High-crack-resistance self-leveling dry-mixed mortar as well as preparation method and construction method thereof

Abstract

The invention relates to the technical field of building material preparation, in particular to high-crack-resistance self-leveling dry-mixed mortar as well as a preparation method and a construction method thereof. According to the invention, the gypsum is used for replacing cement, the gypsum, the fly ash and the steel slag powder form a composite cementing material, and the incineration slag is used for replacing natural sand as fine aggregate to prepare the high-crack-resistance self-leveling dry-mixed mortar, so that a new way is opened up for resource utilization of solid wastes. Moreover, the prepared self-leveling dry-mixed mortar has good anti-cracking ability, good workability and water-retaining property; the construction layer is fast to cure and short in maintenance period; after construction, the adhesive force is strong, shrinkage and hollowing are avoided, and the surface is smooth and flat.

Description

Technical Field

[0001] The invention relates to the technical field of building material preparation, and in particular to a highly crack-resistant self-leveling dry-mix mortar and a preparation method and a construction method thereof. Background Art

[0002] Self-leveling mortar is a dry-mixed powder material composed of a variety of active ingredients. It has very good fluidity and self-leveling ability and can be used by mixing with water on site. It is widely used in indoor floor leveling projects of public buildings such as residences, hospitals, supermarkets, and industrial floors.

[0003] Self-leveling mortar materials are usually divided into organic and inorganic types. Organic self-leveling materials are mainly epoxy resin self-leveling materials, which have good construction performance, but are relatively expensive, have high construction requirements, and have poor wear resistance. Inorganic self-leveling materials are divided into gypsum-based self-leveling materials and cement-based self-leveling materials. Cement-based self-leveling materials use cement as a gelling material, which has high production costs, is prone to cracking, and has poor crack resistance. Gypsum-based self-leveling materials use building gypsum to replace part or all of the cement, and have improved crack resistance compared to cement-based self-leveling materials, but the extent of improvement needs to be further improved. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a highly crack-resistant self-leveling dry-mix mortar and a preparation method and construction method thereof. The self-leveling dry-mix mortar provided by the present invention has good crack resistance and opens up a new way for the resource utilization of solid waste.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a high-cracking-resistant self-leveling dry-mix mortar, which comprises the following components based on 100% total mass:

[0007]

[0008] Calculated by mass percentage, the content of hemihydrate gypsum in the gypsum is ≥95%, the content of dihydrate gypsum is ≤2%, and the content of anhydrous gypsum is 0%.

[0009] Preferably, in terms of mass percentage, the retarder includes 35-45% of aminoacetic acid, 15-25% of malic acid and 35-45% of disodium ethylenediaminetetraacetate.

[0010] Preferably, the particle size of the gypsum is 35-50 μm; the gypsum is obtained by calcining and then grinding desulfurized gypsum.

[0011] Preferably, the particle size of the steel slag powder is 30-45 μm.

[0012] Preferably, the particle size of the fly ash is 10 to 30 μm.

[0013] Preferably, the particle size composition of the incineration slag is 10-30 mesh, 30-60 mesh, 60-90 mesh and 90-120 mesh, each accounting for 25% by mass.

[0014] Preferably, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, and the water reducing rate is greater than 35%.

[0015] Preferably, the defoaming agent is a silicone powder defoaming agent; and the thickening agent is hydroxypropyl methylcellulose.

[0016] The present invention provides a method for preparing the highly crack-resistant self-leveling dry-mix mortar described in the above scheme, comprising the following steps: mixing the components to obtain the highly crack-resistant self-leveling dry-mix mortar.

[0017] The present invention provides a construction method for the high crack-resistant self-leveling dry-mix mortar described in the above scheme or the high crack-resistant self-leveling dry-mix mortar prepared by the preparation method described in the above scheme, comprising the following steps: mixing the high crack-resistant self-leveling dry-mix mortar with water and then applying the mixture; the mass ratio of the water to the high crack-resistant self-leveling dry-mix mortar is 0.20 to 0.23:1.

[0018] The invention provides a highly crack-resistant self-leveling dry-mix mortar, which includes the following components based on 100% of the total mass: 35-45% of gypsum; 5-10% of steel slag powder; 5-10% of fly ash; 40-50% of incineration slag; 0.1-0.3% of retarder; 0.1-0.3% of thickener; 0.5-1.5% of water reducer; 0.01-0.15% of defoamer; the content of hemihydrate gypsum in the gypsum is ≥95%, the content of dihydrate gypsum is ≤2%, and the content of anhydrous gypsum is 0%. The invention uses gypsum to replace cement and form a composite cementitious material with fly ash and steel slag powder, which gives the self-leveling dry-mix mortar a certain water resistance, which is conducive to reducing cracking. At the same time, the gypsum of the invention has a micro-expansion effect, which can reduce shrinkage and prevent cracks, so the self-leveling dry-mix mortar has high crack resistance.

[0019] Furthermore, existing gypsum-based materials usually need to be added with retarders to adjust the setting time for construction, but the retarders will cause serious loss of strength to the gypsum-based materials while having a retarding effect. The present invention adopts a composite retarder with a small addition amount, good retarding effect, and small loss of strength of the gypsum-based materials. The obtained self-leveling dry powder mortar has good strength (including compressive strength, flexural strength and tensile bonding strength).

[0020] In addition, the main raw materials of the highly crack-resistant self-leveling dry-mixed mortar prepared by the present invention are desulfurized gypsum, steel slag powder, fly ash and incineration slag, which can reduce the production cost of the highly crack-resistant self-leveling dry-mixed mortar and open up a new way for the resource utilization of solid wastes such as desulfurized gypsum, steel slag powder, fly ash and incineration slag.

[0021] The high crack-resistant self-leveling dry mortar provided by the present invention can be mass-produced in factories. The high crack-resistant self-leveling dry mortar is a dry powder material, which can be packaged in bags, has a long storage period, and is easy to transport. Water is added in a certain proportion at the construction site, and the water-cement ratio is controlled, so that machine spraying construction can be performed. Moreover, the construction can be carried out at a temperature above -5°C in winter without affecting the construction quality requirements.

[0022] The highly crack-resistant self-leveling dry-mix mortar of the present invention has excellent workability and water retention; the construction layer solidifies quickly and the curing period is short (it solidifies after 1 hour of construction, and the 24-hour compressive strength reaches more than 19 MPa, and it is cured at room temperature); after construction, it has strong bonding force, no shrinkage, no hollowing, and a smooth and flat surface. DETAILED DESCRIPTION

[0023] The present invention provides a high-cracking-resistant self-leveling dry-mix mortar, which comprises the following components based on 100% total mass:

[0024]

[0025] Calculated by mass percentage, the content of hemihydrate gypsum in the gypsum is ≥95%, the content of dihydrate gypsum is ≤2%, and the content of anhydrous gypsum is 0%.

[0026] The high crack-resistant self-leveling dry-mix mortar provided by the present invention comprises 35-45% of gypsum, which can be 35%, 37%, 38%, 40%, 42%, 44% or 45% in a specific embodiment. In the present invention, in terms of mass percentage, the content of hemihydrate gypsum in the gypsum is ≥95%, the content of dihydrate gypsum is ≤2%, the content of anhydrous gypsum is 0%, and the remainder is unavoidable impurities; in a specific embodiment, the content of hemihydrate gypsum in the gypsum can be 95%, 96%, 97%, 98%, 98.5%, 99%, 99.5% or 100%, and the content of dihydrate gypsum can be 0%, 0.5%, 1%, 1.5% or 2%. In the related art, building gypsum is used as a gelling material, and the building gypsum is made from natural gypsum or industrial by-product gypsum through calcination and dehydration at a certain temperature, wherein the content of hemihydrate gypsum is ≥60%, and it is difficult to reach such a high content of 95%. The present invention adopts the gypsum of the above composition, which has a micro-expansion effect and can reduce shrinkage, but the water resistance of the gypsum-based material is poor. The fly ash and steel slag powder can improve its water resistance to a certain extent, and the improvement of water resistance is also conducive to preventing cracking.

[0027] In the present invention, the particle size of the gypsum is preferably 35 to 50 μm. In the present invention, the gypsum is preferably obtained by grinding desulfurized gypsum after calcination. The present invention has no special requirements for the calcination conditions, as long as the stable three-phase gypsum (semi-hydrated gypsum, dihydrated gypsum, anhydrous gypsum) is obtained after calcination: that is, the content of β-type semi-hydrated gypsum is ≥95%, the content of dihydrated gypsum is ≤2%, and the content of anhydrous gypsum is 0%. The present invention preferably cools the calcined gypsum to below 50°C before grinding. The present invention has no special requirements for the grinding speed, and the grinding speed well known in the art can be used. In the embodiment of the present invention, the grinding speed is specifically 15t / h. In the present invention, the desulfurized gypsum is the waste residue produced after flue gas desulfurization in a coal-fired power plant, and its main component is calcium sulfate dihydrate. The present invention uses desulfurized gypsum as the main raw material to realize the resource utilization of desulfurized gypsum.

[0028] The high crack resistance self-leveling dry powder mortar provided by the present invention includes 5-10% steel slag powder, which can be 5%, 6%, 7%, 8%, 9% or 10% in specific embodiments. In the present invention, the particle size of the steel slag powder is preferably 30-45 μm, and the mass content of metallic iron in the steel slag micropowder is preferably <0.5%. Since the slag and iron in the steel slag are wrapped together, the present invention controls the iron content to less than 0.5% by removing iron, so that the particle size of the steel slag powder can be ground to 30-45 μm. In the present invention, the steel slag powder is preferably obtained by grinding and repeatedly removing iron from converter or electric furnace steel slag that meets the requirements of YB / TO22 standards. The present invention has no special requirements for the grinding, and the grinding process well known in the art can be used, such as using a pre-grinding closed-loop circulation system with a column mill as the main equipment and a final grinding closed-loop circulation system with a high fine grinder and a K-type powder selector as the main equipment for grinding. In the present invention, the steel slag powder is used as a composite cementitious material in combination with gypsum and fly ash to improve the water resistance of gypsum.

[0029] The high crack resistance self-leveling dry powder mortar provided by the present invention includes 5-10% fly ash, which can be 5%, 6%, 7%, 8%, 9% or 10% in a specific embodiment. In the present invention, the particle size of the fly ash is preferably 10-30 μm. The present invention has no special requirements on the source of the fly ash, and commercially available products can be used, or it can be prepared by methods well known in the art. In an embodiment of the present invention, the fly ash discharged from a coal-fired power plant is put into a QM-480-600 horizontal high-fine grinding test machine, the speed is adjusted to 48 rpm, and the grinding is carried out for 10 minutes; the ground fly ash is then put into an OS-Ⅰ type superfine classifier, the rotor linear speed is adjusted to 100 m per second, the automatic feeding button is started, and air selection and classification are carried out. After 1 hour, fly ash with a particle size of 10-30 μm is obtained. In the present invention, the role of the fly ash is to cooperate with gypsum and steel slag powder as a composite cementitious material to improve the water resistance of gypsum.

[0030] The highly crack-resistant self-leveling dry-mix mortar provided by the present invention comprises 40-50% of incineration slag, which can be 40%, 42%, 44%, 45%, 46%, 48% or 50% in a specific embodiment. In the present invention, the particle size distribution composition of the incineration slag is preferably 10-30 mesh, 30-60 mesh, 60-90 mesh and 90-120 mesh particles, each accounting for 25% by mass. The present invention controls the particle size of the incineration slag so that the incineration slag particles of different sizes can fill the gaps with each other, thereby increasing the density of the self-leveling dry-mix mortar.

[0031] Incineration slag is a solid residue of the melt produced during the incineration of garbage. It is mainly composed of SiO2, Al2O3, CaO and MgO, and also contains other metals such as iron, aluminum, and copper. Since the main physical components of the slag are hard, it can be guaranteed to have a certain strength when used as an aggregate. In the present invention, the incineration slag must comply with the standard of GB / T25032-2010 "Aggregate of Domestic Waste Incineration Slag", have good firmness, relatively stable chemical properties, good durability, and a certain strength, and can meet the requirements of aggregate utilization.

[0032] In the present invention, the incineration slag is preferably obtained by processing using a process well known in the art. In the embodiment, specifically: the slag produced by garbage incineration is crushed by a crusher to a particle size of 10 mm, and then treated by a magnetic separator, which removes and collects iron; the slag after preliminary iron removal enters an eddy current sorting to separate the non-ferrous metal in the slag; the slag after iron removal and non-ferrous metal separation is crushed by a crusher to a particle size of 5 mm, and then iron removal and non-ferrous metal treatment are performed, and then washed and dried, and then a vibrating screen is used to obtain slag aggregates with particle sizes of 10-30 mesh, 30-60 mesh, 60-90 mesh and 90-120 mesh, respectively, for standby use.

[0033] In the present invention, the incineration slag is used as fine aggregate to replace natural sand for preparing highly crack-resistant self-leveling dry-mix mortar.

[0034] The high crack resistance self-leveling dry powder mortar provided by the present invention includes 0.1-0.3% retarder, which can be 0.1%, 0.15%, 0.2%, 0.25% or 0.3% in a specific embodiment. In terms of mass percentage, the retarder preferably includes 35-45% aminoacetic acid, 15-25% malic acid and 35-45% disodium ethylenediaminetetraacetate. In a specific embodiment, the content of aminoacetic acid in the retarder can be 35%, 37%, 40%, 43% or 45%, the content of malic acid can be 15%, 17%, 20%, 22% or 25%, and the content of disodium ethylenediaminetetraacetate can be 35%, 37%, 40%, 43% or 45%. Gypsum-based materials usually need to be added with retarders to adjust the setting time for construction due to their fast solidification, but the retarder will cause serious loss of strength to the gypsum-based materials while the retarder has a retarding effect. The present invention adopts a composite retarder, which has good retarding effect, small addition amount and small strength loss of gypsum-based materials.

[0035] The highly crack-resistant self-leveling dry-mix mortar provided by the present invention includes 0.1-0.3% thickener, which can be 0.1%, 0.15%, 0.2%, 0.25% or 0.3% in a specific embodiment. In the present invention, the thickener is preferably hydroxypropyl methylcellulose. In the present invention, the thickener plays the role of thickening, water retention, bonding and improving construction properties, and can improve the water retention and bonding strength of the mortar and improve the crack resistance of the mortar.

[0036] The highly crack-resistant self-leveling dry-mix mortar provided by the present invention includes 0.1-0.3% of a water reducer, which can be 0.1%, 0.15%, 0.2%, 0.25% or 0.3% in a specific embodiment. In the present invention, the water reducer is preferably a polycarboxylic acid high-efficiency water reducer, and the water reduction rate is preferably greater than 35%. The polycarboxylic acid high-efficiency water reducer used in the present invention can significantly reduce the water consumption of the mortar and reduce the water-cement ratio of the mortar, thereby improving the fluidity, stability and density of the mortar, and helping to improve the compressive strength, tensile bonding strength and crack resistance of the mortar.

[0037] The high crack resistance self-leveling dry powder mortar provided by the present invention includes 0.01-0.15% of defoamer, which can be 0.01%, 0.03%, 0.05%, 0.08%, 0.10%, 0.12% or 0.15% in a specific embodiment. In the present invention, the defoamer is preferably an organosilicon type powder defoamer. The present invention adopts an organosilicon type powder defoamer, which has strong defoaming ability and fast speed. After adding, it will not affect the basic properties of the system, and has good stability, which can increase the density of the mortar.

[0038] The present invention provides a method for preparing the highly crack-resistant self-leveling dry-mix mortar described in the above scheme, comprising the following steps: mixing the components to obtain the highly crack-resistant self-leveling dry-mix mortar.

[0039] In the present invention, the mixing preferably comprises: first mixing gypsum, steel slag powder, fly ash, retarder, thickener, water reducer and defoamer, and adding incineration slag to the obtained mixture for second mixing.

[0040] In the present invention, the first mixing and the second mixing are preferably carried out under stirring conditions. The present invention does not specifically limit the time and stirring rate of the first mixing and the second mixing, as long as the purpose of uniform mixing can be achieved. In an embodiment of the present invention, the time of the first mixing and the second mixing is 5 minutes, the stirring rate of the first mixing is 60 to 75 rpm, and the stirring rate of the second mixing is 55 to 70 rpm. In the present invention, the mixing is preferably carried out in a mixer.

[0041] The present invention preferably packs the highly crack-resistant self-leveling dry mortar into 50 kg bags for storage.

[0042] The present invention provides a construction method of the above-mentioned high crack-resistant self-leveling dry-mix mortar, comprising the following steps: mixing the high crack-resistant self-leveling dry-mix mortar with water and then applying it; the mass ratio of the water to the high crack-resistant self-leveling dry-mix mortar (i.e., the water-cement ratio) is 0.20-0.23:1.

[0043] In specific embodiments, the water-cement ratio may be 0.20:1, 0.21:1, 0.22:1 or 0.23:1.

[0044] The present invention has no special requirements for the coating method, and can adopt coating methods well known in the art, such as spraying. The present invention preferably uses large-scale pumping equipment and special spraying equipment for construction. This construction method is fast and efficient, reduces labor intensity, improves the construction environment, saves construction costs, and ensures excellent construction quality. The present invention can adjust and control the spraying thickness of the high crack-resistant self-leveling dry powder mortar according to actual needs. The high crack-resistant self-leveling dry powder mortar provided by the present invention has good crack resistance and can be constructed above -5°C in winter without affecting the construction quality requirements. The high crack-resistant self-leveling dry powder mortar can be used in various indoor floors.

[0045] The high crack-resistant self-leveling dry powder mortar of the present invention has good workability and water retention; the construction layer solidifies quickly, and can be solidified after 1 hour of construction; the curing period is short, and it only needs to be cured for 24 hours at room temperature; after construction, the bonding force is strong, there is no shrinkage, no hollowing, and the surface is smooth and flat.

[0046] The highly crack-resistant self-leveling dry-mix mortar and its preparation method and construction method provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] This embodiment takes the preparation of 100kg of high crack-resistant self-leveling dry mortar as an example, and the preparation method is as follows:

[0049] The dosage of each raw material is:

[0050] Gypsum (particle size is 35-50μm, the content of hemihydrate gypsum is 97%, the content of dihydrate gypsum is 1%, and the content of anhydrous gypsum is 0%) 44kg, steel slag powder (particle size is 30-45μm, the mass content of metallic iron is <0.5%) 7.15kg, fly ash (particle size is 10-30μm) 5kg, incineration slag (slag aggregates with particle sizes of 10-30 mesh, 30-60 mesh, 60-90 mesh, and 90-120 mesh each account for 25%) 42kg, composite retarder (composed of 0.12kg of aminoacetic acid, 0.6kg of malic acid, and 0.12kg of disodium ethylenediaminetetraacetate) 0.3kg, thickener (hydroxypropyl methylcellulose) 0.25kg, polycarboxylic acid high-efficiency water reducing agent (water reduction rate >35%) 1.2kg, and silicone powder defoaming agent 0.1kg.

[0051] Weigh the ingredients according to the above ratio, first put gypsum, steel slag powder, fly ash, composite retarder, thickener, water reducer, defoamer into the mixer in turn, stir and mix, mix thoroughly and evenly, stir and mix for 5 minutes, stir at a speed of 60-75rpm, then put the incineration slag into the mixer, stir and mix for 5 minutes, stir at a speed of 55-70rpm to obtain high crack resistance self-leveling dry mortar. Then pack 50kg per bag and put into storage.

[0052] Example 2

[0053] This embodiment takes the preparation of 100kg of high crack-resistant self-leveling dry mortar as an example, and the preparation method is as follows:

[0054] The dosage of each raw material is: gypsum (particle size is 35-50μm, the content of hemihydrate gypsum is 95%, the content of dihydrate gypsum is 2%, and the content of anhydrous gypsum is 0%) 37kg, steel slag powder (particle size is 30-45μm, the mass content of metallic iron is <0.5%) 7.7kg, fly ash (particle size is 10-30μm) 9kg, incineration slag (slag aggregates with particle sizes of 10-30 mesh, 30-60 mesh, 60-90 mesh, and 90-120 mesh each account for 25%) 45kg, composite retarder (composed of 0.04kg of aminoacetic acid, 0.02kg of malic acid, and 0.04kg of disodium ethylenediaminetetraacetate) 0.1kg, thickener (hydroxypropyl methylcellulose) 0.2kg, polycarboxylic acid high-efficiency water reducing agent (water reduction rate>35%) 0.9kg, and silicone powder defoaming agent 0.1kg.

[0055] Weigh the ingredients according to the above ratio, first put gypsum, steel slag powder, fly ash, composite retarder, thickener, water reducer, defoamer into the mixer in turn, stir and mix, mix thoroughly and evenly, stir and mix for 5 minutes, stir at a speed of 60-75rpm, then put the incineration slag into the mixer, stir and mix for 5 minutes, stir at a speed of 55-70rpm to obtain high crack resistance self-leveling dry mortar. Then pack 50kg per bag and put into storage.

[0056] Example 3

[0057] This embodiment takes the preparation of 100kg of high crack-resistant self-leveling dry mortar as an example, and the preparation method is as follows:

[0058] The dosage of each raw material is:

[0059] Gypsum (particle size is 35-50μm, the content of hemihydrate gypsum is 96%, the content of dihydrate gypsum is 1.5%, and the content of anhydrous gypsum is 0%) 40kg, steel slag powder (particle size is 30-45μm, the mass content of metallic iron is <0.5%) 5kg, fly ash (particle size is 10-30μm) 6kg, incineration slag (slag aggregates with particle sizes of 10-30 mesh, 30-60 mesh, 60-90 mesh, and 90-120 mesh each account for 25%) 48kg, composite retarder (composed of 0.08kg of aminoacetic acid, 0.04kg of malic acid, and 0.08kg of disodium ethylenediaminetetraacetate) 0.2kg, thickener (hydroxypropyl methylcellulose) 0.1kg, polycarboxylic acid high-efficiency water reducing agent (water reduction rate >35%) 0.6kg, and silicone powder defoaming agent 0.1kg.

[0060] Weigh the ingredients according to the above ratio, first put gypsum, steel slag powder, fly ash, composite retarder, thickener, water reducer, defoamer into the mixer in turn, stir and mix, mix thoroughly and evenly, stir and mix for 5 minutes, stir at a speed of 60-75rpm, then put the incineration slag into the mixer, stir and mix for 5 minutes, stir at a speed of 55-70rpm to obtain high crack resistance self-leveling dry mortar. Then pack 50kg per bag and put into storage.

[0061] Comparative Example 1

[0062] The only difference from Example 1 is that gypsum is replaced by commercially available building gypsum powder with a fineness of 80-200 meshes, of which hemihydrate gypsum accounts for 75%, and the rest is the same as Example 1.

[0063] Comparative Example 2

[0064] The self-leveling mortar formula using relevant technology uses desulfurized building gypsum powder and silicate cement as cementitious materials and river sand as aggregate. Specifically:

[0065] The dosage of each raw material is: desulfurized building gypsum powder (particle size is 45-60μm, of which hemihydrate gypsum is 80%) 48kg, 42.5 Portland cement 5kg, heavy calcium powder 5.55kg, river sand (particle size is 0.16-0.63mm) 39kg, protein retarder 0.3kg, polyvinyl alcohol 0.4g, cellulose ether 0.2kg, polycarboxylic acid water reducer (water reduction rate > 35%) 1.4kg, silicone powder defoaming agent 0.15kg.

[0066] The performance of the self-leveling dry-mix mortar prepared in the embodiment and the comparative example was tested with reference to the method in JC / T1023-2021 “Gypsum-based self-leveling mortar”, and the test results are shown in Table 1.

[0067] Table 1 Technical performance indicators of high crack resistance self-leveling dry mortar

[0068]

[0069] It can be seen from the results in Table 1 that the crack resistance of the self-leveling dry-mixed mortar prepared by the present invention is better than that of the comparative example, which is manifested by a small dimensional change rate. This is because the gypsum used in the present invention has a stable gypsum three-phase (i.e., the content of β-type hemihydrate gypsum is ≥95%, the content of dihydrate gypsum is ≤2%, and the content of anhydrous gypsum is 0%). The present invention uses gypsum instead of cement and forms a composite cementitious material with fly ash and steel slag powder, so that the gypsum-based material has a certain water resistance. At the same time, the gypsum-based material has a micro-expansion effect, reduces shrinkage, and does not produce cracks. In addition, in terms of fluidity, flexural strength and compressive strength, the self-leveling dry-mixed mortar prepared by the present invention is also better than the comparative example. Comparative Example 1 uses commercially available building gypsum that does not have these properties, and the prepared self-leveling dry-mixed mortar has poor performance. In addition, Comparative Example 2 uses desulfurized building gypsum powder and silicate cement as cementitious materials and river sand as aggregate, and the crack resistance and strength of the self-leveling dry-mixed mortar prepared by it are also poor.

[0070] 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 highly crack-resistant self-leveling dry mortar, characterized in that: The total mass is 100%, including the following components: Calculated by mass percentage, the content of hemihydrate gypsum in the gypsum is ≥95%, the content of dihydrate gypsum is ≤2%, and the content of anhydrous gypsum is 0%.

2. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: Calculated by mass percentage, the retarder comprises 35-45% of aminoacetic acid, 15-25% of malic acid and 35-45% of disodium ethylenediaminetetraacetate.

3. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: The particle size of the gypsum is 35-50 μm; the gypsum is obtained by calcining and then grinding desulfurized gypsum.

4. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: The particle size of the steel slag powder is 30-45 μm.

5. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: The particle size of the fly ash is 10 to 30 μm.

6. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: The particle size composition of the incineration slag is 10-30 mesh, 30-60 mesh, 60-90 mesh and 90-120 mesh, and the mass proportion of particles is 25%.

7. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid high efficiency water reducing agent, and the water reducing rate is greater than 35%.

8. The highly crack-resistant self-leveling dry-mix mortar according to claim 1, characterized in that: The defoaming agent is a silicone powder defoaming agent; the thickening agent is hydroxypropyl methylcellulose.

9. The method for preparing the highly crack-resistant self-leveling dry-mix mortar according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the components to obtain the highly crack-resistant self-leveling dry mortar.

10. A construction method for the highly crack-resistant self-leveling dry-mix mortar according to any one of claims 1 to 8 or the highly crack-resistant self-leveling dry-mix mortar prepared by the preparation method according to claim 9, comprising the following steps: The highly crack-resistant self-leveling dry-mix mortar is mixed with water and then applied; the mass ratio of the water to the highly crack-resistant self-leveling dry-mix mortar is 0.20 to 0.23:1.

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