A high-performance cement-based grouting material based on modified coral sand, its preparation method and application

Abstract

The present invention provides a high-performance cement-based grouting material based on modified coral sand, its preparation method and application. The high-performance cement-based grouting material is prepared by mixing the following raw materials according to a mass ratio: 30-50 parts of cement; 40-60 parts of modified coral sand; 5-15 parts of ion migration inhibitor; 0.3-0.7 parts of water reducer; 0.5-1.5 parts of rubber powder; 0.05-0.15 parts of defoamer; 0.08-0.12 parts of silicone water repellent; 0.02-0.08 parts of plastic expansion agent; 1.5-4.5 parts of plastic expansion regulator; 9-12 parts of mixing water. The high-performance cement-based grouting material disclosed by the present invention has the advantages of high strength, micro-expansion, high durability, etc. on the basis of high fluidity. It can use local materials and meet the urgent needs for high-performance grouting materials in repair and reinforcement, high-strength protection projects after the island reef engineering construction enters a new development stage.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, particularly to grouting materials, and specifically to a high-performance cement-based grouting material based on modified coral sand, its preparation method, and application. Background Art

[0002] In recent years, the importance of remote island reef construction has been increasing day by day. At present, the main infrastructure construction in the island reef areas of our country has been basically completed, and island reef construction is shifting towards high-quality and high-performance directions such as improving living and production conditions, enhancing the performance of building facilities, and regular maintenance and reinforcement. There is an urgent need for high-performance grouting materials. Chinese Patent Application CN118359415A discloses a high-performance cement-based grouting material, but river sand is selected as the aggregate in this patent, and the transportation cost from the mainland to the island reefs is huge, which is not conducive to island reef construction. Chinese Patent Application CN110272221A discloses a preparation method of modified coral sand concrete. First of all, it exists and is used in the form of concrete. The specific method is to crush the coral sand and then wrap it with cement slurry to form wrapped sand as the aggregate. This is just crushing the coral sand and wrapping it with cement slurry. In fact, the coral sand is not really modified, and the enhancement of the coral sand itself cannot be achieved. It can only delay and restrict the outward leakage of chloride ions in the coral sand to a certain extent, and there is no improvement in the fluidity and expansion of the grouting material, so the grouting material cannot be truly improved in terms of fluidity, strength, expansion rate, and durability. It can be said that at present, the technology of preparing high-performance cement-based grouting materials with modified coral sand as the aggregate is still blank.

[0003] Therefore, it is necessary to develop a high-performance grouting material based on coral sand to fill the gap in this field and meet the urgent needs of high-performance grouting materials in the new development stage of island reef construction for repair and reinforcement, and high-strength protection projects. Summary of the Invention

[0004] To solve the above problems, the first aspect of the present invention discloses a high-performance cement-based grouting material based on modified coral sand, which has the characteristics of large fluidity, high strength, qualified micro-expansion, and high durability, so as to fill the gap in this field.

[0005] The second aspect of the present invention discloses a preparation method of a high-performance cement-based grouting material, which can use local materials and is easy to implement.

[0006] The third aspect of the present invention discloses an application of a high-performance cement-based grouting material, which meets the urgent needs of high-performance grouting materials in the new development stage of island reef construction for repair and reinforcement, and high-strength protection projects.

[0007] The above aspects of the present invention are achieved as follows:

[0008] The present invention first provides a high-performance cement-based grouting material based on modified coral sand, which is mixed from the following raw materials by mass ratio:

[0009] Cement, 30-50 parts;

[0010] Modified coral sand, 40-60 parts;

[0011] Ion migration inhibitor, 5-15 parts;

[0012] Water reducing agent, 0.3-0.7 part;

[0013] Rubber powder, 0.5-1.5 parts;

[0014] Defoaming agent, 0.05-0.15 part;

[0015] Organosilicon water repellent, 0.08-0.12 part;

[0016] Plastic expansion agent, 0.02-0.08 part;

[0017] Plastic expansion regulator, 1.5-4.5 parts;

[0018] Mixing water, 9-12 parts.

[0019] The present invention makes use of local materials. By using modified coral sand and combining with ion migration inhibitor, organosilicon water repellent, plastic expansion agent, plastic expansion regulator and necessary additives, a high-performance cement-based grouting material with large fluidity, high strength, qualified micro-expansion and high durability is obtained.

[0020] Preferably, the cement is one or more of portland cement, ordinary portland cement, sulphoaluminate cement, ferroaluminate cement and aluminate cement;

[0021] Preferably, the mixing water is one or more of seawater, desalinated seawater, fresh water and rainwater naturally collected from the roofs of island reef buildings.

[0022] Preferably, the raw material of the modified coral sand is obtained by crushing, ball milling and screening the coral reef flat, with the maximum particle size of 1.25 mm, and the mass ratio of each particle size range is: the proportion of 0.04 mm < particle size ≤ 0.16 mm is 5-20%, the proportion of 0.16 mm < particle size ≤ 0.315 mm is 5-20%, the proportion of 0.315 mm < particle size ≤ 0.63 mm is 40-50%, and the proportion of 0.63 mm < particle size ≤ 1.25 mm is 30-40%.

[0023] Preferably, the continuously graded coral sand raw material with a particle size of 0.04 mm to 1.25 mm is subjected to modification treatment, specifically:

[0024] (1) Take another portion of cement, ion migration inhibitor, and mixing water. Put the continuously graded coral sand raw material, cement, ion migration inhibitor, and mixing water into a vacuum mixer at a mass ratio of 1:0.9:0.1:0.4.

[0025] (2) Turn on the vacuum mixer and stir for 3 - 5 minutes with the vacuum pump off, including 1 - 2 minutes of low-speed stirring at 960 - 1200 r / h and 2 - 3 minutes of high-speed stirring at 7200 - 12000 r / h. Stop stirring when the mixture is fully homogenized.

[0026] (3) Turn on the vacuum pump and evacuate to 5% - 10% of the atmospheric pressure inside the device. Conduct high-speed stirring at 7200 - 12000 r / h for 3 - 5 minutes until the surface of the coral sand is fully wrapped by the cement slurry and forms relatively regular spherical particles. Then stop stirring.

[0027] (4) Take out the mixture, spread it evenly, and conduct drying treatment for 24 hours. During this period, use a high-frequency vibrating table to vibrate the mixture regularly to prevent bonding and affecting the uniformity of the modified coral sand.

[0028] (5) Take the dried mixture and sieve it with a sieve. The target coral sand with a particle size range of 0.04 mm - 1.25 mm is the prepared modified coral sand.

[0029] Preferably, the ion migration inhibitor is one or more of hydrophobic modified ultra-fine high-alumina slag powder, hydrophobic modified metakaolin, hydrophobic modified silica fume, and nano-silica.

[0030] Preferably, the specific surface area of the hydrophobic modified ultra-fine high-alumina slag powder is 1000 - 2500 m 2 / kg, and the Al 2 O 3 content is greater than 15%;

[0031] Preferably, the specific surface area of the hydrophobic modified metakaolin is 10000 - 15000 m 2 / kg, and the Al 2 O 3 content is greater than 40%;

[0032] Preferably, the specific surface area of the hydrophobic modified silica fume is 20000 - 30000 m 2 / kg, and the SiO 2 content is greater than 95%;

[0033] The specific surface area of the nano-silica is 160000 - 200000 m 2 / kg, and the SiO 2 content is greater than 99.5%.

[0034] Preferably, the water reducing agent is an early strength type high - efficiency polycarboxylate water reducing agent with a water reduction rate greater than 40%;

[0035] Preferably, the rubber powder is one or two of vinyl acetate - ethylene copolymer;

[0036] Preferably, the defoaming agent is one or two of powdered silicone defoaming agent and polyether defoaming agent;

[0037] Preferably, the effective component of the silicone water repellent is silane, in the form of emulsion with an effective content of 50%.

[0038] Preferably, the main component of the plastic expansion agent is azodicarbonamide;

[0039] Preferably, the plastic expansion regulator comprises a setting - adjusting component and an expansion component. The setting - adjusting component includes one or more of calcium chloride, calcium formate, sodium carbonate, and sodium sulfate, and the expansion component includes one or more of calcium oxide type, calcium sulfoaluminate type, magnesium oxide type, and calcium oxide - calcium sulfoaluminate composite expansion agent.

[0040] The present invention also provides a preparation method of the high - performance cement - based grouting material according to the above, including:

[0041] (1) Put the modified coral sand, cement, ion migration inhibitor, rubber powder, silicone water repellent, and mixing water into a mixer according to a mass ratio of 1:0.1:0.05:0.01:0.002:0.1;

[0042] (2) Stir at a low speed for 5 - 10 min until the surface of the modified coral sand is evenly coated with a dry and thick water - repellent neat cement film;

[0043] (3) After standing for 5 - 10 min, when there is no clear water on the surface of the coral sand particles, put in the remaining raw materials and continue to stir for 3 - 5 min, wherein: the low - speed stirring time is 1 - 2 min, and the high - speed stirring time is 2 - 3 min. After the materials are fully and evenly mixed, the high - performance cement - based grouting material is obtained.

[0044] The present invention also provides an application of the high - performance cement - based grouting material according to the above in the construction, repair, and reinforcement of island reefs and high - strength protection projects.

[0045] The beneficial effects of the present invention on the prior art are:

[0046] (1) The high-performance cement-based grouting material of the present invention has a large fluidity. First, the present invention modifies the coral sand in view of its characteristics of being loose, porous and easy to absorb water. Before preparing the slurry, the coral sand is first modified, which is a pre-procedure for slurry preparation. Specifically, a slurry prepared by mixing cement, an ion migration inhibitor and mixing water is filled into the pores of the coral sand and evenly wrapped on the surface of the coral sand to form relatively regular spherical particles, obtaining modified coral sand, so as to reduce the absorption of mixing water by the coral sand during stirring and reduce the decrease in fluidity caused by the irregular shape of the coral sand; secondly, during the preparation process, by wrapping a hydrophobic neat cement film on the surface of the modified coral sand, the influence of the modified coral sand on the fluidity of the grouting material is further reduced; thirdly, among the ion migration inhibitors used in the present invention, ultra-fine high-alumina slag powder, metakaolin and silica fume have all been subjected to hydrophobic modification, the water demand is reduced, and the fluidity of the grouting material is further improved; fourthly, the present invention uses a high-efficiency polycarboxylate water reducer with a water reduction rate greater than 40%, and the fluidity of the grouting material is further improved.

[0047] (2) The high-performance cement-based grouting material of the present invention has high strength. First, the present invention modifies the coral sand. After the slurry is filled into the pores of the coral sand, it continues to hydrate and harden, and the strength of the coral sand is greatly enhanced. The gradation is designed and the packing is compact, and the aggregate support effect is strong; secondly, the ion migration inhibitor used in the present invention improves the strength of the grouting material after hardening through the principle of closest packing, and the ion migration inhibitor has a secondary hydration effect, and the hydration products gradually fill the internal pores of the grouting material, further improving the long-term strength of the grouting material; thirdly, the setting adjustment component in the plastic expansion regulator used in the present invention has an early strength effect and can further improve the early strength of the grouting material; fourthly, the rubber powder used in the present invention forms a nano-emulsion after being dissolved in the mixing water, which can improve the microstructure of the grouting material at the nano level and improve the flexural strength of the grouting material; fifthly, the defoamer used in the present invention can effectively reduce the inclusion of air bubbles during the preparation and stirring of the high-performance cement-based grouting material, making the grouting material more dense after hardening and further effectively improving the strength.

[0048] (3) The high-performance cement-based grouting material of the present invention has a qualified micro-expansion. The present invention uses a plastic expansion regulator. On the one hand, through the setting-adjusting component, the synergistic relationship between the gas generated by the plastic expansion agent and the strength development of the grouting material can be reasonably adjusted, and the early plastic expansion window period of the grouting material can be designed, so that the grouting material can retain gas within 3 hours and reach a certain strength within 3 - 24 hours to restrain the gas from continuing to expand, avoiding excessive vertical expansion rate within 3 - 24 hours, thereby achieving the early micro-expansion effect of the grouting material. On the other hand, the expansion component in the plastic expansion regulator can compensate for the shrinkage of the grouting material, and at the same time produce a synergistic effect with the plastic expansion agent. Based on the tiny pores generated by the plastic expansion agent, chemical expansion is caused by the products generated through the hydration reaction, further providing micro-expansion during the hardening process and improving the compactness of the grouting material substrate, thereby further increasing the strength. The present invention uses a plastic expansion regulator and gives the full curve of the vertical expansion rate, realizing the controllable adjustment of the vertical expansion rate.

[0049] (4) The high-performance cement-based grouting material of the present invention has the characteristics of high durability. First, the present invention uses modified coral sand, which greatly improves the compactness of the matrix after the grouting material hardens, and at the same time can block the leakage of harmful ions in the coral sand, improving the durability; Second, the ion migration inhibitor used in the present invention can inhibit the migration of harmful ions such as Cl - , SO 4 2- , Mg 2 + etc. through physical and chemical adsorption, and dissolves Al 3+ ions during the hardening process of the grouting material, avoiding the dissolution of hydration products in the grouting material matrix. The secondary hydration of the ion migration inhibitor makes the grouting material matrix more compact and improves the durability; Third, the cement used in the present invention can effectively prevent the corrosion of harmful substances such as acids and alkalis and improve the durability by reasonably compounding aluminate cement, sulphoaluminate cement, and ferroaluminate cement. For example, C 3 A (tricalcium aluminate) and C 4 A (tetracalcium aluminoferrite) in the aluminate cement can hydrate to form stable compounds to resist the erosion of sulfates; Fourth, the present invention uses a plastic expansion regulator to keep the grouting material always in a slightly expanded state, effectively preventing it from shrinking and cracking, avoiding the formation of internal channels for harmful ions to enter the matrix, and further improving the durability of the grouting material.

[0050] (5) The high-performance cement-based grouting material of the present invention has a high rate of using local materials. Combining the current situation of island reef engineering construction, the present invention uses coral reef disks broken and screened on-site to obtain coral sand to replace traditional aggregates such as quartz sand and river sand, and seawater can be used for mixing, saving transportation and raw material costs, saving economic costs, and effectively promoting the sustainable development of island reef construction.

[0051] It should be understood that the implementation of any embodiment of the present invention does not necessarily mean that multiple or all of the above beneficial effects are simultaneously achieved or met. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are merely exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained based on the provided drawings.

[0053] The structures, proportions, sizes, etc. illustrated in this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they do not have technical substantial significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the efficacy that the present invention can produce and the purpose that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention.

[0054] Figure 1 Exemplarily shown is a process flow chart for preparing a high-performance cement-based grouting material based on modified coral sand according to the present invention, where: the left side is the process flow chart for modifying coral sand, and the right side is the process flow chart for preparing the grouting material;

[0055] Figure 2A Exemplarily shown is a diagram of the regulation mechanism of the vertical expansion rate window period for ordinary coral sand grouting material;

[0056] Figure 2B Exemplarily shown is a diagram of the regulation mechanism of the vertical expansion rate window period for the modified coral sand grouting material according to the present invention;

[0057] Figure 3 Exemplarily shown is a schematic diagram of the regulation effect on the vertical expansion rate window period according to the present invention.

[0058] In each of the drawings, the same or corresponding reference numerals represent the same or corresponding parts. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer and more understandable, the following will further elaborate on the embodiments of the present invention in conjunction with the embodiments and the drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not limit the present invention.

[0060] It should be understood that the terms "comprising / including", "consisting of" or any other variants are intended to cover non-exclusive inclusion, so that a product, device, process or method comprising a series of elements not only includes those elements, but may also include other elements not expressly listed when necessary, or elements inherent to such product, device, process or method. Without further limitation, an element defined by the statement "comprising / including..." or "consisting of" does not exclude the presence of additional identical elements in the product, device, process or method comprising said element.

[0061] The following will elaborate in detail on the specific implementation and preferred solutions of a high-performance cement-based grouting material based on modified coral sand proposed by the present invention.

[0062] The present invention first provides a high-performance cement-based grouting material based on modified coral sand, which is prepared by mixing the following raw materials according to a mass ratio: 30 - 50 parts of cement; 40 - 60 parts of modified coral sand; 5 - 15 parts of ion migration inhibitor; 0.3 - 0.7 parts of water reducer; 0.5 - 1.5 parts of rubber powder; 0.05 - 0.15 parts of defoamer; 0.08 - 0.12 parts of organosilicon water repellent; 0.02 - 0.08 parts of plastic expansion agent; 1.5 - 4.5 parts of plastic expansion regulator; 9 - 12 parts of mixing water. The high-performance cement-based grouting material disclosed by the present invention, on the basis of high fluidity, also has the advantages of high strength, slight expansion, high durability, etc., and can use local materials to meet the urgent demand for high-performance grouting materials in repair and reinforcement, high-strength protection projects after the island reef engineering construction enters a new development stage.

[0063] In some embodiments, it is preferable to use one or a combination of silicate cement, ordinary portland cement, sulfoaluminate cement, ferroaluminate cement and aluminate cement as the cement. The cement used in the present invention can effectively prevent the corrosion of harmful substances such as acids and alkalis and improve durability by reasonably compounding aluminate cement, sulfoaluminate cement and ferroaluminate cement. For example, C 3 A (tricalcium aluminate) and C 4 A (tetracalcium aluminoferrite) in aluminate cement can hydrate to form stable compounds to resist the erosion of sulfates.

[0064] In some embodiments, the ion migration inhibitor is one or more of hydrophobic modified ultra-fine high-alumina slag powder, hydrophobic modified metakaolin, hydrophobic modified silica fume, and nano-silica.

[0065] In some specific embodiments, the specific surface area of the hydrophobic modified ultra-fine high-alumina slag powder is 1000 - 2500m 2 / kg, and the Al 2 O 3The content is greater than 15%; the specific surface area of the hydrophobic modified metakaolin is 10,000 - 15,000 m 2 / kg, and the content of Al 2 O 3 is greater than 40%; the specific surface area of the hydrophobic modified silica fume is 20,000 - 30,000 m 2 / kg, and the content of SiO 2 is greater than 95%; the specific surface area of the nano - silica is 160,000 - 200,000 m 2 / kg, and the content of SiO 2 is greater than 99.5%.

[0066] In the present invention, the ultra - fine high - alumina slag powder, metakaolin, and silica fume are all subjected to hydrophobic modification treatment, the water demand is reduced, and the fluidity of the grouting material is further improved. When the technology of the present invention is not used, if the same high fluidity is to be achieved, more water - reducing agents need to be added or the water consumption needs to be increased. As a result, the mechanical properties and durability of the grouting material will be significantly reduced, and it will also cause the grouting material to have super - slow setting, and the effect of the plastic expansion agent will not meet the standard, resulting in the vertical expansion rate not meeting the national standard requirements either.

[0067] Furthermore, the ion migration inhibitor in the present invention inhibits the migration of harmful ions such as Cl - , SO 4 2- , Mg 2 + through physical and chemical adsorption, and dissolves Al 3+ ions during the hardening process of the grouting material, avoiding the dissolution of hydration products in the grouting material matrix. The secondary hydration of the ion migration inhibitor makes the grouting material matrix more dense and improves the durability; in addition, according to the principle of the closest packing, the strength of the hardened grouting material is increased, and the ion migration inhibitor has a secondary hydration effect, and the hydration products gradually fill the internal pores of the grouting material, further improving the long - term strength of the grouting material.

[0068] In some embodiments, the raw material of the modified coral sand is obtained by crushing, ball - milling, and screening the coral reef flat. Its maximum particle size is 1.25 mm, and the mass proportion in each particle size range is as follows: 30 - 40% for 0.63 mm < particle size ≤ 1.25 mm, 40 - 50% for 0.315 mm < particle size ≤ 0.63 mm, 5 - 20% for 0.16 mm < particle size ≤ 0.315 mm, 5 - 20% for 0.04 mm < particle size ≤ 0.16 mm; the apparent density is 2350 - 2450 kg / m³, and the bulk density is 1005 - 1065 kg / m³.

[0069] Furthermore, before preparing the slurry, the present invention first performs a modification treatment on the coral sand raw material, that is, a modification treatment is performed on the continuously graded coral sand raw material with a particle size of 0.04 mm to 1.25 mm obtained, which is a pre-procedure for slurry preparation. As Figure 1 shown, it includes the following steps:

[0070] (1) Separately take cement, an ion migration inhibitor, and mixing water, and put the continuously graded coral sand raw material, cement, hydrophobic modified silica fume, and mixing water into a vacuum mixer at a mass ratio of 1:0.9:0.1:0.4; it is easy to understand that the cement, ion migration inhibitor, and mixing water taken at this time have nothing to do with the main materials for preparing the slurry and are materials taken separately for the purpose of modification. The specific amounts taken are based on the coral sand raw material and are put in proportion;

[0071] (2) Start the vacuum mixer and stir for 3 to 5 minutes with the vacuum pump closed, among which the low-speed stirring (960 - 1200 r / h) time is 1 to 2 minutes, and the high-speed stirring (7200 - 12000 r / h) time is 2 to 3 minutes. Wait until the mixture is fully stirred evenly and then stop stirring;

[0072] (3) Start the vacuum pump and evacuate to 5% - 10% of the atmospheric pressure inside the device, and perform high-speed stirring (7200 - 12000 r / h) for 3 to 5 minutes. Wait until the surface of the coral sand is fully wrapped by the cement slurry and forms relatively regular spherical particles, and then stop stirring;

[0073] (4) Take out the mixture, spread it evenly, and perform sun drying treatment for 24 hours. During this period, use a high-frequency vibrating table to vibrate the mixture regularly to prevent bonding and affecting the uniformity of the modified coral sand;

[0074] (5) Take the mixture after the drying treatment and screen it with a sieve. The target coral sand with a particle size range of 0.04 mm to 1.25 mm is the obtained modified coral sand.

[0075] The present invention first modifies coral sand in view of its characteristics of being loose, porous and easy to absorb water. The principle of the modification method is to suck in cement slurry under negative pressure, which is different from ordinary soaking or granulation, so as to enhance the hardening of the cement slurry. Specifically, a negative pressure environment formed by a vacuum mixer is used to fill the pores of coral sand with a slurry prepared by mixing cement, hydrophobically modified silica fume and mixing water, and evenly wrap it on the surface of coral sand to form relatively regular spherical particles, so as to reduce the absorption of mixing water by coral sand during the mixing process and reduce the decrease in fluidity caused by the irregular shape of coral sand. Secondly, during the preparation process, by wrapping a hydrophobic neat cement film on the surface of the modified coral sand, the influence on the fluidity of the grouting material is further reduced, thereby obtaining a large fluidity state. Moreover, after the slurry is filled into the pores of coral sand, it continues to hydrate and harden, the strength of coral sand is greatly enhanced, the grading is designed, the packing is dense, and the aggregate support effect is strong, thereby obtaining high strength. In addition, through the modification of coral sand, the compactness of the matrix after the hardening of the grouting material is greatly improved, and the durability is improved.

[0076] In some embodiments, the water reducing agent is an early-strength high-performance polycarboxylate water reducing agent, and the water reducing rate is greater than 40%.

[0077] In some embodiments, the rubber powder is one or two of ethylene-vinyl acetate copolymer. After the rubber powder is dissolved in the mixing water, it forms a nano-emulsion, which can improve the microstructure of the grouting material at the nano level and improve the flexural strength of the grouting material, thereby obtaining high strength.

[0078] In some embodiments, the defoaming agent is one or two of powdered silicone defoaming agent and polyether defoaming agent. The defoaming agent can effectively reduce the entrainment of air bubbles during the preparation and mixing of high-performance cement-based grouting materials, make the grouting material more dense after hardening, and further effectively improve the strength.

[0079] In some embodiments, the active ingredient of the silicone water repellent is silane, in the form of an emulsion, and the effective content is 50%. The silicone water repellent is used to prepare hydrophobic neat cement. By preparing hydrophobic neat cement and wrapping a hydrophobic neat cement film on the surface of the modified coral sand, the influence on the fluidity of the grouting material is further reduced, thereby obtaining a large fluidity state.

[0080] In some embodiments, the main component of the plastic expansion agent is azodicarbonamide. The plastic expansion agent plays a decisive role in the vertical expansion rate of the grouting material within the first 24 hours of the ultra-early stage. Its mechanism of action is to generate nitrogen gas under alkaline conditions, and at the same time, the matrix strength is reasonable, neither allowing the gas to escape due to too low strength nor sealing the gas due to too high strength.

[0081] In some embodiments, the plastic expansion regulator comprises a setting regulating component and an expansion component, wherein the setting regulating component comprises one or more of calcium chloride, calcium formate, sodium carbonate, and sodium sulfate; and the expansion component comprises one or more of calcium oxide type, calcium sulfoaluminate type, magnesium oxide type, and calcium oxide-calcium sulfoaluminate composite type expansion agents. The present invention uses a plastic expansion regulator to keep the grouting material in a micro-expansion state at all times, effectively preventing it from shrinking and cracking, avoiding the formation of channels for harmful ions to enter the matrix, and further improving the durability of the grouting material.

[0082] It should be noted that the plastic expansion regulator used in the present invention has an early strength effect and can improve the early strength of the grouting material. In addition, the present invention has the characteristics of micro-expansion reaching the standard and the expansion process being designable, as shown in Figure 2, Figure 3 As shown, the present invention uses a plastic expansion regulator, which can reasonably adjust the synergistic relationship between the gas generated by the plastic expansion agent and the strength development of the grouting material through the setting adjustment component. Figure 2B As shown in the figure, the early plastic expansion window of the grouting material is designed so that the grouting material can retain gas within 3 hours, reach a certain strength within 3-24 hours to restrain the gas from continuing to expand, and avoid excessive vertical expansion rate in 3-24 hours, thereby achieving the early micro-expansion effect of the grouting material. On the other hand, the expansion component in the plastic expansion regulator can compensate for the shrinkage of the grouting material, and at the same time, synergize with the plastic expansion agent. On the basis of the tiny pores produced by the plastic expansion agent, the products generated by the hydration reaction cause chemical expansion, further provide micro-expansion during the hardening process, and improve the density of the grouting material base material, thereby further improving the strength. Figure 2A As shown, under the premise of large flow state, the coral sand grouting material without the technology of the present invention often has super slow setting phenomenon due to excessive use of water reducing agent and mixing water, which will cause the window period for the plastic expansion agent to exert its expansion efficiency to be delayed, which is manifested as the gas escape generated by the plastic expansion agent within 3 hours, resulting in too small vertical expansion rate. Within 3-24 hours, due to the large amount of ineffective consumption of plastic expansion agent and the shrinkage of cementitious materials, effective expansion can no longer be generated. At this time, if the amount of plastic expansion agent is increased, the 3h vertical expansion rate will not meet the standard, and the 3-24h vertical expansion rate will exceed the standard.

[0083] In some embodiments, the mixing water is one or more of seawater, desalinated seawater, fresh water, and rainwater naturally collected from the roof of island and reef buildings. In the present invention, the mixing water is obtained locally, saving the cost of transportation and raw materials.

[0084] The present invention also provides a method for preparing a high-performance cement-based grouting material based on modified coral sand, such as Figure 1 As shown, including:

[0085] (1) Put the modified coral sand, cement, ion migration inhibitor, rubber powder, silicone water repellent, and mixing water into a mixer at a mass ratio of 1:0.1:0.05:0.01:0.002:0.1;

[0086] (2) Stir at a low speed (960 - 1200 r / h) for 5 - 10 min until a dry and thick water-repellent neat cement film uniformly coats the surface of the modified coral sand;

[0087] (3) After standing for 5 - 10 min, when there is no visible free water on the surface of the coral sand particles, add the remaining raw materials and continue to stir for 3 - 5 min, among which the low-speed stirring (960 - 1200 r / h) time is 1 - 2 min, and the high-speed stirring (7200 - 12000 r / h) time is 2 - 3 min. After the materials are fully and uniformly mixed, a high-performance cement-based grouting material based on modified coral sand is obtained.

[0088] It should be noted that during the preparation process, by coating a water-repellent neat cement film on the surface of the modified coral sand, the influence on the fluidity of the grouting material is further reduced. The modified coral sand used in the present invention greatly improves the denseness of the matrix after the grouting material hardens, and the durability is improved.

[0089] Example 1

[0090] For the material prepared in this example, the mass ratio of each component is as follows: 40 parts of cement, 50 parts of modified coral sand, 10 parts of ion migration inhibitor, 0.5 part of water reducer, 0.5 part of rubber powder, 0.1 part of defoamer, 0.1 part of silicone water repellent, 0.04 part of plastic expansion agent, 3 parts of plastic expansion regulator, and 10 parts of mixing water.

[0091] The cement is composed of 80% of P·II 52.5 grade Portland cement, 10% of ferroaluminate cement, and 10% of aluminate cement; the ion migration inhibitor is composed of 40% hydrophobic modified ultra-fine high-alumina slag powder, 32% hydrophobic modified metakaolin, 27% hydrophobic modified silica fume, and 1% nano-silica; the plastic expansion regulator is composed of 33% setting adjustment component and 67% expansion component, where the setting adjustment component is composed of 50% sodium carbonate and 50% calcium formate, and the expansion component is a calcium oxide-calcium sulfoaluminate composite expansion agent.

[0092] Example 2

[0093] For the material prepared in this example, the mass ratio of each component is as follows: 30 parts of cement, 60 parts of modified coral sand, 10 parts of ion migration inhibitor, 0.4 part of water reducer, 0.4 part of rubber powder, 0.05 part of defoamer, 0.12 part of silicone water repellent, 0.02 part of plastic expansion agent, 2 parts of plastic expansion regulator, and 9 parts of mixing water.

[0094] The cement is composed of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor is composed of 40% hydrophobic modified ultra-fine high-alumina slag powder, 32% hydrophobic modified metakaolin, 27% hydrophobic modified silica fume and 1% nano-silica; the plastic expansion regulator is composed of 33% setting adjusting component and 67% expansion component, wherein the setting adjusting component is composed of 50% sodium carbonate and 50% calcium formate, and the expansion component is a calcium oxide-calcium sulfoaluminate composite expansion agent.

[0095] Example 3

[0096] For the material prepared in this embodiment, the mass ratio of each component is as follows: 50 parts of cement, 40 parts of modified coral sand, 10 parts of ion migration inhibitor, 0.7 parts of water reducing agent, 1 part of rubber powder, 0.12 parts of defoaming agent, 0.08 parts of silicone water repellent, 0.06 parts of plastic expansion agent, 4 parts of plastic expansion regulator, and 12 parts of mixing water.

[0097] The cement is composed of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor is composed of 40% hydrophobic modified ultra-fine high-alumina slag powder, 32% hydrophobic modified metakaolin, 27% hydrophobic modified silica fume and 1% nano-silica; the plastic expansion regulator is composed of 33% setting adjusting component and 67% expansion component, wherein the setting adjusting component is composed of 50% sodium carbonate and 50% calcium formate, and the expansion component is a calcium oxide-calcium sulfoaluminate composite expansion agent.

[0098] Example 4

[0099] For the material prepared in this embodiment, the mass ratio of each component is as follows: 45 parts of cement, 40 parts of modified coral sand, 15 parts of ion migration inhibitor, 0.6 parts of water reducing agent, 0.8 parts of rubber powder, 0.1 parts of defoaming agent, 0.08 parts of silicone water repellent, 0.08 parts of plastic expansion agent, 3.5 parts of plastic expansion regulator, and 11 parts of mixing water.

[0100] The cement is composed of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor is composed of 40% hydrophobic modified ultra-fine high-alumina slag powder, 32% hydrophobic modified metakaolin, 27% hydrophobic modified silica fume and 1% nano-silica; the plastic expansion regulator is composed of 33% setting adjusting component and 67% expansion component, wherein the setting adjusting component is composed of 50% sodium carbonate and 50% calcium formate, and the expansion component is a calcium oxide-calcium sulfoaluminate composite expansion agent.

[0101] Comparative Example 1

[0102] For the material prepared in this comparative example, the mass ratios of each component are as follows: 40 parts of cement, 50 parts of coral sand, 10 parts of ion migration inhibitor, 0.5 part of water reducer, 0.5 part of rubber powder, 0.1 part of defoamer, 0.2 part of silicone water repellent, 0.04 part of plastic expansion agent, 3 parts of plastic expansion regulator, and 10 parts of mixing water.

[0103] The cement consists of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor consists of 40% of hydrophobic modified ultra-fine high-alumina slag powder, 32% of hydrophobic modified metakaolin, 27% of hydrophobic modified silica fume and 1% of nano-silica; the plastic expansion regulator consists of 33% of setting adjustment component and 67% of expansion component, where the setting adjustment component consists of 50% of sodium carbonate and 50% of calcium formate, and the expansion component is a calcium oxide-calcium sulfoaluminate composite expansion agent.

[0104] The difference between this comparative example and Example 1 is that the coral sand was not modified, and the dosage of the water reducer was increased to meet the large fluidity performance.

[0105] Comparative Example 2

[0106] For the material prepared in this comparative example, the mass ratios of each component are as follows: 40 parts of cement, 50 parts of modified coral sand, 10 parts of ion migration inhibitor, 0.5 part of water reducer, 0.5 part of rubber powder, 0.1 part of defoamer, 0.2 part of silicone water repellent, 0.04 part of plastic expansion agent, 3 parts of plastic expansion regulator, and 10 parts of mixing water.

[0107] The cement consists of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor consists of 40% of hydrophobic modified ultra-fine high-alumina slag powder, 32% of hydrophobic modified metakaolin, 27% of hydrophobic modified silica fume and 1% of nano-silica; the plastic expansion regulator consists of 33% of setting adjustment component and 67% of expansion component, where the setting adjustment component consists of 50% of sodium carbonate and 50% of calcium formate, and the expansion component is a calcium oxide-calcium sulfoaluminate composite expansion agent.

[0108] The difference between this comparative example and Example 1 is that the aggregate was not coated with a hydrophobic neat cement film during mixing, and the dosage of the water reducer was increased to meet the large fluidity performance.

[0109] Comparative Example 3

[0110] For the material prepared in this example, the mass ratios of each component are as follows: 40 parts of cement, 50 parts of modified coral sand, 10 parts of ion migration inhibitor, 0.5 part of water reducer, 0.5 part of rubber powder, 0.1 part of defoamer, 0.2 part of silicone water repellent, 0.04 part of plastic expansion agent, 3 parts of plastic expansion regulator, and 10 parts of mixing water.

[0111] The cement is composed of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor is composed of 40% hydrophobic modified superfine high-alumina slag powder, 32% hydrophobic modified metakaolin, 27% hydrophobic modified silica fume and 1% nano-silica; the plastic expansion regulator is composed of 33% setting adjustment component and 67% expansion component, wherein the setting adjustment component is composed of 50% sodium carbonate and 50% calcium formate, and the expansion component is calcium oxide-calcium sulfoaluminate composite expansion agent.

[0112] The difference between this comparative example and Example 1 is only that no early strength agent is added.

[0113] Comparative Example 4

[0114] For the material prepared in this example, the mass ratio of each component is as follows: 40 parts of cement, 50 parts of modified coral sand, 10 parts of ion migration inhibitor, 0.5 part of water reducing agent, 0.5 part of rubber powder, 0.1 part of defoaming agent, 0.2 part of silicone water repellent, 0.04 part of plastic expansion agent, 3 parts of plastic expansion regulator, and 10 parts of mixing water.

[0115] The cement is composed of 80% of P·II 52.5 grade portland cement, 10% of ferroaluminate cement and 10% of aluminate cement; the ion migration inhibitor is composed of 40% hydrophobic modified superfine high-alumina slag powder, 32% hydrophobic modified metakaolin, 27% hydrophobic modified silica fume and 1% nano-silica; the plastic expansion regulator is composed of 33% setting adjustment component and 67% expansion component, wherein the setting adjustment component is composed of 50% sodium carbonate and 50% calcium formate, and the expansion component is calcium oxide-calcium sulfoaluminate composite expansion agent.

[0116] The difference between this comparative example and Example 1 is that the coral sand is not modified, the hydrophobic neat cement is not prepared during stirring, no early strength agent is added, and the dosage of the water reducing agent is increased to meet the large fluidity performance.

[0117] To verify the performance of the high-performance cement-based grouting material based on modified coral sand proposed by the present invention, the high-performance cement-based grouting material with modified coral sand of the present invention is prepared according to Figure 1 the operation steps and reference specifications shown, and the performance of the obtained grouting material is tested. The test results are shown in Table 1.

[0118] Table 1 Performance of grouting materials in each case

[0119]

[0120] Note: According to GB / T 50448-2015 "Technical Specification for Application of Cementitious Grouting Materials", the vertical expansion rate of cementitious grouting materials should meet the following requirements: the vertical expansion rate at 3 hours is 0.1% - 3.5%, and the difference between the vertical expansion rates at 24 hours and 3 hours is 0.02% - 0.50%.

[0121] As can be seen from Table 1, the high-performance cementitious grouting material based on modified coral sand proposed by the present invention has high fluidity, with the initial fluidity all above 350 and the fluidity at 30 minutes not less than 320. It has high early strength (the compressive strength at 1 day is greater than 20 MPa), and the compressive strength at 28 days can reach above 120 MPa. Its expansion performance is stable and lasting. The vertical expansion rate at 3 hours and the difference between the vertical expansion rates at 24 hours and 3 hours are ten times or even dozens of times that of the comparative example. The raw materials can be obtained locally, and it is applicable to repair and reinforcement, and high-strength protection projects.

[0122] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

[0123] Although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present invention. Certain features described in the context of a single embodiment can also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation can also be implemented separately or in any suitable sub-combination in multiple implementations.

Claims

1. A high-performance cement-based grouting material based on modified coral sand, characterized in that: The following raw materials are mixed by weight ratio: cement, 30-50 parts; modified coral sand, 40-60 parts; ion migration inhibitor, 5-15 parts; water reducer, 0.3-0.7 parts; rubber powder, 0.5-1.5 parts; defoamer, 0.05-0.15 parts; organosilicon hydrophobic agent, 0.08-0.12 parts; plastic expansion agent, 0.02-0.08 parts; plastic expansion regulator, 1.5-4.5 parts; mixing water, 9-12 parts; the ion migration inhibitor is one or more of hydrophobically modified ultrafine high-aluminum slag powder, hydrophobically modified metakaolin, hydrophobically modified silica fume, and nano-silicon dioxide; The raw material of the modified coral sand is obtained by crushing, ball milling and screening coral reef discs, with a maximum particle size of 1.25 mm, and the mass proportion of each particle size range is: 0.04 mm < particle size ≤ 0.16 mm accounts for 5-20%, 0.16 mm < particle size ≤ 0.315 mm accounts for 5-20%, 0.315 mm < particle size ≤ 0.63 mm accounts for 40-50%, and 0.63 mm < particle size ≤ 1.25 mm accounts for 30-40%; The obtained continuously graded coral sand raw material with a particle size of 0.04 mm to 1.25 mm is modified as follows: (1) Separately take cement, ion migration inhibitor and mixing water, and put the continuously graded coral sand raw material, cement, ion migration inhibitor and mixing water into a vacuum mixer in a mass ratio of 1:0.9:0.1:0.4; (2) Turn on the vacuum mixer and stir for 3 to 5 minutes with the vacuum pump turned off, stirring at a low speed of 960 to 1200 r / h for 1 to 2 minutes and at a high speed of 7200 to 12000 r / h for 2 to 3 minutes. Stop stirring when the mixture is fully mixed; (3) Turn on the vacuum pump and evacuate the device to 5% to 10% of the atmospheric pressure. Stir at a high speed of 7200 to 12000 r / h for 3 to 5 minutes. When the surface of the coral sand is fully coated by the cement slurry and relatively regular spherical particles are formed, stop stirring. (4) Take out the mixture, spread it evenly and dry it in the sun for 24 hours. During this period, use a high-frequency vibration table to vibrate the mixture regularly to prevent it from sticking and affecting the uniformity of the modified coral sand. (5) The dried mixture is screened with a sieve, and the target coral sand with a particle size range of 0.04 mm to 1.25 mm is the prepared modified coral sand.

2. The high performance cement-based grouting material according to claim 1, characterized in that: The cement is one or more of silicate cement, ordinary silicate cement, sulphoaluminate cement, ferroaluminate cement and aluminate cement.

3. The high performance cement-based grouting material according to claim 1, characterized in that: The mixing water is one or more of seawater, desalinated seawater, fresh water, and rainwater naturally collected from the roofs of island and reef buildings.

4. The high performance cement-based grouting material according to claim 1, characterized in that: The specific surface area of ​​the hydrophobically modified ultrafine high-alumina slag powder is 1000-2500m 2 / kg, Al2O3 content greater than 15%; and / or The specific surface area of ​​the hydrophobically modified metakaolin is 10000-15000m 2 / kg, Al2O3 content greater than 40%; and / or The specific surface area of ​​the hydrophobically modified silica fume is 20000-30000m 2 / kg, SiO2 content greater than 95%; and / or The specific surface area of ​​the nano silicon dioxide is 160000~200000m 2 / kg, SiO2 content is greater than 99.5%.

5. The high performance cement-based grouting material according to claim 1, characterized in that: The water reducer is an early strength high efficiency polycarboxylate water reducer with a water reduction rate greater than 40%.

6. The high performance cement-based grouting material according to claim 1, characterized in that: The rubber powder is one or both of vinyl acetate and ethylene copolymer.

7. The high performance cement-based grouting material according to claim 1, characterized in that: The defoamer is one or both of a powdered organosilicon defoamer and a polyether defoamer.

8. The high performance cement-based grouting material according to claim 1, characterized in that: The organic silicon water repellent agent has silane as an effective ingredient and is in the form of an emulsion with an effective content of 50%.

9. The high performance cement-based grouting material according to claim 1, characterized in that: The main component of the plastic expansion agent is azodicarbonamide.

10. The high performance cement-based grouting material according to claim 1, characterized in that: The plastic expansion regulator comprises a setting regulating component and an expansion component, wherein the setting regulating component comprises one or more of calcium chloride, calcium formate, sodium carbonate, and sodium sulfate, and the expansion component comprises one or more of calcium oxide type, calcium sulfoaluminate type, magnesium oxide type, and calcium oxide-calcium sulfoaluminate composite expansion agents.

11. A method for preparing the high-performance cement-based grouting material according to any one of claims 1 to 10, comprising: (1) Add modified coral sand, cement, ion migration inhibitor, rubber powder, silicone water repellent and mixing water into a mixer at a mass ratio of 1:0.1:0.05:0.01:0.002:0.1; (2) Stir at a low speed for 5 to 10 minutes until the surface of the modified coral sand is evenly coated with a layer of dry and thick hydrophobic slurry film; (3) After standing for 5 to 10 minutes, observe that there is no visible water on the surface of the coral sand particles, add the remaining raw materials and continue stirring for 3 to 5 minutes, including: low-speed stirring time for 1 to 2 minutes, and high-speed stirring time for 2 to 3 minutes. After all materials are fully and evenly mixed, the high-performance cement-based grouting material is obtained.

12. Use of the high-performance cement-based grouting material according to any one of claims 1 to 10 in island and reef construction, repair and reinforcement, and high-strength protection projects.

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