Iowa Field Conference on "D"-Cracking: Nov. 20 & 21, 1967

(1967) Iowa Field Conference on "D"-Cracking: Nov. 20 & 21, 1967. Transportation, Department of

Preview

PDF IADOT_ISHC_Welp_Iowa_Field_Conference_on_D_Cracking_1967.pdf File Size:6MB

Abstract

During the summer of 1963 the Materials Department noted the three to four ·year old concrete pavement on I-80 in Cass County was showing extensive surface cracking adjacent to joints and cracks. An examination of the pavement and a few cores from the cracked areas was made by the I.S.H.C. Materials Department and later by David Stark of the P.C.A. Additional surveys were conducted on other concrete pavement made with coarse aggregate from similar rock from two different sources. Blue-line cracking was found on some primary pavement and the indications of incipient cracks were seen on I-29 in Pottawattamie County, north of Council Bluffs. A good "D"-crack pattern is now evident. Surveys were then made of the entire Interstate concrete pavement. No other sections of Interstate were "D"-cracking, although some sections showed joint discoloration. None of these pavements, including the discolored sections, contained "D"-crack associated aggregates. At the same time as the Interstate survey additional pavements and sources were checked. Some "D"-cracking was noticed on certain sections of primary pavement 5-10 years old, in the vicinity of Waterloo and Cedar Rapids. The "D"-cracked pavement was from three aggregate sources, the Newton, Otis, and Burton Ave. quarries. Other pavements in this area that were older or from· different· coarse aggregate sources were not "D"-cracked. We believe that all the "D"-cracking is related, although dedolomitization is probably involved in the intermediate dolomite rocks.