EFFECT OF PAVEMENT VARIABLES ON AVERAGE JOINT DEFLECTIONS IN EXPERIMENTAL CONCRETE PAVEMENT

Knowledge of the magnitude of joint deflections in a concrete pavement caused by truck traffic is important because the larger the deflection the larger the stresses and the lower the fatigue life of the pavement. For improved design of concrete pavements it is important to evaluate the effects of various factors on pavement joint deflections. For this purpose an experimental concrete pavement was built in 1972 in Chillicothe, Ohio, by the Ohio Department of Transportation. The variables built into the pavement included two types of bases, different joint spacings, one section with skewed joints, and joints with no dowels, standard dowels, and plastic-coated dowels. The University of Cincinnati researchers have investigated this pavement for several years, first in the middle 1970s and then between 1989 and 1991. This last phase included a thorough investigation of vertical joint deflections. The deflections were produced by a two-axle truck moving at 80 km/h and were measured by an electronic transducer. The ways in which the type of base, season, joint spacing and crack patterns, presence of dowels, type of dowels, and time of day affected the joint deflections of the experimental pavement are described. The test procedures and measuring methods used are discussed, and the results, analysis, and conclusions are presented.