Use of Recycled Fine Aggregates from C&DW for Unbound Road Sub-Base

Area of Science:

• Civil Engineering
• Materials Science
• Geotechnical Engineering

Background:

• Construction and demolition waste (C&DW) generates significant quantities of fine recycled aggregates.
• Fine recycled aggregates are often discarded due to concerns about their impact on foundation behavior.
• Coarse recycled aggregates are widely used, but fine particles require further investigation.

Purpose of the Study:

• To characterize fine recycled aggregates from C&DW.
• To understand the effects of preparation, compaction, and freeze-thaw cycles on fine particle properties.
• To evaluate the suitability of fine recycled aggregates for road foundations.

Main Methods:

• Physicochemical, mineralogical, and mechanical characterizations were performed.
• Techniques included X-ray diffraction, X-ray fluorescence, Los Angeles abrasion, and micro-Deval resistance tests.
• Static plate load tests and image analysis for shape characterization were utilized.

Main Results:

• Sieving curve and grade proportion are key parameters for fine recycled aggregates.
• Higher proportions of fine particles (<63 µm) increase water demand and capillary rise due to increased specific surface area and roughness.
• Compaction had minimal impact on fine particle production and material shape, though some breakdown occurred.

Conclusions:

• Fine recycled aggregates exhibit properties that can be suitable for secondary road foundations, particularly concerning wear resistance.
• Blending lower-quality recycled aggregates with other materials can enhance their applicability in upper-level road foundations.
• Further research into the long-term behavior and optimal utilization of fine recycled aggregates is warranted.