Stefan A. Romanoschi, Ph.D.
http://hdl.handle.net/10106/24355
2024-03-29T12:26:25ZTHE FIRST FULL-SCALE ACCELERATED PAVEMENT TEST IN LOUISIANA: DEVELOPMENT AND FINDINGS
http://hdl.handle.net/10106/24553
THE FIRST FULL-SCALE ACCELERATED PAVEMENT TEST IN LOUISIANA: DEVELOPMENT AND FINDINGS
Metcalf, J.B.; Romanoschi, Stefan; Li, Y.; Rasoulian, M.
The Pavement Research Facility in Port Allen, Louisiana houses the first full-scale accelerated
pavement testing experiment in the state. The purpose of the first experiment was to evaluate the
historically prevalent flexible crushed stone and in-place soil cement stabilized base construction
in comparison to several alternative base construction materials and construction processes for
pavements designed for a semi-tropical climate. Loading is provided by an Accelerated Loading
Facility (ALF) machine, the second of its type in the United States. More than six million
equivalent axle loads (ESALs) were applied to the nine test lanes. Performance of the pavement
structures and materials was evaluated using the information provided by the monitoring of
pavement surface deterioration, deflection testing during loading and post-mortem investigations.
This paper presents development of the project as well as the major findings of this first
experiment. The implementation of these findings in pavement design and construction practice
is discussed.
1999-01-01T00:00:00ZSeasonal and Spatial Variation of Subgrade Response
http://hdl.handle.net/10106/24532
Seasonal and Spatial Variation of Subgrade Response
Hossain, Mustaque; Romanoschi, Stefan; Gisi, Andrew J.
Temperature, subgrade moisture content, and Falling Weight Defleetometer
(FWD)-deflection data were collected monthly on four asphalt pavement test sections
in Kansas for a year. The subgrade moduli were baekealeulated using the elastic layer
theory. It was found that for almost all sites, the monthly variation in subgrade
moisture content was not very significant over the seasons. The patterns of subgrade
response, in terms of subgrade moduli versus time, simulated sine-shaped forms
signifying a possible temperature effect. Higher variabilities across the site were
associated with the extreme temperature conditions, usually very low or high average
pavement temperatures. In all cases, the measured precipitation was nominal thereby
excluding this climatic variable as a major factor. Extreme test temperatures, both
high and low, result in higher variation of measured deflections and subsequently,
backcalculated subgrade moduli across a site. Thus, some variabilities in
baekealculated subgrade moduli can be minimized by conducting FWD tests in a
moderate temperature regime. The analysis of variance (ANOVA) indicated that both
seasonal and site variabilities can be significant. ARer correction for temperature,
variations in deflections and moduli become approximately equal to the site
variabilities which was also eorrfirmed by ANOVA.
2000-01-01T00:00:00ZField Verification of Superpave Dynamic Modulus
http://hdl.handle.net/10106/24531
Field Verification of Superpave Dynamic Modulus
Gedafa, Daba S.; Hossain, Mustaque; Romanoschi, Stefan; Gisi, Andrew J.
In the mechanistic-empirical pavement design guide, prediction of flexible pavement response and performance needs an input
of dynamic modulus of hot-mix asphalt at all three levels of hierarchical inputs. This study was intended to find the best way to
predict/derive this input. Nine Superpave pavement sections were selected as test sections in this study. Deflection data on all test sections
was collected with a Dynatest 8000 falling weight deflectometer shortly after construction. The deflection data, normalized with respect
to 40-kN load, were used to back-calculate asphalt layer moduli using three back-calculation algorithms. Laboratory dynamic modulus
tests were conducted on asphalt concrete AC cores and laboratory-compacted samples. Dynamic modulus was also estimated with the
Witczak model, new Witczak model, and Hirsch model. The results show that the AC moduli obtained from various back-calculation
programs used in the study are generally comparable. Laboratory dynamic modulus is comparable at 4°C, but the variation increases as
the test temperature increases. The Witczak model underestimates the dynamic modulus at low temperature and overestimates it at higher
temperature. The parameter estimate when the laboratory dynamic modulus is used as a dependent variable and the moduli from other
approaches as independent variables is close to 1. This is especially true for the AC moduli estimated by various prediction methods. The
Hirsch model appears to be the best for estimation and is closely followed by the new Witczak model.
2010-05-01T00:00:00ZFirst Findings from the Kansas Perpetual Pavements Experiment
http://hdl.handle.net/10106/24530
First Findings from the Kansas Perpetual Pavements Experiment
Romanoschi, Stefan; Gisi, Andrew J.; Portillo, Miguel M.; Dumitru, Cristian
To investigate the suitability of the perpetual pavements concept for
Kansas highway pavements, the Kansas Department of Transportation
(KDOT) constructed four thick, flexible pavement structures on a new
alignment on US-75 near Sabetha, Kansas. They were designed to have
a perpetual life and have layer thicknesses close to those recommended
by KDOT’s structural design method for flexible pavements, which is
based on the 1993 AASHTO Design Guide. To verify the approach of
designing perpetual pavements on the basis of an endurance strain limit,
the four pavements were instrumented with gauges for measuring the
strains at the bottom of the asphalt base layers. Seven sessions of pavement
response measurements under known vehicle load were performed
between July 2005 and October 2007, before and after the pavement
sections were opened to traffic. The analysis of the strain data indicated
that, even during hot summer days, the strains of all four test sections
were smaller than the endurance limit of asphalt–concrete. As expected,
the strains were affected by the temperature in the asphalt layers and the
speed of the loading vehicle. The analysis of the strain signals revealed
that the transverse strain under the front axle did not recover completely
before the arrival of the rear axles, a situation causing the accumulation
of dynamic transverse strain to values higher than those of the corresponding
longitudinal strains. A comparison between the measured
response and that predicted by a linear-elastic model indicated that
the predicted transverse strains were close to half the corresponding
measured dynamic transverse strains, while the predicted longitudinal
strains were close to twice the measured dynamic longitudinal strains.
Furthermore, the predicted vertical stresses at the top of the subgrade
layer were close to five times the measured stresses.
2008-01-01T00:00:00Z