The following specifications apply to the purchase of trailer mounted, asphalt patching machines by the Iowa Department of Transportation, Iowa DOT. Units must use a spray injection method for the repair of cracks, potholes and broad distressed areas. Units must blow water, dust and debris from the pothole or surface to be repaired, apply a tack coat of hot emulsion, bring patch to grade with emulsion coated aggregate and apply a cover of dry aggregate. Machine bid must be suitable for use with water emulsified asphalt, such as CRS-2 and its polymerized variant CRS-2P produced in compliance with Iowa DOT Standard Specifications 4140, series 1997 (CRS-2 as per the latest addition of AASHTO M 208 and ASTM D 2397; CRS-P modification as per Standard Specification 4140). 1. ENGINE A. Unit must be powered by an electric start, liquid cooled, industrial diesel engine (John Deere 4045D-30, Cummins 4B3.9 (counterbalanced) or approved equal) developing not less than 74-HP. Power unit must include a fuel tank large enough to insure 10-hours, minimum, of uninterrupted operation at full machine capacity. B. Engine must be equipped with: a. High temperature shutdown. b. Low oil pressure shutdown. c. Full gauge package, to include volt or ammeter, oil pressure, fuel level, temperature and hour meter with oil or alternator excited sensor. d. Keyed ignition. e. Fuel line filter and shutoff. f. Air intake filter, pre-cleaner. g. Engine must be enclosed in a protective cover with easily accessible panels to allow for regular maintenance and servicing. C. Engine must be muffled to not cause an operator to exceed OSHA 8-hour hearing exposure limits as per OSHA standard no.1910.95. 2. AIR SYSTEM A. Air system must be driven directly from the engine and be supply adequate CFM for the proper operation of the machine. B. Blower must be equipped with a silencer for noise suppression. 3. HYDRAULICS – Where Applicable A. Hydraulics must be designed to maintain a system operating temperature range of 120 to 180oF regardless of load or outside temperature. B. All hydraulic control valves, motors, etc. must have a similar flow rating as the hydraulic pump to help reduce restriction and heat buildup in the system. C. All hydraulic system components, hoses and tubes must be rated greater than all anticipated temperatures and pressures with an adequate safety margin. 4. ASPHALT TANK A. Tank must be ASME certified, cylindrical in shape with a 225-300-gallon capacity. B. Tank must be insulated on all surfaces with manufacturer’s standard insulation. C. Tank must have an approximate 8-inch hinged lid for loading of material. D. There must be a minimum 3-inch, direct reading dial thermometer for the emulsion. a. Emulsion thermometer must be installed in such a manner so that it will accurately read with as little as 25-gallons of usable material in the tank. b. Gauge must be visible from the rear of the unit when using the applicator. 5. HEATING SYSTEM A. Units must have an automatic, temperature-controlled heating system to maintain the asphalt emulsion at a temperature of 150 to 170oF during the workday. a. System must sufficiently maintain asphalt emulsion for use in ambient temperatures down to 20°F. b. All components in contact with emulsion, including emulsion tank, hoses and spray nozzle must be heated. c. Application hoses must be contained in an insulated wrap or cover for their entire length. B. A 120-volt, AC electric “overnight” heater will be used for tank preheat and to maintain the emulsion temperature when unit is not in use. a. Heater must be thermostatically controlled and able to maintain a full load of emulsion in an application state. b. Heater operation will not be dependent on the amount of material in the tank and may be used to pre-heat an empty tank prior to filling.
