Properties of construction and demolition waste as a stormwater filter medium : flow properties in deep bed filtration
Adduwa Hewage Jayasekara, Sanduni (2024)
Diplomityö
2024
School of Engineering Science, Kemiantekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2024111894738
https://urn.fi/URN:NBN:fi-fe2024111894738
Tiivistelmä
The generation of construction and demolition waste (CDW) is progressively escalating due to various factors, including urban expansion, infrastructure development, etc. Simultaneously, stormwater management is becoming critical, driven by climate change and urbanization. These crucial issues require comprehensive and integrated strategies to mitigate their environmental impact.
This master’s thesis, part of the StopWa project, aimed to study the feasibility of reprocessing CDW as a porous media for filtration purposes. The experiments utilized two concrete wastes: one from Finland (FLSC) and the other from Estonia (EACB). Three different fractions of each waste type (0.1-0.3 mm, 0.3-0.5 mm, and 0.5-0.8 mm) were tested in a filter column with a diameter of 9.5 cm and a height of 168 cm. Sample preparation included crushing and sieving, which were carried out using Cross Beater Mill SK 300 and HAVER EML 450 Digital Plus Test Sieve Shaker. Flow properties in terms of superficial velocity and pressure drop (Δp) were analyzed using three theoretical equations: Kozeny Carman, Ergun, and Darcy Weisbach. The particle characterization was carried out using Malvern Morphologi G3. True density measurements were done using both pycnometry and water displacement methods.
According to the results, the Kozeny-Carman equation provided values closest to the experimental Δp, followed by the Ergun equation. The Darcy-Weisbach Equation had the largest deviations. The experimental Δp ranges from 10-110 mmH2O, while the calculated values for concrete waste bed materials ranged from 4-60 mmH2O, 4-50 mmH2O, and 2-30 mmH2O for Kozeny Carman, Ergun’s, and Darcy Weisbach equations, respectively. The superficial velocities of 0.5-0.8 mm fraction of FLSC ranged from 400-2000 cm/h, and for the same fraction of EACB, velocities ranged from 600-2700 cm/h. For the 0.3-0.5 mm fraction, the velocities ranged from 100-1200 cm/h for FLSC and 200-1600 cm/h for EACB.
Due to the significant differences between calculated and experimental Δp values, the bed porosities were fitted using the Excel solver. The fitted bed porosities for the larger fraction (0.5.0.8 mm) are 0.336 and 0.331 for FLSC and EACB, respectively. For the fine fraction (0.3-0.5 mm), fitted bed porosities are 0.413 and 0.436 for FLSC and EACB, respectively. Moreover, using the coefficients developed for spherical particles in Kozeny Carman and Ergun equations can lead to deviation for irregular particles like concrete waste. The experimental results using glass beads suggested that bed porosity could be the most critical parameter in predicting the Δp.
This master’s thesis, part of the StopWa project, aimed to study the feasibility of reprocessing CDW as a porous media for filtration purposes. The experiments utilized two concrete wastes: one from Finland (FLSC) and the other from Estonia (EACB). Three different fractions of each waste type (0.1-0.3 mm, 0.3-0.5 mm, and 0.5-0.8 mm) were tested in a filter column with a diameter of 9.5 cm and a height of 168 cm. Sample preparation included crushing and sieving, which were carried out using Cross Beater Mill SK 300 and HAVER EML 450 Digital Plus Test Sieve Shaker. Flow properties in terms of superficial velocity and pressure drop (Δp) were analyzed using three theoretical equations: Kozeny Carman, Ergun, and Darcy Weisbach. The particle characterization was carried out using Malvern Morphologi G3. True density measurements were done using both pycnometry and water displacement methods.
According to the results, the Kozeny-Carman equation provided values closest to the experimental Δp, followed by the Ergun equation. The Darcy-Weisbach Equation had the largest deviations. The experimental Δp ranges from 10-110 mmH2O, while the calculated values for concrete waste bed materials ranged from 4-60 mmH2O, 4-50 mmH2O, and 2-30 mmH2O for Kozeny Carman, Ergun’s, and Darcy Weisbach equations, respectively. The superficial velocities of 0.5-0.8 mm fraction of FLSC ranged from 400-2000 cm/h, and for the same fraction of EACB, velocities ranged from 600-2700 cm/h. For the 0.3-0.5 mm fraction, the velocities ranged from 100-1200 cm/h for FLSC and 200-1600 cm/h for EACB.
Due to the significant differences between calculated and experimental Δp values, the bed porosities were fitted using the Excel solver. The fitted bed porosities for the larger fraction (0.5.0.8 mm) are 0.336 and 0.331 for FLSC and EACB, respectively. For the fine fraction (0.3-0.5 mm), fitted bed porosities are 0.413 and 0.436 for FLSC and EACB, respectively. Moreover, using the coefficients developed for spherical particles in Kozeny Carman and Ergun equations can lead to deviation for irregular particles like concrete waste. The experimental results using glass beads suggested that bed porosity could be the most critical parameter in predicting the Δp.