Upscaling the pollutant emission from mixed recycled aggregates under compaction for civil applications

Transcription

1 1 Upscaling the pollutant emission from mixed recycled aggregates under compaction for civil applications CONFERENCE PAPER Presenting author: Adela P. Galvín. Authors: Adela P. Galvín 1*, Auxi Barbudo 1, Jesús Ayuso 1 and Manuel Cabrera Department of Construction Engineering, University of Córdoba, Spain ATHENS th International Conference on Sustainable Solid Waste Management Athens, Greece. 21st June 2017

2 RECYCLED AGGREGATES IN CIVIL APPLICATIONS INTRODUCTION 2 Previous works focused on unbound applications have demonstrated that recycled materials possess suitable geotechnical properties for use in infrastructures as: many types of general bulk fills earthworks fillings road construction fill for drainage structures embankments The use of recycled aggregates from C&D Wastes as alternative materials are affected by the treatment operations carried out by the management plants.

3 ROLE OF MANAGEMENT PLANTS INTRODUCTION 3 Optimum management operations result in a product with optimum technical properties that also will not have negative environmental consequences after its application. Optimum TECHNICAL PROPERTIES Optimum ENVIROMENTAL PROPERTIES Spanish environmental legislation and the policy for C&DW management is strict. Their application must avoid harmful effects on the environment.

4 INTRODUCTION ENVIROMENTAL REGULATION FOR RECYCLED AGGREGATES 4 Daily operations of Spanish C&DW plants include the environmental assessment of recycled aggregates in laboratory. QUALITY CONTROL SYSTEM Leaching tests Leaching tests for environmental characterization play an important function on the quality control system of construction materials. Plant managers use leaching procedures that are simple, cheap and easy to perform, obtaining laboratory data easily comparable with the legal limits.

5 MAIN OBJECTIVE OF THE PRESENT RESEARCH INTRODUCTION 5 When recycled materials are tested by conventional leaching procedures: Only the portion of particle size less than 4 mm is analysed The material is not physically altered However, during its second cycle-life, when recycled aggregates are used at work: The particle size will be around 0-40 mm (well-graded aggregate) The material is compacted for increasing its bearing capacity. What is the effect of these differences? Are these differences affecting to release of pollutant elements? What is the difference on release levels considering the material conditions at work?

6 MAIN OBJECTIVE OF THE PRESENT RESEARCH INTRODUCTION 6 A new laboratory procedure have been designed (named as UCLT 2014). The main objective is the comparison of release levels on leachates obtained between a conventional leaching method and the new test designed. Data from the new leaching procedure (under compaction) Data from conventional leaching procedure (without compaction) Release levels of Cr on leachate from recycled mixed aggregate

7 EVALUATION OF POLLUTANT POTENTIAL EXPERIMENTAL METHODS 7 Leaching as a method of characterisation of pollutan release of hazardous elements. List of hazardous elements? L/S ratio = LIQUID / SOLID ( l/kg) Metals inductively coupled plasma mass spectrometry Anions ion chromatography (UNE-EN ISO : 2009) Concentration on leachate leachate Landfill Directive of European Comission 12 metals 3 anions Cr Ni Cu Zn As Se Mo Cd Sb Ba Hg Pb Cl - F - SO -2 4 Inert waste Non-hazardous Hazardous

8 LEACHING TESTS FOR GRANULAR MATERIALS LEVEL 1: BATCH LEACHING TEST (UNE-EN ) basic characterisation LEVEL 2: COLUMN LEACHING TEST (NEN 7343) percolation phenomena throught material LEVEL 3: UNDER COMPACTION LEACHING TEST (UCLT) percolation phenomena throught material simulating real application conditions EXPERIMENTAL METHODS 8 2 steps 2 and 10 l/kg particle size <4 mm 7 steps 0.1, 0.2, 0.5, 1, 2, 5, and 10 L/kg particle size <4 mm 7 steps 0.1, 0.2, 0.5, 1, 2, 5, and 10 L/kg Real commercial grain size CONVENTIONAL METHOD PROPOSED METHOD

9 MATERIALS Upscaling the pollutant emission from mixed recycled 9 RECYCLED MIXED AGGREGATE (RMA) Proportions of constituent materials Basic characterisation: RMA Natural aggregate 16.36% Mortar 48.18% Ceramic particles 32.80% Others 0.09% Gypsum 2.57% Cement and products from cement (MC) 48,18% Non-bound natural aggregate (MU) 16,36% Brick and ceramic particles (MB) 32.80% Other materials (MX) 2,57% Light particles (ML) 0,09% Density and water absorption Bulk density mm Water absorption mm Bulk density mm Water absorption mm g/cm % g/cm % Compaction-related test Compaction maximum density 1.81 g/cm3 Compaction optimal humidity 13.2 %

10 RESULTS AND DISCUSSION 10 Upscaling the pollutant emission from mixed recycled DATA FROM LEACHING TESTS LEVEL 1: Leachate concentrations (mg/kg) Cr Ni Cu Zn As Se Mo Cd Sb Ba Hg Pb Fluoride Chloride Sulphate COMPLIANCE TEST BASIC CHARACTERISATION RMA L/S 2 L/S 10 Leachate concentration of As (mg/kg) Legal limit of Landifll Directive At L/S = 10 l/kg MATERIAL CLASSIFIED AS NON-HAZARDOUS 0,0029 RMA L/S 2 0,0092 RMA L/S 10 Inert waste Non-hazardous Hazardous Legal limit of Landifll Directive At L/S = 2 l/kg

11 DATA FROM LEACHING TESTS RESULTS AND DISCUSSION 11 What is the source of Chromium and Sulphate? Previous research confirmed that leached sulphate and Cr were mainly released by the ceramic materials. Project Applications of recycled aggregates from construction and demolition waste (CDW) for the sustainable development of road infrastructure in central area of Andalusia of The ERDF Operational Programme for Andalusia Mainly perforated brick, hollow brick and tiles

12 Upscaling the pollutant emission from mixed recycled RESULTS AND DISCUSSION 12 DATA FROM LEACHING TESTS LEVEL 2: PERCOLATION TEST AT LONG TERM? Leachate concentration of Cr (mg/kg) and legal limit RMA Leachate concentrations (mg/kg) at different L/S ratios Legal limit MATERIAL CLASSIFIED AS NON-HAZARDOUS Legal limit of Landifll Directive At L/S = 0.1 l/kg Concentration curve from conventional leaching procedure

13 DATA FROM LEACHING TESTS RESULTS AND DISCUSSION 13 LEVEL 3: NEW LEACHING PROCEDURE ON SITE CONDITIONS Road subbase of compacted recycled aggregates Portion of subbase infiltration rain evaporation runoff Laboratory on site Experimental design leachates

14 Upscaling the pollutant emission from mixed recycled RESULTS AND DISCUSSION 14 DATA FROM LEACHING TESTS LEVEL 3: RMA Legal limit NEW LEACHING PROCEDURE ON SITE CONDITIONS Leachate concentrations (mg/kg) at different L/S ratios Release levels MATERIAL CLASSIFIED AS INERT New leaching procedure COMPACTED MATERIAL Conventional leaching procedure WITHOUT COMPACTING

15 CONCLUSIONS 15 SULPHATE and CHROMIUM are the most conflictive elements. The main source of both elements in C&DW in CERAMIC PARTICLES and GYPSUM. According to conventional leaching tests RMA was classified as NON-HAZARDOUS material. However according to the designed test the RMA was classified as INERT material. The pollutant potential of RAs is directly proportional to: the density and porosity of the material (influenced by the compaction stage) Contact time water-aggregate Formation of preferential channels of water circulation through the material ACTUALLY THE POLLUTANT POTENTIAN OF RECYCLED AGGREGATES IS BEING OVERESTIMATE MITIGATING THEIR POTENTIAL USE

16 BUILDING A SUSTAINABLE FUTURE 16 Sustainable development is the peace policy of the future. Dr. Klaus Topfer Executive Director of the United Nations Environment Programme

17 17 Upscaling the pollutant emission from mixed recycled aggregates under compaction for civil applications Presenting author: Adela P. Galvín. THANK YOU FOR YOUR ATTENTION