Experimental Cold In-Place Recycling with Hydrated Lime

Abstract

The Kansas Department of Transportation (KDOT) uses cold in-place recycling (CIR) for approximately 120 to 160 km of pavement a year as a part of its 1-R maintenance program. Originally KDOT used asphalt emulsions as the additive in CIR mixtures, but on the basis of performance concerns it currently uses type C fly ash. Recent research indicates that the use of CIR with asphalt emulsion and hydrated lime, introduced as hot slurry, provides improved performance. KDOT constructed two test sections on US-283 using type C fly ash and cationic slow set (CSS-1) with hot lime slurry. Samples of the materials were obtained and laboratory evaluations undertaken to evaluate the performance of CIR with hot lime slurry. Two additional mixing grade asphalt emulsions, cationic medium set (CMS-1) and high float (HFE-150), were evaluated as well. Laboratory samples were tested for tensile strength, moisture sensitivity, and resilient modulus. Laboratory compacted samples were tested for rutting resistance and moisture damage by using the asphalt pavement analyzer (Georgia rut tester). Results indicate that the use of hot lime slurry resulted in an improvement in material properties that affect the performance of CIR pavements, regardless of the emulsion used, and that CIR with hot lime slurry could be an alternative to the use of type C fly ash.