Prototype of Semi-Automatic Deflectometer Equipment for Asphalt Roads

Abstract

Nowadays the main authorities of highway in the country are using high technology equipment for evaluation of pavement bearing capacity. It is impossible for local authorities to afford these expensive equipment. This research aims to develop a prototype of deflectometer equipment for asphalt roads based on the Benkelman Beam which is already available in most of those local authorities. Goals of the development are to get a better BB in terms of testing time, low-price and reliability. At the outcome, the research team is able to develop the prototype with price lower than 300,000 THB/equipment. It comprises of two main units, a new design frame and a control box with electronic assembly which contains sensors for measuring 4 surface deflection points and probes for measuring surface and mid-depth temperatures of asphalt layer. All the measurement results will be real-time and wirelessly delivered to a notebook computer. It has been found from the calibration that the R² is greater than 0.95 and the average standard deviation is 13.78 microns. The standard deviation of changing sensors configuration is about 15 microns. Moreover, all the real surface deflection values can be simply calculated by a spreadsheet program using correction equations proposed in this paper.