PRODUCTION OF THE MANUFACTURING PLANT “CSP-Svir”


WHAT IS THE CEMENT BONDED PARTICLE BOARD (CBPB)?

TECHNICAL CHARASTERISTICS AND COMPOSITION OF CBPB:

csp_chementno_struzhechnaya_plita_shopThe cement bonded particle board (CBPB) is made of cement and wood chips, to which a small amount of chemical additives is added for the mineralization of wood chips. The mineralization process allows wood chips to resist biological attack, erosion, and putrefaction.
This is the transformation of the organic material into a state in which it is able to resist the impact of moisture, rot, rodents, fungi, fire, insects, chemicals, weather conditions, etc. The structure of the cement bonded particle board is monolithic, which is why it does not separate, and cut edges are not sensitive to any effects.

The main advantages and features of the cement bonded particle board (CBPB) are as follows:

  • Strong material
  • Environmentally friendly material – with its use, people all over the world build houses and interior partitions in residential facilities and make window sills and countertops.
  • CBPB is resistant to biological effects: It does not rot, is not affected by fungi, resists the effects of termites, insects, and rodents.
  • Durable material.
  • Firehard material. Group of combustibility G-1.
  • The material with excellent insulating properties ensures high sound insulation.
  • Treated in a similar way to cut lumber.
  • It can be used in different climatic conditions.

COMPOSITION AND PROPERTIES OF THE CEMENT BONDED PARTICLE BOARD (CBPB)

CBPB (cement bonded particle board) is of light gray color and has a smooth cement-like surface. There are two types of finishing: board polishing or calibration. Calibrated boards (polishing on both sides) is usually subjected to painting or veneering at a later stage. Board edges can be either flat or profiled.
The complex of physical and mechanical properties of CBPB boards define application fields and operating features.

This composite material positively combines the properties of the matrix material and wood filler in the form of wood chips. In terms of some indicators, the board under consideration is much better than chipboard and fiberboard. It is firehard, fire- and bioresistant, has lower values of water absorption and swelling in thickness.
When it comes to physical and mechanical properties, boards produced in Russia are divided into two brands: CBPB-1 and CBPB-2. Boards of the first type are used as construction material. With regard to the majority of indicators related to physical and mechanical properties, boards of domestic manufacture produced in accordance with GOST 26816-86, are not only equal to but even better than foreign ones.
The following factors have the greatest impact on the physical and mechanical properties of boards:

  • quantity and quality of wood used,
  • its species composition (especially the content of extractive water-soluble sugar)
  • fractional composition, porosity;
  • quantity and quality of the mineral binder – cement, its activity and mineralogical composition;
  • consumption of chemical additives and water;
  • density and thickness of boards;
  • technological characteristics of production (hardening modes providing optimal conditions for hardening and structuring of cement stone).

The strength indicators of the cement bonded particle board (CBPB) produced at plants are approximately the same and comply with GOST 26816-86.

Studies show that the impact of lumber species on the strength of boards in case of different tyoes of mechanical tests is ambiguous. Thus, the bending strength of boards made of sprucewood is higher than that of those made of aspen and birch wood, while the strength of the board from birch chippings in case of cut and shearing is higher than that of the board from pine and spruce chippings. Resilient modulus does not dependent on lumber species.

The effect of cement type became apparent when testing boards with regard to compression, shear, and resilient modulus. Tensile, bending and shear strength on all types of cement is almost the same. The cement brand affects strength indicators only at the early stages of hardening. When using the product, the most important indicators are those related to the properties characterizing the behavior of boards with respect to different types of moisturizing. It is known that the weight and thickness increase under the influence of moisture, which should be taken into account when developing CBPB-based structures. The water resistance of the board is significantly higher than that of the chipboard, which is due to the differences in the properties of the matrix material and its quantity.
Water absorption depends on the thickness, type of raw wood, as well as board age. Most boards absorb water actively during the first day, following which the process is stabilized. That is why water absorption during 24 hours is normalized.

Swelling in thickness during 24 hours does not exceed 2%, and in case of longer soaking – 3%, which is several times lower than the same indicator in the chipboard. Lumber species affects water absorption and swelling in thickness. CBPB made of softwood are more susceptible to swelling than CBPB made of leaf wood. In addition, board age and density also affect these parameters.
In case of moisturizing, physical and mechanical properties of the product decrease. This is due to uneven swelling in consequence of hydration of cement and wood, which leads to internal stresses and weakening of contact between them. Drying results in an almost complete recovery of physical and mechanical properties.
To improve water resistance of boards, inject a mixture of various water repellent compositions and use paintwork materials based on silicone, perchlorvinyl, and alkyd resins, as well as water-dispersible emulsions.