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CN-121974618-A - Stone-like PC brick prepared based on recycled concrete and preparation method thereof

CN121974618ACN 121974618 ACN121974618 ACN 121974618ACN-121974618-A

Abstract

The invention relates to the technical field of recycling of building waste, in particular to a stone-like PC brick prepared based on recycled concrete and a preparation method thereof, wherein the stone-like PC brick is formed by compounding a surface layer and a bottom layer, the bottom layer comprises recycled coarse aggregate, ordinary Portland cement, natural sand, compound modified recycled aggregate, fly ash, a polycarboxylate water reducer and water, the surface layer comprises white Portland cement, colored sand, ferric oxide inorganic pigment, compound modified recycled aggregate, silica fume, acrylic emulsion and water, the technical scheme of the invention is characterized in that the ultrasonic-microwave synergistic activation modification process is adopted, the microwave energy generates thermal stress by utilizing the electromagnetic property difference of the aggregate and attached mortar, the old mortar is stripped by more than 45%, and simultaneously ultrasonic waves form a micro-flow field in the pores of the aggregate through cavitation effect, so that the penetration depth of modified liquid is improved.

Inventors

  • QIAN XUEFENG
  • QIAN QI
  • WU WENLIAN

Assignees

  • 安徽力峰建材科技有限公司
  • 浙江理工大学

Dates

Publication Date
20260505
Application Date
20251226

Claims (10)

  1. 1. The stone-like PC brick prepared based on recycled concrete is characterized by being formed by compounding a surface layer and a bottom layer; The bottom layer comprises, by weight, 560-590 parts of recycled coarse aggregate, 160-175 parts of ordinary Portland cement, 280-320 parts of natural sand, 60-90 parts of composite modified recycled aggregate, 35-45 parts of fly ash, 2.5-3.5 parts of polycarboxylate superplasticizer and 95-105 parts of water; the surface layer comprises, by weight, 95-105 parts of white Portland cement, 165-175 parts of colored sand, 8-12 parts of ferric oxide inorganic pigment, 35-55 parts of composite modified recycled aggregate, 13-18 parts of silica fume, 10-13 parts of acrylic emulsion and 38-45 parts of water.
  2. 2. The stone-like PC brick according to claim 1, wherein the preparation method of the composite modified recycled aggregate comprises the steps of: a. Crushing construction waste, sieving by a double-layer screen mesh with the diameter of 1-3mm and the diameter of 4.75-9.5mm to obtain recycled aggregate with the corresponding particle size, cleaning, and drying at 80-100 ℃ until the water content is less than or equal to 1%; b. Dipping the recycled aggregate in ultrasonic-microwave synergistic activation modified liquid containing a silane coupling agent, wherein the mass ratio of the dipping liquid to the aggregate is 1 (0.9-1.1); the silane coupling agent is KH-550, accounting for 0.6-0.9% of the total weight of the modifying liquid; c. Ultrasonic treatment with the frequency of 40kHz is assisted for 20-28 minutes in the dipping process, so that the modification liquid permeates into the pores of the aggregate; d. And (3) taking out the aggregate, draining off redundant liquid drops, and drying for 3-5 hours at 130-140 ℃ to obtain the composite modified recycled aggregate.
  3. 3. The stone-like PC brick according to claim 2, wherein the ultrasonic-microwave synergistic activation modified liquid is prepared from, by weight, 100 parts of water, 12-14 parts of sodium silicate, 7-9 parts of nano silica sol, 3-4.5 parts of ammonium acrylate, 2.2-2.8 parts of sodium hexametaphosphate and 1-3 parts of nano calcium carbonate.
  4. 4. The stone-like PC brick according to claim 3, wherein the preparation method of the ultrasonic-microwave synergistic activation modification liquid comprises the steps of heating water to 48-52 ℃, sequentially adding sodium silicate and sodium hexametaphosphate, stirring at a rotating speed of 300-500r/min until the sodium silicate and the sodium hexametaphosphate are completely dissolved, activating for 1-1.5 min by microwaves, stopping stirring at a high speed of 800-1000r/min after the microwaves are stopped, slowly adding nano silica sol, ammonium acrylate, nano calcium carbonate and silane coupling agent KH-550, and simultaneously applying ultrasonic treatment with a frequency of 25kHz for 5-9 min to obtain uniform and stable modification liquid.
  5. 5. The stone-like PC brick of claim 4 wherein the microwave activation parameters are 500W microwave power, 2450MHz frequency.
  6. 6. The stone-like PC tile of claim 1 wherein the acrylic emulsion in the face layer has a solids content of greater than or equal to 45%.
  7. 7. The method for preparing the stone-like PC brick based on the preparation of the recycled concrete according to claim 1, which is characterized by comprising the following steps: S1, preparing raw materials, namely weighing the raw materials according to a proportion; S2, preparing surface layer slurry, namely dry-mixing white cement, colored sand, pigment and silica fume used for the surface layer for 5-8 minutes at the rotating speed of 200-300r/min, adding acrylic emulsion and water, stirring for 10-15 minutes at the rotating speed of 400-600r/min, and controlling the fluidity of the slurry to be 180-200mm; S3, preparing a bottom layer mixture, namely putting the recycled coarse aggregate, the natural sand, the cement, the fly ash and the composite modified recycled aggregate used in the bottom layer into a stirrer, dry-mixing for 10-12 minutes at the rotating speed of 150-250r/min, adding the water reducer after dissolving in water, stirring for 15-20 minutes at the rotating speed of 300-400r/min, and controlling the slump of the mixture to be 0-5mm; S4, compounding cloth and vacuum extrusion molding, namely preheating a die to 30-40 ℃, uniformly laying surface layer slurry with the thickness of 3-5mm, laying bottom layer mixture, feeding the die into a vacuum extruder, and extruding for 2-3 minutes for molding; S5 curing, namely primary steam curing for 4-5.5 hours with a formed green brick, and demoulding and then alternately performing cyclic steam-natural curing to finish curing, thus obtaining a finished product.
  8. 8. The process according to claim 7, wherein the extrusion in S4 is performed under a vacuum of-0.085 to-0.095 MPa and a pressure of 16 to 18 MPa.
  9. 9. The method according to claim 7, wherein the primary steam curing in S5 is performed in an environment of 58-62 ℃ and a humidity of 92% -95%.
  10. 10. The preparation method according to claim 7, wherein the cyclic steam-natural curing in S5 is alternated by curing in a steam environment with a humidity of 85% -90% at 40-45 ℃ for 2-3 days, and curing in a natural environment with a humidity of more than or equal to 60% at 20-25 ℃ for 3-4 days for 2-3 times.

Description

Stone-like PC brick prepared based on recycled concrete and preparation method thereof Technical Field The invention relates to the technical field of recycling of building waste, in particular to a stone-like PC brick prepared based on recycled concrete and a preparation method thereof. Background Along with the acceleration of the urban process, the production amount of the construction waste is continuously increased, and the recycling rate is improved, but the super half recycled aggregate is only used in the low added value fields such as road base layers, and the high value utilization technology is still insufficient. The stone-like PC brick is used as an important substitute for natural stone, is widely applied to municipal engineering due to strong decoration and good durability, but traditional products generally depend on natural aggregate exploitation, exacerbate ecological damage and have high cost, or directly use unmodified recycled aggregate, so that the product performance short plates are outstanding. The existing recycled aggregate stone-like PC brick has the problems that firstly, the recycled aggregate has more old mortar attached to the surface and high porosity, the compressive strength of the brick body is generally lower than 40MPa when the brick is directly used, the water absorption rate exceeds 8%, and the requirement of municipal engineering on the mechanical property of the material is difficult to meet, and secondly, the aggregate is single in treatment, and the brick body is easy to crack and has insufficient wear resistance due to poor interfacial binding force only by chemical soaking or single physical treatment. Based on the above, the invention provides the stone-like PC brick prepared based on the recycled concrete, so as to solve the existing problems. Disclosure of Invention The invention aims to provide a stone-like PC brick prepared based on recycled concrete and a preparation method thereof. In order to achieve the above purpose, the present invention provides the following technical solutions: the stone-like PC brick is prepared based on recycled concrete, and is formed by compounding a surface layer and a bottom layer; The bottom layer comprises, by weight, 560-590 parts of recycled coarse aggregate, 160-175 parts of ordinary Portland cement, 280-320 parts of natural sand, 60-90 parts of composite modified recycled aggregate, 35-45 parts of fly ash, 2.5-3.5 parts of polycarboxylate superplasticizer and 95-105 parts of water; the surface layer comprises, by weight, 95-105 parts of white Portland cement, 165-175 parts of colored sand, 8-12 parts of ferric oxide inorganic pigment, 35-55 parts of composite modified recycled aggregate, 13-18 parts of silica fume, 10-13 parts of acrylic emulsion and 38-45 parts of water. As a further technical scheme, the preparation method of the composite modified recycled aggregate comprises the following steps: a. Crushing construction waste, sieving by a double-layer screen mesh with the diameter of 1-3mm and the diameter of 4.75-9.5mm to obtain recycled aggregate with the corresponding particle size, cleaning, and drying at 80-100 ℃ until the water content is less than or equal to 1%; b. Dipping the recycled aggregate in ultrasonic-microwave synergistic activation modified liquid containing a silane coupling agent, wherein the mass ratio of the dipping liquid to the aggregate is 1 (0.9-1.1); the silane coupling agent is KH-550, accounting for 0.6-0.9% of the total weight of the modifying liquid; c. Ultrasonic treatment with the frequency of 40kHz is assisted for 20-28 minutes in the dipping process, so that the modification liquid permeates into the pores of the aggregate; d. And (3) taking out the aggregate, draining off redundant liquid drops, and drying for 3-5 hours at 130-140 ℃ to obtain the composite modified recycled aggregate. As a further technical scheme, the ultrasonic-microwave synergistic activation modified liquid is prepared from, by weight, 100 parts of water, 12-14 parts of sodium silicate, 7-9 parts of nano silica sol, 3-4.5 parts of ammonium acrylate, 2.2-2.8 parts of sodium hexametaphosphate and 1-3 parts of nano calcium carbonate. The preparation method of the ultrasonic-microwave synergistic activation modified liquid comprises the steps of heating water to 48-52 ℃, sequentially adding sodium silicate and sodium hexametaphosphate, stirring at a rotating speed of 300-500r/min until the sodium silicate and the sodium hexametaphosphate are completely dissolved, activating the microwave for 1-1.5 min, stopping microwave, stirring at a high speed of 800-1000r/min after stopping microwave, slowly adding nano silica sol, ammonium acrylate, nano calcium carbonate and a silane coupling agent KH-550, and simultaneously applying ultrasonic treatment with a frequency of 25kHz for 5-9 min to obtain uniform and stable modified liquid. As a further technical scheme, the microwave activation parameters are microwave power 5