A rapid repair mortar based on desert sand interface functionalization and a preparation method thereof

Abstract

The present application relates to the technical field of building materials, and provides a rapid repair mortar based on desert sand interface functionalization and a preparation method thereof.The rapid repair mortar provided by the present application comprises cementitious materials, fine aggregate, water and additives, wherein the fine aggregate comprises mixed sand and ordinary sand, the mixed sand is obtained by compounding desert sand after grading with natural sand; and the additives comprise polymers, reinforcing fibers, admixtures, desert sand micro-fine powder interface functional material (S-AC) and salt environment controllable water release water-absorbing resin microgel (S-SAP). Through the synergistic effect of mixed sand grading reconstruction, S-AC interface functionalization and S-SAP controllable water release internal curing, the present application can simultaneously improve the workability, early strength, volume stability and salt freeze environment durability of the desert sand rapid repair mortar, thereby effectively solving the problems of salt influence, weak interface and early cracking when the desert sand is used for rapid repair materials, and having a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a rapid repair mortar based on desert sand interface functionalization and its preparation method. Background Technology

[0002] Rapid repair mortar for concrete structures is widely used for the repair of localized damage to infrastructure such as highways, bridges, airport pavements, and hydraulic structures. Its core technical requirements are to achieve early strength sufficient to restore traffic or load-bearing capacity within a short period of closure, while also possessing good workability and adhesion to the existing concrete matrix. Current industry standards typically specify clear requirements for the early strength level of repair materials, control of cosmetic defects, and time to reopen traffic, in order to meet the engineering needs of emergency repairs and rapid restoration of serviceability.

[0003] The service environment of concrete structures in Xinjiang exhibits significant multi-factor coupling characteristics. Local technical specifications categorize environmental effects into freeze-thaw environments, inland salt lake chloride environments, de-icing salt and other chloride environments, and chemical corrosion environments. They point out that chloride ion migration can induce steel reinforcement corrosion, while chemical corrosion environments are often accompanied by physical destructive effects such as salt crystallization, necessitating targeted durability design based on the environmental effect level. In actual engineering projects, repair layers typically undergo combined effects such as temperature cycling, salt solution wetting-drying cycles, and freeze-thaw cycles. Under these conditions, existing quick-repair mortars, designed primarily for "rapid setting and high early strength," are prone to durability problems such as surface peeling, powdering, and debonding at the repair layer-substrate interface, leading to reduced repair effectiveness or even failure. Therefore, relying solely on conventional quick-repair formulations is insufficient to achieve long-term stable repair performance in the salt-freeze composite environment of Xinjiang.

[0004] On the other hand, Xinjiang has a wide distribution of desertified and sandy land, with large and concentrated reserves of desert sand and aeolian sand resources, possessing significant advantages in local sourcing and resource utilization. To reduce dependence on natural river sand resources, decrease long-distance transportation costs, and improve the comprehensive utilization of regional resources, research on rapid repair mortar that partially replaces natural sand with desert sand has clear engineering value and resource significance. Existing research shows that the application of desert sand in cement-based materials needs to be combined with regional environmental characteristics, and performance controllability can be achieved through material design and modification. However, the direct use of desert sand in rapid repair mortar still faces several technical bottlenecks: its excessively fine gradation and high micropowder content, along with its clay adsorption characteristics, easily lead to increased water demand and enhanced sensitivity to admixtures, thus exacerbating the risk of early shrinkage and cracking; simultaneously, the relatively smooth surface of desert sand particles easily weakens the interfacial transition zone (ITZ) structure, increasing the fluctuation of the bonding performance between the repair layer and the substrate, thus restricting the stability and reproducibility of engineering applications.

[0005] In summary, existing repair mortars lack durability and bonding stability in the harsh salt-freeze composite environment of Xinjiang, and cannot achieve efficient resource utilization of desert sand. Summary of the Invention

[0006] In view of this, the present invention provides a rapid repair mortar based on the interface functionalization of desert sand and its preparation method. By functionalizing the interface of desert sand, the present invention improves the resource utilization level of desert sand while significantly enhancing the adaptability, durability, and repair effect of the rapid repair mortar in the typical salt-freeze composite environment of Xinjiang, providing an industrially scalable and widely applicable technical solution for related engineering applications.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A rapid repair mortar based on desert sand interface functionalization includes cementitious materials, fine aggregates, water, and additives; The cementitious material comprises the following components in parts by weight: 40-80 parts of ordinary silicate cement, 10-40 parts of sulfoaluminate cement, 5-30 parts of slag powder, 1-8 parts of microsilica, and 2-10 parts of gypsum. The fine aggregate includes mixed sand and ordinary sand; the mixed sand includes fine segments, medium-fine segments, micro-fine powder and coarse segments, the fine segments, medium-fine segments and micro-fine powder are obtained by screening desert sand; the coarse segments are natural sand; the particle size of the fine segments is 0.075~0.15mm, the particle size of the medium-fine segments is 0.15~0.3mm, the particle size of the micro-fine powder is <0.075mm, and the particle size of the coarse segments is 0.3~1.18mm; The additives include polymers, reinforcing fibers, admixtures, desert sand micropowder interface functional materials, and saline environment controlled-release water-absorbing resin microgels. The desert sand fine powder interface functional material includes desert sand fine powder, a silicon-based functional layer coated on the surface of the desert sand fine powder, and a calcined LDH shell layer coated on the surface of the silicon-based functional layer. The saline environment controlled-release water-absorbing resin microgel includes water-absorbing resin particles and a polysaccharide-inorganic composite shell coating the surface of the water-absorbing resin particles. The polysaccharide-inorganic composite shell includes calcium alginate and silica formed by silica sol condensation.

[0008] Preferably, the total mass fraction of the fine aggregate is 120-320 parts, and the mass fraction of the mixed sand in the fine aggregate is 20-60%; the fineness modulus of the mixed sand is 2.2-2.8, the mass fraction of fine powder is 2%-8%, and the bulk density is 1400-1650 kg / m³. 3 .

[0009] Preferably, the water-cement ratio of the rapid repair mortar based on desert sand interface functionalization is 0.25~0.4.

[0010] Preferably, the polymer is a redispersible latex powder, and the mass of the polymer is 0.5% to 6% of the mass of the gelling material. The reinforcing fiber is one or both of basalt fiber and PVA fiber, and the mass of the reinforcing fiber is 0.05% to 1% of the mass of the cementitious material. The admixtures include a water-reducing agent, an early-strength agent, and a setting regulator. The water-reducing agent accounts for 0.1% to 1.2% of the mass of the cementitious material; the early-strength agent accounts for 0.2% to 2.5% of the mass of the cementitious material; and the setting regulator accounts for 0.01% to 0.2% of the mass of the cementitious material. The mass of the desert sand fine powder interface functional material is 0.2% to 2% of the mass of the cementitious material; The mass of the water-absorbing resin microgel capable of controlled release in a saline environment is 0.05% to 0.4% of the mass of the gelling material.

[0011] Preferably, the preparation method of the desert sand fine powder interface functional material includes the following steps: The fine desert sand powder was mixed with water to obtain a suspension; The suspension and silica sol were mixed to form an active silica layer on the surface of the fine powder; then magnesium salt solution and aluminum salt solution were added dropwise to the system, and after the addition was completed, the system was aged to obtain a composite precursor; the pH value of the system was controlled at 10~10.5 during the addition process. The composite precursor was dried and then calcined to obtain desert sand micro-powder interface functional material.

[0012] Preferably, the solid content of the suspension is 10% to 15%; the solid content of the silica sol is 20% to 40%, and the mass of the silica sol is 2% to 8% of the mass of the suspension. The total mass of the magnesium salt solution and the aluminum salt solution is 3% to 12% of the mass of the system obtained by mixing the suspension and the silica sol. The roasting temperature is 400~450℃, and the holding time is 1~2h.

[0013] Preferably, the preparation method of the salt environment controlled-release water-absorbing resin microgel includes the following steps: The water-absorbing resin particles were immersed in an aqueous solution of sodium alginate for coating pretreatment to obtain water-absorbing resin particles coated with sodium alginate. The sodium alginate-coated water-absorbing resin particles, silica sol, and calcium salt aqueous solution were mixed and cross-linked to obtain a water-absorbing resin microgel with controlled release of water in a salt environment.

[0014] Preferably, the particle size of the water-absorbing resin particles is 0.1~1mm; the mass fraction of the sodium alginate aqueous solution is 0.5%~2%; the mass ratio of the water-absorbing resin particles to the sodium alginate aqueous solution is 1:5~1:30; and the coating pretreatment time is 5~20min. The mass fraction of the calcium salt aqueous solution is 1% to 5%; the mass ratio of the water-absorbing resin particles to the calcium salt aqueous solution is 1:5 to 1:30.

[0015] This invention also provides a method for preparing the rapid repair mortar based on desert sand interface functionalization as described above, comprising the following steps: The cementitious material, fine aggregate, water and additives are mixed to obtain the rapid repair mortar based on desert sand interface functionalization.

[0016] Preferably, the mixing includes: first mixing the polymer, reinforcing fibers and additives to obtain a premix; second mixing the cementitious material, the premix, desert sand micro-powder interface functional material and fine aggregate to obtain a dry mix; mixing the dry mix with water, and then adding a salt environment controlled-release water-absorbing resin microgel for a third mixing to obtain the rapid repair mortar based on desert sand interface functionalization. This invention provides a rapid repair mortar based on the functionalization of desert sand interfaces, comprising cementitious materials, fine aggregates, water, and additives. The cementitious materials comprise the following components by weight: 40-80 parts ordinary Portland cement, 10-40 parts sulfoaluminate cement, 5-30 parts slag powder, 1-8 parts microsilica, and 2-10 parts gypsum. The fine aggregates comprise mixed sand and ordinary sand. The mixed sand comprises fine segments, medium-fine segments, micro-fine powder, and coarse segments, wherein the fine segments, medium-fine segments, and micro-fine powder are obtained by sieving desert sand; the coarse segments are natural sand; the particle size of the fine segments is 0.075-0.15 mm, the particle size of the medium-fine segments is 0.15-0.3 mm, and the particle size of the micro-fine powder is... The coarse segment has a particle size of 0.3~1.18mm, and the additives include polymers, reinforcing fibers, admixtures, desert sand micropowder interface functional material (S-AC), and salt-environment controlled-release water-absorbing resin microgel (S-SAP). The desert sand micropowder interface functional material includes desert sand micropowder, a silicon-based functional layer coated on the surface of the desert sand micropowder, and a calcined LDH shell coated on the surface of the silicon-based functional layer. The salt-environment controlled-release water-absorbing resin microgel includes water-absorbing resin particles and a polysaccharide-inorganic composite shell coated on the surface of the water-absorbing resin particles. The polysaccharide-inorganic composite shell includes silica and calcium alginate. The beneficial effects of this invention are: 1. This invention uses desert sand grading and compounding technology to screen desert sand into different particle sizes and mix it with natural sand to form mixed sand. This can significantly improve the workability and density of mortar, reduce the problems caused by fine desert sand powder such as high water demand, sensitivity to admixtures, and large shrinkage, realize the efficient utilization of desert sand resources, reduce the consumption of natural river sand, and reduce engineering costs.

[0017] 2. This invention modifies the interface of desert sand micropowder with an active silicon layer and a calcined LDH (CLDH) shell. The resulting desert sand micropowder interface functional material can adsorb chloride ions, inhibit salt crystallization expansion, and strengthen the interface transition zone, significantly improving the interfacial bonding strength and bonding durability between the repair layer and the substrate. It maintains a high bonding retention rate under salt-freeze cycling conditions, effectively solving the problems of interface debonding and surface peeling caused by salt corrosion and freeze-thaw cycles.

[0018] 3. This invention uses a polysaccharide-inorganic composite shell formed by calcium alginate and silica to coat superabsorbent polymer (SAP) particles, thereby achieving stable water absorption and slow water release under high-salt conditions, significantly reducing early drying shrinkage of mortar, inhibiting early cracking, and improving volume stability and crack resistance.

[0019] 4. In summary, this invention, through the synergistic effect of mixed sand gradation reconstruction, desert sand fine powder interface functional materials, and water-absorbing resin microgels with controllable water release in salt environments, can effectively solve the engineering uncontrollable problems caused by soluble salts, fine clay adsorption, particle roundness, and sand source fluctuations in desert sand. It also improves the bonding stability and durability of the repair layer and the substrate interface. The resulting rapid repair mortar still has controllable setting, high early strength, low shrinkage crack resistance, low permeability, and salt-freeze peeling resistance under salt-freeze composite environment, and has broad application prospects. Detailed Implementation

[0020] This invention provides a rapid repair mortar based on desert sand interface functionalization, comprising cementitious materials, fine aggregates, water, and additives; The cementitious material comprises the following components in parts by weight: 40-80 parts of ordinary silicate cement, 10-40 parts of sulfoaluminate cement, 5-30 parts of slag powder, 1-8 parts of microsilica, and 2-10 parts of gypsum. The fine aggregate includes mixed sand and ordinary sand; the mixed sand includes fine segments, medium-fine segments, micro-fine powder and coarse segments, the fine segments, medium-fine segments and micro-fine powder are obtained by screening desert sand; the coarse segments are natural sand; the particle size of the fine segments is 0.075~0.15mm, the particle size of the medium-fine segments is 0.15~0.3mm, the particle size of the micro-fine powder is <0.075mm, and the particle size of the coarse segments is 0.3~1.18mm; The additives include polymers, reinforcing fibers, admixtures, desert sand micropowder interface functional materials, and saline environment controlled-release water-absorbing resin microgels. The desert sand fine powder interface functional material includes desert sand fine powder, a silicon-based functional layer coated on the surface of the desert sand fine powder, and a calcined LDH shell layer coated on the surface of the silicon-based functional layer. The saline environment controlled-release water-absorbing resin microgel includes water-absorbing resin particles and a polysaccharide-inorganic composite shell coating the surface of the water-absorbing resin particles. The polysaccharide-inorganic composite shell includes calcium alginate and silica formed by silica sol condensation.

[0021] Unless otherwise specified, all raw materials / components used in this invention are commercially available.

[0022] The rapid repair mortar based on desert sand interface functionalization provided by this invention includes a cementitious material. In this invention, the cementitious material comprises the following components in parts by weight: 40-80 parts of ordinary silicate cement, 10-40 parts of sulfoaluminate cement, 5-30 parts of slag powder, 1-8 parts of microsilica, and 2-10 parts of gypsum; wherein the specific parts by weight of the ordinary silicate cement can be 40, 50, 55, 60, 70, or 80 parts; the specific parts by weight of the sulfoaluminate cement can be 10, 20, 25, 30, or 40 parts; the specific parts by weight of the slag powder can be 5, 10, 15, 20, or 30 parts; the specific parts by weight of the microsilica can be 1, 3, 5, 6, 7, or 8 parts; and the specific parts by weight of the gypsum can be 2, 3, 5, 6, 7, or 8 parts.

[0023] In this invention, the average particle size of the slag powder is preferably 5-20 μm, and the average particle size of the microsilica is preferably 0.05-1 μm. This invention employs a dual-cementing system of ordinary silicate cement and sulfoaluminate cement, compounded with slag powder, microsilica, and gypsum, which enables rapid setting, improves early strength, meets the emergency repair requirements for opening roads, bridges, and other engineering projects to traffic, and simultaneously ensures 28-day strength and long-term mechanical stability.

[0024] The rapid repair mortar based on desert sand interface functionalization provided by this invention includes fine aggregate. In this invention, the fine aggregate includes mixed sand and ordinary sand; the mixed sand is obtained by mixing fine segments, medium-fine segments, micro-fine powder and coarse segments, wherein the fine segments, medium-fine segments and micro-fine powder are obtained by screening desert sand; the coarse segments are natural sand; the particle size of the fine segments is 0.075~0.15mm, the particle size of the medium-fine segments is 0.15~0.3mm, the particle size of the micro-fine powder is <0.075mm, and the particle size of the coarse segments is 0.3~1.18mm.

[0025] In this invention, the fineness modulus of the mixed sand is preferably 2.2~2.8, more preferably 2.4~2.6, specifically 2.4, 2.5 or 2.6; the mass fraction of fine powder is preferably 2%~8%, more preferably 3%~6%, specifically 4% or 5%; and the bulk density is preferably 1400~1650 kg / m³. 3 More preferably, it is 1450~1600 kg / m 3 Specifically, it can be 1500 or 1550 kg / m³ 3 .

[0026] In this invention, the preferred method for preparing the mixed sand includes: sieving dry desert sand to obtain fine, medium-fine, and micro-fine powders; using natural sand as the coarse powder; blending the fine, medium-fine, micro-fine, and coarse powders according to the target fineness modulus and bulk density to obtain the mixed sand; the moisture content of the dry desert sand is preferably ≤1%; the blending is based on the sieving results of each particle size to calculate the initial proportion, and the mass fraction of each particle size is adjusted through 1-3 rounds of trial blending to ensure that the fineness modulus, micro-fine powder content, and bulk density of the mixed sand reach the set range; the sieving and fineness modulus are tested according to the current testing methods for building sand; in this invention, the water-soluble chlorides, sulfates, and clay impurities in the desert sand or natural sand used should be controlled within the allowable range for building sand to reduce the sensitivity of admixtures and the risk of salt-freezing damage.

[0027] In this invention, based on the mass fraction of ordinary silicate cement, the total mass fraction of the fine aggregate is 120-320 parts, specifically 120, 150, 200, 250, 300, or 320 parts; the mass fraction of the mixed sand in the fine aggregate is 20-60%, specifically 30%, 40%, or 60%, with the remainder being ordinary sand; the ordinary sand can be natural sand or manufactured sand, and the natural sand can be natural river sand; the particle size of the ordinary sand is preferably 0.15-1.18 mm, more preferably 0.3-1.18 mm.

[0028] The rapid repair mortar based on desert sand interface functionalization provided by the present invention includes water, and the water-cement ratio of the rapid repair mortar based on desert sand interface functionalization is 0.25~0.4, more preferably 0.3~0.35, specifically 0.31, 0.32 or 0.33; the water-cement ratio is specifically the ratio of the mass of water to the total mass of cementitious materials.

[0029] The rapid repair mortar based on desert sand interface functionalization provided by the present invention includes additives; the additives include polymers, reinforcing fibers, admixtures, desert sand micro-powder interface functional materials, and saline environment controlled-release water-absorbing resin microgels.

[0030] In this invention, the polymer is preferably redispersible latex powder (RDP), and the mass of the polymer is preferably 0.5% to 6% of the mass of the gelling material, specifically 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5% or 6%.

[0031] In this invention, the reinforcing fiber is preferably one or both of basalt fiber and PVA fiber, and the mass of the reinforcing fiber is preferably 0.05% to 1% of the mass of the cementitious material, specifically 0.05%, 0.15%, 0.25%, 0.3%, 0.4%, 0.5% or 1%.

[0032] In this invention, the admixtures preferably include a water-reducing agent, an early-strength agent, and a setting regulator. The water-reducing agent is preferably 0.1% to 1.2% of the mass of the cementitious material, specifically 0.1%, 0.5%, 0.6%, 0.7%, 1%, or 1.2%. The early-strength agent is preferably 0.2% to 2.5% of the mass of the cementitious material, specifically 0.2%, 0.5%, 1%, 1.2%, 1.4%, 1.5%, 2%, or 2.5%. The setting regulator is preferably 0.01% to 0.2% of the mass of the cementitious material, specifically 0.01%, 0.05%, 0.1%, or 0.2%. This invention does not have special requirements on the types of water-reducing agent, early-strength agent, and setting regulator; commercially available products well-known to those skilled in the art can be used. In specific embodiments of this invention, the water-reducing agent can specifically be a polycarboxylate-based high-performance water-reducing agent, the early-strength agent can specifically be calcium formate, and the setting regulator can specifically be citric acid.

[0033] In this invention, the additive may also include air-entraining and defoaming components if necessary; this invention does not have special requirements for the air-entraining and defoaming components, and those well known to those skilled in the art can be used.

[0034] In this invention, the desert sand fine powder interface functional material includes desert sand fine powder, a silicon-based functional layer coating the surface of the desert sand fine powder, and a calcined LDH shell coating the surface of the silicon-based functional layer; the silicon-based functional layer is formed by calcining an active silicon layer and mainly exists in the form of amorphous silica and a silicon-oxygen network; the mass of the desert sand fine powder interface functional material is preferably 0.2% to 2% of the mass of the cementitious material, specifically 0.2%, 0.5%, 1%, 1.2%, 1.5%, or 2%.

[0035] In this invention, the preparation method of the desert sand fine powder interface functional material preferably includes the following steps: The fine desert sand powder was mixed with water to obtain a suspension; The suspension and silica sol were mixed to form an active silica layer on the surface of the fine powder; then magnesium salt solution and aluminum salt solution were added dropwise to the system, and after the addition was completed, the system was aged to obtain a composite precursor; the pH value of the system was controlled at 10~10.5 during the addition process. The composite precursor was dried and then calcined to obtain desert sand micro-powder interface functional material.

[0036] In this invention, the particle size of the desert sand fine powder is <0.075mm and the moisture content is ≤1%; the solid content of the suspension is preferably 10%~15%, specifically 12% or 13%; in this invention, the desert sand is preferably added to water for shear dispersion to obtain the suspension; the rotation speed of the shear dispersion is preferably 2000rpm and the time is preferably 5~8min.

[0037] In this invention, the solid content of the silica sol is preferably 20% to 40%, specifically 20%, 25%, 30%, or 40%, and the mass of the silica sol is preferably 2% to 8% of the mass of the suspension, more preferably 3% to 6%. The silica sol forms an active silica layer on the surface of the desert sand fine powder, and the mass of the active silica layer, based on the mass of SiO2, is 5% to 10% of the mass of the desert sand fine powder. The mixing temperature of the suspension and silica sol is preferably 35 to 45°C, and the mixing time is preferably 30 to 45 minutes. After mixing, the pH value of the system is preferably adjusted to 10 using ammonia water.

[0038] In this invention, the magnesium salt solution is preferably an aqueous solution of magnesium nitrate, and the aluminum salt solution is preferably an aqueous solution of aluminum nitrate; the molar ratio of Mg in the magnesium salt solution to Al in the aluminum salt solution is preferably 3:1; the total mass of the magnesium salt solution and the aluminum salt solution is preferably 3-12% of the mass of the system obtained by mixing the suspension and silica sol, more preferably 4%-8%; the magnesium salt solution and the aluminum salt solution are preferably added dropwise simultaneously, and the pH value of the system is preferably controlled at 10-10.5 during the dropwise addition process, preferably using sodium hydroxide solution to control the pH value of the system; the dropwise addition time is preferably 45-90 min; the aging time is preferably 4-8 h, through which magnesium aluminum hydrotalcite (LDH) nanosheets nucleate, grow and attach on the surface of the active silicon layer to form a composite precursor.

[0039] After aging, the present invention preferably filters the obtained slurry, washes and dries the obtained solid product to obtain a composite precursor; the drying temperature is preferably 80~90℃, and the drying time is preferably 10~16h; the calcination temperature is preferably 400~450℃, and the holding time is preferably 1~2h, and the calcination is carried out in an air atmosphere; through calcination, magnesium aluminum LDH is transformed into a calcined LDH (CLDH) shell with structural memory effect, and at the same time, silicon in the active silicon layer is transformed into amorphous silicon dioxide and silicon-oxygen network to form a silicon-based functional layer; after calcination, the present invention preferably grinds the obtained solid product to obtain the desert sand fine powder interface functional material; the ground D 50 The preferred particle size is 8-20 micrometers.

[0040] In this invention, the controlled-release water-absorbing resin microgel in a saline environment comprises water-absorbing resin particles and a polysaccharide-inorganic composite shell coating the surface of the water-absorbing resin particles. The polysaccharide-inorganic composite shell comprises calcium alginate and silica formed by the condensation of silica sol. The thickness of the polysaccharide-inorganic composite shell is preferably 1-30 micrometers. The mass of the controlled-release water-absorbing resin microgel in a saline environment is preferably 0.05%-0.4% of the mass of the cementing material, specifically 0.05%, 0.1%, 0.16%, 0.18%, 0.2%, 0.22%, 0.3%, or 0.4%.

[0041] In this invention, the preparation method of the controlled-release water-absorbing resin microgel in a salt environment preferably includes the following steps: Superabsorbent polymer (SAP) particles were immersed in an aqueous solution of sodium alginate for coating pretreatment to obtain superabsorbent polymer particles coated with sodium alginate. The sodium alginate-coated water-absorbing resin particles, silica sol, and calcium salt aqueous solution were mixed and cross-linked to obtain a water-absorbing resin microgel with controlled release of water in a salt environment.

[0042] In this invention, the particle size of the water-absorbing resin particles is preferably 0.1~1 mm, more preferably 0.2~0.6 mm; the water absorption ratio of the water-absorbing resin particles in deionized water is ≥100 g / g, and the water absorption ratio in simulated pore liquid is 10~30 g / g; this invention does not have special requirements for the source of the water-absorbing resin particles, and commercially available products can be used. The mass fraction of the sodium alginate aqueous solution is preferably 0.5%~2%, specifically 0.5%, 1% or 2%; the mass ratio of the water-absorbing resin particles to the sodium alginate aqueous solution is preferably 1:5~1:30, more preferably 1:10~1:20; the coating pretreatment time is preferably 5~20 min, specifically 10 or 15 min; this invention uses coating pretreatment to allow sodium alginate to penetrate into the SAP surface layer.

[0043] After the coating pretreatment is completed, the present invention preferably adds the water-absorbing resin particles coated with sodium alginate to a calcium salt aqueous solution after draining the liquid; the calcium salt aqueous solution is preferably a calcium nitrate aqueous solution; the mass fraction of the calcium salt aqueous solution is preferably 1% to 5%, specifically 2%, 3% or 4%; the mass ratio of the water-absorbing resin particles to the calcium salt aqueous solution is preferably 1:5 to 1:30, more preferably 1:10 to 1:20; the silica sol accounts for 0.5% to 5% of the solution mass based on solid content.

[0044] In a specific embodiment of the present invention, it is preferable to first add the water-absorbing resin particles coated with sodium alginate to the calcium salt solution, and then add the silica sol; the cross-linking and curing time is preferably 1~10 min, more preferably 2~5 min; during the cross-linking and curing process, sodium alginate and calcium ions form a calcium alginate cross-linked shell on the SAP surface, while the silica sol simultaneously gels and condenses in the system, and is incorporated in situ into the calcium alginate shell network to form a polysaccharide-inorganic composite shell.

[0045] In this invention, after cross-linking and curing, the solid product is preferably washed with clean water to remove free salt on the surface, and then dried to obtain a water-absorbing resin microgel that can release water in a salt environment; the drying temperature is preferably 40~60℃ and the drying time is preferably 6~16h.

[0046] This invention also provides a method for preparing the rapid repair mortar based on desert sand interface functionalization as described above, comprising the following steps: The cementitious material, fine aggregate, water and additives are mixed to obtain the rapid repair mortar based on desert sand interface functionalization.

[0047] In this invention, the mixing preferably includes: a first mixing of polymer, reinforcing fiber, and additives to obtain a premix; a second mixing of cementitious material, premix, desert sand micro-powder interface functional material, and fine aggregate to obtain a dry mix; mixing the dry mix with water, and then adding a salt-environment controlled-release water-absorbing resin microgel for a third mixing to obtain the rapid repair mortar based on desert sand interface functionalization; the first mixing time is preferably 1-3 minutes; the second mixing time is preferably 2 minutes; the mixing is preferably: first mixing 80% of the water with the dry mix, and then adding the remaining water to adjust to the target flowability; the mixing speed is preferably 500-1500 rpm, and the mixing time is preferably 2 minutes; the third mixing speed is preferably 50-300 rpm; the third mixing is preferably stirring for 1 minute, letting stand for 1 minute, and then stirring for 30 seconds. In this invention, the salt-environment controlled-release water-absorbing resin microgel is added later and stirred at a low speed to avoid shell breakage.

[0048] In a specific embodiment of the present invention, the rapid repair mortar based on desert sand interface functionalization is molded and cured to obtain mortar specimens. In a specific embodiment of the present invention, the molding process preferably includes surface treatment, which preferably involves removing the loose layer and roughening the surface; the curing process preferably involves film curing or curing with a curing agent to prevent early water loss; in a specific embodiment of the present invention, when the curing temperature is low, thermal insulation covering is preferred.

[0049] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] Example 1 1. Preparation of mixed sand (1) The dry desert sand (moisture content ≤1%) was sieved to obtain fine segments (0.075~0.15 mm), medium-fine segments (0.15~0.30 mm), and micro-fine powder (<0.075 mm). (2) Natural sand (0.30~1.18 mm) was selected as the source of the coarse particles. The particle sizes were blended according to the target fineness modulus and bulk density to obtain mixed sand. The initial proportions were calculated based on the sieving results of each particle size, and the mass fraction of each particle size was adjusted through two rounds of trial blending to ensure that the fineness modulus, fine powder content, and bulk density of the mixed sand reached the set range. Sieving and fineness modulus were tested according to the current testing methods for construction sand. The final mixed sand had a fineness modulus of 2.4, a fine powder content of 5 wt%, and a bulk density of 1550 kg / m³. 3 .

[0051] 2. Preparation of interfacial functional materials made from fine desert sand powder (1) Dry desert sand fine powder (particle size < 0.075 mm, moisture content 1%) was added to water and dispersed by high-speed shear (2000 rpm, 6 min) to form a suspension. The solid content of the suspension was controlled to be 12%. (2) Add silica sol (solid content of 30%) to the above suspension. The amount of silica sol added is 4% of the mass of the suspension. An active silica layer is formed on the surface of the fine powder. The mass of the active silica is 7% of the mass of the fine powder based on the SiO2 solids. That is, the mass of SiO2 finally deposited on the surface of the fine powder is about 7% of the mass of the fine powder. Add ammonia water during stirring at 40°C for 35 min. At the end of stirring, adjust the pH of the system to 10 to facilitate the stable formation of the active silica layer and provide an alkaline environment for the subsequent in-situ growth of LDH. (3) Add Mg(NO3)2 solution and Al(NO3)3 solution (Mg / Al molar ratio of 3:1) to the system obtained in step (2) simultaneously. The total amount of magnesium salt solution and aluminum salt solution added accounts for 6% of the mass of the system obtained in step (2). Adjust the pH with NaOH to maintain it at 10.0 and control the addition time to 60 min. After the addition is completed, continue aging for 6 h to allow magnesium aluminum hydrotalcite (LDH) nanosheets to nucleate and grow on the surface of the active silicon layer and attach to form a composite precursor. (4) The obtained slurry was filtered, washed with clean water, and dried at 90℃ for 12 h to obtain a dried composite powder; the composite powder was then calcined in air atmosphere (400℃ for 1 h) to convert the LDH on its surface into a CLDH structure; after calcination, it was cooled and ground to a suitable particle size (D 50 With a thickness of 10 μm, the desert sand fine powder interface functional material (S-AC) is obtained.

[0052] 3. Preparation of SAP microgels with controlled water release in saline environments (1) Select commercially available superabsorbent polymer (SAP) particles with a particle size of 0.3 mm, a water absorption ratio of 120 g / g in deionized water, and a water absorption ratio of 20 g / g in simulated pore liquid; immerse the SAP particles in a 1.0% sodium alginate aqueous solution for coating pretreatment, wherein the mass ratio of SAP to sodium alginate aqueous solution is 1:15, and the immersion time is 15 min, so that sodium alginate penetrates into the surface of SAP; (2) After the pre-treated SAP is drained, it is transferred to a 3% Ca(NO3)2 aqueous solution for ion crosslinking and curing. The mass ratio of SAP to Ca(NO3)2 aqueous solution is 1:15 and the curing time is 3 min, so that sodium alginate forms a calcium alginate crosslinked shell on the SAP surface. During the crosslinking and curing stage of Ca(NO3)2 aqueous solution, silica sol (accounting for 3% of the mass of Ca(NO3)2 aqueous solution by solid content) is added to the calcium nitrate solution system, so that the silica sol and the calcium alginate shell form a polysaccharide-inorganic composite shell. (3) After cross-linking, the surface free salts are quickly washed with water and then dried at 60°C for 12 h to obtain a salt environment controlled water release SAP microgel (S-SAP), the thickness of the coating shell is 20~30 μm.

[0053] 4. Preparation of rapid repair mortar based on desert sand interface functionalization (1) Mortar components The cementitious material is composed of the following components by weight: 55 parts ordinary Portland cement, 25 parts sulfoaluminate cement, 15 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 60% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.33; The additives consist of the following components: 3.0 parts redispersible latex powder (RDP), 0.4 parts basalt fiber, 0.70 parts water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.40 parts early strength agent (calcium formate), 0.05 parts coagulation regulator (citric acid), 1.2 parts S-AC, and 0.22 parts S-SAP.

[0054] (2) Mortar preparation The preparation method of rapid repair mortar based on desert sand interface functionalization is as follows: Redispersible latex powder (RDP), reinforcing fibers, and additives (water-reducing agent, early strength agent, and coagulation regulator) are mixed to obtain a premix. Dry mix the cementitious material, premix, S-AC, and fine aggregate for 2 minutes. Then add 80% water and stir at high speed (1000 rpm) for 2 minutes. Add the remaining water to adjust the fluidity. Finally, add S-SAP at low speed (100 rpm) and stir for 1 minute. Let it stand for 1 minute and then stir for 30 seconds.

[0055] Example 2 1. Preparation of mixed sand (1) The dry desert sand (moisture content ≤1%) was sieved to obtain fine segments (0.075~0.15 mm), medium-fine segments (0.15~0.30 mm), and micro-fine powder (<0.075 mm). (2) Natural sand (0.30~1.18 mm) was selected as the source of the coarse particles. The above particle sizes were blended according to the target fineness modulus and bulk density to obtain mixed sand. The blending was based on the sieving results of each particle size, and the mass fraction of each particle size was adjusted through two rounds of trial blending to ensure that the fineness modulus, fine powder content, and bulk density of the mixed sand reached the set range. Sieving and fineness modulus were tested according to the current testing methods for construction sand. The final mixed sand had a fineness modulus of 2.5, a fine powder content of 4 wt%, and a bulk density of 1500 kg / m³. 3 .

[0056] 2. Preparation of interfacial functional materials made from fine desert sand powder (1) Dry desert sand fine powder (particle size < 0.075 mm, moisture content 1%) was added to water and dispersed by high-speed shear (2000 rpm, 6 min) to form a suspension. The solid content of the suspension was controlled to be 12%. (2) Add silica sol (solid content of 30%) to the above suspension. The amount of silica sol added is 4% of the mass of the suspension, so that it forms an active silica layer on the surface of the fine powder. The mass of the active silica is 8% of the mass of the fine powder based on SiO2 solid. Stir at 40°C for 40 min. At the end of stirring, use ammonia water to adjust the pH of the system to 10. (3) Simultaneously add Mg(NO3)2 solution and Al(NO3)3 solution (Mg / Al molar ratio of 3:1) to the above system. The total amount of magnesium salt solution and aluminum salt solution added accounts for 6% of the mass of the system obtained in step (2). Adjust the pH with NaOH to maintain it at 10.0 and control the addition time to 60 min. After the addition is completed, continue aging for 6 h to allow magnesium aluminum hydrotalcite (LDH) nanosheets to nucleate and grow on the surface of the active silicon layer and attach to form a composite precursor. (4) The obtained slurry was filtered, washed with clean water, and dried at 90℃ for 12 h to obtain a dried composite powder; the composite powder was then calcined in air atmosphere (400℃ for 1 h) to convert the LDH on its surface into a CLDH structure; after calcination, it was cooled and ground to a suitable particle size (D 50 With a thickness of 10 μm, the desert sand fine powder interface functional material (S-AC) is obtained.

[0057] 3. Preparation of SAP microgels with controlled water release in saline environments (1) Select commercially available superabsorbent polymer (SAP) particles with a particle size of 0.3 mm, a water absorption ratio of 120 g / g in deionized water, and a water absorption ratio of 20 g / g in simulated pore liquid; immerse the SAP particles in a 1.0% sodium alginate aqueous solution for coating pretreatment, wherein the mass ratio of SAP to sodium alginate aqueous solution is 1:15, and the immersion time is 15 min, so that sodium alginate penetrates into the surface of SAP; (2) After the pre-treated SAP is drained, it is transferred to a 3% Ca(NO3)2 aqueous solution for ion crosslinking and curing. The mass ratio of SAP to Ca(NO3)2 aqueous solution is 1:15 and the curing time is 3 min, so that sodium alginate forms a calcium alginate crosslinked shell on the SAP surface. During the Ca(NO3)2 crosslinking and curing stage, silica sol (accounting for 3.0% of the mass of Ca(NO3)2 aqueous solution by solid content) is added to the system, so that the silica sol and calcium alginate shell are combined to form a polysaccharide-inorganic composite shell. (3) After cross-linking, the surface free salts are quickly washed with water and then dried at 60°C for 12 h to obtain a salt environment controlled water release SAP microgel (S-SAP), the thickness of the coating shell is 20~30 μm.

[0058] 4. Preparation of rapid repair mortar containing desert sand (1) Mortar components The cementitious material is composed of the following components by weight: 55 parts ordinary Portland cement, 25 parts sulfoaluminate cement, 15 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 40% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.32; The additives consist of the following components: 3.0 parts redispersible latex powder (RDP), 0.3 parts basalt fiber, 0.6 parts water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.2 parts early strength agent (calcium formate), 0.05 parts coagulation regulator (citric acid), 1 part S-AC, and 0.18 parts S-SAP.

[0059] (2) Mortar preparation method The preparation method is the same as in Example 1.

[0060] Example 3 1. Preparation of mixed sand (1) The dry desert sand (moisture content ≤1%) is sieved to obtain fine segments (0.075~0.15 mm), medium-fine segments (0.15~0.30 mm), and micro-fine powder (<0.075 mm). (2) Natural sand (0.30~1.18 mm) was selected as the source of the coarse particles. The above particle sizes were blended according to the target fineness modulus and bulk density to obtain mixed sand. The blending was based on the sieving results of each particle size, and the initial proportions were calculated. Two rounds of trial blending were used to iteratively adjust the mass fraction of each particle size to ensure that the fineness modulus, fine powder content, and bulk density of the mixed sand reached the set range. Sieving and fineness modulus were tested according to the current testing methods for construction sand. The final mixed sand had a fineness modulus of 2.6, a fine powder content of 4 wt%, and a bulk density of 1500 kg / m³. 3 .

[0061] 2. Preparation of interfacial functional materials made from fine desert sand powder (1) Dry desert sand fine powder (particle size < 0.075 mm, moisture content 1%) was added to water and dispersed by high-speed shear (2000 rpm, 7 min) to form a suspension. The solid content of the suspension was controlled to be 13%. (2) Add silica sol (solid content of 30%) to the above suspension. The amount of silica sol added is 5% of the mass of the suspension, so that it forms an active silica layer on the surface of the fine powder. The mass of the active silica is 8% of the mass of the fine powder based on SiO2 solid. Stir at 40°C for 40 min, and at the end of stirring, use ammonia water to adjust the pH of the system to 10. (3) Add Mg(NO3)2 solution and Al(NO3)3 solution (Mg / Al molar ratio of 3:1) to the above system simultaneously. The total amount of magnesium salt solution and aluminum salt solution added accounts for 6% of the mass of the system. Adjust the pH with NaOH to maintain it at 10.0 and control the addition time to 60 min. After the addition is completed, continue aging for 6 h to allow magnesium aluminum hydrotalcite (LDH) nanosheets to nucleate and grow on the surface of the active silicon layer and attach to form a composite precursor. (4) The obtained slurry was filtered, washed with clean water, and dried at 90℃ for 12 h to obtain a dried composite powder; the composite powder was then calcined in air atmosphere (400℃ for 1 h) to convert the LDH on its surface into a CLDH structure; after calcination, it was cooled and ground to a suitable particle size (D 50 With a thickness of 10 μm, the desert sand fine powder interface functional material (S-AC) is obtained.

[0062] 3. Preparation of SAP microgels with controlled water release in saline environments (1) Select commercially available superabsorbent polymer (SAP) particles with a particle size of 0.3 mm, a water absorption ratio of 120 g / g in deionized water, and a water absorption ratio of 20 g / g in simulated pore liquid; immerse the SAP particles in a 1.5% sodium alginate aqueous solution for coating pretreatment, wherein the mass ratio of SAP to sodium alginate aqueous solution is 1:20, and the immersion time is 20 min, so that sodium alginate penetrates into the surface of SAP; (2) After the pre-treated SAP is drained, it is transferred to a 4% Ca(NO3)2 aqueous solution for ionic crosslinking and curing. The mass ratio of SAP to Ca(NO3)2 aqueous solution is 1:15 and the curing time is 5 min, so that sodium alginate forms a calcium alginate crosslinked shell on the SAP surface. During the Ca(NO3)2 crosslinking and curing stage, silica sol (4.0% of the mass of Ca(NO3)2 aqueous solution by solid content) is added to the system, so that the silica sol and the calcium alginate shell form a polysaccharide-inorganic composite shell. (3) After cross-linking, the surface free salts are quickly washed with water and then dried at 60°C for 12 h to obtain a salt environment controlled water release SAP microgel (S-SAP), the thickness of the coating shell is 20~30 μm.

[0063] 4. Preparation of rapid repair mortar containing desert sand (1) Mortar components The composition of the cementitious material by weight is as follows: 55 parts ordinary Portland cement, 30 parts sulfoaluminate cement, 10 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 30% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.31; The additives consist of the following components: 3.0 parts redispersible latex powder (RDP), 0.25 parts basalt fiber, 0.6 parts water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.2 parts early strength agent (calcium formate), 0.05 parts coagulation regulator (citric acid), 1 part S-AC, and 0.16 parts S-SAP.

[0064] (2) Mortar preparation method The preparation method is the same as in Example 1.

[0065] Comparative Example 1 1. Preparation of mixed sand The preparation method of the mixed sand is the same as in Example 2. The fineness modulus of the mixed sand is 2.5, the content of fine powder is 4 wt%, and the bulk density is 1500 kg / m³. 3 .

[0066] 2. Preparation of rapid repair mortar (1) Mortar components The cementitious material is composed of the following components by weight: 55 parts ordinary Portland cement, 25 parts sulfoaluminate cement, 15 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 40% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.32; The additives consist of the following components: 3.0 parts redispersible latex powder (RDP), 0.3 parts basalt fiber, 0.6 parts water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.2 parts early strength agent (calcium formate), and 0.05 parts coagulation regulator (citric acid).

[0067] (2) Mortar preparation method The preparation method is the same as in Example 1, except that the addition of S-AC and S-SAP is omitted.

[0068] Comparative Example 2 1. Preparation of mixed sand The preparation method of the mixed sand is the same as in Example 2. The fineness modulus of the mixed sand is 2.5, the content of fine powder is 4 wt%, and the bulk density is 1500 kg / m³. 3 .

[0069] 2. Preparation of interfacial functional materials made from fine desert sand powder The preparation method of the desert sand micro-powder interface functional material (S-AC) is the same as that in Example 2.

[0070] 3. Preparation of rapid repair mortar (1) Mortar components The cementitious material is composed of the following components by weight: 55 parts ordinary Portland cement, 25 parts sulfoaluminate cement, 15 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 40% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.32; The additives consist of the following components: 3.0 parts of redispersible latex powder (RDP), 0.3 parts of basalt fiber, 0.6 parts of water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.2 parts of early strength agent (calcium formate), 0.05 parts of coagulation regulator (citric acid), and 1.0 parts of S-AC.

[0071] (2) Mortar preparation method The preparation method is the same as in Example 1, except that the addition of S-SAP is omitted.

[0072] Comparative Example 3 1. Preparation of mixed sand The preparation method of the mixed sand is the same as in Example 2. The fineness modulus of the mixed sand is 2.5, the content of fine powder is 4%, and the bulk density is 1500 kg / m³. 3 .

[0073] 2. Preparation of SAP microgels with controlled water release in saline environments The preparation method of the controlled-release water SAP microgel (S-SAP) in a saline environment is the same as that in Example 2.

[0074] 3. Preparation of rapid repair mortar (1) Mortar components The cementitious material is composed of the following components by weight: 55 parts ordinary Portland cement, 25 parts sulfoaluminate cement, 15 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 40% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.32; The additives consist of the following components: 3.0 parts redispersible latex powder (RDP), 0.3 parts basalt fiber, 0.6 parts water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.2 parts early strength agent (calcium formate), 0.05 parts coagulation regulator (citric acid), and 0.18 parts S-SAP.

[0075] (2) Mortar preparation method The preparation method is the same as in Example 1, except that the addition of S-AC is omitted. Comparative Example 4 1. Preparation of mixed sand The preparation method of the mixed sand is the same as in Example 2. The fineness modulus of the mixed sand is 2.5, the content of fine powder is 4 wt%, and the bulk density is 1500 kg / m³. 3 .

[0076] 2. Preparation of interfacial functional materials made from fine desert sand powder Steps (1) to (3) are the same as in Example 2, except that step (4) is changed to: filter the obtained slurry, wash it with water and dry it at 90°C for 12 h to obtain uncalcined LDH-loaded powder.

[0077] 3. Preparation of SAP microgels with controlled water release in saline environments The preparation method of the controlled-release water SAP microgel (S-SAP) in a saline environment is the same as that in Example 2.

[0078] 4. Preparation of rapid repair mortar containing desert sand (1) Mortar components The cementitious material is composed of the following components by weight: 55 parts ordinary Portland cement, 25 parts sulfoaluminate cement, 15 parts slag powder, 3 parts microsilica, and 2 parts gypsum. The total mass fraction of fine aggregate is 250 parts, of which mixed sand accounts for 40% of the mass of fine aggregate, and the remainder is natural sand with a particle size of 0.30~1.18mm; The water-cement ratio of the mortar is 0.32; The additive composition is as follows: 3.0 parts of redispersible latex powder (RDP), 0.3 parts of basalt fiber, 0.6 parts of water-reducing agent (polycarboxylate-based high-performance water-reducing agent), 1.2 parts of early strength agent (calcium formate), 0.05 parts of coagulation regulator (citric acid), 1.0 part of uncalcined LDH-supported powder, and 0.18 parts of S-SAP.

[0079] (2) Mortar preparation method The preparation method is the same as in Example 1, except that S-AC is replaced with uncalcined LDH-supported powder.

[0080] Test case The mortar was molded and cured to prepare 40 mm × 40 mm × 160 mm mortar specimens for flexural and compressive strength tests; specimens bonded to existing concrete substrates were prepared for pull-out bond tests; and standard curing was carried out at 20 ± 2℃ and relative humidity ≥ 95%.

[0081] Test items: fluidity, setting time, compressive strength at 2 h / 4 h / 1 d / 28 d, pull-out bond strength after 7 d and salt-freeze cycle, drying shrinkage at 7 d, and salt-freeze durability; the salt-freeze test uses a 3% NaCl solution as the medium, with a freezing temperature of -18±2℃ and a melting temperature of 5±2℃ as one cycle, and a total of 50 cycles are carried out.

[0082] The test results are shown in Tables 1 and 2.

[0083] Table 1. Working and mechanical performance results for each group

[0084] As shown in Table 1, the rapid repair mortars prepared in Examples 1-3 all exhibit good workability and high early strength, with compressive strength exceeding 20 MPa at 2 hours and exceeding 35 MPa at 4 hours. This indicates that the material system of the present invention can meet the requirements for early open use in rapid repair projects. Furthermore, the 7-day pull-out bond strength of Examples 1-3 is higher than that of the corresponding proportions, demonstrating that the present invention effectively improves the interfacial bonding performance between the repair layer and the substrate through desert sand gradation reconstruction and interface functionalization treatment.

[0085] Table 2 Results of volume stability and durability for each group

[0086] As shown in Table 2, the 7-day shrinkage values ​​of Examples 1-3 were significantly lower than those of Comparative Example 1, and the time to circumferential constraint cracking was significantly prolonged, indicating that the introduction of S-SAP can reduce the risk of early water loss and shrinkage cracking through internal curing. Meanwhile, the mass loss of Examples 1-3 after 50 salt-freeze cycles was significantly lower than that of Comparative Examples 1 and 3, and the adhesion retention rate after salt-freeze was higher, indicating that the interfacial functional layer formed by S-AC and the CLDH structure can effectively improve the durability and stability of the material in the salt-freeze composite environment. In particular, when Comparative Example 4 used uncalcined LDH-loaded powder instead of S-AC, its adhesion retention rate and mass loss after salt-freeze were inferior to those of the Examples, indicating that the calcination conversion of LDH into the CLDH structure plays an important role in improving interfacial stability and durability.

[0087] As can be seen from Tables 1 and 2, this invention, through the synergistic effect of mixed sand gradation reconstruction, S-AC interface functionalization treatment, and S-SAP controlled-release water internal curing, can simultaneously improve the workability, early strength, volume stability, and durability in salt-freezing environments of desert sand rapid repair mortar, thereby effectively solving the problems of salt influence, weak interface, and early cracking that exist when desert sand is used as a rapid repair material.

[0088] In summary, this invention provides a rapid repair mortar based on desert sand interface functionalization and its preparation method, systematically solving the following key problems: (1) Under the harsh salt-freeze composite environment in Xinjiang, existing quick repair materials have insufficient durability and poor bonding stability at the interface between the repair layer and the substrate; (2) The introduction of desert sand may bring adverse effects such as increased input of soluble salts and salt crystallization pressure, increased sensitivity of additives and increased risk of shrinkage cracking; (3) The characteristics of desert sand particles lead to weak interfacial transition zone structure, large dispersion of bonding performance, and difficulty in stably reproducing repair performance under different sand source conditions.

[0089] This invention improves the utilization level of desert sand resources while significantly enhancing the adaptability, durability and repair effect of rapid repair mortar in typical salt-freeze composite environments in Xinjiang, providing an industrializable and scalable technical solution for related engineering applications.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rapid repair mortar based on desert sand interface functionalization, characterized in that, Includes cementitious materials, fine aggregates, water, and additives; The cementitious material comprises the following components in parts by weight: 40-80 parts of ordinary silicate cement, 10-40 parts of sulfoaluminate cement, 5-30 parts of slag powder, 1-8 parts of microsilica, and 2-10 parts of gypsum. The fine aggregate includes mixed sand and ordinary sand; the mixed sand includes fine segments, medium-fine segments, micro-fine powder and coarse segments, the fine segments, medium-fine segments and micro-fine powder are obtained by screening desert sand; the coarse segments are natural sand; the particle size of the fine segments is 0.075~0.15mm, the particle size of the medium-fine segments is 0.15~0.3mm, the particle size of the micro-fine powder is <0.075mm, and the particle size of the coarse segments is 0.3~1.18mm; The additives include polymers, reinforcing fibers, admixtures, desert sand micropowder interface functional materials, and saline environment controlled-release water-absorbing resin microgels. The desert sand fine powder interface functional material includes desert sand fine powder, a silicon-based functional layer coated on the surface of the desert sand fine powder, and a calcined LDH shell layer coated on the surface of the silicon-based functional layer. The saline environment controlled-release water-absorbing resin microgel includes water-absorbing resin particles and a polysaccharide-inorganic composite shell coating the surface of the water-absorbing resin particles. The polysaccharide-inorganic composite shell includes calcium alginate and silica formed by silica sol condensation.

2. The rapid repair mortar based on desert sand interface functionalization according to claim 1, characterized in that, The total mass fraction of the fine aggregate is 120-320 parts, and the mass fraction of the mixed sand in the fine aggregate is 20-60%; the fineness modulus of the mixed sand is 2.2-2.8, the mass fraction of fine powder is 2%-8%, and the bulk density is 1400-1650 kg / m³. 3 .

3. The rapid repair mortar based on desert sand interface functionalization according to claim 1, characterized in that, The water-cement ratio of the rapid repair mortar based on desert sand interface functionalization is 0.25~0.

4.

4. The rapid repair mortar based on desert sand interface functionalization according to claim 1, characterized in that, The polymer is a redispersible latex powder, and the mass of the polymer is 0.5% to 6% of the mass of the gelling material. The reinforcing fiber is one or both of basalt fiber and PVA fiber, and the mass of the reinforcing fiber is 0.05% to 1% of the mass of the cementitious material. The admixtures include a water-reducing agent, an early-strength agent, and a setting regulator. The water-reducing agent accounts for 0.1% to 1.2% of the mass of the cementitious material; the early-strength agent accounts for 0.2% to 2.5% of the mass of the cementitious material; and the setting regulator accounts for 0.01% to 0.2% of the mass of the cementitious material. The mass of the desert sand fine powder interface functional material is 0.2% to 2% of the mass of the cementitious material; The mass of the water-absorbing resin microgel capable of controlled release in a saline environment is 0.05% to 0.4% of the mass of the gelling material.

5. The rapid repair mortar based on desert sand interface functionalization according to claim 1, characterized in that, The preparation method of the desert sand fine powder interface functional material includes the following steps: The fine desert sand powder was mixed with water to obtain a suspension; The suspension and silica sol were mixed to form an active silica layer on the surface of the fine powder; then magnesium salt solution and aluminum salt solution were added dropwise to the system, and after the addition was completed, the system was aged to obtain a composite precursor; the pH value of the system was controlled at 10~10.5 during the addition process. The composite precursor was dried and then calcined to obtain desert sand micro-powder interface functional material.

6. The rapid repair mortar based on desert sand interface functionalization according to claim 5, characterized in that, The solid content of the suspension is 10% to 15%; the solid content of the silica sol is 20% to 40%, and the mass of the silica sol is 2% to 8% of the mass of the suspension. The total mass of the magnesium salt solution and the aluminum salt solution is 3% to 12% of the mass of the system obtained by mixing the suspension and the silica sol. The roasting temperature is 400~450℃, and the holding time is 1~2h.

7. The rapid repair mortar based on desert sand interface functionalization according to claim 1, characterized in that, The preparation method of the controlled-release water-absorbing resin microgel in the salt environment includes the following steps: The water-absorbing resin particles were immersed in an aqueous solution of sodium alginate for coating pretreatment to obtain water-absorbing resin particles coated with sodium alginate. The sodium alginate-coated water-absorbing resin particles, silica sol, and calcium salt aqueous solution were mixed and cross-linked to obtain a water-absorbing resin microgel with controlled release of water in a salt environment.

8. The rapid repair mortar based on desert sand interface functionalization according to claim 7, characterized in that, The water-absorbing resin particles have a particle size of 0.1~1mm; the sodium alginate aqueous solution has a mass fraction of 0.5%~2%; the mass ratio of the water-absorbing resin particles to the sodium alginate aqueous solution is 1:5~1:30; and the coating pretreatment time is 5~20min. The mass fraction of the calcium salt aqueous solution is 1% to 5%; the mass ratio of the water-absorbing resin particles to the calcium salt aqueous solution is 1:5 to 1:

30.

9. The method for preparing rapid repair mortar based on desert sand interface functionalization as described in any one of claims 1 to 8, characterized in that, Includes the following steps The cementitious material, fine aggregate, water and additives are mixed to obtain the rapid repair mortar based on desert sand interface functionalization.

10. The preparation method according to claim 9, characterized in that, The mixing process includes: first mixing the polymer, reinforcing fibers, and additives to obtain a premix; second mixing the cementitious material, premix, desert sand micro-powder interface functional material, and fine aggregate to obtain a dry mix; mixing the dry mix with water, and then adding a salt-environment controlled-release water-absorbing resin microgel for a third mixing to obtain the rapid repair mortar based on desert sand interface functionalization.

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