Evaluation of bituminous mixes in pavement structures interim report V - A study of transverse cracking in Oklahoma flexible highway pavements
Abstract
Field and laboratory studies were made to investigate the nature and extent of
transverse cracks on Oklahoma flexible pavements and to determine the possible causes
of this form of distress. Only the influence and contribution to this type of
cracking from the bituminous components of the pavements were considered. Nine test
sites on State and Interstate highway sections were studied. Examinations of field
cores showed that newly developed transverse cracks did not extend through the pavement
matrix and supported the concept that such cracks are caused by tensile forces
developed at low temperatures. Tensile properties of core sample specimens at o0
, -5° and -10° were determined using a tensile splitting test. Use was made of the "stiffness modulus" concept in
characterizing·the behavior of the recovered asphalt binders and the paving mixtures
from the cores. A satisfactory correlation was found between the tensile splitting
test results and the cracking indices of the test site pavements. That is, cracking
was more pronounced as the failure strains of the samples decreased and the failure
stiffness increased. Stiffness moduli of the recovered asphalts also was significantly
correlated with the cracking indices. The stiffer or harder the asphalt
cement in a pavement the greater was the degree of transverse cracking.