[0014] According to a specific embodiment of the present invention, preferably, the modifier of the coral aggregate further includes: an encapsulating agent, the encapsulating agent comprising: cement and water.

[0015] It should be noted that the composite powder rust inhibitor and the encapsulating agent of the present invention can be stored separately. When modifying coral aggregate, the composite powder rust inhibitor and the encapsulating agent can be used step by step to modify the coral aggregate according to the modification method described below.

[0016] According to a specific embodiment of the present invention, preferably, the weight ratio of the composite powder rust inhibitor to the coating agent is (0.2-0.4):1.

[0017] According to a specific embodiment of the present invention, preferably, the cement includes one or a combination of several of ordinary cement, special cement and corrosion-resistant cement.

[0018] According to a specific embodiment of the present invention, preferably, the coating agent further comprises: a cementitious material; the weight ratio of the cementitious material to the cement is (0.2-0.4):1.

[0019] According to a specific embodiment of the present invention, preferably, the weight ratio (i.e., water-cement / binder ratio) of the total amount of water in the coating agent to cement and selectively included cementitious materials is (0.2-0.6):1.

[0020] According to a specific embodiment of the present invention, preferably, the cementing material includes one or a combination of several of the following: fly ash, blast furnace slag powder, recycled powder, coral sand powder, quartz sand powder, and basalt powder.

[0021] According to a specific embodiment of the present invention, preferably, the density of the encapsulating agent is 3.0-3.5 g / cm³. 3 .

[0022] A second aspect of the present invention provides a method for modifying coral aggregate, the method employing the aforementioned coral aggregate modifier, comprising the following steps:

[0023] (1) The coral aggregate is immersed in a solution of composite powder rust inhibitor to obtain the coral aggregate after being soaked in the composite powder rust inhibitor;

[0024] (2) The coral aggregate after being impregnated with the composite powder rust inhibitor is coated with a coating agent to form a coating agent layer, thereby obtaining a coral aggregate with a coating agent layer.

[0025] (3) The coral aggregate with the coating layer is cured to obtain modified coral aggregate.

[0026] According to a specific embodiment of the present invention, preferably, the particle size of the coral aggregate is 5-20 mm.

[0027] According to a specific embodiment of the present invention, preferably, the mass fraction of the composite powder rust inhibitor in the solution of the composite powder rust inhibitor is 3-50%.

[0028] According to a specific embodiment of the present invention, preferably, the pH value of the solution of the composite powder rust inhibitor is 9-12.

[0029] According to a specific embodiment of the present invention, preferably, the volume ratio of the composite powder rust inhibitor solution to the coral aggregate is (1-3):1.

[0030] According to a specific embodiment of the present invention, preferably, the soaking time is 3-5 hours.

[0031] According to a specific embodiment of the present invention, preferably, the coating agent is used to coat the coral aggregate after it has been impregnated with the composite powder rust inhibitor by spraying or by immersion under vibration, so that the coating agent coats the surface of the coral aggregate and fills the pores of the coral aggregate, forming a coating agent layer on the surface of the coral aggregate.

[0032] According to a specific embodiment of the present invention, preferably, the thickness of the coating layer is 0.05-0.2 cm.

[0033] According to a specific embodiment of the present invention, preferably, the curing includes standard curing, carbonization curing, or steam curing. Specifically, the conditions for standard curing include: curing for 28 days in an environment with a temperature of 20℃±3℃ and a relative humidity of 90% or higher; the conditions for carbonization curing include: curing for 1-28 days in an environment with a carbon dioxide concentration of 20%±3%, a relative humidity of 70%±5%, and a temperature of 20℃±2℃; the conditions for steam curing include: curing for 1-28 days in an environment with a temperature of 50-80℃ and a humidity of 90% or higher.

[0034] A third aspect of the present invention provides a modified coral aggregate, which is prepared by the above-described method for modifying coral aggregate.

[0035] The present invention has at least the following beneficial effects:

[0036] This invention employs a solution of composite powder rust inhibitor to soak coral aggregate for a prolonged period. The inorganic and organic components of the composite powder rust inhibitor fully penetrate the aggregate, creating a synergistic effect that adsorbs and fills the aggregate. This process adsorbs and solidifies chloride ions, reducing the free chloride ion content. Simultaneously, it fills the pores within the aggregate, increasing its density and strength. Following rust inhibitor impregnation, the coral aggregate is treated with a cement-containing coating agent. This fills the surface pores and forms a coating layer, further enhancing density. Subsequently, the coated coral aggregate is cured to fully hydrate the cement, for example, generating calcium silicate hydrate, significantly improving the aggregate's strength and durability. This invention employs a composite modification method, first impregnating with a rust inhibitor and then applying a coating agent, to comprehensively improve the performance of coral aggregate. This results in modified coral aggregate exhibiting increased compressive strength, reduced crushing index, and decreased free chloride ion content, thereby enhancing aggregate strength and corrosion resistance and extending the service life of concrete structures. Furthermore, the modified coral aggregate of this invention is non-toxic, harmless, and has a simple preparation process. This invention provides a new approach to the application of coral aggregate concrete, expanding its application scope. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the process for modifying coral aggregate in a specific embodiment of the present invention.

[0038] Figure 2 This is an optical image of the modified coral aggregate from Example 1.

[0039] Figure 3 Optical image of the modified coral aggregate in Comparative Example 1.

[0040] Figure 4 Optical image of the modified coral aggregate in Comparative Example 2.

[0041] Figure 5 Optical image of unmodified coral aggregate. Detailed Implementation

[0042] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0043] According to a specific embodiment of the first aspect of the present invention, the present invention provides a modifier for coral aggregate, which comprises at least: a composite powder rust inhibitor, which, based on 100% of the total weight of the composite powder rust inhibitor, comprises: 30-40% inorganic salt, 10-30% carboxylic acid compound, and 20-35% inorganic nanomaterial; wherein the carboxylic acid compound comprises one or more of aminocarboxylate and unsaturated carboxylic acid.

[0044] In some embodiments, the inorganic salt includes zinc sulfate (ZnSO4) and / or calcium sulfate (CaSO4), etc. Preferably, the inorganic salt includes a combination of zinc sulfate and calcium sulfate, and the content of zinc sulfate is 15-20% and the content of calcium sulfate is 15-25% based on 100% of the total weight of the composite powder rust inhibitor.

[0045] In some embodiments, the aminocarboxylate salt includes glycine salts, and the unsaturated carboxylic acid includes acrylic acid, etc. Specifically, the glycine salt may include sodium glycine, etc.

[0046] In some embodiments, the inorganic nanomaterials include nano-titanium dioxide (TiO2) and / or nano-zinc oxide (ZnO), etc. Preferably, the particle size of the inorganic nanomaterials is 5-50 nm.

[0047] In some embodiments, the composite powder rust inhibitor, based on 100% of its total weight, further comprises 5-10% stabilizer, wherein the stabilizer includes surfactants. Specifically, the stabilizer includes one or a combination of several of anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0048] In some embodiments, the composite powder rust inhibitor, based on 100% of its total weight, further comprises: a pH adjuster of 5-10%. Specifically, the pH adjuster may include dilute sulfuric acid and / or sodium hydroxide, etc.

[0049] This invention develops a composite powder rust inhibitor. The inorganic salts in this agent react with chlorides, reducing steel corrosion during application. Carboxylic acid compounds form a protective film on coral aggregate, slowing down the corrosion rate of the steel. Inorganic nanomaterials, due to their high specific surface area and unique physicochemical properties, enhance the overall performance of the rust inhibitor. The components of this composite powder rust inhibitor can fully penetrate the aggregate and exert a synergistic effect, adsorbing and filling the aggregate.

[0050] In some embodiments, the modifier for the coral aggregate further comprises an encapsulating agent, which includes cement and water.

[0051] In some embodiments, the weight ratio of the composite powder rust inhibitor to the coating agent is (0.2-0.4):1, preferably 0.3:1.

[0052] In some embodiments, the cement includes one or a combination of several of ordinary cement, special cement, and corrosion-resistant cement. This invention does not impose any special limitations on the specific substances / materials included in ordinary cement, special cement, and corrosion-resistant cement; conventional cements in the art can be used, such as, but not limited to, silicate cement, aluminate cement, etc.

[0053] In some embodiments, the coating agent further comprises: a cementitious material; the weight ratio of the cementitious material to the cement is (0.2-0.4):1, preferably 0.3:1.

[0054] In some embodiments, the weight ratio of water in the coating agent to the total amount of cement and selectively included cementitious materials (i.e., water:(cement + selectively included cementitious materials), also referred to as water-cement / binder ratio) is (0.2-0.6):1, preferably (0.4-0.5):1.

[0055] In some embodiments, the cementing material includes one or a combination of several of the following: fly ash, blast furnace slag powder, recycled powder, coral sand powder, quartz sand powder, and basalt powder. The cementing material preferably uses basalt powder or coral sand powder, which more easily fills aggregate pores and coats them, enhancing aggregate strength. Preferably, the particle size of the cementing material is 60μm-100μm.

[0056] In some embodiments, the density of the encapsulating agent is 3.0-3.5 g / cm³. 3 The preferred value is 3.3 g / cm³. 3 .

[0057] By controlling the formulation of the coating agent and the water-cement / binder ratio, the present invention enables the coating agent to have better fluidity and uniformity, thereby enabling it to fill the surface pores of the aggregate more fully and uniformly, and forming a uniform coating agent layer on the surface of the aggregate.

[0058] According to a specific embodiment of the second aspect of the present invention, the present invention provides a method for modifying coral aggregate, the method employing the aforementioned coral aggregate modifier, such as... Figure 1 As shown, it includes the following steps:

[0059] (1) The coral aggregate is immersed in a solution of composite powder rust inhibitor to obtain the coral aggregate after being soaked in the composite powder rust inhibitor;

[0060] (2) The coral aggregate after being impregnated with the composite powder rust inhibitor is coated with a coating agent to form a coating agent layer, thereby obtaining a coral aggregate with a coating agent layer.

[0061] (3) The coral aggregate with the coating layer is cured to obtain modified coral aggregate.

[0062] In some embodiments, the coral aggregate has a particle size of 5-20 mm. Specifically, methods such as sieving can be used to ensure that the coral aggregate meets the above particle size range. The particle size distribution of the coral aggregate can be referenced in the standard "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010). If the particle size of the coral aggregate does not meet the 5-20 mm continuous gradation, aggregate crushing is required. Furthermore, before performing step (1), the coral aggregate can be dried at 100±5℃ for 24-26 hours.

[0063] In some embodiments, the mass fraction of the composite powder rust inhibitor in the solution is 3-50%.

[0064] In some embodiments, the pH value of the solution of the composite powder rust inhibitor is 9-12.

[0065] In some embodiments, the volume ratio of the composite powder rust inhibitor solution to the coral aggregate is (1-3):1.

[0066] In some embodiments, after placing the coral aggregate into the solution of the composite powder rust inhibitor, it can be stirred for 8-10 minutes to allow the solution of the composite powder rust inhibitor to penetrate the interior of the coral aggregate more fully and to expel air from the interior of the coral aggregate.

[0067] In some embodiments, the soaking time is 3-5 hours. The soaking temperature can be room temperature, typically 23±2℃. The soaking pressure can be atmospheric pressure or vacuum soaking under suitable vacuum conditions.

[0068] In some embodiments, after the soaking process is completed, the coral aggregate soaked in the composite powder rust inhibitor can be removed from the solution and placed on a sieve for shaking to drain the water. The shaking time on the sieve can be 3-5 minutes. Draining the water ensures that the coral aggregate reaches a saturated surface-dry state, so as to avoid the rust inhibitor solution remaining on the surface of the aggregate affecting the final assessment of the modification and strengthening.

[0069] In some embodiments, the coating agent is applied to the coral aggregate after it has been impregnated with the composite powder rust inhibitor by spraying or by immersion under vibration, so that the coating agent coats the surface of the coral aggregate and fills the pores of the coral aggregate, forming a coating agent layer on the surface of the coral aggregate. Spraying is preferred, as it results in a more uniform coating agent layer thickness.

[0070] In some embodiments, the soaking under vibration conditions specifically includes: placing the coral aggregate, after being impregnated with the composite powder rust inhibitor, into the coating agent, stirring, then vibrating, then soaking, and finally filtering to obtain coral aggregate with a coating agent layer. Specifically, the stirring time can be 3-5 minutes to ensure sufficient contact between the coral aggregate and the coating agent. The vibration time can be 8-10 minutes, and the soaking time can be 15-30 minutes to facilitate the coating agent entering and filling the pores of the aggregate. A fine mesh can be used for filtration to remove excess coating agent from the surface of the coral aggregate; the filtration time can be 10-20 minutes to prevent aggregate adhesion caused by subsequent cement hardening.

[0071] In some embodiments, the thickness of the coating layer is 0.05-0.2 cm.

[0072] In some embodiments, the coral aggregate with the coating layer may be dried before the maintenance is performed. The drying may be carried out under natural conditions, and the coral aggregate should be spread out as much as possible during the drying process to ensure the uniformity of the coating layer on the surface of the aggregate.

[0073] In some embodiments, the curing includes standard curing, carbonation curing, or steam curing. Specifically, the conditions for standard curing include: curing for 28 days in an environment with a temperature of 20℃±3℃ and a relative humidity of ≥90%; the conditions for carbonation curing include: curing for 1-28 days in an environment with a carbon dioxide concentration of 20%±3%, a relative humidity of 70%±5%, and a temperature of 20℃±2℃; the conditions for steam curing include: curing for 1-28 days in an environment with a temperature of 50-80℃ and a humidity of ≥90%. This curing process allows for full hydration and development of the cement, thereby improving the modification effect of the coral aggregate.

[0074] According to a specific embodiment of the third aspect of the present invention, the present invention provides a modified coral aggregate, which is prepared by the above-described method for modifying coral aggregate.

[0075] The present invention is illustrated in detail below by way of examples, but the present invention is not limited to these examples. Of course, various modifications can be made within the scope of the present invention.

[0076] Example 1

[0077] 1. Weigh coral aggregate with a particle size of 5-20mm, ensuring that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010), and dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0078] 2. Add the composite powder rust inhibitor (composed of: 15% zinc sulfate, 25% calcium sulfate, 20% sodium glycine, 30% nano titanium dioxide with a particle size of 5-50nm, 5% sodium dodecylbenzene sulfonate as a stabilizer, and 5% sodium hydroxide and / or dilute sulfuric acid as a pH adjuster) to tap water and stir to prepare a 5% (w / w) composite powder rust inhibitor solution with a pH of 10. Place the coral aggregate into the composite powder rust inhibitor solution, with a volume ratio of 1.5:1 between the composite powder rust inhibitor solution and the coral aggregate. First, stir the coral aggregate for 8-10 minutes, then soak it at room temperature and normal pressure for 3-5 hours. After soaking, remove the coral aggregate from the solution, place it on a sieve and shake it for 3-5 minutes to drain the water, thus obtaining the coral aggregate after being soaked in the composite powder rust inhibitor.

[0079] 3. A coating agent is prepared by mixing ordinary Portland cement, basalt micro powder with a particle size of 60μm-100μm, and water. The weight ratio of the composite powder rust inhibitor to the coating agent is 0.3:1, the weight ratio of cement to basalt micro powder is 1:0.3, the water-cement / binder ratio of the coating agent is 0.4:1, and the density of the coating agent is 3.3 g / cm³. 3 The coating agent is applied by spraying to coat the surface of the coral aggregate after it has been impregnated with the composite powder rust inhibitor and fills the pores of the coral aggregate to form a coating agent layer, thus obtaining coral aggregate with a coating agent layer; the thickness of the coating agent layer is 0.1 cm.

[0080] 4. The coral aggregate with the coating layer is placed in the sun to dry naturally, and then subjected to standard maintenance. The standard maintenance conditions include: maintenance for 28 days in an environment with a temperature of 20℃±3℃ and a relative humidity of over 90%, resulting in modified coral aggregate. The optical image of this modified coral aggregate is shown below. Figure 2 As shown. Optical images of unmodified coral aggregate are shown below. Figure 5 As shown.

[0081] Example 2

[0082] 1. Weigh coral aggregate with a particle size of 5-20 mm (the same as in Example 1) to ensure that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010). Dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0083] 2. Add the composite powder rust inhibitor (composed of: 15% zinc sulfate, 25% calcium sulfate, 20% sodium glycine, 30% nano titanium dioxide with a particle size of 5-50nm, 5% sodium dodecylbenzene sulfonate as a stabilizer, and 5% sodium hydroxide and / or dilute sulfuric acid as a pH adjuster) to tap water and stir to prepare a 5% (w / w) composite powder rust inhibitor solution with a pH of 10. Place the coral aggregate into the composite powder rust inhibitor solution, with a volume ratio of 1.5:1 between the composite powder rust inhibitor solution and the coral aggregate. First, stir the coral aggregate for 8-10 minutes, then soak it at room temperature and normal pressure for 3-5 hours. After soaking, remove the coral aggregate from the solution, place it on a sieve and shake it for 3-5 minutes to drain the water, thus obtaining the coral aggregate after being soaked in the composite powder rust inhibitor.

[0084] 3. A coating agent is prepared by mixing ordinary Portland cement, basalt micro powder with a particle size of 60μm-100μm, and water. The weight ratio of the composite powder rust inhibitor to the coating agent is 0.3:1, the weight ratio of cement to basalt micro powder is 1:0.3, the water-cement / binder ratio of the coating agent is 0.4:1, and the density of the coating agent is 3.3 g / cm³. 3 The coral aggregate, after being soaked in the composite powder rust inhibitor, is placed in the coating agent and stirred with a stirrer for 3-5 minutes, then vibrated for 8-10 minutes, and then soaked for 15-30 minutes. After that, it is filtered with a fine mesh for 10-20 minutes. After filtration, the aggregate is spread out to obtain coral aggregate with a coating agent layer; the thickness of the coating agent layer is 0.1 cm.

[0085] 4. Place the coral aggregate with the coating layer in the sun to dry naturally, and then carry out standard maintenance. The standard maintenance conditions include: maintaining in an environment with a temperature of 20℃±3℃ and a relative humidity of more than 90% for 28 days to obtain modified coral aggregate.

[0086] Example 3

[0087] 1. Weigh coral aggregate with a particle size of 5-20 mm (the same as in Example 1) to ensure that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010). Dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0088] 2. Add the composite powder rust inhibitor (composed of: 15% zinc sulfate, 25% calcium sulfate, 20% sodium glycine, 30% nano zinc oxide with a particle size of 5-50nm, 5% sodium dodecylbenzene sulfonate as a stabilizer, and 5% sodium hydroxide and / or dilute sulfuric acid as a pH adjuster) to tap water and stir to prepare a 5% (w / w) composite powder rust inhibitor solution with a pH of 10. Place the coral aggregate into the composite powder rust inhibitor solution, with a volume ratio of 1.5:1 between the composite powder rust inhibitor solution and the coral aggregate. First, stir the coral aggregate for 8-10 minutes, then soak it at room temperature and normal pressure for 3-5 hours. After soaking, remove the coral aggregate from the solution, place it on a sieve and shake it for 3-5 minutes to drain the water, thus obtaining the coral aggregate after being soaked in the composite powder rust inhibitor.

[0089] 3. A coating agent is prepared by mixing ordinary Portland cement, basalt micro powder with a particle size of 60μm-100μm, and water. The weight ratio of the composite powder rust inhibitor to the coating agent is 0.3:1, the weight ratio of cement to basalt micro powder is 1:0.3, the water-cement / binder ratio of the coating agent is 0.4:1, and the density of the coating agent is 3.3 g / cm³. 3 The coating agent is applied by spraying to coat the surface of the coral aggregate after it has been impregnated with the composite powder rust inhibitor and fills the pores of the coral aggregate to form a coating agent layer, thus obtaining coral aggregate with a coating agent layer; the thickness of the coating agent layer is 0.1 cm.

[0090] 4. The coral aggregate with the coating layer is placed in the sun to dry under natural conditions, and then carbonized. The carbonization conditions include: in an environment with a carbon dioxide concentration of 20% ± 3%, a relative humidity of 70% ± 5%, and a temperature of 20℃ ± 2℃, the aggregate is maintained for 28 days to obtain modified coral aggregate.

[0091] Example 4

[0092] 1. Weigh coral aggregate with a particle size of 5-20 mm (the same as in Example 1) to ensure that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010). Dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0093] 2. Add the composite powder rust inhibitor (with the same composition as in Example 1) to tap water and stir to prepare a 5% (w / w) composite powder rust inhibitor solution with a pH of 10. Place the coral aggregate into the composite powder rust inhibitor solution with a volume ratio of 1.5:1. First, stir the coral aggregate for 8-10 minutes, then soak it at room temperature and normal pressure for 3-5 hours. After soaking, remove the coral aggregate from the solution and place it on a sieve and shake it for 3-5 minutes to drain the water, thus obtaining the coral aggregate after being soaked in the composite powder rust inhibitor.

[0094] 3. A coating agent is prepared by mixing ordinary silicate cement, coral sand powder with a particle size of 60μm-100μm, and water. The weight ratio of the composite powder rust inhibitor to the coating agent is 0.3:1, the weight ratio of cement to coral sand powder is 1:0.3, the water-cement / binder ratio of the coating agent is 0.4:1, and the density of the coating agent is 3.3 g / cm³. 3 The coral aggregate, after being soaked in the composite powder rust inhibitor, is placed in the coating agent and stirred with a stirrer for 3-5 minutes, then vibrated for 8-10 minutes, and then soaked for 15-30 minutes. After that, it is filtered with a fine mesh for 10-20 minutes. After filtration, the aggregate is spread out to obtain coral aggregate with a coating agent layer; the thickness of the coating agent layer is 0.1 cm.

[0095] 4. Place the coral aggregate with the coating layer in the sun to dry naturally, and then carry out standard maintenance. The standard maintenance conditions include: maintaining in an environment with a temperature of 20℃±3℃ and a relative humidity of more than 90% for 28 days to obtain modified coral aggregate.

[0096] Comparative Example 1

[0097] 1. Weigh coral aggregate with a particle size of 5-20 mm (the same as in Example 1) to ensure that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010). Dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0098] 2. Add the composite powder rust inhibitor (with the same composition as in Example 1) to tap water and stir to prepare a 5% (w / w) composite powder rust inhibitor solution with a pH of 10. Place the coral aggregate into the composite powder rust inhibitor solution with a volume ratio of 1.5:1. First, stir the coral aggregate for 8-10 minutes, then soak it at room temperature and normal pressure for 3-5 hours. After soaking, remove the coral aggregate from the solution and place it on a sieve and shake it for 3-5 minutes to drain the water, thus obtaining the coral aggregate after being soaked in the composite powder rust inhibitor.

[0099] 3. The coral aggregate impregnated with the composite powder rust inhibitor was placed under natural conditions and dried to obtain modified coral aggregate. The optical image of this modified coral aggregate is shown below. Figure 3 As shown.

[0100] Compared to Example 1, this comparative example omits the steps of coating and curing with a coating agent.

[0101] Comparative Example 2

[0102] 1. Weigh coral aggregate with a particle size of 5-20 mm (the same as in Example 1) to ensure that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010). Dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0103] 2. Prepare the same coating agent as in Example 1, and apply the coating agent to the surface of the coral aggregate by spraying, filling the pores of the coral aggregate to form a coating agent layer, thereby obtaining coral aggregate with a coating agent layer; the thickness of the coating agent layer is 0.1 cm;

[0104] 3. The coral aggregate with the coating layer was placed under natural conditions to dry, and then subjected to standard maintenance, the conditions of which were the same as in Example 1. The optical image of this modified coral aggregate is shown below. Figure 4 As shown.

[0105] Compared to Example 1, this comparative example omits the step of impregnating the composite powder rust inhibitor.

[0106] Comparative Example 3

[0107] This comparative example is basically the same as Example 1, except that the rust inhibitor is different. The rust inhibitor in this comparative example is calcium nitrite rust inhibitor. A 5% calcium nitrite solution is prepared, and the coral aggregate is placed in the calcium nitrite solution. The volume ratio of calcium nitrite solution to coral aggregate is 1.5:1. Other modification steps and conditions are the same as in Example 1.

[0108] Comparative Example 4

[0109] This comparative example is basically the same as Example 1, except that the composition of the composite powder rust inhibitor is different. The composition of the composite powder rust inhibitor in this comparative example is (by weight percentage): 35% sodium glycine, 50% nano-titanium dioxide with a particle size of 5-50nm, 10% sodium dodecylbenzenesulfonate stabilizer, and 5% sodium hydroxide and / or dilute sulfuric acid pH adjuster. A solution of 5% composite powder rust inhibitor by mass is prepared, and the pH value of the solution of the composite powder rust inhibitor is 10. That is to say, the inorganic salt in the composite powder rust inhibitor of Example 1 is omitted in this comparative example. Other modification steps and conditions are the same as those in Example 1.

[0110] Comparative Example 5

[0111] This comparative example is basically the same as Example 1, except that the composition of the composite powder rust inhibitor is different. The composition of the composite powder rust inhibitor in this comparative example is (by weight percentage): 20% zinc sulfate, 30% calcium sulfate, 35% sodium glycine, 10% sodium dodecylbenzene sulfonate stabilizer, and 5% sodium hydroxide and / or dilute sulfuric acid pH adjuster. A solution of the composite powder rust inhibitor with a mass fraction of 5% is prepared, and the pH value of the solution is 10. That is to say, the inorganic nanomaterials in the composite powder rust inhibitor of Example 1 are omitted in this comparative example. Other modification steps and conditions are the same as in Example 1.

[0112] Comparative Example 6

[0113] This comparative example is basically the same as Example 1, except that the composition of the composite powder rust inhibitor is different. The composition of the composite powder rust inhibitor in this comparative example is (by weight percentage): 20% zinc sulfate, 30% calcium sulfate, 35% nano-titanium dioxide with a particle size of 5-50nm, 10% sodium dodecylbenzenesulfonate stabilizer, and 5% sodium hydroxide and / or dilute sulfuric acid pH adjuster. A solution of 5% composite powder rust inhibitor by mass is prepared, and the pH value of the solution of the composite powder rust inhibitor is 10. That is to say, the aminocarboxylate in the composite powder rust inhibitor of Example 1 is omitted in this comparative example. Other modification steps and conditions are the same as those in Example 1.

[0114] Comparative Example 7

[0115] This comparative example is basically the same as Example 1, except that: the basalt powder in the encapsulating agent is omitted, the water-cement ratio of the encapsulating agent is 0.4:1, and the density of the encapsulating agent is 3.3 g / cm³. 3 Other modification steps and conditions are the same as in Example 1.

[0116] Comparative Example 8

[0117] 1. Weigh coral aggregate with a particle size of 5-20mm, ensuring that the particle size distribution of the coral aggregate meets the requirements of "Lightweight Aggregates and Their Test Methods" (GB / T 17431-2010), and dry the coral aggregate in an oven at 100±5℃ for 24-26 hours.

[0118] 2. The composite powder rust inhibitor (with the same composition as in Example 1) and the coating agent (with the same composition as in Example 1, the water-cement / binder ratio of which is 0.4:1 and the density is 3.3 g / cm³) were mixed. 3 The composite modifier is prepared by mixing the coral aggregates at a weight ratio of 0.3:1. The coral aggregates are then placed in the composite modifier and stirred for 3-5 minutes, followed by vibration for 8-10 minutes, and then soaked for 15-30 minutes. After that, the aggregates are filtered through a fine mesh for 10-20 minutes. After filtration, the aggregates are spread out evenly to obtain coral aggregates with a composite modifier layer. The thickness of this composite modifier layer is 0.1 cm.

[0119] 3. The coral aggregate with the composite modifier layer is placed in the sun to dry under natural conditions, and then subjected to standard maintenance. The standard maintenance conditions include: maintenance for 28 days in an environment with a temperature of 20℃±3℃ and a relative humidity of more than 90%, to obtain modified coral aggregate.

[0120] Compared to Example 1, this comparative example involves mixing a composite powder rust inhibitor and a coating agent, and then soaking and coating the coral aggregate.

[0121] According to the standards "Lightweight aggregates and their test methods Part 2: Lightweight aggregate test methods" (GB / T 17431.2), "Construction pebbles and crushed stone" (GB / T 14685), and "Construction sand" (GB / T 14684), the cylinder compressive strength, crushing index, and free chloride ion content of the modified coral aggregates in the above examples and comparative examples were determined and compared with those of unmodified coral aggregates. The results are shown in Table 1.

[0122] Table 1. Cylinder compressibility, crushing index, and free chloride ion content

[0123]

[0124] As shown in Table 1, the embodiments of the present invention modify coral aggregate by first impregnating it with a composite powder rust inhibitor and then using a coating agent. This double-filling of the pores in the coral aggregate and the formation of a coating agent layer on the surface of the aggregate increases the porosity and strength of the coral aggregate and significantly solidifies chloride ions. This composite modification method comprehensively improves the performance of the coral aggregate. Compared with the unmodified coral aggregate, the modified coral aggregate of the present invention has a cylinder compressive strength increased by more than 120%, a crushing index reduced by about 19%, and a free chloride ion content reduced by about 70%.

Claims

1. A modifier for coral aggregate, comprising: Composite powder rust inhibitors and coating agents; The composite powder rust inhibitor, by weight of 100%, comprises: 30-40% inorganic salts, 10-30% carboxylic acid compounds, and 20-35% inorganic nanomaterials; wherein the inorganic salts include a combination of zinc sulfate and calcium sulfate, and by weight of 100% of the composite powder rust inhibitor, the content of zinc sulfate is 15-20%, and the content of calcium sulfate is 15-25%; the carboxylic acid compounds include one or more of aminocarboxylates and unsaturated carboxylic acids, wherein the aminocarboxylates include glycine salts, and the unsaturated carboxylic acids include acrylic acid; the inorganic nanomaterials include nano-titanium dioxide and / or nano-zinc oxide. The encapsulating agent comprises: cement, cementitious material, and water; the weight ratio of the cementitious material to the cement is (0.2-0.4):1, and the weight ratio of water in the encapsulating agent to the total amount of cement and cementitious material is (0.2-0.6):1; the cementitious material comprises one or a combination of several of the following: fly ash, blast furnace slag powder, recycled powder, coral sand powder, quartz sand powder, and basalt powder. The weight ratio of the composite powder rust inhibitor to the coating agent is (0.2-0.4):

1.

2. The modifier for coral aggregate according to claim 1, wherein, Based on the total weight of the composite powder rust inhibitor as 100%, it further comprises: 5-10% stabilizer, wherein the stabilizer includes surfactant.

3. The modifier for coral aggregate according to claim 1, wherein, Based on the total weight of the composite powder rust inhibitor as 100%, it further includes: 5-10% pH adjuster.

4. The modifier for coral aggregate according to claim 1, wherein, The cement includes one or a combination of ordinary cement, special cement and corrosion-resistant cement.

5. The modifier for coral aggregate according to claim 1, wherein, The density of the encapsulating agent is 3.0-3.5 g / cm³.

6. A method for modifying coral aggregate, the method using the coral aggregate modifier according to any one of claims 1-5, comprising the following steps: (1) The coral aggregate is immersed in a solution of composite powder rust inhibitor to obtain coral aggregate after being impregnated with composite powder rust inhibitor; (2) The coral aggregate after being impregnated with the composite powder rust inhibitor is coated with a coating agent to form a coating agent layer, thereby obtaining a coral aggregate with a coating agent layer; (3) The coral aggregate with the coating layer is cured to obtain modified coral aggregate.

7. The method for modifying coral aggregate according to claim 6, wherein, The coral aggregate has a particle size of 5-20 mm.

8. The method for modifying coral aggregate according to claim 6, wherein, The mass fraction of the composite powder rust inhibitor in the solution is 3-50%.

9. The method for modifying coral aggregate according to claim 6, wherein, The pH value of the solution of the composite powder rust inhibitor is 9-12.

10. The method for modifying coral aggregate according to claim 6, wherein, The volume ratio of the composite powder rust inhibitor solution to the coral aggregate is (1-3):

1.

11. The method for modifying coral aggregate according to claim 6, wherein, The soaking time is 3-5 hours.

12. The method for modifying coral aggregate according to claim 6, wherein, The coating agent is applied to the coral aggregate after it has been impregnated with the composite powder rust inhibitor by spraying or by immersion under vibration. The coating agent coats the surface of the coral aggregate and fills the pores of the coral aggregate, forming a coating agent layer on the surface of the coral aggregate.

13. The method for modifying coral aggregate according to claim 6, wherein, The thickness of the coating layer is 0.05-0.2 cm.

14. The method for modifying coral aggregate according to claim 6, wherein, The curing process includes standard curing, carbonization curing, or steam curing. Standard curing conditions include curing for 28 days in an environment with a temperature of 20℃±3℃ and a relative humidity of 90% or higher. Carbonization curing conditions include curing for 1-28 days in an environment with a carbon dioxide concentration of 20%±3%, a relative humidity of 70%±5%, and a temperature of 20℃±2℃. Steam curing conditions include curing for 1-28 days in an environment with a temperature of 50-80℃ and a humidity of 90% or higher.

15. A modified coral aggregate, which is prepared by the modification method of the coral aggregate according to any one of claims 6-14.

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