Presentation on theme: "THESIS EFFECTIVENESS OF BACK- FLUSHING FOR CLEANING POROUS PAVEMENTS Fall 2006 By- Nilesh Shirke."— Presentation transcript:
THESIS EFFECTIVENESS OF BACK- FLUSHING FOR CLEANING POROUS PAVEMENTS Fall 2006 By- Nilesh Shirke
Outline Introduction Problem Statement Research Question Methodology Construction of a Model Detailed Procedure of Experiments Experiments and Results Analysis of Data Result and Conclusion Future Research
Committee Members Dr. Scott Shuler (Adviser/Chair) Dr. Angela Guggemos Dr. Charles Smith Dr. Ramchand Oad (Outside Committee member)
Introduction Increased runoff Drainage Alternative pavement Void content Direct infiltration of rain water Replenish ground water Sustainable construction Bean, Hunt, Bidelspach, & Smith, 2004; Leopold, Wolman, & Miller, 1964 James, W., & Langsdorff, H., 2003; Bachtle, 1974; Caltrans, 2004; Georgia concrete and products association, 2005, p. 2; Surface System Drainage Design, 2005
Typical Cross-section of Porous Pavements The Urban Land Institute, 1992, p 6.
Advantages of porous pavements Percolation of rainwater into the soil Aquifer recharge Ambient air temperature Snow and ice Soil erosion Decreases need of storm drains Adams, 2003; Bachtle, 1974; Field, 1982; Ferguson 1994; Magnus, 2000; Pratt 1997; The Pervious Company, 2005; Georgia Concrete and Products Association, 2005; Miller, 2005
Disadvantage of Porous Pavements Susceptibility to clogging Reduces infiltration levels Groundwater contamination High failure rate Field, 1982; UNI-Group U.S.A., 1998; United States Environmental Protection Agency, 1999.
Maintaining infiltration capacity Clogging at the bottom Periodic maintenance Traffic levels and type of usage Severe clogging Problem Statement James & Langsdorff, 2003; The Urban Land Institute, 1981; United States Environmental Protection Agency, 1999; Siew-Ann et al., 2003; Georgia Stormwater Management Manual, 2002
Periodic Maintenance Georgia Stormwater Management Manual, 2002, p 37
Research Hypothesis When water is flushed through the pavement from bottom to the top with enough pressure, it removes the debris particles trapped in the pores of porous concrete layer.
When water is pumped into the stone reservoir of the pavement, it will try to come out through the clogged porous concrete layer. While coming out from bottom to the top of the pavement, water should remove the particles and debris trapped in the pores of the pavement. The result of this flushing should make the pavement permeable again. Research Question
Diagram of a Model Constructed for the Analysis of Back-Flush
Methodology Fabrication of steel frame Construction of a porous concrete layer Installation of model on a steel frame Construction of various layers Sieve analysis for clogging materials Calculation of initial permeability Clogging Back-flushing
Methodology Measurement of permeability cleaned concrete layer Back flush it for the second time. Measurement permeability after 2 nd back-flush Repetition of the procedure Data collection Analysis of the results Conclusion
Section 1 A two feet long and 8” diameter pipe for the construction of porous concrete layer Material Weight Proportions - Cement-600 lbs, Aggregates 3/8”-2900 lbs, Water-242 lbs Sampling - ASTM C 702-98 splitting method Sieve Analysis - for 3/8” aggregates as per ASTM C 136-01 Curing of concrete - ASTM 192 & C511 Storage tank in hydrated lime
Analysis of 3/8” aggregates as per ASTM C 136-01
Section 2 A three feet long and 8” diameter pipe for construction of filter layers, stone layer of the pavement in it.
Section 3, 4 & 5 Section 3: A ten feet long and 8” diameter pipe to store water to create head difference Section 4: A 1½” diameter pipe connected to tap water with water flow control valve in between. Section 5: A 1½” diameter pipe connected to section 1 and which is used to drain the water out after back-flushing.
Procedure of experiment Calculation of permeability: k = QL / Ath Where, k = permeability, in/s Q = quantity of flow, cu. inch L = length of specimen, inch A = cross-sectional area of specimen, sq. inch t = interval of time over which flow Q occurs, s h = difference in hydraulic head across the specimen, in
Procedure of experiment Unclamp Section 1 Check permeability Clogging Measurement of permeability Placement of section 1 over section 2 Attach section 5 to the section 1 Choose the head and fill section 3 Back-flush Close the valve after back-flush Detach section 5 from section 1
Procedure of experiment Unclamp section 1 Check permeability after back-flush Attach Section 1 for 2 nd back- flush Attach section 5 to section 1 Back-flush for the 2 nd time Check permeability Repeat the procedure Efficiency of back-flush = k (back-flush)- k (clogged) / k (Initial) – k (clogged)
Experiments and Results Average Strength of porous concrete High Porous Concrete - 895.59 psi Low Porous Concrete - 1164 psi
Classification of clogging materials Classification and gradation of soils by ASTM D 2487-00 Cu = D60/D10 & Cc = (D30*D30) / (D60*D10) Where, Cu = Coefficient of Uniformity Cc = Coefficient of Curvature D10, D60 and D30 = Particle size diameters corresponding to 10, 60 and 30 % respectively, passing on cumulative particle-size distribution
Classification of Sand 1 & Sand 2 Sand 1: A Graph gives the value for D10 = 0.15, D60 = 1.15 and D30 = 0.4 Hence, Cu = 8.33, Cc = 1.05 Cu>6 and 3>Cc>1 Hence, it is a Well Graded Sand (SW). Sand 2: A Graph gives the value for D10 = 0.45, D60 = 1.8 and D30 = 0.8 Hence, Cu = 4, Cc = 0.79 Cu Cc. Hence, it is a Poorly Graded Sand (SP).
Percentage Removal of Clogged Particles After Back-Flush
Average Permeability Recorded on High Porous Concrete Sample
A Chart for Average Permeability Recorded on High Porous Concrete Sample
Average Permeability Recorded on Less Porous Concrete Sample
A Chart for Average Permeability Recorded on Less Porous Concrete Sample
Analysis of Data ANOVA Four variables Class Levels Values Pressure 4 H L M VL Porosity 2 High Low Clogging 2 Sand 1 Sand 2 Flush 2 Q1 Q2
Student-Newman-Keuls Test Alpha = 0.05 Error Degrees of Freedom 64 Error Mean Square 198.7347 Number of Means 2 3 4 Critical Range 8.1301265 9.7646019 10.734814 ***Means with the same letter are not significantly different. SNK Grouping Mean N Pressure A 79.953 24 H A B A 72.753 24 M B B 66.196 24 VL B B 65.321 24 L
Analysis No fixed pattern in particle removal Pressure- significant variable No significance of number of flushes Less water requirement Low pressure efficiency
Results and Conclusion Simplified Maintenance Monthly or quarterly back-flushing Increased use of porous pavements Low pressure works good Possible to create in the field
FUTURE RESEARCH More research work Laboratory study and Field study A very low pressure of water (0.5 psi) Drainage pipes in the porous pavement Division of porous pavement Storage of drained water
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