Testing and analysis of LWT and SCB properties of asphalt concrete mixtures.

PDFTech Reporthttp://www.ltrc.lsu.edu/pdf/2016/FR_536.pdfFinal Report 536LTRC Project Number: 11-3BState Project Number: 30000220Asphalt concretePlant mixWarm mix paving mixturesLouisianaCooper, Samuel B.King, WilliamKabir, SharearLouisiana Transportation Research CenterLouisiana. Dept. of Transportation and DevelopmentUS Transportation CollectionCurrently, Louisiana\ue2\u20ac\u2122s Quality Control and Quality Assurance (QC/QA) practice for asphalt mixtures inpavement construction is mainly based on controlling properties of plant produced mixtures that includegradation and asphalt content, voids filled with asphalt, air voids, moisture susceptibility tests (ModifiedLottman), and roadway parameters such as pavement density [1]. These controlling properties have servedLouisiana well, yet with growing interest in considering alternative paving materials such as rubber modifiedasphalts, reclaimed asphalt pavement (RAP), recycled shingles, and warm-mix asphalt (WMA) technologies,there is a pressing need to implement laboratory mechanical testing capable of ascertaining an asphalt mixture\ue2\u20ac\u2122sability to resist common distresses. This research presents an evaluation of LWT and SCB tests for rutting andcracking evaluation of commonly produced mixtures from around the state. This research also presents theresults of a balanced mixture design methodology being developed by DOTD. A total of 51 mixtures wereevaluated with both the SCB and LWT tests. With respect to LWT Testing, 46 of the 51 mixtures evaluated(90%) passed the criteria specified for acceptable rutting resistance. The criteria (10 mm at 20,000 passes forunmodified binder; 6 mm at 20,000 passes for polymer-modified binder) currently being utilized by DOTDappears to be appropriate for mixtures being produced. With respect to Semi-Circular Bend Testing, the percentof mixtures passing this criterion for mixtures containing PG 64-22, PG 70-22M, PG 76-22M and PG 82-22CRM is 38, 68, 91, and 20 respectively. For the mixtures designed according to the DOTD proposed balancedmixture design specifications, 7 out of 11 met or exceeded the cracking criteria and rutting criteria. Thecomparison of field and laboratory compacted specimens shows there may be an effect of specimen type on thecomputed Jc. This relationship would need to be further investigated before using field cores for qualityassurance practices