Automated lines for non autoclaved aerated concrete production
Aerated concrete is one of the most popular building materials. Due to its characteristics aerated concrete takes its place in the market of construction materials for erection of walls and dividing walls.
The modern plant for aerated concrete production is a computerized system of technological processes automation which guarantees high accuracy of proportioning of components, homogeneity and permanence of mixture ratio, and also provides manufacturing of quality and competitive products.
- sector of storage, preparation and feeding of raw materials;
- mixing sector;
- moulding sector;
- thermal treatment section;
- sector of aerated concrete mass sawing;
- storage area for finished product.
Sector of storage, preparation and feeding of raw materials
Primary components (raw materials) for aerated concrete products manufacturing should meet the requirements of standards and technical specifications for such materials and provide production of products with desired properties.
Portland cement according to GOST 10178 (without admixtures of tripoli, burnt clay, trass, glinite, gaize and ashes). We would recommend marks PC-500 DO, PC-400D20. It is possible to use portland-slag cement SHPC 500 and SHPC 400 after an additional check.
- CHP fly ash containing min 45% of SiO2, max 10% of СaO, max 3% of R2O, max 3% of SO3;
- granulated blust-furnace slag (GOST 3476) - grinding to surface area required, depending on needed average density;
- sand (GOST 8736), containing min 90% of SiO2, or min 75% of quartz, max 0,5% of mica, max 3% of clay and argillic admixtures
Water (GOST 23732)
Gas forming agent: aluminum powder of marks PAP-1 and PAP-2 according to GOST 5494.
Regulators of structure formation, development of plastic strength regulators, hardeners and plasticizers:
- gypsum stone and gypsum-anhydrite stone (GOST 4013);
- potassium carbonate (GOST 4221);
- soda ash (GOST 5100);
- sodium water glass (GOST 13078);
- triethanolamine (TU 6-09-2448);
- trisodium phosphate (GOST 201);
- superplasticizing agent S-3 (TU 6-14-625);
- technical caustic soda (GOST 2263).
Besides, other chemical admixtures for speeding-up of structure formation, plastic strength, hardening, etc. , and also structure-forming agent of gas pores can be used.
1. Acceptance and storage of fine materials (cement, fly ash)
For acceptance and storage of fine materials special bunkers (silos) are used. Volume of such silos is calculated due to plant production. Materials are delivered by cement trucks. Cement and fly ash are fed to the silos through cement line with the help of pneumatic concrete placer. The silos are provided with aeration system, filters and vibroactivators.
2. Acceptance, storage and preparation of sand
Sand is delivered by dump trucks. Sand is loaded by dump truck or front loader to receiving bunker (volume of the bunker is calculated due to plant production). From the bunker sand goes to vibrating screen which sieves garbage and grains of sand larger than 2mm. Screened sand goes through belt conveyor to hopper. All mechanisms are managed with the help of single remote control.
3. Preparation of tempering water
For preparation of tempering water through-type water treatment complex is used. The complex is designed to heat, maintain the desired temperature and pressure batching of water in an amount specified by the operator. Heating and transportation of water to the storage container is made with electric boiler and hydro-circulation system. The operator controls management and regulation of parameters. Batching is carried in a certain volume predetermined by the operator.
4. Preparation of aluminum suspension
Aluminum suspension is prepared in the mixer. Preparation of aluminum suspension includes mixing water, aluminum powder and surface active agent.
Mixing sector consists of platform, control panel, weigh hopper of dry components, batcher of aluminum suspension, batcher of chemical admixtures and mixer for aerated concrete mix preparation. Batchers with strain sensors are established on the platform. The mixer is set under the batchers. A consumable material feeding is performed by remote control which is served by one person. Batching of water is performed with the help of electronic water dispenser which is a part of a water treatment complex. Fine materials (cement, fly ash) enter to the weigh hopper with the help of screw feeder, in accordance with the consumption rate for the corresponding average density of aerated concrete. After that materials go to the mixer. If you use sand as silica component, sand goes from the storage tank to the vibrating screen for screening, then with the help of the belt conveyor goes to the weight hopper and to the mixer. After that chemical admixtures are added to the mixer. After all components are loaded preparation is mixed for 2-5 min until it is smooth. When mixture is done, aluminum suspension goes to the mixer and preparation is mixed for 2-3 min.
Ready aerated concrete mixture through the drain valve of the mixer proportionally dumps to the mould. The mould consists of two parts – pallet and removable and interchangeable edges. The pallet is a four-wheeled cart with a metal frame and underframe from water-resistant plywood.
Before pouring the aerated concrete mixture the removable edges are lubricated and installed on the pallet. The mould is transported by rail track to the mixing sector and installed under the mixer.
Thermal treatment section
After the moulds are filled with the aerated concrete mixture, they are moved to thermal treatment chamber. Thermal treatment process is performed according to the technical regulations. Using the chamber allows to speed-up the process of stripping strength, as well as to get aerated concrete with higher strength properties.
Sector of aerated concrete mass sawing
After thermal treatment the mould with aerated concrete mass moves by the rail tracks to the sawing sector. The edges of the mould are removed, and the underframe with mass moves to the cutting set and is fixed with gripper on the railway track. Moving the cutting set saws off blocks of given sizes in vertical and horizontal plane. The cutting set makes eight cuts per four passes, and thus divides the block into eight equal parts, as well as trims the mass on both sides. Using the cutting set eliminates a number of manual operations, increases labor capacity and reduces staff (the set is serviced by one person).
The cutting technology provides to manufacture products with geometric fidelity of ± 1 mm and product’s surface quality which meets necessary standards. This fact allows making settings using special types of glue and significantly increases thermal efficiency of exterior walls. Using the mobile moulds with removable edges eliminates use of hoisting mechanisms, which means decrease of materials consumption and material costs reduction.
Storage area for finished product
After cutting the ready blocks are put on the pallet and wrapped with wrap tape. the pallets with aerated concrete blocks are kept in the storage area for finished product until they pick up 70% strength and moisture max 25-35 %. The pallets with blocks are put in 2-3 layers. The storage area is calculated due to daily production.
Advantages of the suggested automated factories:
Automation of working operations control processes. Electronic control systems of raw materials feed and batching in the mixing sector are used in these production lines. One operator controls the mixing sector functioning. Also only one operator controls functioning of the cutting set in the mass sawing sector.
Permanence of batching. Consumable materials are put to the weigh hopper with strain sensors and balance controller, which allows getting precision weighing.
High productivity. Provided by the automated system of feeding and batching of raw materials, as well as speed of loading the mixer with water and raw components. The high-capacity cutting set provides high speed of sawing of mass into blocks of given sizes is provided.
The company “Siberian Constructing Technologies” provides full service for your production setup of aerated concrete:
- Design and technological work in view of a customer’s production area.
- Manufacture and supply of equipment.
- Installation supervision and start-up.
- Technologist’s visit for start-up of the equipment, development of processing methods for products manufacturing and also staff training.
- Development of individual process regulations of goods’ production.
- Researches of main characteristics of output products.
- Help with certification of output products.
- After-sales service.
- Consulting service.
- Adaptation of new technologies and upgrading of functioning equipment.