Download presentation
Presentation is loading. Please wait.
Published byCheyenne Cosby Modified over 3 years ago
1
Evaluation of Cracking Resistance of Superpave Mixtures Using Texas Overlay Test Syeda Rubaiyat Aziz Mustaque Hossain Greg Schieber Department of Civil Engineering Kansas State University
2
Outline ● Background ● Objective ● Materials & Test Method ● Laboratory Testing ● Results ● Conclusions & Recommendations ● Acknowledgements 2
3
Research Background ● About 94% of paved road in the United States is Hot-Mix Asphalt (HMA) ● Annual HMA production is about 500-550 million tons ● Reasons for increased use of reclaimed asphalt pavement (RAP): Rise in oil price, emphasis on sustainability, limited virgin aggregate availability ● High RAP content sometimes leads to drier mix, prone to early cracking
4
Objective ● Investigate cracking resistance of Superpave mixtures with varying RAP content ● Investigate effect of RAP source on cracking resistance
5
Materials & Test Method ● Materials: Superpave 12.5-mm NMAS mixture with PG 70-28 Five virgin aggregates Three RAP contents (20%, 30% and 40%) Two sources ● Test: Texas Overlay Test and Semi-Circular Bending Test
6
Aggregate Blending SR-12.5A (with RAP) First RAP source (Shiling) Second RAP source (Konza)
7
Texas Overlay Test (TEX-248-F) ● Simulates opening or closing of joints, which accelerates crack initiation and propagation ● Controlled displacement mode ● Test performed at 25° C
8
Texas Overlay Test (Cont…) Courtesy: TTI manual Tex-248-F After cutting, air void is checked (7±1)%, then glued on base plates 3 replicates from each Mixture
9
Texas Overlay Test (Cont…) Gluing Attaching to base plates using Epoxy glue 8 hours curing Placement Placing in side OT jig LVDT attached at back Test Input Cyclic triangular loading @ 10 sec/cycles Fixed opening displacement 0.025 inch Termination Load reduction to 93% of initial load or 1000 cycles Output Initial load % of load reduction No of OT cycles of failure
10
Semi-circular Bending Test (SCB) ● Half disc shaped (3’’ diameter, 2’’ thick) ● Must satisfy 7±1 % air void ● Notched at bottom ● Three point bending setup ● Loaded in compression ● Test temperature at 25° C ● 3 Static & 12 Cyclic test specimens for each mixture
11
SCB Test (Cont…) s = 0.8 R Static Static load applied @ 0.05 inch/min on 3 replicates Peak Load Average of the Peak Failure load from Static tests recorded Cyclic Cyclic haversine load applied @ 10 Hz frequency with no rest period Cyclic Input 30%, 40%, 50% & 60% of Avg. Peak Static load given as inputs & 3 specimen tested for each Output Load, Duration and No. of Cycles to failure 2S 2R S = 0.8 R
12
Results
13
Results (Overlay Test)
14
Repetitive SCB Test Shiling RAP
15
Statistical Analysis Comparison of Means SR-12.5A (Shilling RAP) RAP%403020 Asphalt%4.34.84.7 Groups*aaa SR-12.5A (Konza RAP) RAP%302040 Asphalt%4.44.34.1 Groups*aab SR-12.5A (Shilling RAP) RAP%403020 Asphalt%4.34.84.7 Groups*abc SR-12.5A (Konza RAP) RAP%302040 Asphalt%4.44.34.1 Groups*abb *Mix types not connected by same letter have statistical significant difference R-SCB TestOT Test
16
Conclusions ● Based on the Texas Overlay test results: Increase in RAP content reduces cracking resistance Overall, mixtures with first RAP source carried higher no. of OT cycles prior to failure compared to second RAP source ● Based on SCB test results: Similar trend of results as OT tests were obtained 20% RAP performed well for first RAP source and 40% RAP performed well for second RAP source
17
Recommendations ● Study more RAP sources ● Correlate cracking test results with actual field data
18
Acknowledgements ● This study has been sponsored by the Kansas Department of Transportation (KDOT)
19
Thank You!
Similar presentations
© 2018 SlidePlayer.com Inc.
All rights reserved.
Ppt on cleanliness in islam Ppt online shopping project in jsp Ppt on sound navigation and ranging system restore Ppt on business etiquettes training and development Ppt on sea level rise in india Ppt on ministry of corporate affairs in india Ppt on rf remote control robot Ppt on 3 allotropes of carbon Free ppt on air conditioner Tissue anatomy and physiology ppt on cells