Damping of impact sound transmission
When walking on a floor of chipboard, gypsum, plywood or on a massive wood floor this often causes a disturbing noise both in the room you are in and also to the underlying and surrounding areas.
Viscoelastic damping of the floorboards with Swedac Damping Glue DG-A2, ACM or DG-U6 provides a considerable improvement of this problem.
Swedac DG-A2 is mostly used when working with plywood, MDF, chipboard and gypsom floorboards.
Swedac ACM can be used in the case of concrete structure and/or a massive wood floor that needs damping. ACM contains less water than DG-A2 and therefore cures faster when used instead of DG-A2.
Swedac DG-U6 that are a 2 component polyurethane is often used when combining steel or stainless steel with wood or tiles.
Airborne sound insulation
For a single wall construction the airborne noise transmission loss is determined by the surface weight. Theoretically, the transmission loss will increase by 6 dB per octave and with 6 dB per doubling of the surface weight.
For stiff and lightweight construction materials such as plywood, chipboard and foam sandwich laminate the transmission loss will deviate from above due to the coincidence resonance.
The transmission loss at the coincidence frequency range is determined by the internal loss of the structure (loss factor).
By lamination with Swedac Damping glue DG-A2 the airborne sound insulation can therefore also be improved.
Structure borne noise
Viscoelastic damping materials are designed to take the energy out of resonant vibration by damping the structure
– you must have seen the demonstration where a cymbal treated with a damping material goes off with a dull instead of the expected sharp ring.
The same damping principle can be applied to all types of stiff structure which transmit vibration too easily, and specific solutions are available for wood, steel, concrete and glass fibre
Typical construction materials such as plywood, chipboard, plasterboard and steel have a very low loss factor typical in the range off 0,005 – 0,03.
By lamination with SWEDAC viscoelastic layers DG-A 2 the loss factor can be increased to 0,2 – 0,4. This gives a decrease in noise radiated from a surface at resonance by 8 – 16 dB.
Construction, Application and Workability
DG A2 should be applied to a thickness of about 1mm (wet) as a damping layer between two sheets of plywood, chipboard, or plasterboard. The best damping effect is achieved with sheets of equal thickness, but a thickness ratio of up to 1:3 can give good damping. Because of the viscoelastic characteristics of the combined sheet, the bending stiffness of the combined construction is lower than that of a homogeneous sheet of equal thickness, and in order to retain the same stiffness as for a homogeneous sheet, the thickness should be increased by 50% for a symmetrical laminate and 30% for an unsymmetrical laminate.
After lamination the sheet can be cut and drilled in the same way as a homogenous sheet.