For aerated concrete blocks, its strength determines the performance of the product and the quality of the whole aerated concrete block equipment. So for aerated concrete block production line, it is especially important to strengthen the quality of the finished blocks.

 

During the production of aerated concrete block equipment, there are many factors that affect the strength of the finished blocks, so we need to go in the production process to try to avoid the impact of certain factors on the quality of the blocks. Aerated concrete block strength factors are affected by the autoclave maintenance, concrete block cutting and molding, need to be transported to the autoclave for autoclaving, autoclaving has a certain time limit to ensure adequate autoclaving time to ensure the normal development of the strength of aerated concrete, if the autoclave maintenance time is not enough, then the quality of block products will be seriously affected, serious the whole production line Block scrapping, so that the strict implementation of the autoclave maintenance system to ensure good autoclave maintenance measures to ensure the quality of finished blocks of aerated concrete block equipment is very important.

 

The maintenance system not only provides sufficient and reasonable maintenance for the billet, so that the product can reach the design strength in a short time, but also avoids the possible damage to the billet and the product to the maximum extent. Because products such as tolbo mullite are only produced in large quantities above 174.5°C, the autoclaved aerated concrete blocks have good overall physical properties only at this temperature and pressure level and for a certain period of time. Depending on whether the vacuum and so on, the general maintenance time of autoclaved aerated concrete blocks needs 6h~12h.

When the aerated concrete production line is working, the general environment is at room temperature, the application of mixing equipment to promote the reaction between raw materials and water, releasing gas expansion slurry, while hardening cement and lime, so that the finished product of aerated concrete equipment to present a porous structure, the second stage occurs under high temperature conditions, CaO and gas reaction in the aerated concrete equipment, greatly increasing the final product of The strength of the final product is greatly increased to ensure the high quality and standard of the final aerated concrete.

 

     Features of the batching process in aerated concrete production line  

 

    There are three kinds of raw materials for batching from physical form: liquid materials, slurry materials and powder materials, in addition to aluminum powder or aluminum powder paste. 

 

    1 liquid material measurement 

    Liquid materials are often measured in volume measurement tanks. Its structure is a certain volume of the cylinder (the lower part of the cone), in and out of the material tube is equipped with solenoid valve, the simplified version is connected to the liquid level indicator controller.  

 

    2 slurry material measurement

    Slurry materials using slurry metering tank metering, volume metering and weight metering type two. Volume metering type slurry metering tank with glass liquid level meter observation surface for control. Its structure is relatively simple, the measurement accuracy is not high, not convenient for automatic control; weight type slurry metering tank generally with sensors for the measurement of components, measurement accuracy is high, convenient for automatic control, but the structure is more complex.  

 

    3 powder material measurement

    Powdered materials are measured by weight measurement, the use of more is the lever type powder metering scale and electronic sensing type powder metering scale two. Lever weighing scale structure is relatively simple, but the measurement accuracy is not high, the material in and out of the material is not intuitive, easy to cause misoperation, and most can only measure a material, so that the batching system layout complicated; electronic sensor type weighing scale measurement accuracy is high, can achieve automatic recording and full program control, and can be multi-material measurement. Metering in and out of material instructions clear, not to form misoperation, but the equipment maintenance requirements are high.  

 

    4 Aluminum powder metering 

    Aluminum powder and aluminum powder paste dosage is relatively small, the general use of manual measurement, but poor sanitary conditions, foreign use of aluminum powder first formulated into aluminum powder suspension, and then the aluminum powder suspension according to the amount of ingredients for measurement, generally applicable to larger enterprises; domestic small and medium-sized enterprises also use aluminum powder paste concentrated in a silo, through the feeder into the measurement scale, measurement and then sent to the aluminum powder mixer for mixing, but because of the aluminum powder The amount of aluminum powder used is small, the impact on the gas, measurement of a slight error, it is easy to cause quality accidents, so most domestic factories are still using manual measurement to ensure the accuracy of measurement.

 

    5 Mixing of materials 

 

    Mixing of materials and slurry pouring by the mixer to complete, the mixer must make a variety of materials in a short time to mix uniformly, and can be heated to adjust the temperature. In a shorter time (within 1min) the aluminum powder suspension, etc. will be quickly dispersed into the slurry, and finally pouring.

 

 So what do you need to consider when batching aerated concrete?

 

    First, to give full play to the dual role of chemical properties of raw materials and admixtures, and use the best combination of the two effectiveness, in order to reduce the water-cement ratio and cement and water consumption, should choose suitable customers to put into operation aerated concrete equipment admixtures and admixtures, and to ensure the matching of the two.

 

    Second, consider the best amount of raw materials, must be derived from the trial ratio. To strictly prevent the ratio of insufficient amount and to avoid the side effects of excess admixture auxiliary raw materials, try to minimize the water-cement ratio to improve the pore structure of aerated concrete equipment products, thereby increasing the denseness, which is a key factor in improving the durability of finished products, strength, etc.. It is particularly worth reminding the point that the choice of high-efficiency compound admixture, and to test the best amount of admixture; different role of aerated concrete products to be designed according to its use of specific planning raw material ratios.

 

    Third, the use of small water requirements to replace the high rate of raw material admixtures. Try to reduce the cement and water consumption, because the cement dosage is high or the volume of cementitious material slurry is too large, then will bring certain losses.

To understand the impact of the aerated concrete equipment industry from upstream and downstream, firstly we need to understand what are the upstream industries of the industry, and what are the downstream industries of the industry, from the analysis of the upstream and downstream industries to understand the prospects for the development of the industry.

 

  The downstream industry of aerated concrete equipment industry mainly refers to projects that can make use of aerated concrete, which accounts for the largest proportion is the real estate project, since the reform and opening up, we will find more high-rise buildings here. In the construction of high-rise buildings, building materials with light weight and thermal insulation are needed, and aerated concrete with a thickness of 4cm can achieve the thermal insulation effect of 240cm clay bricks, with obvious thermal insulation performance, while the bulk weight is generally 400kg/m3-700kg/m3, which is equivalent to 1/3 of hollow clay bricks, 1/5 of solid clay bricks, 1/4 of concrete, and lower than the general light aggregate concrete. It is also lower than the weight of general light-aggregate concrete, and it is easy to construct and can help builders save construction cost, so naturally it is widely used in real estate projects. Nowadays, most of the floors are frame structures, and aerated concrete is also an ideal material for renovation of houses. Its upstream industries are mainly the steel industry, parts suppliers and other basic industries. The upstream industry, especially the steel industry, has a large impact on it. The amount of steel used in a set of equipment is huge, and the price of steel directly affects the manufacturing cost to a certain extent.

 

  The upstream industry directly affects the manufacturing cost of aerated concrete equipment industry, especially in the past two years, the steel market fluctuations are more violent, which has caused a certain impact on the development of the industry, but the biggest impact is still the downstream real estate industry. The real estate industry directly affects the investment in the construction of aerated concrete plants, if the market demand slows down, the project investment fever will also be reduced, which will naturally affect the development of the manufacturing industry. The understanding of the upstream industry will be beneficial to the development of manufacturing enterprises.

 

1. Cement. The main inspection indexes of cement are as follows: stability, fineness, standard consistency, water consumption, setting time, flexural strength and compressive strength. The strength of aerated brick depends on its components: the comprehensive effect of hardened cement paste, interface transition zone and aggregate strength, and the cement strength is closely related to the strength of aerated brick equipment block, The factors affecting the cement strength also affect the strength of aerated brick blocks.

 

2. Fine aggregate. Fine aggregate has a great impact on the strength of aerated brick mainly due to the fineness modulus and mud content. The finer the sand is, the more unfavorable it is to the strength of aerated brick. The increase of mud content not only affects the strength of aerated brick, but also adversely affects the frost resistance and other characteristics of aerated brick.

 

3. Coarse aggregate. The main factors affecting the strength of aerated brick equipment block by coarse aggregate include orthopedic strength, mineral composition, large particle size and so on. Because the strength of aggregate is much higher than that of cement slurry matrix and interface transition zone, the strength of aggregate has not been fully utilized. Only when the strength of cement slurry matrix and transition zone is higher than or close to the strength of aggregate, it is necessary to seriously consider the strength of aggregate. Secondly, the different composition of aggregate minerals will also affect the strength of aerated brick blocks. The increase of the needle and flake content of the aggregate will have a great adverse impact on the aerated brick block, because the needle and flake orthopedics has large surface area and large internal friction. When the content increases, it will increase the surface area and porosity of the coarse aggregate, reduce the fluidity of the aerated brick mixture, and aggravate the phenomenon of dew stone and segregation. Needle flake particles will not only affect the workability, cement dosage and strength of aerated brick block, but also affect its durability. How to place the embryo in the mold of aerated concrete production line will deteriorate the performance of aerated brick block, increase the porosity of aggregate and increase the unit water consumption and deformation.

 

The price of non fired brick machine is not important. The price of non fired brick machine is not the standard for selecting equipment. As customers who buy brick machine equipment now, they always put the purchase standard on the price when buying hydraulic brick machine. If the price is cheap, they have a strong desire to buy. If the price is high, they will directly dispel their desire, I don't consider the quality and performance of the equipment at all. I'm only interested in the price of the equipment. As a manufacturer, I'm also very confused. It's incorrect to think so. In terms of considering the price of brick machines without considering other aspects, this view should be improved. As customers, they should pay more attention to the overall performance of the equipment, whether they can produce normally and whether they can keep up with the output demand. As every manufacturer, they will encounter the problem of bargaining when customers buy equipment, This problem is very common in the market. There is no standard for the sales of brick machinery equipment in the market, and the equipment price fluctuates. The user can communicate with the seller, try to talk about the price that can be agreed by both sides, and ensure that the manufacturer has income, so that the agreement can be reached between the two sides. Especially with the rapid development of brick machinery and equipment, the scope of use of non fired brick is becoming larger and larger. It can be said that its application has been extended to every corner of people's life from now on, The appearance of colored bricks has changed people's life. The pavement is not only bright in color, but also can quickly absorb the ponding on the pavement. No matter how large or heavy vehicles roll, they will not deform the highway. According to the relevant departments, this kind of polymer permeable pavement that can also reduce noise will become a wide range of bricks to be promoted nationwide in the future. This new type of brick will also break the original black-and-white pattern of traditional black-and-white roads. With new changes, it can also brighten people's eyes, have a refreshing feeling, and instantly make people feel happy.

Autoclave curing system is a specific control measure related to temperature and time for full and effective curing of products. There are four stages: vacuum pumping, heating, constant temperature and cooling.

(1) Curing before entering the autoclave: curing before entering the autoclave after cutting. It can improve the state of the green body, reduce the temperature difference inside and outside the green body, and enhance the strength of the green body into the kettle and the ability to resist internal stress. After entering the kettle, the temperature rise can be faster.

(2) Vacuumizing: discharge the air in the kettle and part of the gas in the green body bubble to form a negative pressure state. Only when the saturated steam can quickly transfer the heat to the center of the green body and make the temperature of the whole green body rise rapidly. Shorten the heating time to make the temperature of each part of the green body basically the same. The temperature of each part in the kettle tends to be uniform to improve the thermal efficiency. The speed and degree of vacuum pumping depend on the air permeability and hardening of the green body. Good air permeability, high green body plastic strength when entering the kettle, faster vacuum pumping and higher vacuum degree. On the contrary, it should be pumped slowly and the vacuum degree should be appropriately lower to avoid damage to the green body. The speed of vacuum pumping should not be too fast. It usually takes 30 minutes, and the vacuum degree is -0.06 MPa.

(3) Temperature rise: after vacuum pumping, air shall be supplied immediately for temperature rise. During the heating process, there is a temperature difference between the inside and outside of the billet. The initial heating should be slow. With the gradual increase of the billet temperature, the internal and external temperature difference will gradually reduce. In the later heating stage, the heating speed can be accelerated. Generally, the heating time is 2.5-3 hours.

(4) Constant temperature: when the raw materials of aerated concrete are different, the formula is different, and the unit weight is different, the curing temperature of the green body and the curing time at this temperature are also different. Considering the characteristics of heat transfer in aerated concrete kettle. To ensure the strength and uniformity of products. And ensure better production efficiency. Constant temperature pressure is usually 1.3mpa; Constant temperature time is to enable the product to carry out sufficient hydration reaction and reach a certain crystallinity. The inner layer of the billet also achieves this effect. The constant temperature time shall be determined according to the specific situation on the basis of this principle. The constant temperature time is usually 6 ~ 8 hours. However, to ensure constant temperature, the constant temperature shall not fluctuate greatly with humidity.

(5) Cooling: at the beginning of cooling, the cooling speed shall be slow to avoid explosive damage to products due to internal and external temperature difference; The cooling can be fast in the medium term and slow in the later stage (when the gauge pressure is below 0.1MPa). On the one hand, the external pressure difference in the kettle is very small, and the steam exhaust power is weakened. On the other hand, the water of the product still needs to be evaporated, and the amount of steam is also large. Generally, the cooling is controlled within 2 hours.

After liberation, China began to pay attention to the research and production of aerated concrete. By 1965, China established its first aerated concrete plant. Since then, China has entered the era of aerated concrete industrial production. Aerated concrete equipment products have the characteristics of light weight, high strength, energy saving, soil saving, thermal insulation, waste utilization, fire prevention, superior economic indicators and easy processing. They can be widely used in industrial plants and civil buildings as load-bearing materials such as walls, floors and roof panels, non load-bearing materials or enclosure filling materials.

 

  1. Light weight. The unit weight of aerated concrete is generally 400 ~ 700kg / m3, equivalent to 1 / 3 of clay brick and 1 / 5 of ordinary brick, which is also lower than that of ordinary lightweight aggregate concrete. Therefore, the use of aerated concrete as wall material can not only greatly reduce the self weight of buildings, but also save building materials and engineering costs.

 

  2. Good thermal insulation performance. Aerated concrete contains a large number of bubbles and micropores, so it has good thermal insulation performance. The thermal conductivity of aerated concrete with unit weight of 400 ~ 700kg / m3 is usually 0.09 ~ 0.17w / (m.k), and the thermal insulation capacity is 3 ~ 4 times that of clay brick and 4 ~ 8 times that of ordinary concrete.

 

  3. Machinability. Aerated concrete can not only produce a variety of specifications in the factory, but also saw, planed, drilled and nailed like wood. Therefore, it is very convenient to process according to the user's requirements and specifications in the manufacturer or reprocess according to the actual needs at the use site.

 

  4. Wide sources of raw materials, high production efficiency and low production energy consumption. Aerated concrete equipment blocks can be produced with a variety of raw materials such as fly ash, slag, coal gangue, sand, cement, quicklime and so on. Generally speaking, the production efficiency of aerated concrete equipment products factory is relatively high. Aerated concrete consumes less energy, and its production energy consumption per unit product is only 11% of that of clay brick with the same volume, which is also relatively low compared with other traditional building materials.

 

  in recent years, the contradiction of energy supply around the world has become increasingly prominent. Energy conservation has become a major issue, and China is no exception. According to relevant calculations, the external wall accounts for about 24% of the dissipation and consumption of heat energy in various parts of the building. In order to reduce the heat loss of the wall, we must use building materials with good thermal insulation performance. In this regard, aerated concrete equipment blocks highlight their excellent thermal insulation performance and will play an important role.

 

  aerated concrete equipment block is widely valued by the construction industry all over the world, and has become a new kind of building materials vigorously promoted and developed by many countries. After China implements the national policy of wall material reform and sustainable development of energy conservation, because aerated concrete block has the unique advantages of integrating new wall materials and thermal insulation materials, aerated concrete block will be further developed and developed in China, and is developing towards large-scale and high technology.

When the aerated concrete production line is working, the general environment is under normal temperature. The mixing equipment is used to promote the reaction between raw materials and water and release gas to expand the slurry. While hardening cement and lime, the finished products of aerated concrete equipment show porous structure. The second stage occurs under high temperature conditions, Cao and gas react in the aerated concrete equipment, which greatly increases the strength of the final product and ensures the high quality and high standard of the final aerated concrete.

 

Technological characteristics of batching in aerated concrete production line

 

There are three kinds of raw materials for batching: liquid materials, slurry materials and powder materials. In addition, there are aluminum powder or aluminum powder paste.

 

1. measurement of liquid materials

 

Liquid materials are usually measured by volume measuring tank. The structure is a cylinder with a certain volume (the lower part is conical), the inlet and outlet pipe is equipped with a solenoid valve, and the simplified body is connected with a liquid level indication controller.

 

2. measurement of slurry materials

 

Slurry materials are measured by slurry metering tank, which can be divided into volume metering type and weight metering type. The volume metering slurry metering tank is controlled by the observation surface of the glass level gauge. Its structure is relatively simple, the measurement accuracy is not high, and it is not convenient for automatic control; The weight slurry metering tank generally takes the sensor as the metering element, which has high metering accuracy and is convenient for automatic control, but the structure is complex.

 

3. measurement of powdery materials

 

Powder materials are measured by weight, and lever type powder weighing scales and electronic sensor type powder weighing scales are widely used. The structure of the lever scale is relatively simple, but the measurement accuracy is not high, the incoming and outgoing materials are not intuitive, which is easy to cause misoperation, and most of them can only measure one material, which complicates the layout of the batching system; The electronic sensing scale has high measurement accuracy, can realize automatic recording and full program control, and can measure multiple materials. The indication of metering incoming and outgoing materials is clear, so as to avoid misoperation, but it has high requirements for equipment maintenance.

 

4. measurement of aluminum powder

 

The amount of aluminum powder and aluminum powder paste is small, which are generally measured manually, but the sanitary conditions are poor. In foreign countries, aluminum powder is prepared into aluminum powder suspension, and then the aluminum powder suspension is measured according to the proportioning amount, which is generally suitable for large-scale enterprises; Domestic small and medium-sized enterprises also use to concentrate aluminum powder paste in one silo, send it to the metering scale through the feeder, and then send it to the aluminum powder mixer for mixing. However, due to the small amount of aluminum powder, it has a great impact on gas generation, and a slight error in measurement, it is easy to cause quality accidents. Therefore, most domestic factories still use manual measurement to ensure the accuracy of measurement.

 

5. mixing of materials

 

The mixing of materials and the pouring of slurry are completed by the mixer. The mixer must make all kinds of materials mix evenly in a short time and can be heated to adjust the temperature. Quickly disperse the aluminum powder suspension into the slurry in a shorter time (within 1min), and finally pour.

 

So what aspects should be considered in the batching of aerated concrete?

 

1、 To give full play to the dual role of chemical properties of raw materials and admixtures, and make use of their best combination efficiency to reduce water binder ratio and cement and water consumption, admixtures and admixtures suitable for customers to put into operation aerated concrete equipment should be selected to ensure the matching of the two.

 

2、 Considering the optimum content of raw materials, it must be obtained through trial mixing and comparison. It is necessary to strictly prevent the insufficient proportion and avoid the side effects of excessive auxiliary raw materials of admixtures, and minimize the water binder ratio to improve the pore structure of aerated concrete equipment products, so as to increase the compactness, which is the key factor to improve the durability and strength of finished products. In particular, it is worth reminding that high-efficiency composite admixtures should be selected, and the best dosage should be tested; For aerated concrete products with different functions, the proportion of raw materials shall be designed and planned according to their uses.

 

3、 Raw material admixtures with low water demand and high substitution rate shall be selected. Reduce cement and water consumption as much as possible, because high cement consumption or excessive volume of cementitious material slurry will bring certain losses.