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CN-121990775-A - Method for preparing building material by recycling urban building garbage

CN121990775ACN 121990775 ACN121990775 ACN 121990775ACN-121990775-A

Abstract

The invention relates to the field of building materials, in particular to a method for preparing building materials by recycling urban building waste, which comprises the steps of mixing amorphous silicon dioxide, ionic liquid, sodium hydroxide and water, heating to 60-80 ℃, filtering to remove insoluble substances after stirring reaction, regulating pH to 9-10 to obtain an active silicon solution, dipping recycled aggregate by the active silicon solution, adding the recycled aggregate into sodium metaaluminate solution, stirring reaction, collecting solids, and drying.

Inventors

  • Hong Riming
  • HE YING
  • Shu Dianwang
  • YAN PINGPING
  • LU QIMING
  • PENG XIAOHONG

Assignees

  • 广东中邺山河建筑工程有限公司

Dates

Publication Date
20260508
Application Date
20260210

Claims (10)

  1. 1. A method for preparing building materials by recycling urban building wastes is characterized by comprising the following steps: Immersing urban construction waste treated by a silane coupling agent into the dissolution liquid, and collecting solids after ultrasonic treatment to obtain recycled aggregate; Mixing amorphous silicon dioxide, ionic liquid, sodium hydroxide and water, heating to 60-80 ℃, stirring, reacting, filtering to remove insoluble substances, and adjusting pH to 9-10 to obtain active silicon solution; and (3) immersing the recycled aggregate in the active silicon solution, adding the recycled aggregate into the sodium metaaluminate solution, stirring for reaction, collecting the solid, and drying.
  2. 2. The method for preparing the building material by recycling the urban construction waste according to claim 1, wherein the urban construction waste is prepared by mechanically crushing, cleaning and grading the waste concrete in the urban construction removing site, sieving the two fractions of 5-16mm and 16-31.5mm, and mixing and compounding according to the mass ratio of 1:1.
  3. 3. The method for preparing building materials by recycling municipal construction waste according to claim 1, wherein said solution comprises tartaric acid, disodium edetate and penetrant, and the pH is adjusted to 11-12 with sodium hydroxide.
  4. 4. The method for preparing building materials by recycling municipal construction waste according to claim 3, wherein the mass ratio of tartaric acid, disodium edetate and penetrant is 80-100:3-6:1-2.
  5. 5. The method for preparing building materials by recycling municipal construction waste according to claim 1, wherein the ionic liquid is a hydroxyl functional ionic liquid.
  6. 6. The method for preparing building materials by recycling municipal construction waste according to claim 5, wherein the hydroxyl functional ionic liquid is obtained by reacting N-methylimidazole with chlorine substituted fatty alcohol.
  7. 7. The method for preparing building materials by recycling municipal construction waste according to claim 6, wherein the chlorine-substituted fatty alcohol is any one or a combination of two or more of 2-chloroethanol, 3-chloropropanol, 4-chlorobutanol, 5-chloropentanol and 6-chlorohexanol.
  8. 8. The method for preparing building materials by recycling municipal construction waste according to claim 1, wherein the mass ratio of amorphous silica, ionic liquid and sodium hydroxide is 20-40:3-6:60-80.
  9. 9. The method for preparing building materials by recycling municipal construction waste according to claim 1, wherein the activated silicon solution is impregnated with recycled aggregate by vacuum-pressure impregnation.
  10. 10. The method for preparing building materials by recycling municipal construction waste according to claim 8, wherein the number of cycles of vacuum-pressure impregnation is 3 or more.

Description

Method for preparing building material by recycling urban building garbage Technical Field The invention relates to the field of building materials, in particular to a method for preparing a building material by recycling urban building waste. Background The annual output of the building rubbish in China is over 30 hundred million tons, and the proportion of the waste concrete is over 70 percent. The method for preparing the recycled coarse aggregate by crushing and screening the waste concrete is a main way for recycling, but 30-50% of old hardened cement mortar is attached to the surface of the recycled aggregate, and the bonding strength of the interface between the recycled aggregate and the cement paste is only 40-60% of that of the natural aggregate, so that the application of the recycled coarse aggregate in concrete is severely restricted. At present, the regenerated aggregate is chemically modified by adopting strong acid such as sulfuric acid to erode the old mortar, but the method only removes the old mortar, does not generate a reinforcing phase and has high strength loss rate. Although the vacuum impregnation treatment of the nano silicon dioxide or nano calcium carbonate solution can strengthen the recycled aggregate, the nano particles are easy to agglomerate and difficult to permeate into the internal micropores, and the improvement range of the bonding performance of the recycled aggregate and the cement paste interface is smaller. Disclosure of Invention The invention aims at solving the technical problems and provides a method for preparing building materials by recycling urban building wastes. The technical scheme adopted is as follows: a method for preparing building materials by recycling urban building wastes comprises the following steps: Immersing urban construction waste treated by a silane coupling agent into the dissolution liquid, and collecting solids after ultrasonic treatment to obtain recycled aggregate; Mixing amorphous silicon dioxide, ionic liquid, sodium hydroxide and water, heating to 60-80 ℃, stirring, reacting, filtering to remove insoluble substances, and adjusting pH to 9-10 to obtain active silicon solution; and (3) immersing the recycled aggregate in the active silicon solution, adding the recycled aggregate into the sodium metaaluminate solution, stirring for reaction, collecting the solid, and drying. Further, the urban construction waste is formed by mechanically crushing, cleaning and grading the waste concrete in the urban construction removal site, sieving the two particle fractions of 5-16mm and 16-31.5mm, and mixing and compounding according to the mass ratio of 1:1. Further, the dissolution liquid comprises tartaric acid, disodium ethylenediamine tetraacetate and a penetrating agent, and the pH is adjusted to 11-12 by sodium hydroxide. The molecular structure of the silane coupling agent (such as KH-550, KH-560 and KH-570) comprises an inophilic group and an inophilic group, and the dual-functional structure enables the silane coupling agent to form a 'molecular bridge' between dissolved chelated calcium ions and holes in the construction waste, and the chemical bonding enables the chelated calcium ions to be reserved in the holes in the construction waste, so that the chelated calcium ions are reduced to enter the dissolution liquid, a foundation is laid for the heterogeneous nucleation of the hydrated calcium silicate gel in a follow-up driving manner, and the 'repairing of defects by calcium aluminum resources of the aggregate' is realized. Tartaric acid is a hydroxycarboxylic acid chelating agent, and has retarding effect on calcium ions, although the chelating ability of the tartaric acid is weaker than that of disodium ethylenediamine tetraacetate, the retarding effect has the significance of reducing the temperature difference stress caused by hydration heat inside the recycled aggregate, avoiding the loss of calcium ions caused by cracks, prolonging the reaction time of disodium ethylenediamine tetraacetate and calcium ions and improving the dissolution efficiency. In addition, the hydroxyl group of tartaric acid can form a weak complex with calcium ions to assist the chelation of disodium edentate, which is a polydentate chelating agent, and the amino group and the carboxyl group in the molecular structure of the disodium edentate can form a stable chelate with the calcium ions, so that the chelation has high selectivity, and under alkaline conditions, disodium edentate preferentially combines with the calcium ions without obviously complexing magnesium ions or aluminum ions, and the selectivity is due to the high matching degree of the ionic radius of the calcium ions and the chelating cavity of the disodium edentate, while the radius or charge density of other ions are greatly different, so that the stable chelate is difficult to form. The penetrating agent can enhance penetration and promote calcium ion contact, so that the mixed solution of t