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Iune 13,2023 <br />HWA Project No. 2022-188-21 <br />4.11.5 HMA Binder Selection <br />The selection of the optimum asphalt binder type for the prevailing climate is critical to ensure <br />long-term pavement performance. Use of the wrong binder can result in low temperature <br />cracking or perrnanent deformation at high temperatures. <br />Based on the climate in Ellensburg, we recommend Superpave Performance Grade binder <br />PG 64H-28 be used for HMA pavement. <br />Placement of HMA should be in accordance with Section 5-04 of the WSDOT Standard <br />Specifications (WSDOT,2023). Particular attention should be paid to the following: <br />4.11.6 Pavement Construction <br />HMA should not be placed until the engineer has evaluated and approved the crushed aggregate <br />base rock layer. <br />o HMA should not be placed on any frozen or wet surface. <br />o HMA should not be placed when precipitation is anticipated before the pavement can <br />be compacted, or before any other weather conditions which could prevent proper <br />handling and compaction of HMA. <br />o HMA should not be placed when the average surface temperatures are less than 45o F <br />o HMA temperature behind the paver should be in excess of 240oF. Compaction <br />should be completed before the mix temperature drops below 180" F. Comprehensive <br />temperature records should be kept during the HMA placement. <br />o Sufficient tack coat must be applied uniformly and allowed to break and set before <br />placing HMA above an existing HMA layer in order to create a strong bond between <br />layers. The surface of the pavement should be thoroughly cleaned prior to tack coat <br />application. Improper tack coat application can cause unbonded layers and will lead <br />to premature pavement distress/failure. <br />o For cold joints, tack coat should be applied to the edge to be joined and the paver <br />screed should be set to overlap the first mat by I to 2 inches. <br />o The longitudinal joints in the HMA wearing course should coincide with a line lane <br />or an edge line. <br />Crushed Surfacing Top Course (CSTC) can be substituted with for the upper 2 inches of <br />Crushed Surfacing Base Course (CSBC) as specified by WSDOT Standard Specifications <br />(WSDOT, 2023), in order to provide a smooth surface for placing the HMA layet. <br />2022-188-21 KCTS - Final Geotechnical Report 2l HWAGEOSCIENCES INC.