Load cells for tie rods (toroidal cells) are most commonly used for measuring the stress state of tie rods and reinforcing bars.
Use in other situations requiring compression measurements is possible with the appropriate choice of instrument and application.
Load cells are available in various models, differing both in diameter (external and internal) and range.
Vibrating wire load cells are used for checking the stress state within earthfill embankments and for measuring earth pressure on structures and foundations.
In order to obtain measurements with maximum sensitivity, cell thickness is very thin (approx 5mm) with respect to the surface .
The main surfaces of the instrument are also free because the measuring transducer is separate.
Load cells proposed by Pizzi Instruments have all the well-known advantages of vibrating wire instruments, as this is the type of sensor used, measuring is simple and the device is reliable and durable.
The instrument is formed of two thin plates of stainless steel, soldered together, filled with oil and connected via a thin airtight tube to a vibrating wire piezometer.
The tensiometric capsules, embedded directly in concrete, measure the stress state present at the point of application.
These models have great robustness, sensitivity and reliability over time; the thermal expansion coefficient of the entire instrument is very close to that of concrete and connection cables and joints do not influence measurements.
The instrument consists of a cylindrical steel body 200 mm in diameter and 130 mm in height.
The NATM pressure cells are constituted of two membranes made of shaped steel, soldered and connected to a pressure transducer via a tube. The pressure cells are equipped with a pressurizing valve for attachment to the manual pump in the case of loss of load, or to enable adhesion to a structure. The cell and the hydraulic connecting tube are vacuum filled with deaerated oil.
The transducer is protected by a thick and sturdy steel exterior and is connected directly to the pressure cell.