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Leaching behaviour of synthetic aggregates.
H A van der Sloot1, D Hoede, D J Cresswell
1ECN, Soil & Waste Research, Petten, The Netherlands. vandersloot@ecn.nl
Waste Management (New York, N.Y.)
|March 31, 2001
Summary
This study assessed synthetic aggregate environmental compatibility. Results show low buffer capacity, requiring avoidance of acidic conditions, but safe for concrete use.
Area of Science:
- Environmental Science
- Materials Science
- Waste Management
Background:
- Synthetic aggregates are produced using innovative kiln technology for waste recycling.
- Assessing environmental compatibility is crucial for various applications of these aggregates.
- Leaching behavior under diverse conditions requires thorough investigation.
Purpose of the Study:
- To evaluate the environmental compatibility of synthetic aggregates through leaching behavior analysis.
- To understand the pH dependence and buffering capacity of synthetic aggregates.
- To assess the suitability of synthetic aggregates for concrete and end-of-life scenarios.
Main Methods:
- pH dependence tests were conducted to assess material sensitivity and buffering capacity.
- Column leaching tests were performed to simulate environmental exposure.
- A concise test was applied to evaluate leaching for different production mixes.
Main Results:
- Synthetic aggregates exhibit low buffer capacity, making them sensitive to pH changes.
- Acidic conditions during utilization and storage should be avoided.
- Leaching test results (pH dependence and column tests) are consistent.
- The CEN TC 154 method may underestimate leaching due to arbitrary test conditions.
- Synthetic aggregates are unlikely to negatively impact concrete during its service life.
Conclusions:
- Synthetic aggregates are environmentally compatible for concrete applications.
- The primary concern is the 'end-of-life' stage, with oxyanions (Cr VI, Mo) being key leachates.
- Further testing is needed to refine leaching assessments for diverse production mixes.