Early Opening of Concrete Pavements to Traffic
Lev Khazanovich, Lucio Salles, Katelyn Kosar, Haoran Li IRISE ANNUAL MEETING MAY 24, 2021 1 University of Pittsburgh | Swanson School of Engineering
The Research Problem The current empirical methods for determining traffic-opening criteria are overly conservative.
An innovative mechanistic-based procedure for quantifying the risk of premature failure and long-term damage caused by traffic opening will facilitate reduction of unnecessary construction delays, construction and user costs. University of Pittsburgh | Swanson School of Engineering
Project Approach
Task A: Literature review Task B: Laboratory and field testing Task C: Develop mechanistic-empirical model Task D: Conduct traffic simulation Task E: Final Report
University of Pittsburgh | Swanson School of Engineering
ACPA Guidelines (1994)
University of Pittsburgh | Swanson School of Engineering
Laboratory and Field Testing Two concrete mixtures: 1. Long-Life Conventional 2. High Early Strength (7 hours) Three tests: 1. Laboratory: Compressive and flexural strength 2. Maturity: Lab and Field 3. Ultrasound: Lab and Field University of Pittsburgh | Swanson School of Engineering
Laboratory Testing High Early Strength (HES) mix compressive strength development 4000
4000
Maturity
3000 2500
7h
2000
y = 1666.87ln(x) - 7544.51 R² = 0.96
1500 1000
3500
1 day
5h
Compressive Strength (psi)
Compressive Strength (psi)
3500
3000
2000 1500 5h 1000
3h
0 0
200
400
600
L abor ator y M atur ity (℃-hr s )
800
1000
7h
2500
500
500
1 day
Shear Wave Velocity
0 1000
y = 6.2377e0.002751x R² = 1.00
3h 1200
1400
1600
1800
2000
Slab Shear Wave Velocity (m/s)
University of Pittsburgh | Swanson School of Engineering
2200
2400
Laboratory Testing Long-Life Conventional Mix Compressive Strength Development 6000
6000
Compressive Strength (psi)
7 days
5000 3 days
4500
5 days
y = 855.83ln(x) - 2,360.74 R² = 0.94
4000 3500
14 days
Compressive Strength (psi)
Maturity
5500
5500
14 days
5 days
4500
3 days 4000 y = 11.29x - 26,286.23 R² = 0.99
3500 1 day
3000 1800
7 days
5000
1 day
800
Shear Wave Velocity
2800
3800
4800
5800
6800
Cyllinder M atur ity (℃-hr s )
7800
8800
9800
3000 2600
2650
2700
2750
Beam Shear wave velocity (m/s)
University of Pittsburgh | Swanson School of Engineering
2800
2850
Field Testing Variability of concrete properties 2500 Construction day: 3 to 24 hours after pavement construction
24 h
1 day
9h
TC
CLS
TE
CRS
a.m.
TE
Subsequent days
CRN
S1 HES2 HES3
1500
CLN
Thermocouples
CLN
1700
CLS
1900
TC
CRN
5h
CRS
2100
C1.1
1300 3.5h
1100 900
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
University of Pittsburgh | Swanson School of Engineering
C1.3
Measurement Cycles
.2
Shear Wave Velocity (m/s)
2300
14 days
Mechanistic-Empirical Model
The research team was directed by the Technical Panel to develop a comprehensive procedure rather than a simple equation. The proposed model: Uses ultrasound-based strength development assessment Assesses a probability of failure due to early opening Will be implemented into a web-based tool
University of Pittsburgh | Swanson School of Engineering
Project Status Tasks 1 and 2 have been completed Task 3 ME procedure and web-based tool development – a significant progress was made The model has been developed: A discrepancy between lab- and field- measured shear wave velocity was identified A maturity-based correction was developed A re-evaluation of the velocity calculation is underway
An alpha–version of the tool has been developed and currently is under debugging
A 3-month time-extension will be requested University of Pittsburgh | Swanson School of Engineering
Task C: Develop Mechanistic-Empirical Model
The tool needs to be finalized University of Pittsburgh | Swanson School of Engineering
Discrepancy Between Lab and Field Velocities
Compressive Strength (psi)
6000
5000
4000
3000
2000
Maturity
SWV
4
8
Adjusted SWV
1000
0 0
2
6
10
Concrete Age (days)
12
14
16
University of Pittsburgh | Swanson School of Engineering
Application of Research Results
Relatively early concrete strength can be achieved with conventional concrete mixes PennDOT (Neal Fannin) and FHWA Concrete Mobil Lab will further investigate the use of the ultrasound dry point contact technology for the strength development assessment A web-based tool for the early opening analysis will be available soon
University of Pittsburgh | Swanson School of Engineering