LU506954B1

LU506954B1 - Production of green concrete products with natural mud and waste concrete

Info

Publication number: LU506954B1
Application number: LU506954A
Authority: LU
Inventors: Wang Gao; Wei Wang; Shifeng Zhu; Yang Lu; Xiaoyun Ma; Wei Chen; Yicai Sang; Shaolin Yue
Original assignee: Cccc Special Eng Co Ltd
Priority date: 2022-08-23
Filing date: 2023-03-21
Publication date: 2024-05-24
Also published as: CN115594446B; WO2024040952A1; CN115594446A

Abstract

The invention discloses a method for production of green concrete products with natural mud and waste concrete, including step S1: nature mud pretreatment, step S2: waste concrete crushing, step S3: treatment of recycled fine aggregates, step S4: treatment of recycled coarse aggregates and step S5: preparing green concrete products. The invention utilizes a large amount of construction wastes such as waste concrete and nature mud from rivers, lakes, and seas as raw materials, thereby effectively disposing of a significant amount of construction waste. It not only achieves the resource reuse of construction waste but also reduces the high energy consumption associated with traditional methods, which makes it a green recycling technology. The concrete produced from this invention can be widely used for rural cement concrete pavements or other structures, thereby offering broad applications and significant benefits.

Description

Production of Green Concrete Products with Natural Mud and Waste

Concrete

Field of the Invention

The invention relates to the field of preparation method of green concrete products with natural mud and waste concrete. More specifically, the invention relates to the production of green concrete products with natural mud and waste concrete.

Background of the Invention

With high moisture content and complex composition of natural mud, it is prone to secondary pollution, and improper disposal will have extremely adverse effects on the environment. Therefore, the treatment and disposal of the natural mud on dredged river bottom have become a common concern. The current utilization technologies for natural mud mainly include solidified soil, sintered ceramsites, unbaked ceremsites, natural mud bricks, natural mud cement, etc, among which the unbaked ceremsites have the most extensive prospects. The current recycling pathways for waste concrete are relatively clear and mature. After the demolition of waste concrete, it is preliminarily crushed on site and then transported to a recycled crushing material recovery plant. Through fine crushing, it is processed into coarse aggregates (gravel) and powder (crushed materials of sand and cement slurry), then the coarse aggregates are mixed into fresh concrete to prepare concrete, while the powder is mixed into base materials for constructing the base course.

The patent with Chinese patent application announcement number CN 110156409 A discloses a kind of concrete containing natural mud and its preparation method. The method involves adding cement, natural mud, fly ash, basalt rubble, river sand, polypropylene fibers, and nano-reinforcing agents into a concrete mixer and mixing them uniformly, then the mixture is further mixed with a mixed liquor to obtain the desired concrete, which poses a strength of approximately 30-35MPa. The patent with Chinese patent authorized announcement number CN 103755267 B discloses a concrete with natural mud and its preparation method. The method involves cement, water, gravel, fly ash, mineral powder, sand, and additives, and natural mud is used as fine aggregate and to replace part of sand. The resulting concrete poses a final strength of approximately 35MPa. The patent with Chinese patent application announcement number CN 108558337 A discloses a method for preparing organic activated concrete with natural mud for improvement and modification. Specifically, the natural mud is first subjected to deodorization treatment and then reacted with an organic synthetic curing agent.

Afterwards, the modified natural mud is mixed with Portland cement, fly ash, and so on to obtain the organic activated concrete. The concrete obtained by the above three patented technologies has a lower strength, with less natural mud participated in. Compared with ordinary C30 concrete, its ¢4506954 is higher and added value is low, resulting in weak market competitiveness.

The patent with Chinese patent application announcement number 114436601A discloses a self-compacting concrete with recycled aggregates and its preparation method. Specifically, after crushing, sorting, and sieving waste concrete, aggregate particles can be obtained. Then mix sodium silicate, PVA, nano-silica, phosphoric acid, and water together to obtain a composite solution, and place the aggregate particles into the composite solution and immerse them. Afterwards, place the immersed particles in a sealed container, vacuumize, and introduce carbon dioxide gas and pressurize it to 0.1-0.4MPa and maintain the pressure for 20-24h to produce strengthened aggregate particles, and soak the strengthened aggregate particles in a water-based silicone resin emulsion, then dry them, and finally mix them until forming the self-compacting concrete. The self-compacting concrete has advantages including compact structure, high mechanical strength, and strong frost resistance. The patent with Chinese patent authorized announcement number CN 113024199 B discloses a method for preparing recycled concrete using waste building concrete. The preparation method comprises: 1)

Crush, clean and sieve waste building concrete to obtain recycled aggregate; 2) Mix the recycled aggregate with magnesium sulfate, lithium carbonate, sodium sulfate, and potassium dihydrogen phosphate to obtain a mixture; 3) Mix the mixture with cementitious materials, coarse aggregates, fine aggregates, additives, synergists, and water to obtain recycled concrete prepared from waste building concrete. This improves the impermeability of the concrete and provides good crack resistance. The materials used in the above two patents are relatively large in quantity and the manufacturing process is cumbersome. Furthermore, they still do not break away from the convention of treating coarse and fine aggregates differently. After sieving, the coarse aggregates are divided into three sizes: 20-30cm, 10-20cm, and 5-10cm. They are added to different grades of concrete separately and are generally not added to the same concrete at the same time. Fine aggregates cannot be added to the concrete and are typically used in the base course (downgraded use), which results in a large amount of powder being utilized only for lower-grade structures such as base course and mortar.

In conclusion, there are rare cases in the existing technology where river or lake sediment and waste concrete are combined for use. The maximum green application of construction waste such as natural mud and waste concrete in construction and road projects has not been achieved yet.

Description of the Invention

In order to achieve these purposes and other advantages of the invention, a preferred embodiment of the invention provides a method for production of green concrete products with natural mud and waste concrete, comprising the following steps:

Step S1: Nature mud pretreatment

Mix the nature mud with calcium lime, and keep it standing, dry it, and then grind it to obtä566954 treated nature mud and divide it into two parts, i.e., Part A and Part B;

Step S2: Waste concrete crushing

Remove the foreign matters from waste concrete and then crushed and crush and sieve it to obtain recycled coarse aggregates and recycled fine aggregates;

Step S3: Treatment of recycled fine aggregates

Fully mix the recycled fine aggregates obtained from step S2, Part A of the treated nature mud obtained from pretreatment in step S1, and metakaolin, then, fully mix the mixture with water;

Step S4: Treatment of recycled coarse aggregates

Spray water to the recycled coarse aggregates obtained from step S2 to keep the saturated surface of coarse aggregates dry;

Step SS: Preparing green concrete products

Mix the recycled coarse aggregates obtained from step S4, Part B of the recycled fine aggregates obtained from step S3, the treated nature mud, Cement and water obtained from step S1 with water reducing agent to ultimately obtain the desired product, i.e., green concrete products.

Preferably, as specified in step S1, mix the nature mud with calcium lime, and keep it standing, dry it, and then grind it, specifically including the following operations:

Sieve the nature mud, and then mix the sieved nature mud with calcium lime in a weight ratio of 100:6-16, and keep it standing and dry it. After it is dried, grind it to a particle size of 0.08mm for further use.

Preferably, the step S2, i.e., remove the foreign matters from waste concrete and then crushed and crush and sieve it to obtain recycled coarse aggregates and recycled fine aggregates, specifically includes the following operations:

Step S21: Initially crush the waste concrete and clear away the foreign matters in it;

Step S22: Continue the secondary crushing to obtain mixture with a diameter of less than 35cm;

Step S23: Further sieve the mixture obtained in step S22 to obtain recycled coarse aggregate and recycled fine aggregate respectively.

Preferably, the step S3, i.e., fully mix the recycled fine aggregates obtained from step S2, Part A of the treated nature mud obtained from pretreatment in step S1, and metakaolin, then, fully mix the mixture with water, specifically includes the following operations:

Step S31: Mix the recycled fine aggregates obtained from step S2, nature mud obtained from pretreatment in step S1, and metakaolin based on the mass ratio of 100:5-10:0-5:2 to obtain a mixture;

Step S32: Mix the mixture with water in a mass ratio of 100:1-4. Add the water gradually Wbi866954 mixing until all the water is added. After that, cure the mixture for at least 7 days for further use.

Preferably, the step S5, i.e., mix the recycled coarse aggregates obtained from step S4, Part B of the recycled fine aggregates obtained from step S3, the treated nature mud, Cement and water obtained from step S1 with water reducing agent to ultimately obtain the desired product, i.e., green concrete products, specifically includes the following steps:

Step S51: Fully mix the recycled coarse aggregate obtained from step S4 and the recycled fine aggregate obtained from step S3;

Step S52: Continue to add the nature mud treated in step S1 and mix thoroughly;

Step S53: Add water and water reducing agent and fully mix them to finally obtain target product, 1.e., green concrete products;

In this process, the weight ratio of the recycled coarse aggregates obtained from step S4, the recycled fine aggregates obtained from step S3, the treated nature mud obtained from step S1, as well as cement, water, and water reducing agent is 65-75:190-200:20-30:90-110:35-40: 2-4.

Preferably, the cement mentioned above is ultra-fine cement, with a median particle diameter (D50) of less than lum and a maximum particle size not exceeding 18um. More than 80% of the particles have a size below Sum.

Preferably, the water reducing agent is anti-mud high-range water reducing agent.

Preferably, the metakaolin mentioned above is obtained by grinding kaolinite and calcining it at atemperature of 600-900°C. It has a fineness of 4000-18000m*/Kg.

Preferably, the weight ratio of Part A and Part B is 100:(50-200).

The invention shall include at least the following beneficial effects: (1) The present invention utilizes a large amount of waste materials such as waste concrete and nature mud from rivers, lakes, and seas as raw materials, thereby effectively disposing of a significant amount of construction waste. It not only achieves the resource reuse of construction waste but also reduces the high energy consumption associated with traditional methods, which makes it a green recycling technology. The concrete produced from this invention can be widely used for rural cement concrete pavements and low-grade roads, and used as non-structural concrete, thereby offering broad applications and significant benefits. (2) In addressing the issue of waste concrete fine aggregates and dredged nature mud, the present invention avoids the problems existing in traditional techniques (e.g., making ceramic particles, bricks, and roadbeds) such as low added value, high energy consumption, intense market competition,

and the need for the acceptance by downstream projects, which maximizes the value of construtt506954 waste and demonstrates noticeable economic benefits. (3) The present invention utilizes the expansive components in nature mud (or adds a small amount of calcined metakaolin if lacking such expansive components), and the expansive 5 components are dry mixed with the recycled fine aggregates to fill the voids in the fine aggregates. By spraying a small amount of water, the expansive components in the voids expand to provide expansive force, so as to effectively improve the issue of low strength in recycled fine aggregates by densely filling the voids in the fine aggregates. (4) In the present invention, the waste concrete is utilized in a full-grade manner, thereby avoiding the conventional practice of using fine aggregates solely for base course, which minimize the repeated transportation costs and loss in added value due to the downgrading use of materials. (5) The concrete prepared by the present invention is able to consume approximately 40% waste concrete and over 5% nature mud while ensuring a concrete strength of not less than 30MPa.

Compared to ordinary C30 concrete, this method saves approximately 45% new construction materials.

Other advantages, objectives and characteristics of the invention will be partly explained below and partly understood by the technical personnel in the field through the research and practice of the invention.

Detailed Description of the Preferred Embodiments

A more detailed description for the invention is given below by combining with the embodiments to command the technical personnel in this field to implement by referring to the contents of the Specification.

The following description is intended to illustrate the invention to enable technicians of the field to embody the invention. The preferred embodiments described below are only examples, and technicians of the field can think of other obvious variations. The basic principles of the invention defined in the following descriptions may be applied to other embodiments, variations, improvements, equivalents and other technical schemes that do not deviate from the spirit and scope of the invention.

It also should be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, and in another embodiments, the number of the element may be multiple, so the term "one" should not be understood as a limitation of quantity.

Embodiment 1: (1) Nature mud pretreatment:

After filtering the sediment from rivers, lakes, and seas through a 10cm sieve, add 6 pieceW506954 calcium lime for every 100 pieces of nature mud (including water weight), mix it and keep it standing for 2 days. After drying, grind it to a particle size below 0.08mm for further use, and divide it into two parts, i.e., Part A and Part B. (2) Waste concrete crushing 1) Initially crush the waste concrete and clear away the foreign matters in it such as rebar; 2) Conduct secondary crushing for above waste concrete to obtain mixture with a diameter of less than 35cm; 3) Sieve above mixture with a Smm square-hole sieve to obtain recycled coarse aggregate and recycled fine aggregate respectively. (3) Treatment of recycled fine aggregates 1) Fully mix the recycled fine aggregates with Part A of the pre-treated nature mud obtained from step (1) in a ratio of fine aggregates : nature mud : cement = 100:10:2. 2) Mix above mixture with water in a ratio of 100:3, add water by spraying while continuously mixing the mixture until all the water is added. After that, cure the mixture for at least 7 days for further use. (4) Treatment of recycled coarse aggregates

Spray water to the recycled coarse aggregates to keep the saturated surface of coarse aggregates dry. (5) Preparation of green concrete products

Mix the recycled coarse aggregates and ordinary aggregates from (4), recycled fine aggregates from (3), Part B of pre-treated nature mud from (1), as well as cement, water, and water reducing agent in a ratio of 65:210:190:20:110:35:3. When mixing, mix the recycled coarse aggregates, ordinary aggregates, and recycled fine aggregates thoroughly for 1min, then, add the nature mud and cement and mix them for another 1min, finally, add water and water reducing agent and mix them for 3min to obtain green concrete products containing nature mud and full-grade waste concrete.

The green concrete products containing nature mud and full-grade waste concrete is finally obtained. In this embodiment, the total weight of the consumed full-grade waste concrete is approximately 40.3%, the weight of the absolutely dried nature mud is approximately 5.9% of the total weight, and the compressive strength is approximately 39.5MPa.

Embodiment 2: (1) Nature mud pretreatment:

After filtering the sediment from rivers, lakes, and seas through a 10cm sieve, add 16 piece506954 calcium lime for every 100 pieces of nature mud (including water weight), mix it and keep it standing for 4 days. After drying, grind it to a particle size below 0.08mm for further use, and divide it into two parts, i.e., Part A and Part B. (2) Waste concrete crushing 1) Initially crush the waste concrete and clear away the foreign matters in it such as rebar; 2) Conduct secondary crushing for above waste concrete to obtain mixture with a diameter of less than 35cm; 3) Sieve above mixture with a Smm square-hole sieve to obtain recycled coarse aggregate and recycled fine aggregate respectively. (3) Treatment of recycled fine aggregates 1) Fully mix the recycled fine aggregates with Part A of the pre-treated nature mud obtained from step (1) in a ratio of fine aggregates : nature mud : metakaolin : cement = 100:5:5:2; 2) Mix above mixture with water in a ratio of 100:2, add water by spraying while continuously mixing the mixture until all the water is added. After that, cure the mixture for at least 7 days for further use. (4) Treatment of recycled coarse aggregates

Mix the recycled coarse aggregates and ordinary aggregates from (4), recycled fine aggregates from (3), Part B of pre-treated nature mud from (1), as well as cement, water, and water reducing agent in a ratio of 75:190:200:30:110:40:4. When mixing, mix the recycled coarse aggregates, ordinary aggregates, and recycled fine aggregates thoroughly for 1min, then, add the nature mud and cement and mix them for another 1min, finally, add water and water reducing agent and mix them for 3min to obtain green concrete products containing nature mud and full-grade waste concrete.

The green concrete products containing nature mud and full-grade waste concrete is finally obtained. In this embodiment, the total weight of the consumed full-grade waste concrete is approximately 43.4%, the weight of the absolutely dried nature mud is approximately 7.6% of the total weight, and the compressive strength is approximately 30.4MPa.

Embodiment 3: (1) Nature mud pretreatment:

After filtering the sediment from rivers, lakes, and seas through a 10cm sieve, add 10 pieckS06954 calcium lime for every 100 pieces of nature mud (including water weight), mix it and keep it standing for 4 days. After drying, grind it to a particle size below 0.08mm for further use, and divide it into two parts, i.e., Part A and Part B. (2) Waste concrete crushing 1) Initially crush the waste concrete and clear away the foreign matters in it such as rebar; 2) Conduct secondary crushing for above waste concrete to obtain mixture with a diameter of less than 35cm; 3) Sieve above mixture with a Smm square-hole sieve to obtain recycled coarse aggregate and recycled fine aggregate respectively. (3) Treatment of recycled fine aggregates 1) Fully mix the recycled fine aggregates with Part A of the pre-treated nature mud obtained from step (1) in a ratio of fine aggregates : nature mud : metakaolin : cement = 100:10:5:2; 2) Mix above mixture with water in a ratio of 100:3, add water by spraying while continuously mixing the mixture until all the water is added. After that, cure the mixture for at least 7 days for further use. (4) Treatment of recycled coarse aggregates

Mix the recycled coarse aggregates and ordinary aggregates from (4), recycled fine aggregates from (3), Part B of pre-treated nature mud from (1), as well as cement, water, and water reducing agent in a ratio of 70:200:195:30:90:40:4. When mixing, mix the recycled coarse aggregates, ordinary aggregates, and recycled fine aggregates thoroughly for 1min, then, add the nature mud and cement and mix them for another 1min, finally, add water and water reducing agent and mix them for 3min to obtain green concrete products containing nature mud and full-grade waste concrete.

The green concrete products containing nature mud and full-grade waste concrete is finally obtained. In this embodiment, the total weight of the consumed full-grade waste concrete is approximately 41.9%, the weight of the absolutely dried nature mud is approximately 8.8% of the total weight, and the compressive strength is approximately 31.2MPa.

Embodiment 4: (1) Nature mud pretreatment:

After filtering the sediment from rivers, lakes, and seas through a 10cm sieve, add 10 pieckS06954 calcium lime for every 100 pieces of nature mud (including water weight), mix it and keep it standing for 5 days. After drying, grind it to a particle size below 0.08mm for further use, and divide it into two parts, i.e., Part A and Part B. (2) Waste concrete crushing 1) Initially crush the waste concrete and clear away the foreign matters in it such as rebar; 2) Conduct secondary crushing for above waste concrete to obtain mixture with a diameter of less than 35cm; 3) Sieve above mixture with a Smm square-hole sieve to obtain recycled coarse aggregate and recycled fine aggregate respectively. (3) Treatment of recycled fine aggregates 1) Fully mix the recycled fine aggregates with Part A of the pre-treated nature mud obtained from step (1) in a ratio of fine aggregates : nature mud : metakaolin : cement = 100:5:5:2; 2) Mix above mixture with water in a ratio of 100:2, add water by spraying while continuously mixing the mixture until all the water is added. After that, cure the mixture for at least 7 days for further use. (4) Treatment of recycled coarse aggregates

Mix the recycled coarse aggregates and ordinary aggregates from (4), recycled fine aggregates from (3), Part B of pre-treated nature mud from (1), as well as cement, water, and water reducing agent in a ratio of 70:205:190:20:100:35:4. When mixing, mix the recycled coarse aggregates, ordinary aggregates, and recycled fine aggregates thoroughly for 1min, then, add the nature mud and cement and mix them for another 1min, finally, add water and water reducing agent and mix them for 3min to obtain green concrete products containing nature mud and full-grade waste concrete.

The green concrete products containing nature mud and full-grade waste concrete is finally obtained. In this embodiment, the total weight of the consumed full-grade waste concrete is approximately 41.1%, the weight of the absolutely dried nature mud is approximately 7.1% of the total weight, and the compressive strength is approximately 34. 1MPa.

In conclusion, it can be seen from the data of embodiments 1-4 that the concrete prepared by the present invention is able to consume approximately 40% waste concrete and over 5% nature mud while ensuring a concrete strength of not less than 30MPa. Compared to ordinary C30 concretel tHi86954 method saves approximately 45% construction materials, posing a good application prospect.

The implementation plan of the invention has been disclosed as above, but it is not limited to the application listed in the specification and embodiment mode. It can be fully applied to various fields suitable for the invention. For those who are familiar with the field, additional modifications can be easily realized. So, the invention is not limited to specific details and illustrations shown and described here without departing from the general concept defined by the claim and the equivalent range.

Claims

Claims LU506954

1. The production of green concrete products with natural mud and waste concrete comprises the following steps: Step S1: Nature mud pretreatment Mix the nature mud with calcium lime, and keep it standing, dry it, and then grind it to obtain treated nature mud and divide it into two parts, i.e., Part A and Part B; Step S2: Waste concrete crushing Remove the foreign matters from waste concrete and then crushed and crush and sieve it to obtain recycled coarse aggregates and recycled fine aggregates; Step S3: Treatment of recycled fine aggregates Fully mix the recycled fine aggregates obtained from step S2, Part A of the treated nature mud obtained from pretreatment in step S1, and metakaolin and cement, then, fully mix the mixture with water; Step S4: Treatment of recycled coarse aggregates Spray water to the recycled coarse aggregates obtained from step S2 to keep the saturated surface of coarse aggregates dry; Step SS: Preparing green concrete products Mix the recycled coarse aggregates obtained from step S4, recycled fine aggregates obtained from step S3, Part B of treated nature mud, cement and water obtained from step S1 with water reducing agent to ultimately obtain the desired product, 1.e., green concrete products.

2. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics as specified in step SI, i.e., mix the nature mud with calcium lime, and keep it standing, dry it, and then grind it, comprising the following operations: Sieve the nature mud, and then mix the sieved nature mud with calcium lime in a weight ratio of 100:6-16, and keep it standing and dry it. After it is dried, grind it to a particle size of 0.08mm for further use.

3. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics as specified in step S2, i.e., remove the LU506954 foreign matters from waste concrete and then crushed and crush and sieve it to obtain recycled coarse aggregates and recycled fine aggregates, comprising the following operations: Step S21: Initially crush the waste concrete and clear away the foreign matters in it; Step S22: Continue the secondary crushing to obtain mixture with a diameter of less than 35cm; Step S23: Further sieve the mixture obtained in step S22 to obtain recycled coarse aggregate and recycled fine aggregate respectively.

4. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics as specified in step S3, 1.e., fully mix the recycled fine aggregates obtained from step S2, Part A of the treated nature mud obtained from pretreatment in step S1, and metakaolin, then, fully mix the mixture with water, specifically includes the following operations: Step S31: Mix the recycled fine aggregates obtained from step S2, nature mud obtained from pretreatment in step S1, and metakaolin based on the mass ratio of 100:5-10:0-5:2 to obtain a mixture; Step S32: Mix the mixture with water in a mass ratio of 100:1-4. Add the water gradually while mixing until all the water is added. After that, cure the mixture for at least 7 days for further use.

5. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics as specified in step S5, i.e., mix the recycled coarse aggregates obtained from step S4, recycled fine aggregates obtained from step S3, Part B of treated nature mud, cement and water obtained from step S1 with water reducing agent to ultimately obtain the desired product, i.e., green concrete, specifically including the following steps: Step S51: Fully mix the recycled coarse aggregate obtained from step S4 and the recycled fine aggregate obtained from step S3; Step S52: Continue to add the nature mud treated in step S1 and mix thoroughly; Step S53: Add water and water reducing agent and fully mix them to finally obtain target product, i.e., green concrete products; LU506954 In this process, the weight ratio of the recycled coarse aggregates obtained from step S4, the recycled fine aggregates obtained from step S3, Part B of treated nature mud obtained from step S1, as well as cement, water, and water reducing agent is 65-75:190-200:20-30:90-110:35-40:2-4.

6. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics that the cement mentioned above is ultra-fine cement, with a median particle diameter (D50) of less than lum and a maximum particle size not exceeding 18um. More than 80% of the particles have a size below Sum.

7. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics that the water reducing agent is anti-mud high-range water reducing agent.

8. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics that the metakaolin mentioned above is obtained by grinding kaolinite and calcining it at a temperature of 600-900°C. It has a fineness of 4000-18000m*Kg.

9. As described in Claim 1, the production of green concrete products with natural mud and waste concrete has the characteristics that the weight ratio of Part A and Part B is 100:(50-200).