AC&A continues to bet on innovation for the inspection of works, as evidenced by the incorporation of the Light Weight Deflectometer.
It’s a superior release and fixation mechanism that keeps the falling weight at a constant height and then releases it to allow for the weight to drop freely and transmit the load pulse through the plate resting on the material to be tested. This portable version of the FWD is based on the dynamic deformation equivalent to a truck loaded with 10 tons driving at 80 km/h and applying the load of a double rear tyre. This deformation occurs by dropping a 10kg weight on a 30mm diameter loading plate, measuring the deflection in the center and recording the applied force with a load cell. From this data, the dynamic module of the structure is calculated based on the force required to generate a given deflection on a specific type of soil.
Key benefits of the Light Weight Deflectometer
- One person operation.
- The quick test allows for close test point spacing, ensuring uniformity of the test section.
- Modulus output at the time of the test.
- Evaluation of the compaction and stiffness of the material with the same unit.
- Quality control of the base, sub-base, and subgrade layers before applying an overlay.
- Testing of trench restorations to determine the compacting conditions and reduce the chance of settlement over time.
ASTM Standards and Calibration
The design of the LWD equipment is based on ASTM E 2583 Standard Test Method for Measuring Deflections with a Light Weight Deflectometer. The load cell and geophone calibration is performed annually following the AASHTO R-32 Standard which is based on the Boussinesq equation for uniform circular distribution and calculation of the Modulus.
In this way, AC&A continues to bet on perfecting its work control and supervision processes. This tool was used during 2019 in the inspection of the site on the CA-6 highway in Honduras, obtaining the conclusive results for our company.
AC&A is People Innovating for People