Search

CN-121974597-A - Preparation method and application of cement shrinkage-enhancement synergistic regulation material based on bacterial cellulose hydrogel

CN121974597ACN 121974597 ACN121974597 ACN 121974597ACN-121974597-A

Abstract

A preparation method and application of a cement shrinkage-enhancement cooperative regulation and control material based on bacterial cellulose hydrogel relate to the technical field of cement-based composite materials with low water-cement ratio. The invention aims to solve the contradiction between the self-shrinkage inhibition and the deterioration of mechanical properties of the traditional internal curing material. The method comprises the steps of preparing a novel cement shrinkage-reducing material (BCH) and application of the novel cement shrinkage-reducing material (BCH) in cement, purifying and crushing bacterial cellulose synthesized by acetobacter xylinum fermentation, and preparing Bacterial Cellulose Hydrogel (BCH). Finally, mixing the BCH with cement with low water-cement ratio to realize the shrinkage reduction-enhancement cooperative regulation and control of the cement-based material. The novel shrinkage-reducing material provided by the invention has the advantages that the BCH self-assembled structure and the multi-scale pore characteristics thereof are utilized, no additional preparation means are needed, and meanwhile, the shrinkage-reducing material is insensitive to the internal environment of the cement-based material, so that the synergistic effect on internal maintenance and performance regulation is realized. The invention is applied to the field of cement-based composite materials.

Inventors

  • ZHONG JING
  • WANG XINMING
  • ZHANG YU

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260505
Application Date
20260203

Claims (10)

  1. 1. A preparation method of a cement shrinkage-enhancement cooperative regulation material based on bacterial cellulose hydrogel, which is characterized by comprising the following steps: 1) Bacterial cellulose is prepared by a biological fermentation method; 2) The bacterial cellulose prepared in the step 1) is taken for purification treatment, namely, the bacterial cellulose is soaked in sodium hydroxide solution and placed at room temperature for continuous soaking for 12-24 h, so as to prepare purified bacterial cellulose; 3) Performing neutralization treatment on the bacterial cellulose prepared in the step 2), soaking the bacterial cellulose in deionized water, and preserving the bacterial cellulose for later use; 4) And 3) taking the raw material prepared in the step 3), and carrying out high-speed shearing and crushing to prepare the cement self-shrinkage inhibiting material-bacterial cellulose hydrogel.
  2. 2. The method for preparing the cement shrinkage-enhancement cooperative regulation and control material based on the bacterial cellulose hydrogel according to claim 1, wherein the specific process of preparing the bacterial cellulose by the biological fermentation method in the step 1) is as follows: inoculating the activated acetobacter xylinum on a solid agar culture medium plate, and placing the acetobacter xylinum in a constant-temperature incubator for culture to obtain a strain with stable growth state; transferring the strain into a bioreactor for fermentation culture, uniformly spraying a liquid nutrient medium on the upper part of the reactor in the fermentation process, wherein the liquid nutrient medium comprises 30-70 g/L glucose, 3-7 g/L yeast extract, 1-3 g/L citric acid, and buffer solution consisting of 2-6 g/LNa 2 HPO 4 and 1-3 g/L KH 2 PO 4 , and fermenting and culturing the strain by 5-7 d to form a bacterial cellulose film on the surface of a solid substrate, and stripping the bacterial cellulose film to obtain bacterial cellulose.
  3. 3. The method for preparing a cement shrinkage-enhancing synergistic regulatory material based on bacterial cellulose hydrogel according to claim 1, wherein 8-10 mm thick bacterial cellulose is prepared in step 1).
  4. 4. The method for preparing the cement shrinkage-enhancement cooperative control material based on the bacterial cellulose hydrogel according to claim 1, wherein the specific process of purifying the bacterial cellulose in the step 2) is as follows: Cutting bacterial cellulose, soaking in NaOH solution at room temperature for 12h, and preparing purified bacterial cellulose, wherein the concentration of the NaOH solution is 0.1-0.5 mol/L.
  5. 5. The method for preparing the cement shrinkage-enhancement cooperative control material based on the bacterial cellulose hydrogel according to claim 1, wherein the specific process of purifying the bacterial cellulose by the neutralization treatment in the step 3) is as follows: and soaking the purified bacterial cellulose in deionized water, changing water once at intervals of 8-12 hours until the solution is neutral, and then soaking all the purified bacterial cellulose in ionized water, and storing in an environment of 10 ℃ for later use.
  6. 6. The method for preparing the cement shrinkage-enhancing synergistic regulatory material based on the bacterial cellulose hydrogel according to claim 1, wherein the specific process of the bacterial cellulose hydrogel in the step 4) is as follows: Placing the purified bacterial cellulose after the neutralization treatment in a high-speed stirring crusher, adding deionized water with the same mass, and performing high-speed shearing and crushing to obtain the cement self-shrinkage inhibition material BCH.
  7. 7. The method for preparing the cement shrinkage-enhancing synergistic regulation material based on the bacterial cellulose hydrogel according to claim 1 or 6, wherein the average particle size of the cement self-shrinkage inhibition material is 40-60 μm.
  8. 8. Use of a cement shrinkage-enhancing synergistic regulatory material based on bacterial cellulose hydrogels prepared as claimed in claim 1 for the preparation of low self-shrinkage cement-based composites.
  9. 9. The use according to claim 8, wherein the method for preparing a cement-based composite material comprises: Accurately weighing bacterial cellulose hydrogel for standby, dispersing a polycarboxylate water reducer into mixing water for standby, mixing cement, the mixing water containing the water reducer and the bacterial cellulose hydrogel to prepare a cement-based composite material, and finally pouring cement paste into a mould to prepare the BCH cement-based composite material.
  10. 10. The use according to claim 9, wherein the bacterial cellulose hydrogel accounts for 0.01% -0.05% of the mass of the cementing material of the BCH cement-based composite material, the polycarboxylate water reducer accounts for 0.06% -0.10% of the mass of the BCH cement-based composite material, and the total water cement ratio is 0.3% -0.354.

Description

Preparation method and application of cement shrinkage-enhancement synergistic regulation material based on bacterial cellulose hydrogel Technical Field The invention relates to the technical field of intelligent cement-based composite materials, in particular to preparation of a novel cement shrinkage-enhancement cooperative regulation and control material (bacterial cellulose hydrogel, BCH) and application of a cement-based material modified based on the BCH. Background Modern building materials are developed towards high strength and high toughness, and low water to gel ratio is considered as a key factor for refining pore structures and improving mechanical properties of cement-based materials. However, as the water to gel ratio decreases, the free water content of the matrix decreases during hydration of the cement, resulting in a rapid decrease in the relative humidity within the matrix, thereby increasing capillary pore pressure and promoting rapid development of self-shrinkage of the cement-based material. Meanwhile, the cement-based material has lower mechanical property in the early stage of hydration, and under the external or internal constraint condition, the shrinkage stress generated by self shrinkage increases the cracking risk, so that the erosion and expansion of external harmful ions are accelerated, and the service life of the cement-based material is reduced. Therefore, it is a key to improve the durability of cement-based materials to suppress the development of self-shrinkage. A common method of reducing self-shrinkage of cement is to incorporate an internal curing material. The commonly used internal curing material is super-absorbent polymer (SAP-adsorption polymer, shown by SAP), through its three-dimensional network and high molecular chain structure rich in hydrophilic groups, water is absorbed and swelled in the initial stage of cement stirring, and pre-absorbed water is released in the capillary pore drying stage, so that self-shrinkage caused by capillary pore acting force is reduced. While the water absorption of SAP in ultrapure water can be hundreds of times its own mass, its water absorption capacity in cement materials will drop by one to two orders of magnitude. SAP absorbs and releases water driven by solution ion osmotic pressure and humidity gradients, and is therefore extremely sensitive to the application environment. The cement-based material system is an overbased environment, and the presence of a large amount of divalent alkali metal ions (Ca 2+ ions) will significantly reduce the water absorption capacity of the SAP, even leading to its failure. Meanwhile, the SAP can leave obvious holes after releasing water in the cement matrix, so that the porosity of the matrix is increased, and the mechanical property of the cement-based material is further reduced. Therefore, development of a novel internal curing material is needed, namely higher internal curing efficiency can be realized, and meanwhile, the mechanical property of the cement-based material can be maintained or even improved, so that the shrinkage reduction-enhancement cooperative regulation and control of the cement-based material can be realized. At present, researches show that the introduction of bacterial cellulose fibers can improve the mechanical properties of cement-based materials by promoting the cement hydration process, so that the development of self-shrinkage is inhibited to a certain extent. However, bacterial cellulose adopted in the existing research is mostly prepared into particles or aerogel materials through complex processes such as freeze drying, and the preparation process has high energy consumption and high cost, so that engineering application potential of the bacterial cellulose is obviously limited. Meanwhile, related researches mainly focus on the hydrophilic property of bacterial cellulose constituent units and the influence of the hydrophilic property on cement self-shrinkage and mechanical properties, the property improvement is generally attributed to the promotion effect of nanofiber materials on cement hydration, and the self-assembled structure of bacterial cellulose and the multi-scale pore characteristics thereof have no attention to the synergistic effect of internal maintenance and property regulation. Therefore, new designs for bacterial cellulose are needed, and structural characteristics of the bacterial cellulose are fully utilized, so that a novel shrinkage-enhancement cooperative regulation and control material is developed to realize cooperative optimization of self-shrinkage inhibition and mechanical property improvement of a cement-based material with low water-cement ratio. Disclosure of Invention The invention aims to solve the contradiction problem that the traditional internal curing material reduces the self-shrinkage of the cement-based material but has deteriorated mechanical properties, and provides a novel material for realizing the synergetic reg