CN-121990785-A - Viscosity modified material for maintaining uniformity of self-compacting concrete, preparation method and application

CN121990785ACN 121990785 ACN121990785 ACN 121990785ACN-121990785-A

Abstract

The invention discloses a viscosity modified material for maintaining uniformity of self-compacting concrete, a preparation method and application thereof. The material comprises fly ash, slag powder, metakaolin, cellulose ether, limestone powder, zeolite powder, an air entraining agent, a functional component A and a functional component B in parts by mass, wherein the functional component A is prepared by compounding and drying nano silica fume, modified carbon nanotubes subjected to ultrasonic dispersion of sodium dodecyl benzene sulfonate/absolute ethyl alcohol and tungsten disulfide subjected to activation-silanization-polycarboxylic acid modification treatment, and the functional component B is obtained by uniformly shearing and mixing magnesium oxide and a calcareous expanding agent at a high speed. The material can improve viscosity, delay segregation and bleeding and reduce water sensitivity under the condition of not obviously improving yield stress, and simultaneously promote early strength development, improve volume stability and improve durability such as chloride ion permeation resistance, thereby ensuring uniformity and quality consistency of the component after pouring and hardening.

Inventors

WANG HAO
SHAO YU
ZHANG YU
SONG LANPING
ZHANG YUNLONG
ZHANG LIN
GUO YONGZHI
ZHANG QINGTAO
GUO BAOLIN
Xu Kunmiao
WANG YI
WANG WEI
JIANG RUISHUANG
WANG XIAORAN

Assignees

山东高速股份有限公司
山东省交通科学研究院

Dates

Publication Date: 20260508
Application Date: 20260213

Claims (10)

1. The viscosity modifying material for maintaining the homogeneity of the self-compacting concrete is characterized by comprising, by mass, 20-30 parts of fly ash, 18-22 parts of slag powder, 15-25 parts of metakaolin, 0.1-0.3 part of cellulose ether, 11-18 parts of limestone powder, 8-11 parts of zeolite powder, 0.1-0.3 part of air entraining agent, 5-8 parts of functional component A and 3-10 parts of functional component B.
2. The viscosity-modified material for maintaining homogeneity of self-compacting concrete according to claim 1, wherein the functional component a is a mixture of nano silica fume, modified carbon nanotubes and modified tungsten disulfide in a mass ratio of 3-4:1-2:1-2.
3. The viscosity modifying material for maintaining homogeneity of self-compacting concrete according to claim 2, wherein said functional component a is prepared by: s11, preparing a modified carbon nano tube: Respectively weighing sodium dodecyl benzene sulfonate and absolute ethyl alcohol dehydrated for 24-28h by using a 3A molecular sieve according to the mass ratio of 0.006-0.01:10-15, and dissolving the sodium dodecyl benzene sulfonate in the absolute ethyl alcohol to form a dispersion liquid; adding the weighed carbon nano tube into the dispersion liquid, modifying the carbon nano tube dispersion liquid by adopting a probe type ultrasonic processor, and performing ultrasonic power of 400-450W and ultrasonic time of 25-45min to obtain modified carbon nano tube-absolute ethyl alcohol dispersion liquid; S12, preparing modified tungsten disulfide: s121, respectively weighing tungsten disulfide powder and deionized water according to the mass ratio of 0.005-0.02:10-15, adding the tungsten disulfide powder into the deionized water, mechanically stirring for 5-10min, adding hydrogen peroxide solution, controlling the concentration of hydrogen peroxide in a system to be 0.5-2.0 wt%, stirring and reacting for 30-40min at 25-40 ℃, centrifuging, washing, re-suspending with absolute ethyl alcohol and centrifuging for 2-3 times to obtain tungsten disulfide-ethanol wet slurry; S122, mixing ethanol and deionized water according to the mass ratio of 80-85:20-25, regulating the pH value to be 4-5 by glacial acetic acid, stirring for 15-30min, adding tungsten disulfide-ethanol wet slurry and silane coupling agent, stirring and reacting for 1-3h at 40-60 ℃, centrifuging and washing to obtain silanized tungsten disulfide-ethanol wet slurry; S123, re-suspending the silanized tungsten disulfide-ethanol wet slurry with absolute ethanol to form a stirrable slurry, adding a polycarboxylate water reducer, and stirring for 30-60min to obtain a modified tungsten disulfide-absolute ethanol dispersion; S13, pre-dispersing nano silica fume, namely adding the weighed nano silica fume into dehydrated absolute ethyl alcohol, and mechanically stirring for 5-10 min to form nano silica fume pre-dispersed slurry; S14, preparing a functional material A, namely mixing the modified tungsten disulfide-absolute ethyl alcohol dispersion liquid with the modified carbon nano tube-absolute ethyl alcohol dispersion liquid, mechanically stirring for 5-10min for premixing, continuously adding the nano silica fume pre-dispersion slurry, performing ultrasonic treatment for 35-40min under 400-450W power to obtain the silica fume-modified carbon nano tube-modified tungsten disulfide dispersion liquid, and then placing the dispersion liquid in a slightly vacuum blast oven, drying at 65-70 ℃ for 1-2h, and then drying at 75-85 ℃ for 2-3h to obtain the functional material A.
4. The viscosity modifying material for maintaining homogeneity of self-compacting concrete according to claim 3, wherein in step S122, the mass ratio of the wet slurry of tungsten disulfide and ethanol to the silane coupling agent is 1:1-4, in step S123, the mass ratio of the wet slurry of polycarboxylate water reducer and silanized tungsten disulfide and ethanol is 1-6:1, and in step S14, the vacuum degree of the blast oven is-0.02 to-0.05 MPa.
5. The viscosity modifying material for maintaining homogeneity of self-compacting concrete according to claim 1, wherein the functional component B is a mixture of magnesium oxide and a calcareous expanding agent in a mass ratio of 1-2.5:3-5.
6. The viscosity modifying material for maintaining homogeneity of self-compacting concrete of claim 5, wherein said functional component B is prepared by: And respectively weighing magnesium oxide and a calcium expanding agent according to the parts by mass, and uniformly mixing and stirring by adopting a stepless speed change shearing stirrer to obtain the functional component B, wherein the angular speed of the stepless speed change shearing stirrer is 1000-1200r/min, and the linear speed is 10-15m/s, so that the uniform mixing of powder particles is realized by utilizing the generated high-speed shearing stirring force, and the original structure of raw materials is destroyed to the minimum extent.
7. The viscosity-modified material for maintaining the homogeneity of self-compacting concrete according to claim 1, wherein the fly ash has an average particle size of <5 μm, a maximum particle size of <20 μm, a density of <2.6g/cm 3 , a loss on ignition of less than 1.5%, the slag powder has an average particle size of <5 μm, a maximum particle size of <20 μm, a density of not less than 2.88g/cm 3 , a specific surface area of not less than 420m 2 /kg, the metakaolin has an average particle size of <3 μm, a maximum particle size of not less than 8 μm, the limestone powder has a calcium carbonate content of not less than 85%, a methylene blue value of not more than 0.5g/kg, and a fineness of 800 to 1250 mesh.
8. A viscosity modifying material for maintaining the homogeneity of self-compacting concrete as set forth in claim 1 wherein said cellulose ether is further defined as sodium carboxymethylcellulose, having a ph in the range of from 5 to 9 and a viscosity in the range of from 300 to 600 mPa-S and said air entraining agent is further defined as a saponin-based air entraining agent.
9. A method of preparing a viscosity modifying material that maintains homogeneity of self-compacting concrete, for preparing a viscosity modifying material that maintains homogeneity of self-compacting concrete as defined in any one of claims 1-8, comprising the steps of: and respectively weighing the fly ash, the slag powder, the metakaolin, the cellulose ether, the limestone powder, the zeolite powder, the air entraining agent, the functional component A and the functional component B according to the mass parts, and uniformly mixing and stirring by adopting a stepless speed change shearing mixer to obtain the viscosity modified material for keeping the homogeneity of the self-compacting concrete, wherein the angular speed of the stepless speed change shearing mixer is 1000-1200r/min, and the linear speed is 10-15m/s.
10. Use of a viscosity modifying material according to any one of claims 1 to 8 in the field of concrete preparation to maintain the homogeneity of self-compacting concrete.

Description

Viscosity modified material for maintaining uniformity of self-compacting concrete, preparation method and application Technical Field The invention relates to the technical field of concrete slurry preparation, in particular to a viscosity modified material for maintaining the uniformity of self-compacting concrete, a preparation method and application thereof. Background The self-compacting concrete is a high-performance concrete which can realize flowing, filling and self-compacting by means of self gravity, and is particularly suitable for pouring components with dense reinforcement, complex structure or difficult vibration. The existing self-compacting concrete generally obtains high fluidity by improving the slurry volume, optimizing the aggregate gradation and matching with a high-efficiency water reducing agent so as to fully fill the gaps between the corners of the template and the reinforcing steel bars. However, compared with the common vibrating concrete, the self-compacting concrete is in a higher flowing state, the relative movement between the slurry and the aggregate is more obvious, the aggregate sedimentation and the slurry floating are more easy to occur, and segregation, bleeding, local aggregate enrichment or slurry enrichment and other phenomena are caused, so that the hardened concrete has obvious unevenness along the height direction or local area. The non-uniformity not only can cause spatial fluctuation of strength and elastic modulus, but also can lead to uneven distribution of interface transition areas and pore structures, and influence the overall reliability and service life of the structure. To inhibit segregation and bleeding and maintain blend stability, the prior art has generally incorporated viscosity modifying materials or increased the total amount of cementitious materials to retard particle delamination by increasing slurry cohesiveness and structural retention. However, the technical path often has two limitations, namely that firstly, the traditional viscosity modification material is stable by thickening water phase or improving static yield stress, the problem of water sensitivity rise is easily brought, the sensitivity to water-gel ratio, additive mixing amount and environmental condition is more caused under the same target fluidity, the risks of slump expansion attenuation, pumping resistance increase or mixture instability and the like are easily caused after on-site fluctuation amplification, secondly, the consumption of the cementing material is improved to ensure self-compaction performance, the early hydration heat release and self-shrinkage risks of the system are obviously increased, and meanwhile, under the condition that a microstructure is not fully optimized, the early strength is insufficient, the cracking tendency is increased and the anti-permeability and anti-chloride ion invasion capacity is still possibly insufficient due to slurry water-rich area, segregation channel or interface defects. Especially under the condition of high flow, if slurry cohesiveness is obtained mainly by increasing yield stress, the flow retention and filling capability is often sacrificed, so that the stability and fluidity are difficult to be compatible, and if the viscosity is increased by filling with mineral admixture or fine powder, the stability effect is easy to generate obvious fluctuation under different water-gel ratios and different additive systems, and the comprehensive requirements of low segregation, low shrinkage, early strength and durability are difficult to be simultaneously met. Therefore, there is a need for a self-compacting concrete-oriented viscosity modifying material and a matched functional component system thereof, which can effectively improve viscosity and delay segregation occurrence time under the condition of not obviously improving static yield stress and dynamic yield stress of slurry, thereby reducing water sensitivity and improving cohesive and homogeneous retention capacity in a pouring process, and meanwhile, the self-compacting concrete-oriented viscosity modifying material also needs to have the advantages of reducing early strength development and microstructure densification, reducing shrinkage cracking risk and improving durability such as chloride ion permeation resistance, so as to meet the requirements of structural quality consistency and long-term service reliability under the condition of no vibration construction of complex components. Object of the Invention In order to overcome the defects in the prior art, the invention aims to provide a viscosity modification material for maintaining the uniformity of self-compacting concrete, a preparation method and application. The material comprises fly ash, slag powder, metakaolin, cellulose ether, limestone powder, zeolite powder, an air entraining agent, a functional component A and a functional component B in parts by mass, wherein the functional component A is prepared by