阅读说明：本技术 一种低密度、高强、增韧蒸压加气混凝土外加剂及其制备方法与应用 (Low-density, high-strength and toughening autoclaved aerated concrete admixture and preparation method and application thereof ) 是由 朱研 羊中军 吴其胜 李北星 孙赛寅 王皓 于 2020-11-19 设计创作，主要内容包括：本发明公开了一种低密度、高强、增韧蒸压加气混凝土外加剂及其制备方法与应用。该外加剂按重量份数计包括如下原料：超细粉50-60份、碱活性激发剂5-8份、纳米转晶剂10-15份、芳纶纤维1-2份。将超细粉研磨20-30min后,转入微球中粉磨20-30min,得粉末比表面积≥700m～2/kg；向上述粉末中加入碱活性激发剂、纳米转晶剂混合均匀,再加入芳纶纤维继续混合均匀,即得外加剂。本发明的低密度、高强、增韧蒸压加气混凝土外加剂可以保证低密度下加气混凝土的力学性能要求,所述外加剂在制备加气混凝土上的应用。避免加气混凝土制品运输过程中出现裂纹、缺角现象的发生。(The invention discloses a low-density, high-strength and toughening autoclaved aerated concrete admixture and a preparation method and application thereof. The additive comprises the following raw materials in parts by weight: 50-60 parts of superfine powder, 5-8 parts of alkali activity excitant, 10-15 parts of nano crystal modifier and 1-2 parts of aramid fiber. Grinding the superfine powder for 20-30min, transferring into microsphere, and grinding for 20-30min to obtain powder with specific surface area of more than or equal to 700m 2 Per kg; adding alkali-activated activator and nano-crystal modifier into the powder, mixing uniformly, adding aramid fiber, and mixing uniformly to obtain additive. The low-density, high-strength and toughened autoclaved aerated concrete admixture can meet the mechanical property requirement of aerated concrete at low density, and is applied to the preparation of aerated concrete. The phenomena of cracks and unfilled corners in the transportation process of the aerated concrete product are avoided.)

1. The low-density, high-strength and toughening autoclaved aerated concrete admixture is characterized by comprising the following raw materials in parts by weight: 50-60 parts of superfine powder, 5-8 parts of alkali activity excitant, 10-15 parts of nano crystal modifier and 1-2 parts of aramid fiber.

2. The low-density, high-strength and toughening autoclaved aerated concrete admixture according to claim 1, wherein the ultrafine powder is prepared by mixing and ball-milling any of slag, fly ash, boric sludge, strait sand, kaolin or wollastonite;the alkali activity activator is formed by mixing any several of sodium sulfate, sodium hydroxide, sodium silicate, lithium silicate or barium sulfate; the nano crystal modifier is formed by mixing any several of nano calcium carbonate, nano aluminum oxide or nano silicon oxide; the aramid fiber is para-position chopped aramid fiber, the length of the para-position chopped aramid fiber is 1-3mm, and the specific surface area of the para-position chopped aramid fiber is 5-8m²/g。

3. The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture based on the claim 1 is characterized by comprising the following steps: step 1, grinding the ultrafine powder for 20-30min, transferring the ultrafine powder into microspheres for grinding for 20-30min to obtain powder with the specific surface area of more than or equal to 700m²Per kg; and 2, adding an alkali-activity exciting agent and a nano crystal modifier into the powder obtained in the step 1, uniformly mixing, adding aramid fibers, and continuously uniformly mixing to obtain the additive.

4. Use of an admixture according to claim 1 or claim 3 in the preparation of aerated concrete.

5. The application as claimed in claim 4, wherein the concrete in the application comprises the following components in parts by weight: 550 parts of quartz sand tailings, 120 parts of cement, 240 parts of lime 200, 25-30 parts of gypsum, 65-85 parts of aerated concrete admixture, 1-1.2 parts of aluminum powder paste and 500 parts of water 480.

6. The application of claim 4, wherein the concrete in the application is prepared by the following specific steps: firstly, uniformly mixing quartz sand tailings, cement, lime, gypsum and an aerated concrete additive; adding water and continuously stirring uniformly; finally, adding a suspension of aluminum powder paste and water to obtain autoclaved aerated concrete slurry; and secondly, pouring and forming the autoclaved aerated concrete slurry, curing for 8-10h at 50-60 ℃, removing the mold, curing for 8-10h at 180-200 ℃ and 1.20-1.30MPa, and cooling to obtain the low-density, high-strength and toughened autoclaved aerated concrete.

Technical Field

The invention belongs to the field of building material processing, and particularly relates to a low-density, high-strength and toughened autoclaved aerated concrete admixture, and a preparation method and application thereof.

Background

As one of the important varieties of novel wall materials, the autoclaved aerated concrete block has the advantages of good heat preservation and insulation effects, good fireproof performance, sound insulation, light weight, environmental protection and the like compared with the traditional clay sintered brick. However, the aerated concrete block has large volume deformation coefficient, low strength and large water absorption, and when the aerated concrete block is built into a wall, the wall is easy to crack, and a plastering layer is easy to crack, hollows and fall off in a large area, which shows that the aerated concrete block has obvious brittleness and blocks further application and popularization of the autoclaved aerated concrete block to a certain extent.

Chinese patent CN201410159508.6, 15.7.2015, discloses an aerated concrete prepared by taking fly ash-nano silicon dioxide-silica fume as a main siliceous material, which comprises the following raw materials: the formula is low in cost and simple in preparation process, and improves the crystallization degree and the crystal quantity of tobermorite which is a hydration product of the aerated concrete, so that the heat preservation performance and the strength of the aerated concrete are improved.

CN 101182173A relates to the adiabatic and material mechanical properties's of aerated concrete key technical scheme that promotes, belongs to building envelope heat preservation technical field. The invention improves the performance of the aerated concrete by two steps, so that the aerated concrete can meet the national building energy-saving (50-80%) standard requirement by a single material: the first step is to improve the heat insulation performance until the dry heat conductivity coefficient is less than or equal to 0.05W/(m.K); the second step is to enhance the mechanical property of the material until the cubic compressive strengthThe degree is more than or equal to 3.5MPa, and the degree is more than or equal to 2.0MPa after 100 times of freeze thawing. Wherein the first step comprises mixing aerated concrete: (1) the density is minimized; (2) the porosity is maximized; (3) the pore structure is optimized. The second step comprises: (1) enhancement of additives; (2) fiber reinforcement; (3) optimizing the assembly; (4) optimizing the stirring process; (5) improved maintenance process (including CO)₂Variable pressure steam curing, medium temperature high humidity and surface curing by a strength agent).

The autoclaved aerated concrete prepared by the invention is improved in mechanical and thermal insulation properties, but the application of the aerated concrete is restricted by factors such as low surface strength of the aerated concrete, easy powder generation, easy cracking in the plate product transportation process and the like.

Disclosure of Invention

The invention aims to provide an additive capable of effectively improving the compressive strength and toughness of autoclaved aerated concrete at low density;

the second purpose of the invention is to provide a preparation method of the admixture;

the third purpose of the invention is to provide the autoclaved aerated concrete prepared by adopting the additive.

In order to solve the problems of the prior art, the invention adopts the technical scheme that:

a low-density, high-strength and toughening autoclaved aerated concrete admixture comprises the following raw materials in parts by weight: 50-60 parts of superfine powder, 5-8 parts of alkali activity excitant, 10-15 parts of nano crystal modifier and 1-2 parts of aramid fiber.

Furthermore, the ultrafine powder is prepared by mixing and ball milling any of slag, fly ash, boric sludge, strait sand, kaolin or wollastonite; the alkali activity activator is formed by mixing any several of sodium sulfate, sodium hydroxide, sodium silicate, lithium silicate or barium sulfate; the nano crystal modifier is formed by mixing any several of nano calcium carbonate, nano aluminum oxide or nano silicon oxide; the aramid fiber is para-position chopped aramid fiber, the length of the para-position chopped aramid fiber is 1-3mm, and the specific surface area of the para-position chopped aramid fiber is 5-8m²/g。

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

step 1, grinding the ultrafine powder for 20-30min, transferring the ultrafine powder into microspheres for grinding for 20-30min to obtain powder with the specific surface area of more than or equal to 700m²/kg；

And 2, adding an alkali-activity exciting agent and a nano crystal modifier into the powder obtained in the step 1, uniformly mixing, adding aramid fibers, and continuously uniformly mixing to obtain the additive.

Based on the application of the admixture in preparing aerated concrete.

As an improvement, the concrete in the application comprises the following components in parts by weight: 550 parts of quartz sand tailings, 120 parts of cement, 240 parts of lime 200, 25-30 parts of gypsum, 65-85 parts of aerated concrete admixture, 1-1.2 parts of aluminum powder paste and 500 parts of water 480.

The preparation method of the concrete in the application comprises the following specific steps:

firstly, uniformly mixing quartz sand tailings, cement, lime, gypsum and an aerated concrete additive; adding water and continuously stirring uniformly; finally, adding a suspension of aluminum powder paste and water to obtain autoclaved aerated concrete slurry;

and secondly, pouring and forming the autoclaved aerated concrete slurry, curing for 8-10h at 50-60 ℃, removing the mold, curing for 8-10h at 180-200 ℃ and 1.20-1.30MPa, and cooling to obtain the low-density, high-strength and toughened autoclaved aerated concrete.

Has the advantages that:

compared with the prior art, the low-density, high-strength and toughening autoclaved aerated concrete admixture, and the preparation method and the application thereof have the following advantages:

the adoption of the ultrafine powder can improve the compactness of the autoclaved aerated concrete and influence the growth of the tobermorite structure, thereby easily forming a compact network structure. Meanwhile, the crystal structure is changed by doping the nano crystal modifier, a xonotlite structure with a fiber winding structure is formed, the mechanical property of the autoclaved aerated concrete is greatly improved, the strength is improved, and the pulverization phenomenon of the aerated concrete is reduced by adopting a fiber toughening technology.

Detailed Description

The technical scheme of the invention is further explained in detail by combining the embodiment

The autoclaved aerated concrete is prepared by a conventional aerated concrete production process, and the mechanical property and toughness of the autoclaved aerated concrete are improved by adding the ultrafine powder, the alkali activity activator, the nano crystal modifier and the aramid fiber, so that the compressive strength is improved by 20-30% and the flexural strength is improved by 10-30% on the premise of producing an autoclaved aerated concrete product with the dry density of B06 level.

Example 1

A low-density, high-strength and toughening autoclaved aerated concrete admixture comprises the following components in parts by weight: 20 parts of slag, 20 parts of boric sludge, 20 parts of kaolin, 2 parts of sodium sulfate, 4 parts of barium sulfate, 5 parts of nano alumina, 5 parts of nano silicon oxide and 1 part of aramid fiber.

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

(1) 20 parts of slag, 20 parts of boron sludge and 20 parts of kaolin are placed in a small unified test mill with steel forging to be ground for 20min, the obtained mixture is continuously placed in microspheres to be ground for 25min, and the specific surface area of the obtained mixture is 731m²/kg；

(2) And adding 2 parts of sodium sulfate, 4 parts of barium sulfate, 5 parts of nano aluminum oxide and 5 parts of nano silicon oxide, uniformly mixing, adding 1 part of aramid fiber, and uniformly mixing to obtain the low-density, high-strength and toughening autoclaved aerated concrete admixture.

The formula and the steps of preparing the concrete by using the aerated concrete admixture are as follows:

(1) putting 500 parts of quartz sand tailings, 110 parts of cement, 200 parts of lime, 25 parts of gypsum and 77 parts of aerated concrete admixture into a cement mortar stirrer and uniformly stirring; adding 450 parts of 50 ℃ water, and stirring for 120s under the conditions of rotation speed of 140 +/-5 r/min and revolution of 62 +/-5 r/min;

(2) 1 part of aluminum powder paste and 30 parts of water with the temperature of 50 ℃ are prepared into suspension liquid and added into the slurry, and the mixture is continuously stirred for 120s under the conditions of the autorotation speed of 285 +/-10 r/min and the revolution of 125 +/-10 r/min;

(5) and pouring the slurry into a test mold after stirring, standing and maintaining for 8 hours at 50 ℃, removing the mold, sending into a still kettle with the temperature of 180 ℃ and the pressure of 1.2MPa for still pressing for 8 hours, and cooling to obtain the low-density, high-strength and toughened autoclaved aerated concrete product.

Example 2

A low-density, high-strength and toughening autoclaved aerated concrete admixture comprises the following components in parts by weight: 15 parts of fly ash, 15 parts of strait sand, 20 parts of wollastonite, 1 part of lithium silicate, 6 parts of sodium silicate, 12 parts of nano calcium carbonate and 2 parts of aramid fiber.

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

(1) placing 15 parts of fly ash, 15 parts of strait sand and 20 parts of wollastonite in a small unified test mill with steel forging to grind for 25min, continuously placing the obtained mixture in microspheres to grind for 25min, and obtaining the mixture with the specific surface area of 744m²/kg；

(2) Adding 1 part of lithium silicate, 6 parts of sodium silicate and 12 parts of nano calcium carbonate, uniformly mixing, adding 2 parts of aramid fiber, and uniformly mixing to obtain the low-density, high-strength and toughening autoclaved aerated concrete admixture.

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

(1) putting 550 parts of quartz sand tailings, 100 parts of cement, 240 parts of lime, 30 parts of gypsum and 71 parts of aerated concrete admixture into a cement mortar stirrer and uniformly stirring; then 460 parts of 50 ℃ water is added, and the mixture is stirred for 120s under the conditions of the autorotation speed of 140 +/-5 r/min and the revolution of 62 +/-5 r/min;

(2) preparing 1.2 parts of aluminum powder paste and 30 parts of water with the temperature of 50 ℃ into suspension, adding the suspension into the slurry, and continuously stirring for 120s under the conditions of the autorotation speed of 285 +/-10 r/min and the revolution of 125 +/-10 r/min;

(3) and pouring the slurry into a test mold after stirring, standing and maintaining for 8 hours at the temperature of 60 ℃, removing the mold, and steaming and pressing for 10 hours in a steaming and pressing kettle at the temperature of 200 ℃ and the pressure of 1.3MPa to obtain the low-density, high-strength and toughened autoclaved aerated concrete product.

Example 3

A low-density, high-strength and toughening autoclaved aerated concrete admixture comprises the following components in parts by weight: 20 parts of slag, 15 parts of fly ash, 20 parts of strait sand, 6 parts of sodium hydroxide, 4 parts of nano calcium carbonate, 12 parts of nano silicon oxide and 1 part of aramid fiber.

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

(1) placing 20 parts of slag, 15 parts of fly ash and 20 parts of strait sand in a small unified test mill with steel forging to grind for 25min, continuously placing the obtained mixture in microspheres to grind for 30min, and obtaining the mixture with the specific surface area of 746m²/kg；

(2) And adding 6 parts of sodium hydroxide, 4 parts of nano calcium carbonate and 12 parts of nano silicon oxide, mixing uniformly, adding 1 part of aramid fiber, and mixing uniformly to obtain the low-density, high-strength and toughening autoclaved aerated concrete admixture.

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

(1) putting 520 parts of quartz sand tailings, 100 parts of cement, 230 parts of lime, 28 parts of gypsum and 78 parts of aerated concrete admixture into a cement mortar stirrer and uniformly stirring; adding 470 parts of 50 ℃ water, and stirring for 120s under the conditions of rotation speed of 140 +/-5 r/min and revolution of 62 +/-5 r/min;

(2) 1.1 part of aluminum powder paste and 30 parts of water with the temperature of 50 ℃ are prepared into suspension liquid and added into the slurry, and the mixture is continuously stirred for 120s under the conditions of the autorotation speed of 285 +/-10 r/min and the revolution of 125 +/-10 r/min;

(3) and pouring the slurry into a test mold after stirring, standing and maintaining for 9 hours at 70 ℃, removing the mold, and sending the mold into a still kettle at 190 ℃ and 1.25MPa for still pressing for 9 hours to obtain the low-density, high-strength and toughened autoclaved aerated concrete product.

Example 4

A low-density, high-strength and toughening autoclaved aerated concrete admixture comprises the following components in parts by weight: 25 parts of boron sludge, 30 parts of wollastonite, 3 parts of barium sulfate, 3 parts of lithium silicate, 12 parts of nano alumina and 1.5 parts of aramid fiber.

The preparation method of the low-density, high-strength and toughened autoclaved aerated concrete admixture comprises the following steps:

(1) 25 parts of boronPlacing the mud residue and 30 parts of wollastonite in a uniform test small mill with steel forging to grind for 30min, continuously placing the obtained mixture in microspheres to grind for 30min to obtain the mixture with the specific surface area of 755m²/kg；

(2) Adding 3 parts of barium sulfate, 3 parts of lithium silicate and 12 parts of nano-alumina, mixing uniformly, adding 1.5 parts of aramid fiber, and mixing uniformly to obtain the low-density, high-strength and toughening autoclaved aerated concrete admixture.

The formula and the steps of preparing the concrete by using the aerated concrete admixture are as follows:

(1) putting 540 parts of quartz sand tailings, 120 parts of cement, 230 parts of lime, 25 parts of gypsum and 74.5 parts of aerated concrete admixture into a cement mortar stirrer and uniformly stirring; then 460 parts of 50 ℃ water is added, and the mixture is stirred for 120s under the conditions of the autorotation speed of 140 +/-5 r/min and the revolution of 62 +/-5 r/min;

(2) 1 part of aluminum powder paste and 30 parts of water with the temperature of 50 ℃ are prepared into suspension liquid and added into the slurry, and the mixture is continuously stirred for 120s under the conditions of the autorotation speed of 285 +/-10 r/min and the revolution of 125 +/-10 r/min;

(3) and pouring the slurry into a test mold after stirring, standing and maintaining for 8 hours at 50 ℃, removing the mold, and steaming and pressing for 10 hours in a steaming and pressing kettle at 180 ℃ and 1.3MPa to obtain the low-density, high-strength and toughened autoclaved aerated concrete product.

Comparative example

(1) Putting 550 parts of quartz sand tailings, 120 parts of cement, 200 parts of lime and 25 parts of gypsum into a cement mortar stirrer and uniformly stirring; adding 450 parts of 50 ℃ water, and stirring for 120s under the conditions of rotation speed of 140 +/-5 r/min and revolution of 62 +/-5 r/min;

(2) 1 part of aluminum powder paste and 30 parts of water with the temperature of 50 ℃ are prepared into suspension liquid and added into the slurry, and the mixture is continuously stirred for 120s under the conditions of the autorotation speed of 285 +/-10 r/min and the revolution of 125 +/-10 r/min;

(3) and pouring the slurry into a test mold after stirring, standing and maintaining for 8 hours at 50 ℃, removing the mold, and sending the mold into a still kettle with the temperature of 180 ℃ and the pressure of 1.2MPa for still pressing for 8 hours to obtain the low-density, high-strength and toughened autoclaved aerated concrete product.

Performance detection

The autoclaved aerated concrete prepared in the above examples 1 to 4 and comparative example was subjected to dry density, compressive strength and flexural strength tests with reference to GBT 11969-2008 "method for testing autoclaved aerated concrete Performance", and the results obtained are shown in the following Table 1.

TABLE 1 tables of Properties of autoclaved aerated concrete prepared in examples 1 to 4 and comparative examples

And (4) analyzing a performance test result:

as can be seen from Table 1, the autoclaved aerated concrete prepared by the preparation method meets the requirements of national products, and the indexes of the compressive strength and the flexural strength of the autoclaved aerated concrete are superior to those of the autoclaved aerated concrete prepared by the method in the comparative example, the dry density of the autoclaved aerated concrete prepared in the examples 1 to 4 is B06 grade, the compressive strength of the autoclaved aerated concrete is higher than that of a superior product A5.0 to 5.0MPa, the average value of the compressive strength can reach 6.8MPa at most, the flexural strength is superior to that of the comparative example and can reach 2.5MPa at most, and the autoclaved aerated concrete admixture prepared by the method has the effects of low density, high strength and toughening.

The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and any simple modifications or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope of the present invention are within the scope of the present invention.