Timber Protection Methods: Drying, Aging, and Repair

Timber Protection Systems

Felling Season

The sap inside the tree at the time of logging can serve as food for fungi and insects. Therefore, logging should occur when sap flow is lowest, typically during the winter.

Sap Removal

It is necessary to remove the sap from the wood vessels. This is done by washing the timber to dissolve starchy substances.

Sap removal can be achieved through:

• Water Washing (Leaching): This process takes 1 to 3 months.
• Steaming (Vaporization): This method is much faster. The high temperatures used also kill insects and fungi that may have developed in the tree.

Drying

Drying aims to eliminate moisture from the timber. Key objectives include:

• Stabilizing the wood dimensions.
• Preventing the growth and progression of fungi.

• Increasing its mechanical strength.

  Lower humidity generally improves mechanical properties.

Types of Drying

• Natural or Air Drying

  This involves stacking timber pieces allowing air to flow freely through them. This method typically reduces moisture content to around 17%. Drying time can be approximately one year per inch of thickness for hardwoods and half a year per centimeter of thickness for softwoods.

  Disadvantages:

  • Requires significant material storage time.
  • Occupies a large area.
  • Needs constant vigilance to prevent fungal growth.

• Artificial Drying

  This can be achieved using hot air, infrared radiation, or high-frequency heating.

  Advantages over natural drying:

  • Precise control over temperature, humidity, and air speed.
  • System adaptability to the specific wood being dried.
  • Guaranteed output regardless of the time of year.
  • Eliminates fungi and insects during the treatment process.

Artificial Aging

Artificial aging is an intensive drying process that removes almost all water. It aims to make wood tissues antiseptic, preventing biological attacks. This can be achieved through:

• Electric currents, particularly electrolysis.
• Autoclaves using steam fixatives like formalin or acetic acid. This method is considered economical and effective.

Timber Structure Consolidation: Beta Technique

This technique involves replacing damaged wood sections with a composite material made of epoxy mortar, sand, and fiberglass or polyester rods. Epoxy resins are used because their behavior is similar to wood, and they exhibit high adhesion.

Workflow:

1. Cut away the degraded wood section using a chainsaw.
2. Drill holes for reinforcement bars.
3. Install the reinforcement bars (fiberglass or polyester).
4. Assemble formwork around the repair area.
5. Pour epoxy mortar into the formwork.
6. Ensure epoxy mortar also fills the holes around the bars.