MEASURING THE SMOOTHNESS OF NEWLY CONSTRUCTED CONCRETE PAVEMENT FOR ACCEPTANCE SPECIFICATIONS

Abstract

A smooth highway surface is recognized as an important characteristic for achieving good service life and user comfort. A 10-foot straight edge was the traditional instrument used by contractors and owners to check surface deviations until the Profilograph was developed in California in the 1960s, and utilized as a means of evaluating pavement smoothness. In the last decade many highway engineers have noted a decline in initial pavement smoothness and, as a result, other state agencies have incorporated versions of the Profilograph into their acceptance standards. This led AASHTO in 1984 to conduct a survey into smoothness specifications and to recommend a draft guide specification. The Texas State Department of Highways and Public Transportation (SDHPT) engaged the Center for Transportation Research (CTR) at The University of Texas to evaluate this specification with a variety of roughness devices. The paper presents a brief historical background and reports the key results of an AASHTO survey to ascertain state's practices. A modification to the AASHTO guide specification is then discussed, and implications of the bonus and penalty categories discussed. A high resolution profiling device, the Dipstick, which can be used to quantify pavement surface data, has been tested with other roughness devices and the results are presented. Finally, a California-type Profilograph was employed on newly constructed reinforced concrete to test the proposed specification prior to its trial adoption. Problems with the Profilograph were identified which could make the proposed standards difficult to implement. CTR staff believe that a combination of Profilograph and Dipstick instruments, together with a modification to the categories within the Texas draft specification, would result in a more equitable and enforceable standard.