Self-leveling dry-mixed mortar and application

Abstract

The invention provides self-leveling dry-mixed mortar and application. The self-leveling dry-mixed mortar is prepared from the following components in parts by weight: 378 to 399 parts of cement, 81 to 85.5 parts of coal ash, 81 to 85.5 parts of modified waste bentonite cat litter, 756 to 798 parts of fine aggregate, 27 to 27.8 parts of waste bentonite cat litter filter residue powder and 17.6 to 18.8 parts of additive. The treated waste bentonite cat litter is used in the self-leveling dry-mixed mortar, so that the self-leveling dry-mixed mortar has longer setting time and better water-retaining property, the problems of'fast drying 'and'water loss' caused by tropical monsoon climate are solved, and meanwhile, the waste bentonite cat litter is fully utilized.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a self-leveling dry-mixed mortar and an application thereof. Background Art

[0002] In the construction industry, self-leveling dry-mix mortar is widely used in construction sites around the world due to its excellent fluidity and construction performance. However, this mortar has extremely high requirements for setting time and water retention, which are important factors to ensure its performance. There are many factors that affect these properties, including ambient temperature, humidity, and added admixtures. If not handled properly, the mortar may set too early or too late, leading to various problems such as cracks, insufficient strength, or too fast water loss. Especially in tropical monsoon climate areas, these problems are particularly prominent due to their unique climatic characteristics such as high temperatures and obvious dry and rainy seasons.

[0003] The tropical monsoon climate is mainly distributed in the southern part of my country. This climate makes these areas in a high temperature and dry environment for a long time, which poses a severe challenge to the performance of self-leveling dry-mix mortar. In such an environment, the setting time of the mortar will be shortened, resulting in premature setting and cracks. At the same time, the moisture in the mortar will evaporate faster, resulting in premature setting and water loss. These problems will not only affect the performance of the mortar, reduce its service life, but may even cause early damage.

[0004] Waste bentonite cat litter is the waste cat litter left after the cat's excrement is removed after using bentonite cat litter. Its main components are bentonite, cat urine and water. In recent years, the number of pet cats raised in my country has increased year by year. In 2022, the number of pet cats raised in my country has reached 65 million. Due to the large increase in the number of pet cats, the cat litter industry has also emerged. Bentonite cat litter accounts for 2 / 3 of the cat litter production. Since waste bentonite cat litter contains a large amount of bentonite, some urea and bacteria, etc., the discarded cat litter is usually piled up as waste, which not only wastes resources but also pollutes the environment. Therefore, in order to make full use of solid waste waste bentonite cat litter and respond to the national call for the construction of a "waste-free city", it is particularly important to explore the feasibility of waste bentonite cat litter in mortar.

[0005] In order to solve the problems of easy water loss and fast setting time of self-leveling mortar in tropical monsoon climate areas, the traditional method is to add admixtures such as retarders and water retainers to the mortar to prolong the setting time and improve water retention. However, in tropical monsoon climate areas, this method has limited effect, which not only affects the early strength and overall mechanical properties of self-leveling dry-mix mortar, but also increases the cost of mortar. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the deficiencies in the prior art, the present invention provides a self-leveling dry-mix mortar and its application. By using treated waste bentonite cat litter in the self-leveling dry-mix mortar, the mortar has a longer setting time and better water retention, thereby solving the problems of "quick drying" and "water loss" caused by the tropical monsoon climate. At the same time, the waste bentonite cat litter is fully utilized, thereby solving the problems raised in the above-mentioned background technology.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] According to a first aspect of the present invention, a self-leveling dry-mix mortar is provided, which comprises, by weight, 378 to 399 parts of cement, 81 to 85.5 parts of fly ash, 81 to 85.5 parts of modified waste bentonite cat litter, 756 to 798 parts of fine aggregate, 27 to 27.8 parts of waste bentonite cat litter filter residue powder, and 17.6 to 18.8 parts of an admixture.

[0011] Preferably, in parts by weight, the additive includes 10.8 to 11.4 parts of redispersible latex powder, 5.4 to 5.7 parts of water reducing agent and 1.4 to 1.7 parts of defoaming agent, and the relative defoaming rate of the defoaming agent in the present invention is 93%.

[0012] Preferably, the solid content of the redispersible latex powder is 98%;

[0013] The water reducing agent is selected from polycarboxylate water reducing agent powder, and the water reducing efficiency of the water reducing agent in the present invention is 25%;

[0014] The defoamer is selected from defoamer powders.

[0015] Preferably, the type of cement is selected from P.O42.5;

[0016] The fly ash is selected from Class II fly ash;

[0017] The fine aggregate is selected from machine-made sand, and the fineness modulus of the machine-made sand is 1.5.

[0018] Preferably, the preparation method of the modified waste bentonite cat litter and the waste bentonite cat litter filter residue powder is:

[0019] S1, drying the waste bentonite cat litter at a constant temperature of 45-55° C., ball milling, and sieving to obtain waste bentonite cat litter particles with a particle size of ≤0.15 mm;

[0020] S2, immersing the waste bentonite cat litter particles in industrial alcohol, filtering, and obtaining non-toxic waste bentonite cat litter small particles and waste bentonite cat litter alcohol filtrate;

[0021] S3, in an air atmosphere, the non-toxic waste bentonite cat litter particles are first kept at 290-310° C. for 0.45-0.55 h, then heated to 590-610° C., calcined for 2.45-2.55 h, and ball-milled to obtain modified waste bentonite cat litter powder with a particle size of ≤75 μm;

[0022] S4, subjecting the waste bentonite cat litter alcohol filtrate to vacuum distillation and crucible fine grinding to obtain waste bentonite cat litter filtrate residue powder with a particle size of ≤75 μm.

[0023] Preferably, the modified waste bentonite cat litter powder meets the following conditions:

[0024] (1) The modified waste bentonite cat litter powder includes montmorillonite, SiO 2 and Al 2 O 3 ;

[0025] (2) The specific surface area of ​​the modified waste bentonite cat litter powder is ≥450m 2 / kg;

[0026] (3) The activity index of the modified waste bentonite cat litter powder at 28 days is ≥70%.

[0027] Preferably, the waste bentonite cat litter filter residue powder meets the following conditions:

[0028] (1) The waste bentonite cat litter filter residue powder includes urea;

[0029] (2) The specific surface area of ​​the waste bentonite cat litter filter residue powder is ≥450m 2 / kg.

[0030] According to a second aspect of the present invention, there is provided a use of a self-leveling dry-mix mortar in a tropical monsoon climate.

[0031] The present invention adopts modified waste bentonite cat litter powder to replace part of cement. By taking advantage of its large specific surface area and small particle size, the micro-aggregate effect can be exerted in the mortar to improve the mortar density, thereby improving the strength of the mortar. In addition, the main components of the modified waste bentonite cat litter powder are montmorillonite and SiO 2 and Al 2 O 3 , not only can the water absorption property of montmorillonite be utilized to improve the water retention of mortar, but also the active SiO 2 and Al 2 O 3 It can participate in the hydration reaction and improve the early strength of the mortar. In addition, montmorillonite has a certain micro-expansion after absorbing water, which can effectively reduce the porosity inside the mortar, improve the pore structure, increase the early strength of the mortar, and significantly improve the mechanical properties of the mortar.

[0032] Waste bentonite cat litter filter residue powder is added to the mortar as a retarder. The effective component of waste bentonite cat litter filter residue powder is mainly urea, which can absorb heat when cement undergoes hydration reaction, absorb a large amount of hydration heat, thereby weakening the early hydration reaction of the mortar and extending the setting time of the mortar.

[0033] (III) Beneficial effects

[0034] The present invention provides a self-leveling dry-mix mortar and its application. It has the following beneficial effects:

[0035] 1. The self-leveling dry-mixed mortar provided in this scheme adopts low-temperature constant-temperature drying of waste bentonite cat litter, grinds it to a certain fineness, mixes it with alcohol, and then extracts the remaining urea component in the waste bentonite cat litter by vacuum distillation. After that, it grinds it again to obtain the waste bentonite cat litter filter residue powder, which can act as a retarder. When added to the mortar, it prolongs the setting time of the mortar, and gives full play to the characteristic of urea that can undergo endothermic reaction when it meets water, so that the self-leveling dry-mixed mortar will not quickly set due to high temperature in tropical monsoon climate areas, resulting in problems such as cracks, thereby effectively ensuring the excellent performance of the self-leveling dry-mixed mortar.

[0036] 2. The present invention makes full use of waste bentonite cat litter, obtains modified waste bentonite cat litter powder and waste bentonite cat litter filter residue powder respectively by high temperature modification and reduced pressure distillation, and utilizes the excellent water retention performance of modified waste bentonite cat litter powder and the effect of extending the setting time of mortar by waste bentonite cat litter filter residue powder, so that self-leveling mortar can be used normally in high temperature and dry tropical monsoon climate, and will not quickly set due to high temperature, and will not quickly lose water due to drying, effectively ensuring the setting time and water retention of self-leveling dry-mixed mortar, and improving its mechanical properties. In addition, direct stacking or landfilling of waste bentonite cat litter will have a negative effect on the ecological environment. After being added to mortar, it not only helps to improve the mortar performance, but also improves the resource utilization rate.

[0037] 3. The present invention introduces modified waste bentonite cat litter powder, which contains a large amount of montmorillonite and SiO2 with volcanic ash activity. 2 and Al 2 O 3 , added to mortar as a mineral admixture. Montmorillonite is easy to absorb water and has micro-expansion, which can effectively enhance the water retention and early strength of mortar, making up for the shortcomings of insufficient early strength after adding the retarder. In addition, the modified waste bentonite cat litter powder has a large specific surface area, which can play a micro-aggregate effect, effectively improve the internal pore structure of mortar, and improve the internal density and mechanical properties. In addition, SiO 2 and Al 2 O 3It can promote cement hydration reaction and improve the mechanical properties of mortar. DETAILED DESCRIPTION

[0038] In order to better illustrate the content of the present invention, a detailed description is given below in conjunction with specific embodiments.

[0039] According to a specific embodiment provided by the present invention, an ecological self-leveling dry-mix mortar for tropical monsoon climate includes, by weight, 378 to 399 parts of cement, 81 to 85.5 parts of fly ash, 81 to 85.5 parts of modified waste bentonite cat litter, 756 to 798 parts of fine aggregate, 27 to 27.8 parts of waste bentonite cat litter filter residue powder, 10.8 to 11.4 parts of redispersible latex powder, 5.4 to 5.7 parts of water reducer and 1.4 to 1.7 parts of defoamer.

[0040] In one embodiment, cement is selected from P.O42.5 cement; fly ash is grade II fly ash; fine aggregate is machine-made sand with a fineness modulus of 1.5; the solid content of the redispersible latex powder is 98%; the water reducer is polycarboxylic acid water reducer powder with a water reduction efficiency of 25%; the defoamer is selected from defoamer powder with a relative defoaming rate of 93%.

[0041] In one embodiment, the modified waste bentonite cat litter and waste bentonite cat litter filter residue powder are prepared by the following preparation method:

[0042] (1) drying the waste bentonite cat litter at 50° C. and then grinding the waste bentonite cat litter in a ball mill to obtain waste bentonite cat litter particles;

[0043] (2) using a vibrating screen to screen out small particles with a particle size of ≤0.15 mm from the waste bentonite cat litter particles;

[0044] (3) soaking the waste bentonite cat litter particles in industrial alcohol for 1 day and then filtering and taking out to obtain non-toxic waste bentonite cat litter particles and waste bentonite cat litter alcohol filtrate;

[0045] (4) placing the non-toxic waste bentonite cat litter particles in a high-temperature resistance furnace, heating the temperature to 300° C. and maintaining the temperature for 0.5 h, during which air is introduced at a uniform rate, and then heating the temperature to 600° C. at the same heating rate, calcining at 600° C. for 2.5 h, cooling naturally, and grinding the particles again in a ball mill to a particle size of ≤75 μm to obtain modified waste bentonite cat litter powder, which is then taken out for later use;

[0046] (5) separating alcohol from the waste bentonite cat litter alcohol filtrate by vacuum distillation to obtain waste bentonite cat litter filtrate residue;

[0047] (6) Grind the waste bentonite cat litter filter residue into a crucible to a particle size of ≤75 μm to obtain waste bentonite cat litter filter residue powder, and take it out for later use.

[0048] Example 1

[0049] A tropical monsoon climate ecological self-leveling dry-mixed mortar comprises, by weight, 378 parts of cement, 81 parts of fly ash, 81 parts of modified waste bentonite cat litter powder, 756 parts of machine-made sand as fine aggregate, 27 parts of waste bentonite cat litter filter residue powder, 10.8 parts of redispersible latex powder, 5.4 parts of water reducing agent, and 1.6 parts of defoaming agent. The water-cement ratio is 0.45.

[0050] Example 2

[0051] A kind of ecological self-leveling dry-mixed mortar for tropical monsoon climate, including 385 parts of cement, 82.5 parts of fly ash, 82.5 parts of modified waste bentonite cat litter powder, 770 parts of machine-made sand as fine aggregate, 27.5 parts of waste bentonite cat litter filter residue powder, 11 parts of redispersible latex powder, 5.5 parts of water reducing agent, 1.65 parts of defoaming agent, and water-cement ratio of 0.4.

[0052] Example 3

[0053] A kind of ecological self-leveling dry-mixed mortar for tropical monsoon climate, including 399 parts of cement, 85.5 parts of fly ash, 85.5 parts of modified waste bentonite cat litter powder, 798 parts of machine-made sand as fine aggregate, 28.5 parts of waste bentonite cat litter filter residue powder, 11.4 parts of redispersible latex powder, 5.7 parts of water reducing agent, 1.7 parts of defoaming agent, and water-cement ratio of 0.35.

[0054] Comparative Example 1

[0055] A self-leveling dry-mixed mortar, in parts by weight, includes 467.5 parts of cement, 82.5 parts of fly ash, 770 parts of machine-made sand as fine aggregate, 11 parts of redispersible latex powder, 5.5 parts of water reducing agent, and 1.65 parts of defoaming agent. The water-cement ratio is 0.4.

[0056] The setting time, water retention, fluidity and compressive strength of the self-leveling dry-mixed mortar of Examples 1-3 and Comparative Example 1 were tested respectively at different ages. The test methods for fluidity and compressive strength of the self-leveling dry-mixed mortar were based on (JC / T985-2017) "Cement-based self-leveling mortar for floor use"; the test methods for setting time and water retention of the self-leveling dry-mixed mortar were based on (JGJ / T 70-2009) "Standard for Test Methods for Basic Properties of Building Mortar"; the compressive strength test used a 40 mm × 40 mm × 160 mm prism test block.

[0057] The setting time of the self-leveling dry-mixed mortar of Examples 1-3 and Comparative Example 1 is shown in Table 1:

[0058] Table 1

[0059] Example No. Coagulation time (min) Comparative Example 1 65 Example 1 113 Example 2 105 Example 3 72

[0060] The water retention rates of the self-leveling dry-mixed mortars of Examples 1-3 and Comparative Example 1 are shown in Table 2:

[0061] Table 2

[0062] Example No. Water retention rate (%) Comparative Example 1 89.8 Example 1 94.1 Example 2 95.9 Example 3 96.9

[0063] The fluidity of the self-leveling dry-mixed mortars of Examples 1-3 and Comparative Example 1 is shown in Table 3:

[0064] Table 3

[0065] Example No. Fluidity(mm) Comparative Example 1 152 Example 1 145 Example 2 142 Example 3 133

[0066] The compressive strength (MPa) of the self-leveling dry-mixed mortar of Examples 1-3 and Comparative Example 1 at different ages is shown in Table 4:

[0067] Table 4

[0068]

[0069] According to the data in Tables 1 to 4, according to the self-leveling mortar judgment standard given in JC / T 985-2017 "cement-based self-leveling mortar for floor use", it can be seen that Examples 1-3 all meet the fluidity requirements of self-leveling mortar. In addition, due to the introduction of modified waste bentonite cat litter powder and waste bentonite cat litter filter residue powder, the synergistic effect of each component can significantly improve the water retention of the mortar and extend the setting time of the mortar.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A self-leveling dry-mix mortar, characterized in that: Calculated by weight, the invention comprises 378-399 parts of cement, 81-85.5 parts of fly ash, 81-85.5 parts of modified waste bentonite cat litter, 756-798 parts of fine aggregate, 27-27.8 parts of waste bentonite cat litter filter residue powder, and 17.6-18.8 parts of admixture.

2. The self-leveling dry-mix mortar according to claim 1, characterized in that: In parts by weight, the additive includes 10.8 to 11.4 parts of redispersible latex powder, 5.4 to 5.7 parts of water reducing agent and 1.4 to 1.7 parts of defoaming agent.

3. The self-leveling dry-mix mortar according to claim 2, characterized in that: The solid content of the redispersible latex powder is 98%; The water reducer is selected from polycarboxylate water reducer powder; The defoamer is selected from defoamer powders.

4. The self-leveling dry-mix mortar according to claim 1, characterized in that: The type of cement is selected from P.O42.5; The fly ash is selected from Class II fly ash; The fine aggregate is selected from machine-made sand, and the fineness modulus of the machine-made sand is 1.

5.

5. The self-leveling dry-mix mortar according to claim 1, characterized in that: The preparation method of the modified waste bentonite cat litter and the waste bentonite cat litter filter residue powder is: S1, drying the waste bentonite cat litter at a constant temperature of 45-55° C., ball milling, and sieving to obtain waste bentonite cat litter particles with a particle size of ≤0.15 mm; S2, immersing the waste bentonite cat litter particles in industrial alcohol, filtering, and obtaining non-toxic waste bentonite cat litter small particles and waste bentonite cat litter alcohol filtrate; S3, in an air atmosphere, the non-toxic waste bentonite cat litter particles are first kept at 290-310° C. for 0.45-0.55 h, then heated to 590-610° C., calcined for 2.45-2.55 h, and ball-milled to obtain modified waste bentonite cat litter powder with a particle size of ≤75 μm; S4, subjecting the waste bentonite cat litter alcohol filtrate to vacuum distillation and crucible fine grinding to obtain waste bentonite cat litter filtrate residue powder with a particle size of ≤75 μm.

6. The self-leveling dry-mix mortar according to claim 5, characterized in that: The modified waste bentonite cat litter powder meets the following conditions: (1) The modified waste bentonite cat litter powder comprises montmorillonite, SiO2 and Al2O3; (2) The specific surface area of ​​the modified waste bentonite cat litter powder is ≥450m 2 / kg; (3) The activity index of the modified waste bentonite cat litter powder at 28 days is ≥70%.

7. The self-leveling dry-mix mortar according to claim 5, characterized in that: The waste bentonite cat litter filter residue powder meets the following conditions: (1) The waste bentonite cat litter filter residue powder includes urea; (2) The specific surface area of ​​the waste bentonite cat litter filter residue powder is ≥450m 2 / kg.

8. Use of the self-leveling dry-mix mortar according to any one of claims 1 to 7 in a tropical monsoon climate.

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