Presentation on theme: "Feasibility Study of Reusing Glass Aggregate From Crushed Cathode-Ray Tubes In Concrete Structures Hinkley Center Presentation 5-15-20091 College of Engineering."— Presentation transcript:
Feasibility Study of Reusing Glass Aggregate From Crushed Cathode-Ray Tubes In Concrete Structures Hinkley Center Presentation 5-15-20091 College of Engineering Department of Civil, Architectural, and Env. Engineering Jacqueline P. James, Ph.D., P.E. Rodrigo Mora, Ph.D., P. Eng.
2 Background Proposal: To study the feasibility to reuse CRTs as fine aggregates &/or cement replacements in concrete. Premisse: concrete encapsulates CRT metals & reduces leachability to below regulatory limits @ POC Benefits to the construction industry, to waste disposers &, most importantly, the environment: Less hazardous wastes going to landfills Reduced use of raw materials for construction Hinkley Center Presentation 5-15-2009
Metals in CRTs Hinkley Center Presentation 5-15-2009 3
4 Research Hypothesis CRT-Concrete, monolithic & crushed, can immobilize CRT contaminants to reduce their short & long term concentration at POC to acceptable levels. Under worst-case conditions, technically & economically viable measures can be adopted to mitigate the impact of contaminants at POC. Hinkley Center Presentation 5-15-2009
Previous Work: Concrete Metal Encapsulation Cover two opposite scenarios: TCLP & similar methods conclude: Concrete alone cannot encapsulate CRT metals Biopolymers improve bonding & reduce leaching to below regulatory limits Tank methods conclude: Monolithic concrete encapsulates CRT metals But we don’t want to transfer the problem to future generations Critical issues: Represent realistic concrete life-cycle utilization scenarios Dual relationship: CRT-leaching & concrete durability Hinkley Center Presentation 5-15-2009 5
6 Life-Cycle Exposure/Utilization Scenarios Production & Manufacturing Service life Disposal Water Cement / CRT powder Additives Raw aggregates CRT fine aggregates Recycled CRT-concrete aggregates Mix/ Cast in Place/ Prefab. Seawall Pipe / container Foundation Pavement: previous/impervious Façade Building structure … Loads/ cracking/ erosion/ abrasion/ corrosion High Low Stockpiling, handling, cylinder testing, curing, concrete waste Crush Crush / reuse ( ≈ 10% concrete aggregate) C&D landfill Exposure Hinkley Center Presentation 5-15-2009 Structure demolition ( ≈ 46%) Road work ( ≈ 32%) Road base / sub-base: ≈ 70% compacted Fill: 10% backfill, enbankment fill, drainage, flowable fill, etc. Crush / reuse ( ≈ 80%) EoL
The Most Likely Scenario “By weight, concrete makes the largest portion of the solid waste stream. However, the single most recycled material in the world is asphalt” “The physical properties of coarse aggregates made from crushed demolition concrete make it the preferred material for applications such as road base and sub-base. This is because recycled aggregates often have better compaction properties and require less cement for sub-base uses. Furthermore, it is generally cheaper to obtain than virgin material.” Hinkley Center Presentation 5-15-2009 7
8 Research Methodology Determination of required properties of concrete Determination of materials management & utilization scenarios Selection of leaching tests Determination of relevant variables to test Analysis, feasible? Within regulatory limits Concrete structural testing, adequate? Viable mitigation measures? No Phase II Yes Need further testing? Yes CRT metals’ availability testing (reference 1) Concrete mix design Sampling pH PercolationDiffussion CRT-concrete metals’ availability testing (reference 2) Testing Benchmark Tests (SPLP) Testing stage I Testing stage II
9 Environment Material Loads Properties DeteriorationMaterial Loads Properties Deterioration Solid Waste Crushed material C&D waste Waste properties Solid Waste Crushed material C&D waste Waste properties Soil – groundwater – surface water – drinking water Contaminant: concentration Attenuation Dilution Materials Management & Utilization Release Performance-based Approach Contaminant: Maximum Potential release? Concentration-based Approach Hinkley Center Presentation 5-15-2009 Release flux & Long-term cumulative release? Performance-based Approach Extrapolate
10 Sampling & Testing Supplementary Tests Benchmark leaching compliance CRT-glass composition / leaching Concrete structural properties ASR Hinkley Center Presentation 5-15-2009 Leaching Characterization Tests pH dependence Percolation tests Diffusion short tests Diffusion long tests Sampling Measure intrinsic leaching parameters for the material. From previous work, select the most likely material parameters that affect leaching within the specified structural limits. Select extrinsic parameters for release that simluate environmental conditions found in the field (e.g. landfill). Determine a representative number of samples for analysis.
11 Short-term Research Objectives – Phase I 1. Characterize the dominant leaching mechanisms of contaminants from CRT- concrete under critical life-cycle utilization scenarios. To determine: a) Release amounts b) How contaminants reach a certain POC c) Peak concentrations at POC 2. Verify if the concentrations at POC are within regulatory limits. 3. Verify that CRT aggregates are not detrimental to the performance of concrete Hinkley Center Presentation 5-15-2009
12 Long-Term Research Objectives – Phase II 4. Develop & Validate a model of the leaching behavior: release & transport of contaminants to the POC 5. Establish a relationship between the laboratory testing results & the actual release & concentration of the contaminant in the environment. 6. Develop a correlation between characterization leaching results & compliance & field verification test results. 7. Establish risk-management protocols with material/waste management scenarios, & impact mitigation measures for CRT-concrete. Hinkley Center Presentation 5-15-2009
13 Analysis Lead leaching characterization analyses compared to the un- immobilized Pb leaching from CRT glass, as a function of: Time (time-dependent): initial wash-off, short term, and long-term leaching. The intrinsic properties of the CRT-concrete mix. The lifecycle exposure scenarios that simulate diffusion, percolation, and environment pH variabilty. Regulatory analysis The analysis should determine the maximum CRT proportion in a mix to comply with the maximum allowable release rates, and the maximum allowable concentrations at specified points of compliance. Characteristic CRT-concrete properties Evaluate the properties of CRT-concrete in terms of structural performance (strength, strain), workabilty, and durability (i.e. expansion and cracking due to ARS), and compare these to the concrete mix designs. Environmental life-cycle cost analysis Hinkley Center Presentation 5-15-2009
14 Deliverables A feasibility study will be produced addressing the objectives and scope of the proposal under the conditions described in the methodology. Mitigation measures will need to be proposed to minimize risks The study will also include guidelines for further testing & research. Hinkley Center Presentation 5-15-2009
15 Further Work If the outcome is positive, as expected from the previous work: Mathematical modeling of the leaching behavior will be proposed to relate lab. tests data to actual field conditions & better predict the leaching process to POC. Further testing to validate the leaching models will be conducted. If the outcome is not positive for some exposure scenarios: Further modeling & testing will be required with mitigation strategies. CRT-product identification & other materials’ management strategies will be studied along with maintenance & monitoring plans. Correlations with compliance & on-site verification methods will need to be developed. Hinkley Center Presentation 5-15-2009
16 Acknowledgement TECHNICAL AWARENESS GROUP Name: James D. Englehardt, Ph.D., P.E., University of Miami Research/Specialty: Water Quality Engineering Laboratory, Investigation of options for leachate and wastewater management Name: David S. Kosson, Ph.D., Vanderbilt University Research/Specialty: Contaminant Behavior in Soils, Sediments, Wastes and Aquatic Systems, Applications for Contaminated Site Restoration, Beneficial use of by-product Materials, and Environmental Policy. Name: Fabian Montenegro, Department of Transportation Research/Specialty: Roadway Construction Name: Helena Solo-Gabriele, Ph.D., P.E., University of Miami Research/Specialty: Environmental measurements: 1) microbes in water, 2) water flows within the Everglades watershed, and 3) metals in pressure treated wood. Name: Ronald Zollo, Ph.D., P.E., University of Miami /Engineering Analytics Research/Specialty: Construction, Construction Materials Development, Materials Testing, Structural Design and Analysis, Building Code and Standards Development. Hinkley Center Presentation 5-15-2009
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