Agenda - Council - 02/11/2020 - Laserfiche WebLink

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D \ 04E$0,4yO Chapter 4. Minnesota Department of Transportation a a s '''oP Tft PayQo Chapter 5. Memo Office of Materials Office Tel: 651/366-5573 1400 Gervais Avenue, Mail Stop 645 Fax: 651/366-5461 Maplewood, MN 55109 TO: Tom Tesch T.L. DATE: SUBJECT: Task 4 for LRRB 904 Stripping Under Chip Seals In Task 4 we will discuss the different construction practices used for streets among many Cities. Some of the areas discussed are the following: history of the MnDOT HMA specification, type of mixes used, construction methods. Hot Mix Asphalt (HMA) Mixtures History in Minnesota Please see below for a brief history of the HMA specifications: • Specification 2331 (Pre 1988) • Specification 2340 (1988) • Specification 2340 Modified (1997) • Specification 2350 (1998) • Specification 2360 (1998) • Combined 2350/2360 (2003) 2331 MnDOT Specification 2331 was the standard HMA specification prior to 1988. In this specification the MnDOT designed the mixes for the contractor, process control and acceptance testing was performed by MnDOT. The Contractor's only role was to produce and place the HMA mix. 2340 MnDOT Specification 2340 was implemented as a quality management specification in 1988 and modified in 1997. This specification addressed problems with rutting, flushing, and raveling. In this specification, the Contractor was responsible for the mix design and the Quality Control (QC) testing. Air voids was used as the primary acceptance criteria. 2340 was modified in 1997 to include new mixture quality measurements. These were Voids in Mineral Aggregate (VMA) and Tensile Strength Ratio (TSR) testing. TSR testing is a measure of moisture susceptibility in the HMA.