409— Microsurfacing

400-50 Section 409 — Microsurfacing

409.1 Description 1 Construct microsurfacing on an existing road surface. 409.2 Materials 409.2.1 Aggregate 1 Use aggregate screenings conforming to Subsection 401.2.2, except as modified in this S ubsection. Ensure that aggregates shipped to the project are crushed mineral aggregate screenings that are uniform , do not require blending or pre- mixing at the storage area before use, meet the appropriate gradation as shown in the table in Subsection 409.2.7 , and have a s and equivalent value that is not less than 65 when tested according to AASHTO T 176. 2 Do not use limestone aggregate in the mixture. 409.2.2 Mineral Filler 1 Use either Portland cement or hydrated lime meeting the following requirements: •Portland c ement, Type I or Type 1L ― Subsection 701.2.1 •Hydrated lime ― Subsection 401.2.1. 5 409.2.3 Emulsi fied Asphalt 1 Use emulsified asphalt of the grade designated in Subsection 409.2.7 conforming to the requirements of Subsection 401.2.1.3. 409.2.4 Asphalt Tack Coat 1 Use a c ationic emulsion that conforms to AASHTO M 208 and Subsection 401.2.1.3. 409.2.5 Water 1 Use potable water free from any contaminants detrimental to the mixture for microsurfacing mixture. 409.2.6 Other Additives 1 Provide other additives as required by the International Slurry Surfacing Association ( ISSA) requirements to control the set time of the mixture in the field.