Polystyrene concrete, polystyrene concrete blocks. Equipment for polystyrene concrete manufacturing.

Description and basic properties of polystyrene concrete

Polystyrene concrete field of application for objects of housing and industrial construction is extremely wide:

• Production of ready-mixed polystyrene concrete mixtures of different density;
• Monolithic thermal insulation of attic floors and roofs;
• Erection of exterior walls in permanent shuttering for skeleton-type buildings;
• Insulation of external walls and surfaces of reconstructed buildings;
• Monolithic insulation of elements of exterior walls and floors;
• Monolithic exterior and interior walls and partitions;
• Manufacture of light insulation products for the construction of bearing and self-supporting elements (wall blocks, internal partition blocks, etc.).

Main technical characteristics of polystyrene concrete

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* In the Russian Federation, according to SNiP 21-01-97* (building codes and regulations), the construction materials with moderate smoke-generating capacity are classified as D2, with little smoke-generating capacity as D1; as for the toxicity of combustion products moderately hazardous materials are classified as Т2, while the low-hazard ones as Т1.

Polystyrene concrete combines high-quality technical, operational and cost characteristics and is the best alternative to the traditional heat and sound-insulating materials.
Many of Russia's architects, builders and the tenants have appreciated the outstanding properties of polystyrene concretee as the most appropriate modern and promising material for efficient construction.

Manufacturing technique of small-size products of polystyrene concrete

Main technological operations:

• Foaming of polystyrene granules; 
• Drying (maturing)of polystyrene granules; 
• Batching of raw components; 
• Preparation of polystyrene concrete; 
• Molding of polystyrene concrete mass; 
• Hardening of polystyrene concrete mass; 
• Cutting the polystyrene concrete mass into blocks with specified sizes; 
• Storage of polystyrene concrete blocks.
• Foaming of polystyrene granules.

The process of foaming of polystyrene granules consists of pre-foaming and drying (maturing of) foamed polystyrene granules. Polystyrene pellets from feed bind bunkers are delivered to the prefoamer by a screw conveyor. Under the influence of water steam polystyrene pellets grow soft and begin to froth. Polystyrene granules become increased in volume and are being replaced by non-foamed granules. Auger blades mix the foamed polystyrene pellets, preventing adhesion and contributing to the uniform movement of the material to the unloading window of the set, with the constant impact of water steam.

Drying (maturing) of polystyrene granules

Foamed polystyrene pellets contain up to 10-15% of moisture, besides there is a negative pressure inside the pellets due to condensation of water steam. This may lead to deformation (compression) of foamed polystyrene pellets. Pellet compression dramatically reduces the amount of material and leads to a significant increase in bulk density. That’s why foamed polystyrene granules must be dried to stabilize the internal pressure and hardening of the outer walls of the granules. The use of pneumatic drying and transporting units for foamed polystyrene allows us to quickly and effectively reduce the residual moisture content of the material to 6.3%, while moving the material into maturing bins. Foamed polystyrene pellets remain in the maturing bin about 4-12 hours, depending on the grain size, bulk density and residual moisture. Significant reduction in the exposure time can be achieved by applying the method of pumping granules with heated air flow from on bin to another. In this case maturing time is reduced to 2-3 hours.

Batching of raw components

Ready foamed polystyrene granules from the maturing bin are delivered by the air flow through blast line into the receiver-bin of volume batcher. As the batcher is full, the granules fall into the mixer. Cement and fine-dispersed filler (fly ash) from storage bins by means of screw feeders are in turn fed into the bin of the weigh batcher. When the bin of the batcher is filled with necessary quantity of material the screw feeder turns off. Then the batcher pneumatic flap opens and the material goes to the mixer. Water is poured into special tanks before the shift starts. Recommended mixing water temperature is +40-50 * C.

Preparation of polystyrene concrete

Components of polystyrene concrete (foamed polystyrene granules, cement, inert filler, water, additives) in dosed parts are fed into the mixer. Dosage of the components is determined by the technological regulations of the enterprise. The sequence of loading of the mixture components: Loading of polystyrene component into the working mixer is carried out in the following order. First, the mixer is fed with dosed by volume polystyrene, then water and chemical additives. The mixture is stirred for 1-2 minutes. Then the mixer is loaded with dosed cement (filler) and the mix is stirred for not less than 3 minutes to obtain blended homogeneous porous structure. The total duration of polystyrene concrete preparation process, including the time of loading of components and duration of their mixing must be at least 3-5 minutes.   In the process of mixing the components the condition of polystyrene concrete, its plasticity should be visually controlled. Molding of polystyrene mass. It is a process of casting the polystyrene concrete mixture into the pre-greased molds for forming the polystyrene mass.

Hardening of polystyrene mass

The speed of hardening of the polystyrene mass in the molds depends on the following major factors: binder activity, temperature in the room and the presence of thermal processing chamber. Using the chamber allows you to speed up the process of getting demoulding strength, as well as to obtain polystyrene concrete with high strength characteristics. Use of mobile forms with demountable sides allows you to eliminate lifting mechanisms from the process, which in turn reduces the consumption of materials and material costs.

Cutting the mass into polystyrene concrete blocks with target sizes

Cutting the mass into polystyrene concrete wall blocks with target sizes is carried out by using an automated cutting complex. Performance of the complex is 4 - 5 m 3 / h, and during one working shift (12 hours), performance may be 40 - 60 m 3.This is achieved through the features of manufacturing of the cutting complex. The cutting complex is operated by only two people.

Storage of polystyrene concrete blocks

After sawing finished blocks are stacked on a pallet and wrapped in stretch tape. The pallets with polystyrene concrete blocks are kept in stock of finished goods until they have 70% of strength and selling moisture not more than 25% (7-10 days). The temperature must be at least 15 0 C. The pallets with the blocks are set in 2-3 storeys, occupied area is calculated on the basis of daily performance.

Technology of preparation and casting of in-situ polystyrene concrete

Monolithic polystyrene concrete is an effective, environmentally friendly, durable and robust wall material, which is increasingly in demand in the construction market. The developed technology allows production of monolithic polystyrene concrete directly on the construction site and provides transportation of foam concrete mix by gerotor pumps without delamination, and also allows casting of the mixture into the formwork without vibrocompaction. Application of monolithic polystyrene concrete in exterior walls instead of block wall masonry enables to:

• Increase the coefficient of thermotechnical homogeneity and respectively increase by 30% or more wall heat transfer resistance, by excluding masonry joints of heat-conducting cement-sand mortar; 
• Reduce labour coefficient of the walling; 
• Increase rate of progress of the construction work.

Main technological operations:

• Preparation of polystyrene concrete; 
• Laying the monolithic polystyrene concrete; 
• Hardening of monolithic foam concrete;

Preparation of polystyrene concrete

Components of polystyrene concrete (foamed polystyrene granules, cement, inert filler, water, additives) in dosed parts are fed into the mixer.
Dosage of the components is determined by the technological regulations of the enterprise.
The sequence of loading of the mixture components:
Loading of polystyrene component into the working mixer is carried out in the following order.
First, the mixer is fed with dosed by volume polystyrene, then water and chemical additives.
The mixture is stirred for 1-2 minutes. Then the mixer is loaded with dosed cement (filler) and the mix is stirred for not less than 3 minutes to obtain blended homogeneous porous structure.
The total duration of polystyrene concrete preparation process, including the time of loading of components and duration of their mixing must be at least 3-5 minutes.
In the process of mixing the components the condition of polystyrene concrete, its plasticity should be visually controlled.

Laying monolithic polystyrene concrete

Is a process of casting a mixture of polystyrene concrete into prepared formwork.

Hardening of monolithic foam

The rate of solidification of monolithic polystyrene concrete depends on the following major factors:   binder activity, temperature in the room.