CN-121974607-A - Alkali-activated slag cementing material and preparation method thereof

CN121974607ACN 121974607 ACN121974607 ACN 121974607ACN-121974607-A

Abstract

The invention provides an alkali-activated slag cementing material and a preparation method thereof. According to the preparation method of the alkali-activated slag cementing material, the nanocellulose (CNF) is introduced into the alkali-activated metakaolin cementing material, so that the compressive strength and toughness of the material can be improved by inhibiting microcrack expansion caused by stress concentration, and the C-S-H seed crystal can serve as a hydration product nucleation site to accelerate the hydration reaction process and promote uniform growth of compact C-S-H gel, so that the pore structure is optimized and the strength is improved. There is complementarity of CNF with C-S-H seed crystals in enhancing the modification mechanism. The CNF can improve toughness through the physical bridging effect of the nanofiber, and the C-S-H seed crystal can optimize compactness through chemical regulation and control of hydration process, so that the alkali-activated slag cementing material is enhanced and modified.

Inventors

DUAN PING
OuYang Fuchang
CHENG JIAXIN
YANG JIAHAO
HAO ZIHAN
ZHENG HONGXIA
WANG WEI
LI BINGQIAN
WANG ZIMING
XU XI
MENG LINHUI

Assignees

中国地质大学（武汉）

Dates

Publication Date: 20260505
Application Date: 20260204

Claims (10)

1. The preparation method of the alkali-activated slag cementing material is characterized by comprising the following steps of: Mixing nanocellulose, C-S-H seed crystal, alkali excitant and water to obtain dispersion liquid; Mixing the dispersion liquid with slag, adding a water reducing agent, and stirring to obtain geopolymer slurry; Curing the geopolymer slurry after curing to obtain the alkali-activated slag cementing material.
2. The method for producing alkali-activated slag cement according to claim 1, wherein the alkali-activated agent comprises sodium silicate and sodium hydroxide.
3. The method for preparing the alkali-activated slag cementing material according to claim 1, wherein the mass ratio of the nanocellulose, the C-S-H seed crystal, the alkali-activated agent, the water, the slag and the water reducer is (0.01-2): 39.38: (30-32): (100-110): (1-1.2).
4. The method for preparing alkali-activated slag cementing material according to claim 1, wherein the mass ratio of the nanocellulose, the C-S-H seed crystal, the alkali-activated agent, the water, the slag and the water reducer is 0.5:1.5:39.38:30:100:1.
5. The method for preparing alkali-activated slag cementing material according to claim 2, wherein the mass ratio of the water glass to the sodium hydroxide is 100 (8-9).
6. The method for producing alkali-activated slag cement according to claim 5, wherein the mass ratio of the water glass to the sodium hydroxide is 100:8.84, and the modulus of the alkali-activated agent is 1.5.
7. The method for preparing alkali-activated slag cement according to claim 1, wherein the method for preparing nanocellulose comprises the steps of: S1, adding bamboo fiber powder into an NaOH solution, stirring for 18-20 hours at 80-90 ℃, filtering, and washing to obtain alkali-treated bamboo fiber powder, wherein the mass concentration of the NaOH solution is 5-6%, and the mass volume ratio of the bamboo fiber powder to the NaOH solution is 1g (5-10) mL; S2, placing the bamboo fiber powder subjected to alkali treatment into a bleaching solution, bleaching for 8-16 hours at 70-80 ℃, filtering, and washing to obtain bleached bamboo fiber powder, wherein the preparation method of the bleaching solution comprises the steps of adding H 2 O 2 , magnesium sulfate and tetraacetylethylene diamine into water, and then adjusting the pH value to 10-11 to obtain the bleaching solution, wherein the mass fraction of H 2 O 2 in the bleaching solution is 5-6%, the mass fraction of magnesium sulfate is 0.04-0.05%, the mass fraction of tetraacetylethylene diamine is 0.05-0.06%, and the mass-volume ratio of the bamboo fiber powder subjected to alkali treatment to the bleaching solution is 1g (5-10) mL; s3, placing the bleached bamboo fiber powder in an H 2 SO 4 solution, stirring and hydrolyzing at 40-50 ℃ for 60-70 min, and adding water into the H 2 SO 4 solution after the hydrolysis is finished to obtain a diluted solution, centrifuging the diluted solution, removing an acidic supernatant, and adding water to obtain a solution containing cellulose, wherein the mass fraction of the H 2 SO 4 solution is 60-65%, and the mass-volume ratio of the bleached bamboo fiber powder to the H 2 SO 4 solution is 1g (8-10) mL; And (3) placing the solution containing cellulose into a dialysis bag, immersing the dialysis bag into a dialysis tank through which water flows for dialysis until the solution in the dialysis bag is neutral, centrifuging, and freeze-drying to obtain the nanocellulose.
8. The method for preparing alkali-activated slag cement according to claim 1, wherein the geopolymer slurry is placed in a mold, cured at 20-25 ℃ for 24-34 hours, and then cured to obtain the alkali-activated slag cement.
9. The method for preparing alkali-activated slag cement according to claim 1, wherein the curing is performed for 24 to 34 hours at 20 to 25 ℃, and then the curing is performed at 20 to 25 ℃, with a relative humidity of 95 to 99% and a curing time of 1 to 28d.
10. An alkali-activated slag cement, characterized in that the cement is prepared by the preparation method according to any one of claims 1 to 9.

Description

Alkali-activated slag cementing material and preparation method thereof Technical Field The invention relates to the technical field of building materials, in particular to an alkali-activated slag cementing material and a preparation method thereof. Background Among the numerous alkali-activated cementitious materials, alkali-activated slag cementitious materials are a new focus of research due to their wide sources of materials, low cost, and excellent properties. Slag is an industrial solid waste, and its high yield and low resource utilization rate make it a huge pressure on the environment. The alkali-activated slag cement not only can effectively digest the wastes, but also can convert the wastes into a green building material with excellent properties. Although alkali-activated slag cement is a novel green building material, its practical application and popularization are still relatively limited. The main reason is that the volume stability is poor (shrinkage is large), and the remarkable shrinkage characteristic can also lead to the reduction of mechanical properties of the material in the later period, which brings about great uncertainty in practical engineering application. Therefore, the development of the modification research of the alkali-activated slag cementing material has important significance. At present, the research on reinforcing modification of alkali-activated slag cementing materials is focused on composite modification of single materials or similar materials, and the research on synergistic modification of different types of reinforcing materials is limited. At present, researchers introduce CNF into alkali-activated metakaolin cementing materials, and find that the CNF can improve the compressive strength and toughness of the materials by inhibiting the microcrack expansion caused by stress concentration. However, when CNF modification is used singly, the comprehensive improvement of mechanical properties and compactness of the cementing material cannot be realized. Disclosure of Invention The invention aims to solve the problems of large accumulation of solid wastes and lower mechanical property of the later alkali-activated slag cementing material, so that the preparation method of the alkali-activated slag cementing material is capable of improving the compressive strength and toughness of the material by inhibiting the expansion caused by stress concentration, on one hand, fully utilizing solid wastes such as slag and the like to relieve the environmental huge pressure generated by accumulation of industrial solid wastes, on the other hand, the prepared large material can be used for various projects to enable the large material to have better mechanical property, so that a large amount of wastes are consumed, the energy consumption is reduced, the burden of industrial solid waste discharge on the environment is reduced, good economic benefit and social benefit are achieved. In order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, the invention provides a method for preparing alkali-activated slag cement, comprising the following steps: Mixing nanocellulose, C-S-H seed crystal, alkali excitant and water to obtain dispersion liquid; Mixing the dispersion liquid with slag, adding a water reducing agent, and stirring to obtain geopolymer slurry; Curing the geopolymer slurry after curing to obtain the alkali-activated slag cementing material. Preferably, the alkali-activator comprises water glass and sodium hydroxide. Preferably, the mass ratio of the nanocellulose, the C-S-H seed crystal, the alkali excitant, the water, the slag and the water reducer is (0.01-2): 39.38: (30-32): (100-110): (1-1.2). Preferably, the mass ratio of the nanocellulose, the C-S-H seed crystal, the alkali-exciting agent, the water, the slag and the water reducer is 0.5:1.5:39.38:30:100:1. Preferably, the mass ratio of the water glass to the sodium hydroxide is 100 (8-9). Preferably, the mass ratio of the sodium silicate to the sodium hydroxide is 100:8.84, and the modulus of the alkali-activator is 1.5. Preferably, the preparation method of the nanocellulose comprises the following steps: S1, adding bamboo fiber powder into an NaOH solution, stirring for 18-20 hours at 80-90 ℃, filtering, and washing to obtain alkali-treated bamboo fiber powder, wherein the mass concentration of the NaOH solution is 5-6%, and the mass volume ratio of the bamboo fiber powder to the NaOH solution is 1g (5-10) mL; S2, placing the bamboo fiber powder subjected to alkali treatment into a bleaching solution, bleaching for 8-16 hours at 70-80 ℃, filtering, and washing to obtain bleached bamboo fiber powder, wherein the preparation method of the bleaching solution comprises the steps of adding H 2O2, magnesium sulfate and tetraacetylethylene diamine into water, and then adjusting the pH value to 10-11 to obtain the bleaching solution, wherein the mass fraction of