Sub-floor and Wall Mastics

An estimated 75 % of the mastic products sold in North America indicate compH-ance to stringent AFG-01 (i.e. Adhesives for Field Gluing ) requirements. ASTM D 3498 is quite similar to the AFG-01 standard originally written by the American Plywood Association. These methods define a series of six test specifications (Fig. 8-28), five of which involve shearing plywood to lumber wood block specimens in compression mode after various carefully controlled material conditioning and specimen curing protocols (Fig. 8-29). 

The sixth test, called oxidation resistance, is a mandrel flexibiHty check on films of dried mastic after exposure to oxygen at high temperature in an oxygen bomb apparatus. Water based mastics formulated with acrylics or styrene-acryhc polymer dispersions typically pass oxidation resistance requirements. The most challenging pa- 

Frozen lumber 48 h soak lumber 48 h -14 °C for lumber and plywood 5 days, -14 °C 21days,4°C/50%rh 7 days recovery Shear 667 N 

Moisture resistance 48 h, standard conditions 28days,22°C/50%rh 3 cycles of 4 h H20/o.n. dry37°C 7 day recovery Shear 1000 N 10 % bond failure 

Gap filling 48 h, standard conditions 28 days, 22°C/50%rh (16 gauge wire) Shear 667 N 

---