Controlling, Data Acquisition, and Data Processing for Axial and Shear Creep Tests Using a Computer

The objective of this paper is to provide an inexpensive way of conducting uniaxial creep and shear creep tests, data acquisition, and data processing using a computer. A microcomputer, a math coprocessor, and a graphics laser jet printer were used. A multi-function analog-digital-input-output expansion board increased the computer capacity enabling better precision, data acquisition, and signal analysis. A load cell was used to measure the loads while two linear variable differential transducers (LVDT) were used to monitor the deformations. A signal conditioning unit was used to excite the load cell and LVDTs and to transform the voltage output of the two digital analog channels into electric currents.Software developed at the University of California, Berkeley was used to conduct the tests. Hard copies of the computer output were obtained showing the relationship between the creep compliance and the time of loading. An example of the application of the creep test results for predicting the permanent deformation of the asphaltic layer of a heavy duty highway is included.