session 40 prabir kumar das
Post on 04-Jul-2015
446 Views
Preview:
TRANSCRIPT
KTH – Väg- och Banteknik Oct 26, 2011
Page 1
Oct 26, 2011
The objective of this work was to investigate the influence of commercial wax additives for lowering energy consumption during asphalt production and paving with a focus on:
1. Cracking performance 2. Moisture Damage3. Low Temperature-Cracking
Page 2
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Oct 26, 2011
The effects of wax additives for lowering energy consumption during production and construction is known, but no study has focused explicitly on the cracking and durability properties of the resulting asphalt pavement.
Page 3
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Commercial Wax Oct 26, 2011
• Commercial wax (Sasobit, Montan wax) is used as energy reducing agent and flow improver
• Lower the mixing temperature of the asphalt, thus reducing energy consumption and emissions
• Wax may increase the asphalt pavement resistance to plastic deformation
Page 4
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Introduction To Test Materials Oct 26, 2011
Aggregate: Two different types of dense graded aggregate (crushed granite and feldspar, Skärlunda)with maximum size of 11mm used according to Swedish road standards (ATB VÄG, 2004)
Binder:Original (70/100) - as a base binderOriginal + 4% Sasobit Wax (FT-paraffin)Original + 4% Montan Wax (asphalten B)
Page 5
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Binder Test Results shows the improvement in Rutting Resistance
Oct 26, 2011
Page 6
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Characteristics UnitsOriginal 70/100
Original + 4%Sasobit
Original + 4% MW
Softening Point oC 46 89 85
Penetration dmm 81 45 52
Brookfield visc. At 1350C mPas 345 270 263
Brookfield visc. At 1650C mPas 101 80 82
Force Ductility Nm 1.38 4.03 3.54 Bending Beam Rheometer
S / m-value -120C Mpa 150 / 0.395 208 / 0.311 182 / 0.323
S / m-value -180C Mpa 414 / 0.3 462 / 0.252 421/ 0.271
S / m-value -240C Mpa 832 / 0.205 881 / .195 796 / .214
LST 0C -16 -15 -16
LmT 0C -18 -13 -15
Complex Modulus Increase for Improved Rutting Resistance
Oct 26, 2011
Page 7
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
CRACKING PERFORMANCE USING SUPERPAVE IDT Oct 26, 2011
Three specimens from each mixture were tested at 0 0C:
Resilient modulus testStatic creep testIndirect tensile strength test
Page 8
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
ENERGY RATIO CONCEPT Oct 26, 2011
Page 9
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Ref: Florida Cracking Model
HMA FRACTURE MECHANICS PERFORMANCE PREEDICTION Oct 26, 2011
Page 10
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
For example, AG1-O = Aggregate type 1 mixed with Base binder….etc
CONCLUSIONS FROM MIXTURE PERFORMANCE Oct 26, 2011
Page 11
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
• Addition of wax makes the binder stiffer
• Complex modulus results on binder showed improve stiffness at higher temperatures (i.e. improved rutting resistance!)
• Adding wax to the binder increases the cracking resistance measured by the Superpave IDT
APPROACH Oct 26, 2011
Page 12
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
• Moisture damage in asphalt mixtures is typically evaluated by the tensile strength ratio of moisture conditioned and dry samples
• However a single parameter such as tensile strength is not enough to conclude moisture damage performance (Birgisson et al. 2003, 2004)
• In this study the HMA fracture mechanics framework was used to evaluate moisture damage
Creep rate at 1000 sec of the mixtures Oct 26, 2011
Page 13
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
For example, AG1-O = Before Conditioned and AG1-O-C = After Conditioned
Moisture Damage Ratio of ER Oct 26, 2011
Page 14
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
For example, AG1-O = Aggregate type 1 mixed with Base binder….etc
Conclusions from Mixture Performance tests Oct 26, 2011
Page 15
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Compared to unmodified mixtures, wax modified mixtures gives :
- Lower Creep rate.- Higher Energy Ratio
So, addition of wax shows better moisture damage performance.
Low Temperature Cracking Oct 26, 2011
Page 16
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Laboratory Experiments:
Binder Test:DMA (Dynamic Mechanical Analysis)BBR (Bending Beam Rheometer)
Mixture Test:TSRST (Thermal Stress Restrained Test)Superpave IDT (Indirect Tensile Strength Test)
SUMMARY OF MIXTURES FRACTURE PROPERTIES Oct 26, 2011
Page 17
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
TSRST TEST RESULTS Oct 26, 2011
Page 18
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
Conclusions For Low Temperature Performance Oct 26, 2011
Page 19
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
So, Using 4% commercial wax as an additive has a minor or may be no negative effect in Low Temperature Cracking performance.
Test Result
Binder DMA and BBR Minor Negative Effect
MixtureTSRST Minor Negative Effect
Superpave IDT Small Positive Effect
Thank You Oct 26, 2011
Page 20
Motivation
Materials
Cracking Performance
Moisture Damage
Low Temperature Cracking
top related