CN-121494408-B - Preparation method of light self-repairing concrete

Abstract

The invention discloses a preparation method of light self-repairing concrete, and relates to the technical field of concrete. The method comprises the steps of firstly, efficiently packaging a calcium nitrate solution into hollow glass beads by using a negative pressure impregnation technology, then, adopting a sol-gel method to grow a porous zeolite crystal coating on the surfaces of the beads in situ to form self-repairing filler with a core-shell-pore gradient structure, and when the beads are broken due to concrete cracking, rapidly releasing Ca2+ in the cavities and gradually dissociating along with moisture permeation in cooperation with Ca2+ adsorbed in a zeolite layer to continuously repair new microcracks. Then uniformly coating polydopamine on the surface and in the pores of a carboxymethyl cellulose hydrogel network in an in-situ oxidation polymerization mode to form a composite hydrogel with photothermal responsiveness, heating by illumination to trigger dynamic coordination bond dissociation, and simultaneously, driving rapid directional crystallization of a repair product by heat through promoting ion diffusion rate to form a compact mineralized layer. The concrete prepared by the invention has the effects of light weight and self-repairing.

Inventors

• ZOU LONGBIAO

Assignees

• 湖南雄振建材有限公司

Dates

Publication Date

20260508

Application Date

20250522

Claims (1)

1. 1. The preparation method of the light self-repairing concrete is characterized by comprising the following preparation steps of: (1) Dissolving calcium nitrate in deionized water to prepare a calcium nitrate solution with the concentration of 1.5mol/L for later use; immersing hollow glass beads with the particle size of 125 mu m and the cavity ratio of 80 percent and the shell thickness of 1.25 mu m in a calcium nitrate solution, wherein the solid-to-liquid ratio is 1:15, placing the hollow glass beads in a vacuum reaction kettle, vacuumizing to the vacuum degree of-0.095 MPa, reacting for 45min, expelling air in the cavities of the beads, slowly releasing the vacuum to normal pressure, keeping the vacuum release rate at 0.02MPa/min, enabling the calcium nitrate solution to permeate into the cavities of the beads by using the pressure difference, repeating the circulation for 3 times to improve the loading capacity, filtering to obtain the beads, drying for 12h at 60 ℃ to obtain calcium nitrate packaging beads, mixing sodium silicate, sodium aluminate and deionized water according to the silicon-aluminum mol ratio of 2.5:1:10, adding 0.5mol/L sodium hydroxide aqueous solution to adjust the pH to 11.5, stirring for 2h at the speed of 120rpm to form uniform sol, immersing the calcium nitrate packaging beads in the sol, keeping the sol at the constant temperature of 60 ℃ for 6h, enabling the sol to deposit on the surfaces of the beads, transferring the calcium nitrate packaging beads to the high pressure reaction kettle, carrying out heat treatment for 24 ℃ to generate porous crystal at the temperature of 8000 ℃ and carrying out the reaction for 4-80 h, and washing the porous zeolite crystal structure after the porous crystal is subjected to the heat recovery reaction at the temperature of 8000 ℃ for 4-80 ℃ and the porous crystal structure is washed after the porous crystal is washed and washed; (2) Dissolving sodium carboxymethyl cellulose in deionized water to prepare a sodium carboxymethyl cellulose aqueous solution with the concentration of 4wt%, mixing ferric chloride with deionized water to prepare a ferric chloride solution with the concentration of 0.2mol/L, mixing the sodium carboxymethyl cellulose solution with the ferric chloride solution according to the volume ratio of 10:1, stirring for 30min at room temperature at the stirring speed of 300rpm to form Fe & lt3+ & gt crosslinked hydrogel, standing for 12h to complete crosslinking, cutting into gel particles with the particle size of 2mm, immersing the gel particles in a tris (hydroxymethyl) aminomethane buffer solution containing 2mg/mL dopamine hydrochloride, introducing oxygen, introducing the reaction solution with the flow of 0.5L/(min & L), stirring for 24h at the temperature of 25 ℃, flushing for 3 times with deionized water after the stirring is finished, and freeze-drying for 48h at the temperature of-40 ℃ to obtain the photo-thermal response composite hydrogel; (3) The concrete comprises the following raw materials, by mass, 100 parts of P.O 42.5 cement, 20 parts of I-grade fly ash, 5 parts of silica fume, 50 parts of ceramsite with the particle size of 5-10mm serving as lightweight aggregate, 10 parts of self-repairing filler, 4 parts of composite hydrogel, 1.2 parts of polycarboxylate water reducer, 44 parts of water, dry-mixing the cement, the fly ash and the silica fume for 3min, stirring at 25rpm, adding the lightweight aggregate, the self-repairing filler and the composite hydrogel, continuously dry-mixing for 5min, stirring at 50rpm, adding the water and the water reducer, wet-mixing for 8min to be uniform, stirring at 90rpm, preparing the lightweight self-repairing concrete material, pouring into a mould, vibrating and compacting, covering a curing film, and curing for 28d under the conditions of 25 ℃ and 95% humidity, thus preparing the lightweight self-repairing concrete.

Description

Preparation method of light self-repairing concrete Technical Field The invention relates to the technical field of concrete, in particular to a preparation method of light self-repairing concrete. Background The concrete is used as an artificial building material with the greatest global consumption, and is widely applied to the engineering fields of buildings, bridges, tunnels and the like. However, in the conventional concrete, microcracks are easily generated due to factors such as load, shrinkage, temperature change and the like in the service process, and the microcracks become permeation channels of erosion media such as moisture, chloride ions and the like, so that corrosion of internal reinforcing steel bars and matrix degradation are accelerated, and the durability of the structure is seriously reduced. In order to prolong the service life of concrete, the prior art mainly surrounds crack repairing and expanding, namely firstly, a self-repairing technology based on microorganism mineralization is used for inducing calcium carbonate to deposit at a crack through pre-burying carbonic anhydrase-producing bacteria, the activity of strains of the self-repairing technology is easily inhibited by a high-alkali environment, the repairing efficiency is limited by nutrient supply and humidity conditions, secondly, a microcapsule or hollow fiber is used for packaging a repairing agent, the repairing agent is triggered and released depending on crack expansion, the compatibility of the organic repairing agent and a cement matrix is poor, a weak interface is easy to form, the mixing amount of the microcapsule is too high, the strength of the concrete is obviously reduced, thirdly, a shape memory polymer is used for assisting in repairing, and the crack is closed through the deformation restoring force of a temperature-sensitive high polymer material, but the repairing of the wide crack with the thickness of more than 0.3mm is difficult to repair due to external heat source triggering. The technology has the defects of single repairing mechanism, insufficient environmental adaptability, secondary damage risk and the like, and most schemes do not consider the light weight requirement of concrete, so that the technology is limited in application in scenes sensitive to the dead weight of materials, such as high-rise buildings, large-span bridges and the like. The development demand of light self-repairing concrete is derived from the urgent requirement of modern engineering on the multifunctional integration of materials. On one hand, the traditional concrete has high density, so that the dead weight of the structure is overlarge, the base load and the building material consumption are increased, the dead weight of the lightweight concrete can be reduced by 20% -30% by introducing lightweight aggregates such as ceramsite, hollow microsphere and the like, but the crack initiation risk is aggravated by the porous characteristic of the lightweight aggregates, on the other hand, the single self-repairing technology is difficult to cope with complex service environments, such as ocean engineering, and the crack repairing and frost heaving resisting capabilities are required to be simultaneously realized in the freeze thawing areas. Therefore, the light weight and the self-repairing function are cooperatively optimized, and the method becomes a key for breaking through the bottleneck of the prior art. The light self-repairing concrete can realize rapid filling and long-acting inhibition of cracks and maintain mechanical properties of low density and high strength through the combination of gradient structural design and intelligent response materials. Disclosure of Invention The invention aims to provide a preparation method of light self-repairing concrete, which aims to solve the problems in the prior art. In order to solve the technical problems, the invention provides a light self-repairing concrete, which is modified by self-repairing filler with a core-shell-hole structure and photo-thermal response composite hydrogel, and comprises the following preparation steps: (1) Immersing calcium nitrate encapsulated microbeads into sol, wherein the volume of the sol is 3 times of that of the microbeads, stirring the sol at a constant temperature of 60 ℃ for 6 hours, and the stirring speed is 60rpm, so that the sol is deposited on the surfaces of the microbeads, transferring the sol into a high-pressure reaction kettle, performing hydrothermal reaction at 120 ℃ for 24 hours to generate porous zeolite crystals, centrifuging and separating the porous zeolite crystals at 8000rpm after the reaction is finished for 5 minutes, washing the porous zeolite crystals with deionized water for 3 times, and drying the porous zeolite crystals at 80 ℃ for 4 hours to obtain a core-shell-pore structure self-repairing filler; (2) Mixing a carboxymethyl cellulose sodium solution and an ferric chloride solution according to a volume ratio of 10