A field trial was set up to verify the compactive performance of 600-1000kg/m width single drum rollers in relation to the compaction of the bituminous materials permitted for use in the national Specification of Reinstatements for Openings in Highways (SROH). TRL was commissioned as the Project Manager for the study by Benford Ltd, Bomag GB Ltd and the Department for Transport (DfT). Scott Wilson Pavement Engineering (SWPE) was appointed by TRL as the contractor responsible for the verification trial, the reinstatement process and the laboratory and in-situ testing. Overall, the results indicated that the rollers complied with the SROH requirements for the air voids content in the majority of cases for the materials and lift thickness tested, when the maximum densities and theoretical calculations were considered. The SMA and HRA materials met the air voids content requirements after receiving a lower number of passes than currently specified in Table A8.3 of the SROH. A reduction in the number of passes specified in Table A8.3 may therefore be warranted for this class of roller. For the DSC material, surcharge inadequacy may have contributed to the varied compaction performance so there is insufficient evidence to support a reduction in the number of specified roller passes given in Table A8.3 (SROH). Although the requirements for the air voids content were met for the CGSC material, the achieved values were at the extreme of the limits specified in Table S10.1 (SROH). Therefore, in order to cater for materials that may be laid at a temperature approaching the lower limit given in Table A2.4 (SROH), a reduction in the number of specified roller passes given in Table A8.3 may not be appropriate. No significant difference in compaction was shown to exist between the Benford Ltd and Bomag GB Ltd rollers. (Author/publisher)
Samenvatting