Pavement Strain Transducers (PAST)
The PAST series transducer is an “H” shaped precision transducer for measurement of strain in AC (Asphalt Concrete) or PCC (Portland Cement Concrete). The Dynatest PAST series and SOPT series transducers can verify values of stresses and strains in pavement structures. Stress or strain in a certain layer of a road construction if often used as a critical parameter for determining the performance of the pavement sections, including the service life as a function of the number of imposed wheel loads.
The “heart” of the PAST transducer is a strain gauge completely embedded in a strip of glass-fiber reinforced epoxy, a material with a relatively low stiffness and a high flexibility and strength. Each end of the epoxy strip is securely fastened to a stainless steel anchor to ensure proper mechanical coupling to the AC (or PCC) material after installation.
The strain gauge strip is protected against mechanical and chemical deterioration by means of a multi-layer “coating”. This combination of materials, plus a connecting cable made from PTFE, ensures resistance to temperatures in the range of –30°C (–20°F) to 150°C (300°F). The strain gauge strip of the PAST II is so effectively coated and protected that the service life exceeds 36 months and the fatigue life exceeds 100,000,000 cycles.