Method for producing mortar and concrete by using solid waste-based cementitious material and construction waste

Abstract

The application discloses a method for producing mortar and concrete by using solid waste-based cementitious materials and construction waste, and relates to the technical field of solid waste resource utilization and green building materials. The method uses granulated blast furnace slag, steel slag, gypsum, fly ash, iron tailings and other industrial solid wastes as raw materials, and the raw materials are processed and ground to prepare solid waste-based cementitious materials. Meanwhile, the construction waste is sorted, crushed, screened and ground, and is mixed with the solid waste-based cementitious materials and fly ash in proportion, and then is subjected to homogenization, activation, grinding and other processes to produce mortar, concrete and products thereof. The active components in the construction waste and the solid waste-based cementitious materials jointly participate in the hydration reaction, the non-active particles play the filling and skeleton roles, the cement consumption is greatly replaced, the carbon emission is reduced, and the resource utilization rate is improved.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization, and specifically relates to a method for producing mortar and concrete using solid waste-based cementitious materials and construction waste. Background Technology

[0002] Currently, the amount of construction waste and industrial solid waste generated is enormous. Traditional disposal methods primarily rely on landfill, which not only occupies land resources but also causes environmental pollution. On the other hand, cement production generates high carbon emissions, contradicting the national "dual-carbon" strategic goals. Therefore, how to utilize construction waste and industrial solid waste resources to develop low-carbon cementitious materials and replace some cement in the production of green building materials has become an urgent technical problem to be solved. Summary of the Invention

[0003] To address the aforementioned problems, the present invention aims to provide a method for producing mortar and concrete using solid waste-based cementitious materials and construction waste, thereby achieving the synergistic utilization of construction waste and industrial solid waste and preparing green and environmentally friendly mortar and concrete products.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] Industrial solid waste raw materials such as slag, gypsum, steel slag, and tailings are processed and ground, then formulated into a solid waste-based cementitious material in a certain proportion. Construction waste, after being sorted, crushed, screened, and ground, is mixed with the solid waste-based cementitious material in a certain proportion to produce solid waste-based mortar. The specific preparation method is as follows:

[0006] 1. After demolition, construction waste undergoes initial sorting to remove impurities. After crushing, iron removal, and sorting, it undergoes secondary crushing and screening.

[0007] 2. Activated powder from construction waste is obtained through mechanical grinding and activation treatment;

[0008] 3. Industrial solid waste raw materials (slag, steel slag, gypsum, tailings, etc.) are mixed in proportion, homogenized, and then subjected to primary and secondary grinding to obtain cementitious material products.

[0009] 4. The above-mentioned cementitious material product is homogenized with construction waste active powder and fly ash in a certain proportion to obtain a composite cementitious material.

[0010] This composite cementitious material can partially or completely replace cement in the preparation of mortar, concrete and its products.

[0011] This invention has the following beneficial effects: 1. The active ingredients and solid waste-based cementitious materials in construction waste jointly participate in the hydration reaction, while the inactive granular solids play a filling and skeletal support role, significantly increasing the proportion of cement replacement and making the product performance more stable; 2. It realizes the synergistic resource utilization of various industrial solid wastes and construction waste; 3. It significantly reduces cement usage and lowers carbon emissions during the production process; 4. No calcination is required during the preparation process, reducing solid waste and carbon emissions and achieving resource reuse; 5. It conforms to the green and low-carbon development strategy and has good application prospects. Attached Figure Description

[0012] Appendix Figure 1 The process flow diagram of this invention includes two parts: pretreatment of construction waste and preparation of solid waste-based cementitious materials;

[0013] Appendix Figure 2 This is a chemical reaction flow diagram of the present invention;

[0014] Appendix Figure 3 To prepare a table showing the change in compressive strength of solid waste-based mortar over time;

[0015] Appendix Figure 4 The table below shows the change in compressive strength of the solid waste-based mortar prepared in the examples over time. Detailed Implementation

[0016] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0017] Solid waste-based concrete, derived from active components and cementitious materials in construction waste, exhibits rapid hardening, high strength, and more stable performance. The active components and cementitious materials in the construction waste jointly participate in the hydration reaction, while the inactive granular solids act as fillers and provide structural support, significantly increasing the proportion of cement used in their replacement.

[0018] The purpose of this invention is to process construction waste and solid waste-based cementitious materials to obtain a new type of ecological aggregate, enabling its large-scale application in the field of building materials.

[0019] The construction waste concrete aggregate mentioned in this invention is solid waste generated from the demolition and renovation of old houses in urban and rural areas. The construction waste concrete aggregate needs to be processed through processes such as sorting, crushing, iron removal and sorting, secondary crushing, screening, mechanical grinding and activating to prepare aggregate that meets the specifications.

[0020] The solid waste-based cementitious material described in this invention is a permanent cementitious material prepared by using solid wastes such as slag, gypsum, steel slag, and tailings as raw materials, which are processed and ground into fine powder and then mixed in a certain proportion.

[0021] The particle size of the construction waste concrete aggregate described in this invention is 2-20mm.

[0022] The solid waste-based cementitious material described in this invention is prepared by grinding processed and proportioned raw materials, requiring no calcination, being low in carbon, and producing no secondary pollution. The specific preparation method is as follows in the following embodiments:

[0023] Solid wastes such as slag, gypsum, steel slag, and tailings are crushed, homogenized, and then subjected to primary and secondary grinding to obtain adhesive products and fly ash.

[0024] The steel slag mineral composition consists of minerals with cementing activity formed by the crystallization of a high-calcium, high-silicon, high-iron, and high-magnesium solution during the cooling process. The most important mineral is the cementing-active β-crystal C2S, with a small amount of C3S present.

[0025] The slag water quenching process greatly inhibits crystallization, with over 90% of the slag forming an amorphous calcium aluminosilicate glass body. This body is internally coated with highly reactive CaO, SiO2, and Al2O3 in a metastable state, readily stimulating mineral components. When OH... - When ions come into contact with the glass network structure of slag, they cause it to depolymerize and dissolve. The silicate minerals in the slag powder react with water to form CSH gel (3CaO.SiO2.3H2O).

[0026] The industrial solid waste composition of slag, steel slag, gypsum, tailings, and fly ash is as follows: 30-50 parts slag, 10-30 parts steel slag, 5-15 parts gypsum, 5-15 parts tailings, and 10-30 parts fly ash.

[0027] In the gel material preparation method, the first grinding is carried out using a vertical mill with a specific gravity of 430m. 2 / kg, secondary grinding is performed using ball milling, specific surface area 600m 2 / kg, which dissolves fCaO and fMgO in steel slag, mechanically stimulates the distortion and deformation of the crystal structure, increases the surface reaction potential energy, and increases the hydration reaction rate.

[0028] In the gel material preparation method, the hydration reaction in slag powder and steel slag powder is mainly C2S (2CaO·SiO2), with small amounts of C3S (3CaO·SiO2) and C3A (3CaO·Al2O3). The chemical equation for the hydration reaction is: In an alkaline environment, the non-crystalline glassy components in red brick powder, including the active SiO2 and Al2O3, react with Ca(OH)2 in a pozzolanic reaction under high alkalinity. (Calcium silicate hydrate gel) Active Al2O3 generates hydrated calcium aluminate, which reacts with gypsum to form ettringite, filling the gaps and increasing the density of the structure.

[0029] This method is simple in process and the preparation equipment is reliable and safe. It can realize the comprehensive reuse of low-carbon solid waste-based cementitious materials and construction waste. The active ingredients in construction waste and solid waste-based cementitious materials participate in the hydration reaction together. No calcination is required, no secondary pollution is generated, solid waste emissions and carbon emissions are reduced, and the utilization rate of construction waste concrete aggregate is further improved. It has huge economic, social and environmental benefits.

[0030] Example 1:

[0031] The above-mentioned process was used for preparation, specifically as follows: The raw materials used were 220 kg of PO42.5 cement, 90 kg of fly ash, 90 kg of mineral powder, 850 kg of manufactured sand, 210 kg of fine aggregate, 710 kg of 1-2 grade gravel, 170 kg of water, and 7 kg of admixtures. The resulting construction waste concrete aggregate product had a particle diameter of 2-20 mm, and the concrete strength results were as follows. Figure 3 As shown in the figure. The results indicate that the strength of the building concrete aggregate was 18 MPa after 3 days of storage, and it steadily increased to about 36 MPa after 28 days, which meets the design requirements and is almost identical to the strength of ordinary concrete of the same grade.

[0032] Example 2:

[0033] The above-mentioned process was used for preparation, specifically as follows: The raw materials used were 110 kg of PO42.5 cement, 110 kg of adhesive, 90 kg of fly ash, 90 kg of mineral powder, 850 kg of manufactured sand, 210 kg of fine aggregate, 710 kg of 1-2 grade gravel, 175 kg of water, and 7 kg of admixtures. The resulting construction waste concrete aggregate product had a particle diameter of 2-20 mm, and the concrete strength results were as follows. Figure 3 As shown in the figure. The results indicate that the strength of the building concrete aggregate was 20 MPa after 3 days of storage, and it steadily increased to about 40 MPa after 28 days, which meets the design requirements and is almost identical to that of ordinary concrete of the same grade.

[0034] The above description is only a partial embodiment of this application and is not intended to limit this application. For those skilled in the art, this application can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the scope of this application should be included within the protection scope of this application.

Claims

1. A method for the comprehensive utilization of low-carbon solid waste-based cementitious materials and construction waste, characterized in that, Includes the following steps: (1) Construction waste is sorted, crushed, iron removed, crushed again and screened to obtain processed aggregate; (2) The aggregate of construction waste is mechanically ground and activated to obtain active powder; (3) Slag, steel slag, gypsum, tailings and other industrial solid wastes are proportioned and homogenized, and then ground once and twice to obtain cementitious material products; (4) The cementitious material products, construction waste active powder and fly ash are homogenized and mixed in proportion to obtain solid waste-based composite cementitious material.

2. The method according to claim 1, characterized in that, The industrial solid waste is formulated as follows: 30–50 parts slag, 10–30 parts steel slag, 5–15 parts gypsum, 5–15 parts tailings, and 10–30 parts fly ash.

3. The method according to claim 1, characterized in that, The particle size of the construction waste concrete aggregate is 2-20mm.

4. The method according to claim 1, characterized in that, The composite cementitious material replaces 50-90% of the cement.

5. The method according to claim 1, wherein the gel material preparation method comprises a first grinding using a vertical mill with a specific gravity of 430 m² / kg, and a second grinding using a ball mill with a specific gravity of 600 m² / kg.

6. The method according to claim 1, characterized in that, The 28-day compressive strength of the mortar and concrete products shall not be lower than the C30 grade standard.

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