17:15 〜 18:30
[AGE28-P03] Characterization of Physical and Chemical Properties for CDW Fine Residues of Dumped CDW in Hanoi,Vietnam
キーワード：CDW, SEM-EDS, TG-DTA, Thermal property, Element composition, Environmental safety
INTRUDUCTION
Due to rapid urbanization and population increase, the generation of Construction and Demolition Waste (CDW) is increasing in urban areas and industrial zones in developing countries.In developing countries, most of the CDW generated is currently reused on/off-site without any material quality control and dumped in treatment sites along with urban clean-up waste (e.g. sludge and soil). The treatment plant lacks quality control and management of the accepted CDW, hazardous waste containing heavy metals, etc., is also mixed in with the potential risk. Therefore, it is important to determine the environmental status of the clean waste dump site based on an appropriate monitoring program. In order to examine the potential reuse and recycling of fine residues (typically < 2mm) that generate from various construction and demolition activities, this study investigated physical and chemical properties for fine residues including soil-like materials taken from building demolition sites and CDW landfills in Hanoi, Vietnam and the grounded and sieved fines prepared from waste concrete and clay brick debris taken from CDW landfills. Three properties such as i) surface morphology and element composition, ii) thermal property, and iii) environmental safety were analysed in the laboratory using a Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS), Thermogravimeter (TG)-Differential Thermal Analyzer (DTA), and leaching and content tests.
OBJECTIVES Characterize the physical and chemical properties for fine residues including soil-like materials to examine the potential reuse/recycling of fine residues. Examine the connection between the different experiments and discuss the most appropriate experimental Methodology for the subsequent study of the properties of CDW Assessment of the surrounding environment to evaluate the environmental safety of the CDW landfill. METHOTHOGIES
The main experimental methods were TG-DTA, SEM-EDS, and leaching test (Water extractable ions) and content test (Acid extractable ions). Through these different experiments, the chemical composition, thermal reaction, and surface properties of fine residue had been summarized, and the physical and chemical properties of fine residue were discussed in a comprehensive manner. The experimental methods, equipment used, and main experimental objectives parameter are summarized in Table 1.:SEM image and EDS spectrum are shown in figure 1,and the examples of sample after treatment are shown in figure 2
RESULTS
(1) Compared to a reference mortar sample, the measured Ca/Si of waste concrete samples from CDW landfills gave a opposite trend: the waste concrete from Thanh Tri CDW landfill became approximately 30% lower and the waste concrete from Vinh Quynh CDW landfill became 30% higher. It is noted that Ca/Si vales of the fine residues from building demolition sites became similar to the value of the reference mortar sample. Basically, the measured Ca/Si values for waste clay bricks and soil-like materials became small and some samples gave zero values of Ca/Si because the measured Ca % was zero.the result shown in Figure 3.
(2) The tested results of Ca/Si ratio from EDS and TG were summarized in Table 2. It could be understood that the higher Ca/Si samples gave higher TG values. In the previous section Ca/(Si+Al) was also mentioned as an important object, so the results for Ca/(Si+Al) are also summarised in the graph below. In the elemental content, it can be clearly seen, that the clay brick contains about twice as much aluminium as the other samples. The aluminium content of waste concrete is very limited, being only 2.6% in Thanh Tri landfill and 3.78% in Vinh Quynh landfill. The correlation with Tg reduction, on the other hand, is the same as for Ca/Si. The higher Ca/(Si+Al) samples gave higher TG values.
CONCLUSION
The combinational results of Ca/Si ratio and TG might give an effective approach to quantify the cementitious amount in fine residues. The tested results from environmental safety indicated the water- and acid-extractable heavy metals should be examined especially for soil-like materials from CDW landfill sites. But, the tested results shown in this study would give a goof insight to characterize physical and chemical properties of fine residues and to examine the potential reuse/recycling of fine residues in future.
Due to rapid urbanization and population increase, the generation of Construction and Demolition Waste (CDW) is increasing in urban areas and industrial zones in developing countries.In developing countries, most of the CDW generated is currently reused on/off-site without any material quality control and dumped in treatment sites along with urban clean-up waste (e.g. sludge and soil). The treatment plant lacks quality control and management of the accepted CDW, hazardous waste containing heavy metals, etc., is also mixed in with the potential risk. Therefore, it is important to determine the environmental status of the clean waste dump site based on an appropriate monitoring program. In order to examine the potential reuse and recycling of fine residues (typically < 2mm) that generate from various construction and demolition activities, this study investigated physical and chemical properties for fine residues including soil-like materials taken from building demolition sites and CDW landfills in Hanoi, Vietnam and the grounded and sieved fines prepared from waste concrete and clay brick debris taken from CDW landfills. Three properties such as i) surface morphology and element composition, ii) thermal property, and iii) environmental safety were analysed in the laboratory using a Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS), Thermogravimeter (TG)-Differential Thermal Analyzer (DTA), and leaching and content tests.
OBJECTIVES Characterize the physical and chemical properties for fine residues including soil-like materials to examine the potential reuse/recycling of fine residues. Examine the connection between the different experiments and discuss the most appropriate experimental Methodology for the subsequent study of the properties of CDW Assessment of the surrounding environment to evaluate the environmental safety of the CDW landfill. METHOTHOGIES
The main experimental methods were TG-DTA, SEM-EDS, and leaching test (Water extractable ions) and content test (Acid extractable ions). Through these different experiments, the chemical composition, thermal reaction, and surface properties of fine residue had been summarized, and the physical and chemical properties of fine residue were discussed in a comprehensive manner. The experimental methods, equipment used, and main experimental objectives parameter are summarized in Table 1.:SEM image and EDS spectrum are shown in figure 1,and the examples of sample after treatment are shown in figure 2
RESULTS
(1) Compared to a reference mortar sample, the measured Ca/Si of waste concrete samples from CDW landfills gave a opposite trend: the waste concrete from Thanh Tri CDW landfill became approximately 30% lower and the waste concrete from Vinh Quynh CDW landfill became 30% higher. It is noted that Ca/Si vales of the fine residues from building demolition sites became similar to the value of the reference mortar sample. Basically, the measured Ca/Si values for waste clay bricks and soil-like materials became small and some samples gave zero values of Ca/Si because the measured Ca % was zero.the result shown in Figure 3.
(2) The tested results of Ca/Si ratio from EDS and TG were summarized in Table 2. It could be understood that the higher Ca/Si samples gave higher TG values. In the previous section Ca/(Si+Al) was also mentioned as an important object, so the results for Ca/(Si+Al) are also summarised in the graph below. In the elemental content, it can be clearly seen, that the clay brick contains about twice as much aluminium as the other samples. The aluminium content of waste concrete is very limited, being only 2.6% in Thanh Tri landfill and 3.78% in Vinh Quynh landfill. The correlation with Tg reduction, on the other hand, is the same as for Ca/Si. The higher Ca/(Si+Al) samples gave higher TG values.
CONCLUSION
The combinational results of Ca/Si ratio and TG might give an effective approach to quantify the cementitious amount in fine residues. The tested results from environmental safety indicated the water- and acid-extractable heavy metals should be examined especially for soil-like materials from CDW landfill sites. But, the tested results shown in this study would give a goof insight to characterize physical and chemical properties of fine residues and to examine the potential reuse/recycling of fine residues in future.