Hydraulic lime-based mortar with plant growth inhibition function as well as preparation method and application of hydraulic lime-based mortar

Abstract

The invention belongs to the technical field of building material protection, and discloses hydraulic lime-based mortar with a plant growth inhibition function as well as a preparation method and application of the hydraulic lime-based mortar. The hydraulic lime-based mortar disclosed by the invention is prepared from the following components in parts by mass: 60 to 90 parts of hydraulic lime, 1 to 3 parts of modified bentonite, 20 to 40 parts of slaked lime, 200 to 250 parts of calcium fine aggregate, 0.01 to 0.02 part of air entraining agent, 0.1 to 0.2 part of thickening agent, 0.1 to 0.2 part of water reducing agent and 45 to 60 parts of water. The hydraulic lime-based mortar obtained by the invention can effectively inhibit plant growth, also retains the self-healing property and air permeability of a lime material, has good strength, weather resistance and aging resistance, and is especially suitable for building structures and outer walls needing to be prevented from being damaged by plants for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of building material protection, and in particular to a hydraulic lime-based mortar with a plant growth inhibition function, and a preparation method and application thereof. Background Art

[0002] Cultural relics buildings are often damaged by plant growth. Plant growth has many harmful effects on cultural relics buildings, including physical damage, chemical corrosion and biological weathering. These hazards not only affect the beauty and cultural value of the buildings, but also pose a serious threat to their structural integrity. This is mainly manifested in the growth of plants in the cracks of tiles, wooden structures and masonry structures of ancient buildings, especially in summer. On the one hand, the roots of plants have a strong growth ability and can penetrate into the tiny cracks, joints and pores of building materials. As the roots expand, the swelling pressure they generate can cause cracking, falling off and loosening of stones, bricks and mortar, and even cause more serious structural damage, especially in rainy seasons or humid environments. The roots absorb a lot of water and expand, which will aggravate the stress concentration of the building structure and increase the risk of damage. On the other hand, plant growth can also accelerate the weathering of building materials through chemical reactions. The roots and stems and leaves of many plants will secrete organic acids, such as oxalic acid, tannic acid and humic acid. These acidic substances can react with calcium carbonate, silicate and other components in building materials, thereby eroding common building materials such as lime, sandstone and granite. Long-term chemical erosion will make materials loose and fragile, resulting in a significant decrease in the durability of building materials. In addition, moisture-loving plants such as mosses, algae and lichens will form a moist biofilm on the surface of the building, increasing the surface humidity. This moist environment provides ideal conditions for the growth and reproduction of microorganisms, further exacerbating the biological weathering of materials. Algae and mosses will not only change the color of the building surface, affecting the appearance, but may also keep the building in a moist state for a long time by constantly absorbing and retaining moisture, thereby accelerating the erosion and decay of materials.

[0003] The facades and roofs of cultural relics buildings are mostly made of traditional air-hardening lime as a bonding material. Traditional air-hardening lime is widely used in cultural relics buildings because of its good compatibility with traditional building materials (such as bricks, tiles, stones, wood, etc.). However, as an air-hardening cementitious material, traditional air-hardening lime has the disadvantages of low strength, poor frost resistance, and poor water resistance, which greatly reduces the durability of cultural relics buildings.

[0004] Therefore, it is of great significance to develop a hydraulic lime-based mortar with good compatibility with the original materials of cultural relics buildings, moderate strength, good durability and plant growth inhibition effect, as well as a preparation method and application thereof. Summary of the invention

[0005] In view of this, the present invention provides a hydraulic lime-based mortar with plant growth inhibition function and a preparation method and application thereof, the purpose of which is to solve the problem of poor durability of cultural relics buildings caused by low strength, poor frost resistance and poor water resistance of traditional air-hardening lime.

[0006] The present invention provides a hydraulic lime-based mortar having a plant growth inhibition function, wherein the hydraulic lime-based mortar comprises the following components in parts by mass:

[0007] 60-90 parts of hydraulic lime, 1-3 parts of modified bentonite, 20-40 parts of slaked lime, 200-250 parts of calcium fine aggregate, 0.01-0.02 parts of air entraining agent, 0.1-0.2 parts of thickener, 0.1-0.2 parts of water reducer, 45-60 parts of water.

[0008] Preferably, the preparation method of the modified bentonite comprises the following steps:

[0009] 1) mixing a plant growth inhibitor with anhydrous ethanol to obtain a plant growth inhibitor solution;

[0010] 2) Adding bentonite to the plant growth inhibitor solution under stirring, followed by drying to obtain modified bentonite.

[0011] Preferably, the usage ratio of the plant growth inhibitor, anhydrous ethanol and bentonite is 1-3 g:100 mL:1-3 g;

[0012] In the step 1), the plant growth inhibitor is imidacloprid and / or pretilachlor.

[0013] Preferably, in step 2), the stirring speed is 250-350 rpm, the stirring temperature is 30-40° C., and the stirring time is 25-35 min.

[0014] Preferably, in step 2), the drying temperature is 50-70° C. and the drying time is 6-12 hours.

[0015] Preferably, the air entraining agent is dodecyltrimethylammonium bromide, the thickener is carboxypropyl methylcellulose ether, and the water reducer is a polycarboxylate water reducer.

[0016] The present invention also provides a method for preparing the hydraulic lime-based mortar having a plant growth inhibition function, comprising the following steps:

[0017] Natural hydraulic lime-based mortar is obtained by mixing hydraulic lime, modified bentonite, slaked lime, calcium fine aggregate, air entraining agent, thickener, water reducing agent and water.

[0018] Preferably, the mixing time is 100 to 150 seconds, and the mixing speed is 130 to 300 rpm.

[0019] The present invention also provides application of the hydraulic lime-based mortar with plant growth inhibition function in building protection.

[0020] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention uses bentonite as a carrier to prepare a slow-release plant growth inhibitor, and combines the advantages of traditional natural hydraulic lime to provide a long-lasting, environmentally friendly, and hydraulic lime-based mortar with good construction performance. The material can not only effectively inhibit plant growth, but also retain the self-healing and air permeability of the lime material, and has a wide range of application prospects.

[0022] By adsorbing the plant growth inhibitor onto bentonite, the present invention achieves a slow-release function of the plant growth inhibitor. The layered structure of bentonite enables it to gradually release the adsorbed inhibitor, thereby continuously exerting the plant growth inhibitory effect over a long period of time. This long-term release reduces the frequency of repeated applications and improves the durability of the inhibitory effect.

[0023] The preparation process of the present invention is relatively simple, involving conventional stirring, filtering and drying steps, and is easy to implement on an industrial scale. At the same time, anhydrous ethanol is used as a solvent in the preparation process, which is relatively environmentally friendly and has little impact on the environment. In addition, raw materials such as bentonite and hydraulic lime are all natural minerals and have good environmental properties. Modified bentonite adsorbed with plant inhibitors is added to a mixed system of hydraulic lime and slaked lime, which not only retains the air permeability and self-healing properties of the lime-based material, but also gives it a plant growth inhibition function. The hydraulic lime-based mortar prepared by the present invention has good strength, weather resistance and anti-aging properties, and is particularly suitable for building structures and exterior walls that need to be protected from plant invasion for a long time. DETAILED DESCRIPTION

[0024] The present invention provides a hydraulic lime-based mortar having a plant growth inhibition function, wherein the hydraulic lime-based mortar comprises the following components in parts by mass:

[0025] 60-90 parts of hydraulic lime, 1-3 parts of modified bentonite, 20-40 parts of slaked lime, 200-250 parts of calcium fine aggregate, 0.01-0.02 parts of air entraining agent, 0.1-0.2 parts of thickener, 0.1-0.2 parts of water reducer, 45-60 parts of water.

[0026] In the present invention, the mass fraction of the hydraulic lime is preferably 65 to 85 parts, more preferably 70 to 80 parts, and more preferably 75 to 78 parts. The mass fraction of the modified bentonite is preferably 1.5 to 2.5 parts, more preferably 1.8 to 2.4 parts, and more preferably 2 to 2.2 parts. The mass fraction of the slaked lime is preferably 24 to 38 parts, more preferably 28 to 35 parts, and more preferably 30 to 32 parts. The mass fraction of the calcium fine aggregate is preferably 205 to 240 parts, more preferably 210 to 235 parts, and more preferably 220 to 230 parts. The mass fraction of the air entraining agent is preferably 0.012-0.018 parts, more preferably 0.014-0.016 parts, more preferably 0.015 parts, the mass fraction of the thickener is preferably 0.12-0.18 parts, more preferably 0.14-0.16 parts, more preferably 0.15 parts, the mass fraction of the water reducer is preferably 0.12-0.18 parts, more preferably 0.14-0.16 parts, more preferably 0.15 parts, and the mass fraction of water is preferably 48-58 parts, more preferably 50-55 parts, more preferably 52-54 parts.

[0027] In the present invention, the hydraulic lime is preferably natural hydraulic lime.

[0028] In the present invention, the preparation method of the modified bentonite comprises the following steps:

[0029] 1) mixing a plant growth inhibitor with anhydrous ethanol to obtain a plant growth inhibitor solution;

[0030] 2) Adding bentonite to the plant growth inhibitor solution under stirring, followed by drying to obtain modified bentonite.

[0031] In the present invention, the bentonite is preferably calcium-based bentonite.

[0032] In the present invention, the usage ratio of the plant growth inhibitor, anhydrous ethanol and bentonite is preferably 1-3 g:100 mL:1-3 g, more preferably 1.2-2.5 g:100 mL:1.5-2.5 g, and more preferably 1.8-2 g:100 mL:2-2.2 g;

[0033] In the step 1), the plant growth inhibitor is preferably imidacloprid and / or pretilachlor. When the plant growth inhibitor is imidacloprid and pretilachlor, the mass ratio of imidacloprid to pretilachlor is preferably 1:1.

[0034] In the present invention, in the step 2), the stirring speed is preferably 250 to 350 rpm, more preferably 280 to 340 rpm, more preferably 300 to 320 rpm, the stirring temperature is preferably 30 to 40° C., more preferably 32 to 38° C., more preferably 35 to 36° C., and the stirring time is preferably 25 to 35 min, more preferably 27 to 32 min, more preferably 28 to 30 min;

[0035] In the present invention, in the step 2), the stirring is preferably carried out in a water bath environment; before the drying, solid-liquid separation and washing are carried out, the washing reagent is preferably water, the number of washings is preferably 3 to 5 times, more preferably 4 times, and the purpose of washing is to remove the plant growth inhibitor solution remaining on the solid surface after solid-liquid separation; after the drying, grinding is carried out, and the particle size of the product after grinding is preferably ≤90μm, more preferably ≤85μm, and more preferably ≤80μm.

[0036] In the present invention, in the step 2), the drying temperature is preferably 50-70°C, more preferably 55-65°C, more preferably 58-60°C, and the drying time is preferably 6-12h, more preferably 7-10h, more preferably 8-9h; the drying is preferably vacuum drying, and the vacuum degree of vacuum drying is preferably 8-12Pa, more preferably 9-11Pa, more preferably 10Pa.

[0037] In the present invention, the calcareous fine aggregate is preferably limestone machine-made sand, the continuous grading of the limestone machine-made sand is preferably 0.075-1.5 mm, more preferably 0.080-1.4 mm, more preferably 0.085-1.35 mm, the particle shape of the limestone machine-made sand is preferably pointed sand, and spherical or nearly spherical round sand is avoided; the limestone machine-made sand is preferably cleaned, screened and dried before use to remove particles with a particle size of less than 0.075 mm in the limestone machine-made sand, the cleaning agent is water, the screening is preferably through a 200 mesh sieve, the drying time is preferably 20-26 h, more preferably 21-25 h, more preferably 22-24 h, the drying temperature is preferably 100-110 ° C, more preferably 102-108 ° C, more preferably 105-106 ° C.

[0038] In the present invention, the air entraining agent is preferably dodecyltrimethylammonium bromide, the thickener is preferably carboxypropyl methylcellulose ether, and the water reducer is preferably a polycarboxylate water reducer.

[0039] The present invention also provides a method for preparing the hydraulic lime-based mortar having a plant growth inhibition function, comprising the following steps:

[0040] Natural hydraulic lime-based mortar is obtained by mixing hydraulic lime, modified bentonite, slaked lime, calcium fine aggregate, air entraining agent, thickener, water reducing agent and water.

[0041] In the present invention, the mixing time is preferably 100 to 150 s, more preferably 110 to 140 s, more preferably 120 to 130 s, and the mixing speed is preferably 130 to 300 rpm, more preferably 180 to 250 rpm, more preferably 200 to 220 rpm.

[0042] In the present invention, the mixing order is preferably to first mix hydraulic lime, slaked lime and calcium fine aggregate to obtain a mixed powder, then mix modified bentonite, air entraining agent, thickener, water reducer and water to obtain a mixed solution, and finally mix the mixed powder with the mixed solution.

[0043] In the present invention, the mixing of the mixed powder and the mixed solution is preferably carried out in a stirring pot, and the mixing of the mixed powder and the mixed solution is preferably carried out in sequence by low-speed stirring, first high-speed stirring, stopping stirring and second high-speed stirring;

[0044] The rotation speed of the low-speed stirring is preferably 130-150rpm, more preferably 135-145rpm, more preferably 140-142rpm, and the time of the low-speed stirring is preferably 25-35s, more preferably 27-32s, and more preferably 28-30s; the rotation speeds of the first high-speed stirring and the second high-speed stirring are independently preferably 270-300rpm, more preferably 275-290rpm, and more preferably 280-285rpm, the time of the first high-speed stirring is preferably 25-35s, more preferably 27-32s, and more preferably 28-30s, and the time of the second high-speed stirring is preferably 50-80s, more preferably 60-75s, and more preferably 65-70s; the time of the stop stirring is preferably 80-100s, more preferably 85-95s, and more preferably 90-92s. During the stop stirring process, a rubber scraper is used to scrape the mortar on the blades and the pot wall into the middle of the pot within the first 15s.

[0045] The present invention also provides application of the hydraulic lime-based mortar with plant growth inhibition function in building protection.

[0046] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0047] In the embodiment of the present invention, the natural hydraulic lime is NHL5 produced by StAstier Company of France, and its chemical composition is shown in Table 1, and its apparent density is 0.85 g / cm 3, the 28-day compressive strength is 5-15MPa, which meets the requirements of European standard EN459-12010;

[0048] Table 1 Chemical composition of natural hydraulic lime

[0049] Element <![CDATA[SiO2(%)]]> CaO(%) <![CDATA[Fe2O3(%)]]> <![CDATA[SO3(%)]]> <![CDATA[K2O(%)]]> content 36.56 62.00 0.64 0.56 0.24

[0050] Bentonite was produced from Shanghai Adamas Reagent Co., Ltd., with a cation exchange capacity of 0.82 mmol / g;

[0051] The calcareous fine aggregate is sharp-angled limestone machine-made sand with a continuous grading of 0.075 to 1.5 mm;

[0052] The air entraining agent is dodecyltrimethylammonium bromide, purity ≥99%;

[0053] The thickener is carboxypropyl methyl cellulose ether powder, produced by BASF (China) Co., Ltd., with a purity of ≥99%;

[0054] The water reducer is polycarboxylate water reducer powder 556P, produced by Sika (China) Co., Ltd.

[0055] Example 1

[0056] The raw materials for the preparation of this embodiment are as follows:

[0057] 80 parts of natural hydraulic lime, 1 part of modified bentonite, 20 parts of slaked lime, 250 parts of sharp-angle limestone machine-made sand, 0.01 parts of dodecyltrimethylammonium bromide, 0.1 parts of carboxypropyl methylcellulose ether powder, 0.1 parts of polycarboxylate water-reducing agent powder, and 50 parts of water;

[0058] The preparation steps are as follows:

[0059] The sharp-angled limestone machine-made sand was washed with water before use, passed through a 200-mesh sieve, and dried at 105°C for 24 hours;

[0060] 2 g of imidacloprid was mixed with 100 mL of anhydrous ethanol to obtain a plant growth inhibitor solution, 3 g of bentonite was added to the plant growth inhibitor solution stirred at 300 rpm in a water bath at 35° C., and the solution was filtered after continued stirring for 30 min. The solid obtained by filtration was washed three times with water to obtain bentonite adsorbed with the plant growth inhibitor, and the bentonite adsorbed with the plant growth inhibitor was vacuum dried at 60° C. at a vacuum degree of 10 Pa for 12 h, and then ground to a particle size of 80 μm to obtain modified bentonite;

[0061] Mixing natural hydraulic lime, slaked lime and sharp-angled limestone machine-made sand to obtain a mixed powder; mixing modified bentonite, dodecyltrimethylammonium bromide, carboxypropylmethylcellulose ether powder, polycarboxylate water-reducing agent powder and water to obtain a mixed solution;

[0062] The obtained mixed solution and mixed powder were placed in a stirring pot and stirred at 140 rpm for 30 s, then at 285 rpm for 30 s, and stopped stirring for 90 s (within the first 15 s of the stopping process, the mortar on the blades and the pot wall was scraped into the middle of the pot with a rubber scraper), and then stirred at 285 rpm for 60 s to obtain hydraulic lime-based mortar.

[0063] Example 2

[0064] The raw materials prepared in Example 1 are modified to "70 parts of natural hydraulic lime, 2 parts of modified bentonite, 30 parts of slaked lime, 250 parts of sharp-angle limestone machine-made sand, 0.01 parts of dodecyltrimethylammonium bromide, 0.1 parts of carboxypropyl methylcellulose ether powder, 0.1 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0065] Example 3

[0066] The raw materials prepared in Example 1 are modified to "60 parts of natural hydraulic lime, 3 parts of modified bentonite, 40 parts of slaked lime, 250 parts of sharp-angle limestone machine-made sand, 0.01 parts of dodecyltrimethylammonium bromide, 0.1 parts of carboxypropyl methylcellulose ether powder, 0.1 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0067] Example 4

[0068] The raw materials prepared in Example 1 are modified to "80 parts of natural hydraulic lime, 2 parts of modified bentonite, 20 parts of slaked lime, 250 parts of sharp-angle limestone machine-made sand, 0.01 parts of dodecyltrimethylammonium bromide, 0.1 parts of carboxypropyl methylcellulose ether powder, 0.1 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0069] Example 5

[0070] The raw materials prepared in Example 1 are modified to "70 parts of natural hydraulic lime, 3 parts of modified bentonite, 30 parts of slaked lime, 200 parts of sharp-angle limestone machine-made sand, 0.02 parts of dodecyltrimethylammonium bromide, 0.1 parts of carboxypropyl methylcellulose ether powder, 0.1 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0071] Example 6

[0072] The raw materials prepared in Example 1 are modified to "60 parts of natural hydraulic lime, 1 part of modified bentonite, 40 parts of slaked lime, 200 parts of sharp-angle limestone machine-made sand, 0.02 parts of dodecyltrimethylammonium bromide, 0.2 parts of carboxypropyl methylcellulose ether powder, 0.2 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0073] Example 7

[0074] The raw materials prepared in Example 1 are modified to "80 parts of natural hydraulic lime, 3 parts of modified bentonite, 20 parts of slaked lime, 200 parts of sharp-angle limestone machine-made sand, 0.02 parts of dodecyltrimethylammonium bromide, 0.2 parts of carboxypropyl methylcellulose ether powder, 0.2 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0075] Example 8

[0076] The raw materials prepared in Example 1 are modified to "70 parts of natural hydraulic lime, 1 part of modified bentonite, 30 parts of slaked lime, 200 parts of sharp-angle limestone machine-made sand, 0.02 parts of dodecyltrimethylammonium bromide, 0.2 parts of carboxypropyl methylcellulose ether powder, 0.2 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0077] Example 9

[0078] The raw materials prepared in Example 1 are modified to "60 parts of natural hydraulic lime, 2 parts of modified bentonite, 30 parts of slaked lime, 200 parts of sharp-angle limestone machine-made sand, 0.02 parts of dodecyltrimethylammonium bromide, 0.2 parts of carboxypropyl methylcellulose ether powder, 0.2 parts of polycarboxylic acid water-reducing agent powder, and 50 parts of water", and the other steps are the same as in Example 1.

[0079] The performance of the hydraulic lime-based mortars obtained in Examples 1 to 9 was tested, and the test results are shown in Table 2:

[0080] Compressive strength and fluidity: tested in accordance with EN 459-2-2021 "Building lime - Part 2: Test methods";

[0081] Weed inhibition rate and root inhibition rate: Tested in accordance with GB / T 17980-2000 "Guidelines for Field Efficacy Tests of Pesticides";

[0082] Residual period: Tested in accordance with GB / T 8321-2018 Guidelines for the Rational Use of Pesticides.

[0083] Table 2 Performance test results of hydraulic lime-based mortar obtained in Examples 1 to 9

[0084]

[0085] As can be seen from Table 2, the hydraulic lime-based mortar obtained by the present invention can effectively inhibit plant growth, retain the self-healing and air permeability of the lime material, and has good strength, weather resistance and anti-aging properties, and is suitable for building structures and exterior walls that require long-term protection from plant invasion.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hydraulic lime-based mortar with plant growth inhibition function, characterized in that: The hydraulic lime-based mortar comprises the following components in parts by weight: 60-90 parts of hydraulic lime, 1-3 parts of modified bentonite, 20-40 parts of slaked lime, 200-250 parts of calcium fine aggregate, 0.01-0.02 parts of air entraining agent, 0.1-0.2 parts of thickener, 0.1-0.2 parts of water reducer, 45-60 parts of water.

2. A hydraulic lime-based mortar with plant growth inhibition function according to claim 1, characterized in that: The preparation method of the modified bentonite comprises the following steps: 1) mixing a plant growth inhibitor with anhydrous ethanol to obtain a plant growth inhibitor solution; 2) Adding bentonite to the plant growth inhibitor solution under stirring, followed by drying to obtain modified bentonite.

3. The hydraulic lime-based mortar with plant growth inhibition function according to claim 2, characterized in that: The usage ratio of the plant growth inhibitor, anhydrous ethanol and bentonite is 1-3 g:100 mL:1-3 g; In the step 1), the plant growth inhibitor is imidacloprid and / or pretilachlor.

4. The hydraulic lime-based mortar with plant growth inhibition function according to claim 3, characterized in that: In the step 2), the stirring speed is 250-350 rpm, the stirring temperature is 30-40° C., and the stirring time is 25-35 min.

5. The hydraulic lime-based mortar with plant growth inhibition function according to claim 3, characterized in that: In the step 2), the drying temperature is 50-70° C. and the drying time is 6-12 hours.

6. The hydraulic lime-based mortar with plant growth inhibition function according to claim 1, characterized in that: The air entraining agent is dodecyl trimethyl ammonium bromide, the thickener is carboxypropyl methyl cellulose ether, and the water reducer is a polycarboxylate water reducer.

7. A method for preparing a hydraulic lime-based mortar having a plant growth inhibition function according to any one of claims 1 to 6, characterized in that: The steps include: Hydraulic lime, modified bentonite, slaked lime, calcium fine aggregate, air entraining agent, thickener, water reducing agent and water are mixed to obtain hydraulic lime-based mortar.

8. The method for preparing a hydraulic lime-based mortar having a plant growth inhibition function according to claim 7, characterized in that: The mixing time is 100 to 150 seconds, and the mixing speed is 130 to 300 rpm.

9. Use of the hydraulic lime-based mortar having plant growth inhibition function according to any one of claims 1 to 6 in building protection.

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