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Study on Performance Tests and the Application of Construction Waste as Subgrade Backfill
Qingbiao Wang1,2,3, Jie Zhang4, Kang Liu5
1State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China.
Materials (Basel, Switzerland)
|June 2, 2021
Summary
Recycling construction waste as subgrade backfill improves road engineering. Lime-fly ash construction waste mixture (LFCWM) showed optimal properties at a 4:6 cement-aggregate ratio (CAR), enhancing shear strength and California bearing ratio (CBR).
Area of Science:
- Civil Engineering
- Materials Science
- Environmental Engineering
Background:
- Construction waste utilization is crucial for sustainable development.
- Subgrade backfilling is a key application area for recycled materials.
- Lime-fly ash construction waste mixture (LFCWM) offers a viable recycling option.
Purpose of the Study:
- To evaluate the performance of LFCWM as a subgrade backfill material.
- To determine the optimal cement-aggregate ratio (CAR) for LFCWM.
- To analyze the influence of normal stress and aggregate size on LFCWM properties.
Main Methods:
- Compaction tests were conducted to determine optimum water content and maximum dry density.
- California bearing ratio (CBR) tests assessed the load-bearing capacity.
- Shear strength tests evaluated the material's resistance to deformation under varying stresses and aggregate sizes.
Main Results:
- Optimal performance was achieved with a 4:6 CAR, yielding maximum dry density (2.03 g/cm³), optimum water content (10.1%), maximum CBR (42.5%), and shear strength.
- Shear stress initially increased rapidly with displacement, then decreased slowly before stabilizing.
- Increased normal stress positively impacted shear strength.
- Maximum shear strength was observed when the aggregate size (P₄.₇₅) was 40%.
Conclusions:
- LFCWM is a suitable material for subgrade backfilling, offering significant recycling benefits.
- The study provides valuable data for optimizing LFCWM composition and application in road engineering.
- Findings support the use of construction waste as aggregate in roadbed construction.
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