Introduction<br />In-place asphalt recycling techniques are among the most important modern methods for road maintenance and rehabilitation. They contribute to resource conservation and reduce environmental waste. These techniques rely on reusing the existing asphalt layers directly on site without transporting materials off-site, thereby saving time, cost, and protecting the environment.<br /><br />Definition of In-Place Asphalt Recycling<br />In-place asphalt recycling refers to processes that treat and modify the existing asphalt layers directly on the road to rehabilitate and improve their engineering properties using specialized equipment such as milling machines, mixers, and pavers.<br /><br />Types of In-Place Asphalt Recycling Techniques<br />Hot In-Place Recycling (HIPR):<br />Involves heating the old asphalt layer using special equipment, then remixing it with additives such as new asphalt or modifiers to improve properties, followed by laying and compacting the mixture in the same place.<br /><br />Warm In-Place Recycling:<br />Uses lower temperatures than hot recycling, with moderate heating of materials, reducing energy consumption and emissions.<br /><br />Cold In-Place Recycling (CIR):<br />Involves milling the old asphalt layer and mixing it with binders like cement or asphalt emulsions, then laying the mixture without heating. It is suitable for roads with light to moderate traffic loads.<br /><br />Advantages of In-Place Asphalt Recycling<br />Reduces consumption of raw materials as new materials are minimized.<br /><br />Lowers transportation and waste disposal costs.<br /><br />Decreases carbon emissions and environmental pollution.<br /><br />Faster execution compared to traditional rehabilitation methods.<br /><br />Improves engineering performance of the existing pavement layer.<br /><br />Challenges and Constraints<br />Requires high technical skills and specialized equipment.<br /><br />Assessment of the existing pavement’s suitability for recycling is critical.<br /><br />Possible impact on heavy load resistance in some cases.<br /><br />Weather conditions may affect the quality of the work.<br /><br />Practical Applications<br />In-place asphalt recycling has been successfully used in numerous projects worldwide, especially on secondary roads and urban streets, achieving cost savings and extending pavement life while reducing environmental impact.<br /><br />Conclusion<br />In-place asphalt recycling techniques represent an effective and sustainable option for road rehabilitation, aligning with sustainable development and environmental protection goals. With ongoing advances in equipment and materials, it is expected that these techniques will expand to cover more types of roads and load conditions.