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A waste concrete-based recycled cementitious material and its preparation method

A technology of recycled cementitious materials and waste concrete, which is applied in the direction of cement production, etc., can solve the problems of low strength grade of recycled cementitious materials, limit the application range of recycled concrete, and low compressive strength of recycled concrete, and achieve significant industrial practical value, Improve hydration performance and solve the effect of large heat release in the early stage

Active Publication Date: 2022-06-21
NANJING TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The second is to use the separated recycled aggregate to partially or completely replace the natural aggregate to prepare recycled aggregate concrete. The research shows that the separated recycled aggregate has high water absorption due to the fact that some old cement mortar is attached to its surface. rate and slightly poor physical properties, resulting in the preparation of recycled concrete with defects such as low compressive strength, large elastic modulus and poor durability, which limits the application range of recycled concrete
But due to C-S-H gel, Ca(OH) 2 and CaCO 3 Thermal decomposition will generate more f-CaO, and Ca(OH) will be formed rapidly when in contact with water 2 , not only need to consume a lot of mixing water
At the same time, the reaction between f-CaO and water is a sharp exothermic process, and the heat generated will accelerate the hydration reaction of other components, which will make its work performance poor, and the strength level of the recycled cementitious material is also low, so it cannot be obtained. use efficiently

Method used

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  • A waste concrete-based recycled cementitious material and its preparation method
  • A waste concrete-based recycled cementitious material and its preparation method
  • A waste concrete-based recycled cementitious material and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The composition of the recycled cementitious material in this example includes:

[0032]

[0033] The preparation method of the regenerated cementitious material in this example is as follows: drying the waste hardened cement slurry particles and coal gangue at 50° C. for 24 hours, and then grinding them into waste hardened cement slurry powder and coal gangue powder with a particle size of ≤100 mesh, respectively. The mixer is used for mixing and homogenization; the mixed waste hardened cement slurry powder and coal gangue powder are put into a muffle furnace and heated to 750 ° C and kept for 2 hours, and then quenched to room temperature by wind. The calcined product was mixed with dihydrate gypsum, mixed and homogenized with a mixer, and then digested for 2 days in a curing box at a temperature of 20±1° C. and a humidity of 99%. Mix high-efficiency water reducer and retarder in water to make an aqueous solution, stir evenly, then pour into a mixer and stir with t...

Embodiment 2

[0035] The composition of the recycled cementitious material in this example includes:

[0036]

[0037] The preparation method of the regenerated cementitious material in this example is as follows: drying the waste hardened cement slurry particles and coal gangue at 50° C. for 24 hours, and then grinding them into waste hardened cement slurry powder and coal gangue powder with a particle size of ≤100 mesh, and mixing them with Mix and homogenize with a feeder; put the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace to heat up to 750 ° C and keep it for 2 hours, and then quench it to room temperature with wind. The calcined product was mixed with dihydrate gypsum, mixed and homogenized with a mixer, and then digested for 2 days in a curing box at a temperature of 20±1° C. and a humidity of 99%. Mix high-efficiency water reducer and retarder in water to make an aqueous solution, stir evenly, then pour into a mixer and stir with the abo...

Embodiment 3

[0039] The composition of the recycled cementitious material in this example includes:

[0040]

[0041]

[0042] The preparation method of the regenerated cementitious material in this example is as follows: drying the waste hardened cement slurry particles and coal gangue at 50° C. for 24 hours, and then grinding them into waste hardened cement slurry powder and coal gangue powder with a particle size of ≤100 mesh, and mixing them with Mix and homogenize with a feeder; put the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace to heat up to 750 ° C and keep it for 2 hours, and then quench it to room temperature with wind. The calcined product was mixed with dihydrate gypsum, mixed and homogenized with a mixer, and then digested for 2 days in a curing box at a temperature of 20±1° C. and a humidity of 99%. Mix high-efficiency water reducer and retarder in water to make an aqueous solution, stir evenly, then pour into a mixer and stir ...

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Abstract

The invention discloses a waste concrete-based regenerated cementitious material and a preparation method thereof, which comprises calcining waste hardened cement slurry, calcining coal gangue, dihydrate gypsum, water reducer, retarder and water. Break the hardened cement slurry in the waste concrete into fine particles, and then grind it into powder; grind the coal gangue into powder; mix the two evenly, and then calcinate at 700-800°C for 2-3 hours, take it out and cool it to room temperature, then mix with dihydrate gypsum evenly, make water reducer and retarder into aqueous solution and mix with the mixture evenly. In the present invention, the hardened slurry separated from waste concrete is combined with coal gangue, and the material has gelling properties after heat treatment. The regenerated gelling material has high strength and good durability, and can reduce waste treatment costs and become waste. As a treasure, it can also protect the environment and save natural resources.

Description

technical field [0001] The invention belongs to the field of building materials, in particular to a regenerated cementitious material prepared by using hardened cement slurry and coal gangue in waste concrete and a preparation method thereof. Background technique [0002] At present, the resource utilization of waste concrete is mainly concentrated in two aspects: First, the waste concrete is crushed and used as a filling material for roadbed or low-strength products such as blocks and paving bricks. Nearly 90% of the waste concrete is produced through such materials. method is processed. The second is to use the separated recycled aggregate to partially or completely replace the natural aggregate to prepare recycled aggregate concrete. The research shows that the separated recycled aggregate has high water absorption because some old cement mortar will be attached to its surface. This leads to the defects of low compressive strength, large elastic modulus and poor durabili...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B28/02C04B7/24C04B7/36
CPCC04B28/02C04B7/246C04B7/24C04B7/36C04B22/143C04B2103/302C04B2103/22C04B22/002Y02P40/10
Inventor 李伟峰纪小敏马素花
Owner NANJING TECH UNIV
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