A method for modifying coral aggregate and modified coral aggregate planted concrete

Abstract

This invention discloses a method for modifying coral aggregate and modified coral aggregate planted concrete. The coral aggregate modification steps are as follows: Coral aggregate is soaked in a mixed solution of sodium dihydrogen phosphate and oxalic acid for 12-24 hours, and then dried to obtain modified coral aggregate. The planted concrete, by weight, comprises the following raw materials: 1000-1200 parts modified coral aggregate, 400-500 parts silicate cement, 10-15 parts rice husk ash, 8-15 parts diatomaceous earth, and 150-180 parts water. This invention utilizes coral to replace the aggregate required for planted concrete, making full use of my country's abundant marine resources and alleviating the shortage of natural aggregates. Taking advantage of the high water absorption of coral aggregate, it is pretreated to lower the pH value of the coral aggregate planted concrete. The addition of rice husk ash and diatomaceous earth improves the performance and strength of the coral aggregate planted concrete, achieving a balance between plant growth and structural protection and ecological conservation.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically a method for modifying coral aggregate and modified coral aggregate planted concrete. Background Technology

[0002] How to protect the ecological environment while meeting the needs of normal human life has become an urgent problem to be solved. Vegetated concrete is a new type of eco-friendly concrete material that allows vegetation to be planted on a porous concrete matrix. It can balance the growth of animals and plants with the needs of daily human life, achieving the goal of harmonious coexistence between concrete and plants and animals.

[0003] In vegetation concrete, aggregates typically account for over 80% of the total volume, thus requiring a large amount of aggregates for its preparation. The construction industry's consumption of natural aggregates from products like ordinary concrete and vegetation concrete is enormous, leading to a gradual depletion of natural aggregate reserves in many regions. Furthermore, the extraction of natural aggregates is complex, damaging topography and impacting the ecological environment. Therefore, finding suitable aggregate substitutes for natural aggregates is crucial for the widespread adoption of vegetation concrete. Coral debris from natural weathering or erosion, as well as from dredging channels or excavating foundations, is generally considered marine waste. In recent years, the utilization of coral waste as a resource has received considerable attention.

[0004] The strength of vegetation concrete primarily relies on the cement hydration reaction that binds the aggregates together. With a reasonable mix design, the higher the cement content, the higher the concrete strength. However, a higher cement content also leads to a higher content of soluble alkali released during the hydration reaction, resulting in a higher pH value for the vegetation concrete. Due to the rough, porous surface of coral aggregate and its numerous layered and cage-like structures, it has a large specific surface area. Consequently, the water and cement requirements for preparing concrete using coral aggregate are 30%-40% higher than for ordinary vegetation concrete. This results in an excessively high pH value for vegetation concrete prepared with coral aggregate. However, by utilizing the porous and highly absorbent properties of coral aggregate and pre-wetting it with acidic substances, the acidic substances in the coral aggregate can be released during the later curing period, thus reducing the alkalinity of the coral aggregate vegetation concrete. Coral aggregate is a natural lightweight aggregate. Without any admixtures, the strength of ordinary coral aggregate concrete prepared with coral aggregate is generally around C20. Therefore, the strength of coral aggregate vegetation concrete prepared with coral aggregate is even lower. Therefore, the present invention will provide a method for modifying coral aggregate and modified coral aggregate planted concrete to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention addresses the problem of excessively high pH values ​​caused by aggregates and coral aggregates in planted concrete by providing a method for modifying coral aggregates and resulting in modified coral aggregate planted concrete. This invention utilizes diatomaceous earth and rice husk ash to replace a portion of the cement, increasing the paste content and the bonding area and number of bonding points between the cement paste and aggregates. Rice husk ash not only has fine particles, providing a good micro-aggregate effect, filling porosity and improving strength, but also possesses pozzolanic activity, allowing it to undergo a secondary hydration reaction with the cement hydration product Ca(OH)2, generating a large amount of additional hydrated calcium silicate gel, improving the internal structure of the paste and increasing the strength of the cement paste. Diatomaceous earth's mineral composition is mainly opal and its variants, with organic matter content ranging from trace amounts to over 30%, exhibiting strong water absorption and permeability, providing favorable conditions for subsequent plant growth.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for modifying coral aggregate includes the following steps: soaking the coral aggregate in a mixed solution of sodium dihydrogen phosphate and oxalic acid for 12-24 hours, and then drying it to obtain modified coral aggregate.

[0008] As a preferred technical solution of the present invention, the particle size of the coral aggregate is 5-30mm.

[0009] As a preferred embodiment of the present invention, the sodium dihydrogen phosphate solution has a mass fraction of 3-4% and an oxalic acid mass fraction of 2-4%.

[0010] As a preferred technical solution of the present invention, the volume ratio of the sodium dihydrogen phosphate and oxalic acid mixed solution to the coral aggregate is 3:1.

[0011] As a preferred technical solution of the present invention, the volume ratio of sodium dihydrogen phosphate to oxalic acid in the mixed solution is 3:4, 1:1, or 1:2.

[0012] Another object of the present invention is to provide a method for preparing vegetation concrete using modified coral aggregate, wherein the vegetation concrete comprises the following raw materials by weight: 1000-1200 parts of modified coral aggregate, 400-500 parts of silicate cement, 10-15 parts of rice husk ash, 8-15 parts of diatomaceous earth, and 150-180 parts of water.

[0013] The method for preparing the vegetation concrete includes the following steps:

[0014] (1) Weigh out 1000-1200 parts of modified coral aggregate, 400-500 parts of silicate cement, 10-15 parts of rice husk ash, 8-15 parts of diatomaceous earth, and 150-180 parts of water by mass.

[0015] (2) First, put the coral aggregate into the mixer, add half of the cement, rice husk ash, diatomaceous earth and water-modified coral aggregate for pre-coating treatment, and mix for no less than 100 seconds. Then add the remaining raw materials and mix for no less than 180 seconds.

[0016] (3) The mixed modified coral aggregate planted concrete is molded and cured.

[0017] As a preferred technical solution of the present invention: the ash ratio of the planted concrete is 2.5 and the water-cement ratio is 0.5.

[0018] As a preferred technical solution of the present invention, the cement is P·O42.5.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention include:

[0020] 1. This invention utilizes coral as a substitute for aggregate in vegetation concrete, making full use of my country's abundant marine resources and alleviating the shortage of natural aggregates. Taking advantage of the high water absorption of coral aggregate, it is pretreated to lower the pH value of the coral aggregate vegetation concrete. The addition of rice husk ash and diatomaceous earth improves the performance and strength of the coral aggregate vegetation concrete, achieving a balance between plant growth and structural protection.

[0021] 2. This invention utilizes diatomaceous earth and rice husk ash to replace part of the cement, which increases the paste content, the bonding area between the cement paste and the aggregate, and the number of bonding points. Rice husk ash not only has fine particles, which can play a good micro-aggregate effect, fill the porosity, and improve the strength, but it also has pozzolanic activity, which can undergo a secondary hydration reaction with the cement hydration product Ca(OH)2 to generate a large amount of additional hydrated calcium silicate gel, which improves the internal structure of the paste and increases the strength of the cement paste. The mineral composition of diatomaceous earth is mainly opal and its variants, with an organic matter content ranging from trace amounts to more than 30%. It has properties such as strong water absorption and permeability, providing favorable conditions for later plant growth. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation process for modified coral aggregate.

[0023] Figure 2 The image shows the preparation and planting effect of coral aggregate-based planted concrete. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] A modified coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 12 parts of rice husk ash, 8 parts of diatomaceous earth, and 160 parts of water.

[0027] The preparation method of the modified coral aggregate is as follows:

[0028] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0029] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; the mass fraction of sodium dihydrogen phosphate is 3%, the mass fraction of oxalic acid is 2%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 3:4), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.20 MPa.

[0030] Example 2

[0031] A modified coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 12 parts of rice husk ash, 8 parts of diatomaceous earth, and 160 parts of water.

[0032] The preparation method of the modified coral aggregate is as follows:

[0033] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0034] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; wherein the mass fraction of sodium dihydrogen phosphate is 4%, the mass fraction of oxalic acid is 4%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 1:2), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.13 MPa.

[0035] Example 3

[0036] A modified coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1100 parts of 5-30mm modified coral aggregate, 450 parts of silicate cement, 10 parts of rice husk ash, 15 parts of diatomaceous earth, and 172 parts of water.

[0037] The preparation method of the modified coral aggregate is as follows:

[0038] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0039] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; the mass fraction of sodium dihydrogen phosphate is 4%, the mass fraction of oxalic acid is 2%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 1:1), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.09 MPa.

[0040] Example 4

[0041] A modified coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1200 parts of 5-30mm modified coral aggregate, 500 parts of silicate cement, 15 parts of rice husk ash, 13 parts of diatomaceous earth, and 180 parts of water.

[0042] The preparation method of the modified coral aggregate is as follows:

[0043] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0044] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; the mass fraction of sodium dihydrogen phosphate is 3%, the mass fraction of oxalic acid is 3%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 1:2), soak for 21 hours, and then air dry naturally for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.14 MPa.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that the coral aggregate is not modified, and the vegetation concrete does not include rice husk ash and diatomaceous earth.

[0047] A coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 12 parts of rice husk ash, 8 parts of diatomaceous earth, and 160 parts of water.

[0048] Comparative Example 2

[0049] The difference between this comparative example and Example 1 is that the coral aggregate is not modified.

[0050] A coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 12 parts of rice husk ash, 8 parts of diatomaceous earth, and 160 parts of water.

[0051] Comparative Example 3

[0052] The difference between this comparative example and Example 1 is that the coral aggregate was only modified with oxalic acid.

[0053] A modified coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 12 parts of rice husk ash, 8 parts of diatomaceous earth, and 160 parts of water.

[0054] The preparation method of the modified coral aggregate is as follows:

[0055] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0056] Step 2: Place the coral aggregate obtained in Step 1 into an oxalic acid solution (the volume ratio of oxalic acid solution to coral aggregate is 3:1; the mass fraction of oxalic acid is 2%), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.15 MPa.

[0057] Comparative Example 4

[0058] The difference between this comparative example and Example 1 is that the vegetation concrete does not include rice husk ash.

[0059] A modified coral aggregate planted concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 8 parts of diatomaceous earth, and 160 parts of water.

[0060] The preparation method of the modified coral aggregate is as follows:

[0061] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0062] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; the mass fraction of sodium dihydrogen phosphate is 3%, the mass fraction of oxalic acid is 2%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 3:4), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.20 MPa.

[0063] Comparative Example 5

[0064] The difference between this comparative example and Example 1 is that the vegetation concrete does not include diatomaceous earth. A modified coral aggregate vegetation concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, 8 parts of rice husk ash, and 160 parts of water.

[0065] The preparation method of the modified coral aggregate is as follows:

[0066] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0067] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; the mass fraction of sodium dihydrogen phosphate is 3%, the mass fraction of oxalic acid is 2%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 3:4), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.20 MPa.

[0068] Comparative Example 6

[0069] The difference between this comparative example and Example 1 is that the vegetation concrete does not include rice husk ash and diatomaceous earth. A modified coral aggregate vegetation concrete is composed of the following raw materials in parts by weight: 1000 parts of 5-30mm modified coral aggregate, 400 parts of silicate cement, and 160 parts of water.

[0070] The preparation method of the modified coral aggregate is as follows:

[0071] Step 1: Screen the original coral aggregate with a particle size of 5.0-30mm (the compressive strength of the coral aggregate is 2.1MPa), and dry the coral aggregate at 80℃ for 24 hours.

[0072] Step 2: Place the coral aggregate obtained in Step 1 into a mixed solution of sodium dihydrogen phosphate and oxalic acid (the volume ratio of the mixed solution of sodium dihydrogen phosphate and oxalic acid to the coral aggregate is 3:1; the mass fraction of sodium dihydrogen phosphate is 3%, the mass fraction of oxalic acid is 2%, and the volume ratio of sodium dihydrogen phosphate to oxalic acid is 3:4), soak for 12 hours, and then air dry for 2 hours to obtain modified coral aggregate. The compressive strength of the obtained modified coral aggregate is 2.20 MPa.

[0073] Comparative Example 6

[0074] Vegetated concrete was prepared according to the formulations of Examples 1-4 and Comparative Examples 1-6. The preparation method is as follows: First, the modified coral aggregate was placed in a mixer, and half of the cement (P·O42.5), rice husk ash, diatomaceous earth, and water were added. The modified coral aggregate was pre-coated with slurry (water-cement ratio of 0.5), and the mixing time was not less than 100 seconds. Then, the remaining raw materials were added and mixed for not less than 180 seconds. The mixed modified coral aggregate vegetated concrete was then molded and cured to obtain vegetated concrete.

[0075] The compressive strength and pH value of the prepared vegetation concrete were determined using conventional methods. The results are shown in Table 1.

[0076] Table 1: Performance test results of the modified coral aggregate planted concrete prepared according to the present invention

[0077]

[0078] In summary, this invention utilizes the high water absorption of coral aggregate to pre-treat it, thereby reducing the pH value of coral aggregate-grown concrete. The addition of rice husk ash and diatomaceous earth improves the performance and strength of the coral aggregate-grown concrete, achieving a balance between plant growth and structural protection. Furthermore, the modified coral aggregate preparation process is as follows: Figure 1 Preparation and planting experiments of coral aggregate planted concrete, such as Figure 2 As shown.

[0079] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the inventive concept, and all such substitutions or modifications should be considered within the scope of protection of the present invention.

Claims

1. A coral aggregate-based planted concrete, characterized in that: The vegetation concrete comprises the following raw materials by weight: 1000-1200 parts modified coral aggregate, 400-500 parts silicate cement, 10-15 parts rice husk ash, 8-15 parts diatomaceous earth, and 150-180 parts water. The steps for modifying coral aggregate are as follows: Soak the coral aggregate in a mixed solution of sodium dihydrogen phosphate and oxalic acid for 12-24 hours. After soaking, air dry to obtain modified coral aggregate. The mass fraction of sodium dihydrogen phosphate is 3-4%, and the mass fraction of oxalic acid is 2-4%.

2. The coral aggregate planted concrete according to claim 1, characterized in that: The coral aggregate has a particle size of 5-30mm.

3. The coral aggregate planted concrete according to claim 1, characterized in that: The volume ratio of the sodium dihydrogen phosphate and oxalic acid mixed solution to the coral aggregate is 3:

1.

4. The coral aggregate planted concrete according to claim 1, characterized in that: The volume ratio of sodium dihydrogen phosphate to oxalic acid in the mixed solution is 3:4, 1:1, or 1:

2.

5. The method for preparing coral aggregate planted concrete according to claim 1, characterized in that: Includes the following steps: (1) Weigh out 1000-1200 parts of modified coral aggregate, 400-500 parts of silicate cement, 10-15 parts of rice husk ash, 8-15 parts of diatomaceous earth, and 150-180 parts of water by mass. (2) First, put the modified coral aggregate into the mixer, add half of the cement, rice husk ash, diatomaceous earth and water to pre-coat the modified coral aggregate, and mix for no less than 100 seconds. Then add the remaining raw materials and mix for no less than 180 seconds. (3) The mixed coral aggregate planted concrete is molded and cured.

6. The method for preparing coral aggregate planted concrete according to claim 5, characterized in that: The planted concrete has a bone ash ratio of 2.5 and a water-cement ratio of 0.

5.

7. The method for preparing coral aggregate planted concrete according to claim 5, characterized in that: The cement is P·O42.5.

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