CN-122010491-A - Degradable green high-performance concrete and preparation method thereof

CN122010491ACN 122010491 ACN122010491 ACN 122010491ACN-122010491-A

Abstract

The application belongs to the technical field of building materials, and particularly discloses degradable green high-performance concrete and a preparation method thereof, aiming at solving the problems of insufficient strength and durability, uncontrollable degradation rate and poor working performance of the existing degradable concrete. The concrete consists of Portland cement, blast furnace slag micropowder, fly ash, modified bio-based polymer particles, natural and regenerated aggregate, nano silicon dioxide, cellulose ether, polycarboxylic acid water reducer and pH responsive degradation accelerator, and the preparation method comprises the steps of mechanically activating and pickling the regenerated aggregate, coating the surface of the polymer particles, premixing dry powder, introducing the polymer by wet stirring, mixing the aggregate, and carbonizing and curing. By adopting the technical scheme, the application can realize high performance with 28-day compressive strength of over 50 megapascals, chloride ion diffusion coefficient as low as 3 multiplied by 10 < -12 > square meters per second, and the loss rate of 180 natural gift quantity in an acidic environment is more than 50%, and the degradation is controllable and environment-friendly.

Inventors

ZOU JIAWEI
Li Linqu
GAO PENG
ZHAO BINKAI
DU HUI
CHU ZHULEI
XU HUI

Assignees

高晓庆

Dates

Publication Date: 20260512
Application Date: 20260203

Claims (10)

1. The degradable green high-performance concrete and the preparation method thereof are characterized by comprising the following specific steps of 1, preparing 30 to 50 parts of Portland cement, 15 to 25 parts of blast furnace slag micropowder, 10 to 20 parts of fly ash, 5 to 15 parts of modified bio-based polymer particles, 40 to 60 parts of natural aggregate, 20 to 30 parts of recycled aggregate, 2 to 5 parts of nano silica, 0.1 to 0.5 part of cellulose ether, 0.5 to 1.5 parts of polycarboxylic acid water reducer and 1 to 3 parts of pH responsive degradation accelerator according to parts by weight; mechanically activating and pickling the regenerated aggregate to remove surface attachments and improve the surface roughness and activity of the regenerated aggregate, carrying out surface coating treatment on the modified bio-based polymer particles to form a slow release layer with the thickness of 1-5 microns, step 2, premixing dry powder materials, putting the Portland cement, the blast furnace slag micropowder, the fly ash, the nano silica and the cellulose ether into a forced stirrer, dry stirring for 3-5 minutes at the rotating speed of 30-50 revolutions per minute to ensure uniform dispersion of each component, step 3, wet stirring and polymer introduction, slowly adding 70-80% of water of the total water into the dry powder mixture obtained in step 2, simultaneously adding the polycarboxylic acid water reducer, starting the stirrer, stirring for 2-4 minutes at the rotating speed of 60-80 revolutions per minute, subsequently, adding the modified bio-based polymer particles and the pH responsive degradation accelerator in batches, continuing stirring for 3-5 minutes to form uniform slurry, step 4, adding the pretreated natural aggregate and the regenerated aggregate into the slurry obtained in step 3, adding the residual water into the slurry obtained in the step 3, stirring for 100-80 revolutions per minute, the method comprises the steps of continuously stirring for 5 to 8 minutes until a concrete mixture with good workability and no segregation and bleeding phenomenon is obtained, molding and curing, namely, injecting the concrete mixture into a mold, vibrating the concrete mixture for 30 to 60 seconds by adopting a vibrating table with the frequency of 50 Hz and the amplitude of 0.5 mm, then placing a molded test piece into a standard curing chamber with the temperature of 20+/-2 ℃ and the relative humidity of more than or equal to 95% for curing for 24 to 48 hours, transferring the test piece into a carbonization curing box with the temperature of 60 ℃ and the carbon dioxide concentration of 20% for accelerated carbonization curing for 7 to 14 days after demolding, and finally obtaining the degradable green high-performance concrete, wherein the compressive strength of the concrete reaches more than 50 megapascals in 28 days under the standard curing condition, the flexural strength reaches more than 5 megapascals, and the chloride ion diffusion coefficient is 3 times 10 and minus 12 square meters per second.
2. The degradable green high-performance concrete and the preparation method thereof according to claim 1, wherein the modified bio-based polymer particles are a blend of polylactic acid and polyhydroxyalkanoate, wherein the mass ratio of the polylactic acid is 60-80%, the mass ratio of the polyhydroxyalkanoate is 20-40%, the particle size distribution of the particles is 0.1-1.0 mm, and a surface-coated slow-release layer is formed by compounding polycaprolactone and calcium stearate according to a mass ratio of 8-2.
3. The degradable green high-performance concrete and the preparation method thereof according to claim 1, wherein the pH-responsive degradation accelerator is solid particles of which the mass ratio of citric acid to sodium bicarbonate is 1.5 and the particle size ranges from 0.05 mm to 0.2 mm, and the accelerator starts to release carbon dioxide gas and generate organic acid radical ions when the pH value of the environment is lower than 6.5.
4. The degradable green high-performance concrete and the preparation method thereof according to claim 1, wherein the mechanical activation treatment of the recycled aggregate adopts a vertical impact crusher, the treatment time is 5-10 minutes, the impact speed is 40 m/s, the pickling treatment adopts a hydrochloric acid solution with the concentration of 5%, the soaking time is 30 minutes, and then the recycled aggregate is washed to be neutral by clean water and dried.
5. The degradable green high-performance concrete and the preparation method thereof according to claim 1 are characterized in that the clearance between the stirring blades of the forced stirrer and the lining plate in the step 2 is 3 mm, and the temperature of materials is controlled between 15 ℃ and 35 ℃ in the dry mixing process.
6. The degradable green high-performance concrete and the preparation method thereof according to claim 1 are characterized in that in the step 3, water is added in an atomization spraying mode, the particle size of water drops is smaller than 100 microns, the solid content of the polycarboxylic acid water reducer is 40%, and the water reduction rate is greater than or equal to 30%.
7. The degradable green high-performance concrete and the preparation method thereof according to claim 1 are characterized in that the natural aggregate is continuous graded broken stone with the maximum grain diameter not more than 20 mm and the crushing index less than or equal to 10%, the recycled aggregate is obtained by crushing and screening construction waste concrete, the grain diameter is 5mm to 15 mm, and the water absorption is controlled within 5%.
8. The degradable green high-performance concrete and the preparation method thereof according to claim 1 are characterized in that a gas circulation system is arranged in the carbonization curing box, the concentration distribution of carbon dioxide is ensured to be uniform, the fluctuation range is not more than +/-2%, the compressive strength of a test piece is monitored every 24 hours in the curing process, and carbonization curing is finished in advance when the strength reaches 80% of the design strength in 7 days.
9. The degradable green high-performance concrete and the preparation method thereof according to claim 1, wherein the slump of the concrete mixture is controlled to be between 180 and 220 mm, the expansion is more than or equal to 500 mm, and the slump loss after 2 hours is less than 30 mm.
10. The degradable green high-performance concrete and the preparation method thereof according to claim 1, wherein the preparation method further comprises monitoring the degradation process, monitoring the pH value change and the volume strain in the concrete in real time through a pH sensor and a strain gauge pre-embedded in the concrete, and judging that the degradation process is started when the pH value is continuously lower than 6.5 and the volume expansion rate exceeds 0.1 percent.

Description

Degradable green high-performance concrete and preparation method thereof Technical Field The invention belongs to the technical field of building materials, and particularly relates to degradable green high-performance concrete and a preparation method thereof. Background With the deep advancement of the global sustainable development strategy, the development of green building materials has become an important direction in the civil engineering field. The concrete is used as the engineering material with the most extensive application, the traditional formula depends on high-energy-consumption cement and non-renewable aggregate, the carbon emission is large, the concrete is difficult to degrade naturally after being abandoned, and serious environmental burden is caused by long-term accumulation. Under the background, a novel concrete material with mechanical properties and environmental friendly characteristics is developed, and becomes a key break for realizing low-carbon transformation in the building industry. The degradable concrete is introduced with bio-based or environmental response components to realize controllable decomposition after the service period is finished, so that the continuous influence of construction waste on an ecological system is reduced. However, the existing degradable concrete has the problem that the strength and durability of the existing degradable concrete are obviously lower than those of the traditional concrete, and the basic requirements of structural engineering on bearing capacity and long-term stability are difficult to meet. Meanwhile, most degradation mechanisms depend on specific environmental conditions (such as high humidity or microorganism enrichment), and the degradation rate is uncontrollable in the conventional use environment, so that the material is easy to degrade in advance or stay for a long time. In addition, the existing preparation process often sacrifices working performance in exchange for degradation characteristics, so that construction difficulty is increased, compactness is insufficient, and crack sensitivity is further increased and durability is further reduced. Therefore, a green high-performance concrete and a preparation method thereof are needed to realize stable and reliable service period and high-efficiency controllable degradation after service completion under the premise of ensuring high strength and good construction performance. Disclosure of Invention The invention aims to provide degradable green high-performance concrete and a preparation method thereof, which can effectively solve the problems of insufficient strength and durability, uncontrollable degradation rate and reduced working performance caused by a preparation process of the existing degradable concrete in the background art. The degradable green high-performance concrete and the preparation method thereof comprise the following specific steps of 1, preparing and preprocessing raw materials, namely, 30 to 50 parts of Portland cement, 15 to 25 parts of blast furnace slag micropowder, 10 to 20 parts of fly ash, 5 to 15 parts of modified bio-based polymer particles, 40 to 60 parts of natural aggregate, 20 to 30 parts of recycled aggregate, 2 to 5 parts of nano silicon dioxide, 0.1 to 0.5 part of cellulose ether, 0.5 to 1.5 parts of polycarboxylic acid water reducer and 1 to 3 parts of pH responsive degradation accelerator according to parts by weight; mechanically activating and pickling the regenerated aggregate to remove surface attachments and improve the surface roughness and activity of the regenerated aggregate, carrying out surface coating treatment on the modified bio-based polymer particles to form a slow release layer with the thickness of 1-5 microns, step 2, premixing dry powder materials, putting the Portland cement, the blast furnace slag micropowder, the fly ash, the nano silica and the cellulose ether into a forced stirrer, dry stirring for 3-5 minutes at the rotating speed of 30-50 revolutions per minute to ensure uniform dispersion of each component, step 3, wet stirring and polymer introduction, slowly adding 70-80% of water of the total water into the dry powder mixture obtained in step 2, simultaneously adding the polycarboxylic acid water reducer, starting the stirrer to stir for 2-4 minutes at the rotating speed of 60-80 revolutions per minute, subsequently, adding the modified bio-based polymer particles and the pH response type degradation accelerator in batches, continuing stirring for 3-5 minutes to form uniform slurry, step 4, adding the pretreated natural aggregate and the regenerated aggregate into the slurry obtained in step 3, adding the rest water, increasing the rotating speed of a stirrer to 80-100 revolutions per minute, continuously stirring for 5-8 minutes until a concrete mixture with good workability and no segregation and bleeding phenomenon is obtained, molding and curing, namely pouring the concrete mixture into a mold, vibr