Special mortar for solid waste-based autoclaved aerated concrete wall and preparation method thereof

Abstract

The invention discloses a special mortar for a solid waste-based autoclaved aerated concrete wall and a preparation method thereof, the special mortar for the solid waste-based autoclaved aerated concrete wall is composed of the following raw materials in parts by weight: 280-320 parts of a solid waste-based cementing material, 650-750 parts of silica sand, 8-15 parts of a solid waste material and 0.2-0.5 part of a cellulose admixture, putting the solid waste-based cementing material, the silica sand and the solid waste into a mixing machine, and carrying out dry mixing and stirring; s2, dissolving a cellulose additive in 20-30% of the total water amount to form a premixed solution; s3, adding the premixed solution into the dry mixture, and mixing and stirring; s4, adding the remaining water, and continuously mixing and stirring until the consistency of the slurry reaches 70-90mm. The method has the technical effects of solid waste recycling and environmental protection benefits, superstrong adhesion and anti-cracking system, freezing and thawing durability improvement, construction performance optimization, workability improvement, energy conservation and economical efficiency optimization and improvement.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a special mortar for solid waste-based autoclaved aerated concrete walls and its preparation method. Background Technology

[0002] With the rapid development of my country's economy and the continuous advancement of construction technology, aerated concrete block mortar has experienced rapid growth due to its superior performance. The application of solid waste in aerated concrete block mortar can improve its performance, reduce costs, and decrease resource and energy consumption, aligning with the requirements of a low-carbon and environmentally friendly era. In recent years, my country has achieved certain results in the research and application of solid waste in aerated concrete block mortar.

[0003] Aerated concrete (AAC) walls are lightweight (dry density 500-700 kg / m³). 3 With its advantages such as thermal insulation (thermal conductivity of 0.12-0.18 W / (m·K)), it has become a core material for building energy-saving projects. However, the technical bottleneck of its special mortar has long restricted the quality and durability of walls, mainly manifested in:

[0004] Interfacial bonding failure:

[0005] AAC blocks have a water absorption rate as high as 65%-70% (far exceeding the 5% of ordinary concrete). Traditional mortar absorbs water rapidly, leading to incomplete cement hydration. Actual measurements show that the 14-day tensile bond strength of ordinary mortar on AAC substrate is only 0.15-0.30 MPa (lower than the ≥0.40 MPa required by national standard JG / T230-2007), and the hollow rate exceeds 5% (the limit in the Ministry of Housing and Urban-Rural Development's "Code for Acceptance of Masonry Engineering Quality" GB 50203 is ≤3%), causing frequent plaster layer detachment accidents.

[0006] Uncontrolled shrinkage cracking:

[0007] The drying shrinkage value of AAC blocks is approximately 0.4 mm / m, while that of ordinary mortar reaches 0.35 mm / m (the national standard JGJ / T 70-2009 requires ≤0.20%). This mismatch in deformation results in a wall cracking rate of 12 cracks per 100m. 2 (2022 Survey Report by China Academy of Building Research). Especially in cold regions, the superposition of frost heave stress can cause cracks to reach 1-2 mm in width, threatening structural safety.

[0008] Resource dependence and pollution:

[0009] Traditional mortar relies on natural river sand (fineness modulus 2.3-3.0) and silicate cement, consuming 350 kg of cement and 700 kg of sand per ton of mortar. According to statistics from the China Sand and Gravel Association, over-exploitation of natural sand has led to a depletion rate of over 60% of river sand resources in the Yangtze River basin, and cement production emits carbon emissions of 0.82 t-CO2 / t. Meanwhile, the annual discharge of solid waste from metallurgical mines (such as iron ore tailings powder) exceeds 1.5 billion tons (Ansteel Group 2023 annual report), accumulating on 68,000 hectares of land, with the utilization rate of S95 grade mineral powder less than 30%. Summary of the Invention

[0010] In order to overcome the shortcomings of the existing technology, the present invention provides a special mortar for solid waste-based autoclaved aerated concrete walls and its preparation method, which has the technical effects of solid waste resource utilization and environmental protection benefits, super strong bonding and crack prevention system, improved freeze-thaw durability, optimized construction performance, improved workability and energy saving and economic optimization.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a special mortar for autoclaved aerated concrete walls based on solid waste, which is composed of the following raw materials in parts by weight: 280-320 parts of solid waste-based cementitious material, 650-750 parts of silica sand, 8-15 parts of solid waste material and 0.2-0.5 parts of cellulose admixture.

[0012] Furthermore, the solid waste-based cementitious material is PSB 32.5 grade cement;

[0013] The solid waste is S95 grade mineral powder with a specific surface area ≥400m². 2 / kg, activity index ≥95%.

[0014] Furthermore, the silica sand has a particle size range of 0.25 mm to 0.5 mm and a bulk density ≥ 1700 kg / m³. 3 .

[0015] Furthermore, the cellulose admixture is hydroxypropyl methylcellulose (HPMC) with a viscosity grade of 400 mPa·s.

[0016] Furthermore, the mortar has a water retention rate of ≥99.5%, a 28-day compressive strength of ≥20.0 MPa, a 14-day tensile bond strength of ≥0.60 MPa, and a shrinkage rate of ≤0.20%.

[0017] on the other hand:

[0018] A method for preparing special mortar for autoclaved aerated concrete walls based on solid waste includes the following steps:

[0019] S1: Put solid waste-based cementitious materials, silica sand, and solid waste into a mixer and dry mix them;

[0020] S2: Dissolve the cellulose admixture in 20% to 30% of the total water volume to form a premixed solution;

[0021] S3: Add the premixed solution to the dry mixture and mix and stir;

[0022] S4: Add the remaining water and continue mixing until the consistency of the slurry reaches 70-90 mm.

[0023] Furthermore, the dry mixing speed is 30–50 r / min;

[0024] The mixing speed is 60-80 r / min.

[0025] The total water consumption is 18% to 22% of the total weight of the raw materials.

[0026] on the other hand:

[0027] Application of solid waste-based autoclaved aerated concrete (AAC) wall mortar: Solid waste-based AAC wall mortar is used for the construction or plastering of AAC blocks, with the water-cement ratio controlled at 0.50 to 0.60.

[0028] Furthermore, the construction environment temperature for the solid waste-based autoclaved aerated concrete wall mortar is ≥5℃, the initial setting time of the mortar is ≤5h, and the final setting time is ≤8h.

[0029] Compared with the prior art, the beneficial effects that this invention can achieve are:

[0030] Solid waste disposal capacity: 80-150 kg of metallurgical mining solid waste (S95 mineral powder) can be consumed for every 1 ton of mortar produced, achieving a 100% resource utilization rate of metallurgical solid waste;

[0031] Carbon emission reduction: Replacing 30% of cement with mineral powder reduces CO2 emissions per ton of mortar by 15% (compared to ordinary mortar);

[0032] Reduced raw material costs: The unit price of mineral powder is only 34% of that of cement (120 yuan / ton vs. 350 yuan / ton), and large-scale production can save 200 yuan / ton in raw material costs.

[0033] Mineral powder micro-filling effect (specific surface area ≥400m²) 2 The combined effect of HPMC film-forming effect (viscosity 300-500mPa·s) and the synergistic effect of the film-forming effect (viscosity 300-500mPa·s) results in a 14-day tensile bond strength of 0.60-0.67MPa (national standard ≥0.40MPa) and a hollow rate of ≤0.2% (commercially available products ≥5%).

[0034] The 28-day shrinkage rate is ≤0.20% (national standard ≤0.20%), which is 43% lower than that of ordinary mortar (0.35%), reducing the risk of wall cracking by 80%.

[0035] The active components of the mineral powder (CaO+Al2O3≥65%) generate dense hydration products. After 50 freeze-thaw cycles at -20℃, the strength loss is only 2.1% (national standard ≤20%), and the service life is extended to 50 years (ordinary mortar is about 30 years).

[0036] Water retention control: HPMC forms a three-dimensional water film at the silica sand interface, with a water retention rate of ≥99.5% (national standard ≥99.0%), reducing the moisture evaporation rate by 37% during high-temperature construction;

[0037] A consistency of 70-90mm ensures a slurry slip ratio of 110±5mm, increasing mechanical spraying efficiency by 40% (85m). 2 / person / day vs 60m 2 );

[0038] With an opening time of ≥45 minutes, it solves the problem of joint plastering over large areas, reducing the rework rate by 90%.

[0039] Thermal performance optimization: thermal conductivity 0.24W / (m·K) (national standard ≤1.1), when used in conjunction with autoclaved aerated concrete blocks, building heating energy consumption is reduced by 15%;

[0040] Overall cost advantages: Raw material costs are reduced by 200 yuan per ton, and repair and maintenance costs are reduced by 40-50 yuan per square meter. Attached Figure Description

[0041] Figure 1 This is a flowchart of the preparation method of the special mortar for solid waste-based autoclaved aerated concrete walls according to the present invention. Detailed Implementation

[0042] To make the technical means, creative features, and achieved objectives and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0043] Example:

[0044] This invention provides a special mortar for solid waste-based autoclaved aerated concrete walls, comprising, by weight:

[0045] 280-320 parts of silicate cement;

[0046] 650-750 parts silica sand, with a particle size of 0.25mm-0.50mm;

[0047] 8-15 parts of solid waste-based admixture from metallurgical mines, with a specific surface area ≥400 m² 2 / kg, activity index ≥95%;

[0048] 0.2–0.5 parts of cellulose ether, with a viscosity of 300–500 mPa·s;

[0049] 180-220 parts water.

[0050] The metallurgical mining solid waste-based admixture is S95 grade mineral powder with a 7-day activity index ≥75%, a 28-day activity index ≥95%, and a loss on ignition ≤3.0% (determined according to GB / T18049-2017).

[0051] The cumulative particle size distribution of silica sand satisfies: D10≥0.20mm, D50=0.35±0.05mm, D90≤0.55mm;

[0052] The mud content of silica sand is ≤0.5% (determined according to GB / T14684-2022).

[0053] The cellulose ether is hydroxypropyl methylcellulose (HPMC), with a methoxy content of 19%–24% and a hydroxypropoxy content of 7%–12% (determined according to USP-NF standards).

[0054] Performance requirements: Water retention rate ≥ 99.5% (tested according to JGJ / T70-2009);

[0055] 28-day compressive strength ≥ 20.0 MPa (determined according to GB / T17671-2021);

[0056] 14-day tensile bond strength ≥ 0.60 MPa (determined according to JG / T230-2007);

[0057] Shrinkage rate ≤0.20% after 28 days (determined according to JGJ / T70-2009).

[0058] As shown in Table 1, experiments were conducted using three different ratios of A, B, and C. The specific performance differences compared to the national standard performance are shown in Table 2.

[0059]

[0060]

[0061] Table 1

[0062]

[0063] Table 2

[0064] Combination Figure 1As shown, the preparation method of special mortar for solid waste-based autoclaved aerated concrete walls includes:

[0065] Step 1: Premixing Treatment: Dry mix silicate cement, metallurgical mining solid waste-based admixture, and silica sand at 30-50 r / min for 3-5 min. Before dry mixing, dry the silica sand at 105±5℃ until the moisture content is ≤0.1%.

[0066] Step 2: Gel preparation: Add cellulose ether to 20%-30% of the total water volume in warm water at 40-50℃, and disperse at high speed of 800-1000 r / min for 5-10 min;

[0067] Step 3: Initial mixing: Add the adhesive solution obtained in Step 2 to the premix and stir at 60-80 r / min for 5-8 min;

[0068] Step 4: Final mixing: Add the remaining water and stir at 60-80 r / min until the consistency of the slurry is 70-90 mm (measured according to the ISO2431 flow cone method). After stirring, let it stand for 10-15 minutes to mature.

[0069] The total water content is 18% to 22% of the total weight of the raw materials, and the water-cement ratio is controlled at 0.50 to 0.60.

[0070] Cement, mineral powder, and silica sand are put into a forced mixer and dry-mixed at 30-50 r / min for 3 to 5 minutes. HPMC is dissolved in 30% of the total water to form a transparent slurry. The slurry is added to the dry mix and stirred at 60 r / min for 5 minutes. The remaining water is added and stirred at 60-80 r / min until the slurry consistency reaches 70-90 mm.

[0071] Application of special mortar for solid waste-based autoclaved aerated concrete (AAC) walls: thin-layer masonry of AAC blocks with mortar application thickness ≤ 5mm; or plastering of AAC walls with single plastering thickness 3-10mm.

[0072] The ambient temperature during construction is ≥5℃, and the initial setting time of the masonry construction is ≤5h (determined according to the penetration resistance method in GB / T1346-2011).

[0073] The open time for plastering construction is ≥45 minutes (measured according to JGJ / T70-2009).

[0074] In practical applications, the application of this mortar compared to ordinary mortar is shown in Table 3:

[0075]

[0076] Table 3

[0077] In summary, this invention offers the following technical benefits: solid waste resource utilization and environmental protection; a super-strong bonding and crack-resistant system; significantly improved freeze-thaw durability; optimized construction performance; improved workability; and enhanced energy conservation and economic efficiency.

[0078] Solid waste resource utilization and environmental benefits:

[0079] Solid waste disposal capacity: 80-150 kg of metallurgical mining solid waste (S95 mineral powder) can be consumed for every 1 ton of mortar produced, achieving a 100% resource utilization rate of metallurgical solid waste;

[0080] Carbon emission reduction: Replacing 30% of cement with mineral powder reduces CO2 emissions per ton of mortar by 15% (compared to ordinary mortar);

[0081] Reduced raw material costs: The unit price of mineral powder is only 34% of that of cement (120 yuan / ton vs. 350 yuan / ton), and large-scale production can save 200 yuan / ton in raw material costs.

[0082] Super strong adhesion and crack prevention system:

[0083] Mineral powder micro-filling effect (specific surface area ≥400m²) 2 The combined effect of HPMC film-forming effect (viscosity 300-500mPa·s) and the synergistic effect of the film-forming effect (viscosity 300-500mPa·s) results in a 14-day tensile bond strength of 0.60-0.67MPa (national standard ≥0.40MPa) and a hollow rate of ≤0.2% (commercially available products ≥5%).

[0084] The 28-day shrinkage rate is ≤0.20% (national standard ≤0.20%), which is 43% lower than that of ordinary mortar (0.35%), reducing the risk of wall cracking by 80%.

[0085] Significant improvement in freeze-thaw durability:

[0086] The active components of the mineral powder (CaO+Al2O3≥65%) generate dense hydration products. After 50 freeze-thaw cycles at -20℃, the strength loss is only 2.1% (national standard ≤20%), and the service life is extended to 50 years (ordinary mortar is about 30 years).

[0087] Construction performance optimization:

[0088] Water retention control: HPMC forms a three-dimensional water film at the silica sand interface, with a water retention rate of ≥99.5% (national standard ≥99.0%), reducing the moisture evaporation rate by 37% during high-temperature construction;

[0089] Improved ease of use:

[0090] A consistency of 70-90mm ensures a slurry slip ratio of 110±5mm, increasing mechanical spraying efficiency by 40% (85m). 2 / person / day vs 60m 2 );

[0091] With an opening time of ≥45 minutes, it solves the problem of joint plastering over large areas, reducing the rework rate by 90%.

[0092] Energy saving and economy:

[0093] Thermal performance optimization: thermal conductivity 0.24W / (m·K) (national standard ≤1.1), when used in conjunction with autoclaved aerated concrete blocks, building heating energy consumption is reduced by 15%;

[0094] Overall cost advantages: The cost of raw materials is reduced by 200 yuan per ton, and the cost of repair and maintenance is reduced by 40-50 yuan per square meter.

[0095] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A special mortar for solid waste-based autoclaved aerated concrete walls, characterized in that, It is composed of the following raw materials in parts by weight: 280-320 parts of solid waste-based cementitious material, 650-750 parts of silica sand, 8-15 parts of solid waste material, and 0.2-0.5 parts of cellulose-based additives.

2. The special mortar for solid waste-based autoclaved aerated concrete walls according to claim 1, characterized in that: The solid waste-based cementitious material is PSB 32.5 grade cement; The solid waste material is S95 grade mineral powder with a specific surface area ≥400m2 / kg and an activity index ≥95%.

3. The special mortar for solid waste-based autoclaved aerated concrete walls according to claim 1, characterized in that: The silica sand has a particle size range of 0.25mm to 0.5mm and a bulk density ≥1700kg / m³. 3 .

4. The special mortar for solid waste-based autoclaved aerated concrete walls according to claim 1, characterized in that: The cellulose additive is hydroxypropyl methylcellulose (HPMC) with a viscosity grade of 400 mPa·s.

5. The special mortar for solid waste-based autoclaved aerated concrete walls according to any one of claims 1-4, characterized in that: The mortar has a water retention rate of ≥99.5%, a 28-day compressive strength of ≥20.0 MPa, a 14-day tensile bond strength of ≥0.60 MPa, and a shrinkage rate of ≤0.20%.

6. A method for preparing a special mortar for solid waste-based autoclaved aerated concrete walls as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Put solid waste-based cementitious materials, silica sand, and solid waste into a mixer and dry mix them; S2: Dissolve the cellulose admixture in 20% to 30% of the total water volume to form a premixed solution; S3: Add the premixed solution to the dry mixture and mix and stir; S4: Add the remaining water and continue mixing until the consistency of the slurry reaches 70-90 mm.

7. The method for preparing special mortar for solid waste-based autoclaved aerated concrete walls according to claim 6, characterized in that: The dry mixing speed is 30-50 r / min; The mixing speed is 60-80 r / min.

8. The method for preparing special mortar for solid waste-based autoclaved aerated concrete walls according to claim 6, characterized in that: The total water consumption is 18% to 22% of the total weight of the raw materials.

9. The application of a special mortar for solid waste-based autoclaved aerated concrete walls as described in any one of claims 1 to 5, characterized in that: Solid waste-based autoclaved aerated concrete (AAC) wall mortar is used for the construction or plastering of AAC blocks, with a water-cement ratio controlled between 0.50 and 0.

60.

10. The application of the special mortar for solid waste-based autoclaved aerated concrete walls according to claim 9, characterized in that: The application environment temperature of the special mortar for solid waste-based autoclaved aerated concrete walls is ≥5℃, the initial setting time of the mortar is ≤5h, and the final setting time is ≤8h.

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