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June 13, 2023 HWA Project No. 2022-188-21 4.11.5 HMA Binder Selection The selection of the optimum asphalt binder type for the prevailing climate is critical to ensure long-term pavement performance. Use of the wrong binder can result in low temperature cracking or permanent deformation at high temperatures. Based on the climate in Ellensburg, we recommend Superpave Performance Grade binder PG 64H-28 be used for HMA pavement. Placement of HMA should be in accordance with Section 5-04 of the WSD©T Standard Specifications (WSDOT, 2023). Particular attention should be paid to the following: 4.11.6 Pavement Construction HMA should not be placed until the engineer has evaluated and approved the crushed aggregate base rock layer. • HMA should not be placed on any frozen or wet surface. • HMA should not be placed when precipitation is anticipated before the pavement can be compacted, or before any other weather conditions which could prevent proper handling and compaction of HMA. • HMA should not be placed when the average surface temperatures are less than 45' F. • HMA temperature behind the paver should be in excess of 2400 F. Compaction should be completed before the mix temperature drops below 180° F. Comprehensive temperature records should be kept during the HMA placement. • Sufficient tack coat must be applied uniformly and allowed to break and set before placing HMA above an existing HMA layer in order to create a strong bond between layers. The surface of the pavement should be thoroughly cleaned prior to tack coat application. Improper tack coat application can cause unbonded layers and will lead to premature pavement distress/failure. • For cold joints, tack coat should be applied to the edge to be joined and the paver screed should be set to overlap the first mat by 1 to 2 inches. • The longitudinal joints in the HMA wearing course should coincide with a line lane or an edge line. Crushed Surfacing Top Course (CSTC) can be substituted with for the upper 2 inches of Crushed Surfacing Base Course (CSBC) as specified by WSDOT Standard Specifications (WSDOT, 2023), in order to provide a smooth surface for placing the HMA layer. 2022-188-21 KCTS — Final Geotechnical Report 21 HWA GEOSCIENCES INC.