Title:

Evaluation of Curing Effects on Cold In-place Recycled Materials

Cold in-place recycling (CIR) has several advantages over other means of flexible pavement rehabilitation: benefits include in-place use of existing pavement materials and elimination of existing cracks in the pavement to prevent reflective cracking. Most CIR construction use asphalt emulsion or foamed asphalt with or without active fillers as stabilizing agents. To ensure the CIR layer gains appreciable stiffness and strength to support traffic (including that of construction vehicles used to place the wear course on CIR), these stabilizing agents have to cure (dry additional moisture and gain cohesion) prior to traffic exposure. If traffic is allowed on the CIR layer before sufficient strength and structural capacity is gained, premature damage will occur. This research has an overall objective to develop a reliable and practical methodology to monitor and predict the extent of curing and strength gain for CIR layers. This study involves conducting in-situ testing on actual CIR construction projects. The in-situ tests conducted include: Light Weight Deflectometer (LWD), Rapid Compaction Control Device (RCCD), Density Profiling System (DPS) and Nuclear Density Gauge (NDG). Results show the applicability of the LWD and RCCD in detecting the increase in stiffness of the layer as curing progress with time whereas as the NDG and DPS (using dielectric) observe the change in moisture content with time, even in an event of rainfall.

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