Traffic Densification of Asphalt Concrete Pavements

1997 ◽  
Vol 1575 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Mary Stroup-Gardiner ◽  
David E. Newcomb ◽  
Roger Olson ◽  
Jerry Teig
Keyword(s):  
Asphalt Concrete ◽  
Moisture Damage ◽  
Mix Design ◽  
Concrete Pavements ◽  
Air Voids ◽  
Design Procedures ◽  
Low Volume Roads ◽  
Traffic Volumes ◽  
Water Trapping

A 5-year study of newly constructed pavements showed that a reduction in in situ air voids occurred both within and between wheelpaths for highways with an average daily traffic (ADT) load of less than 10,000 vehicles. Regardless of the level of voids immediately after construction, mixtures in the upper 65 mm (2.5 in.) within the wheelpath indicated a reduction in voids by 3 to 5 percent (e.g., from 10 to 6 percent voids), and by between 2 to 4 percent between the wheelpaths. Because only limited densification occurred below this depth for lower–traffic-volume facilities, reducing the mix design level of air voids from 4 percent to 2 percent for the lower lifts was suggested so that lower initial voids could be obtained during construction. An evaluation of older pavements indicated that moisture damage to the lower pavement layers was typical; thus, a change in mix design procedures might also help improve durability by increasing the film thickness. Pavements with high traffic volumes (>50,000 ADT) consistently indicated an increase in voids over time in the upper lift [40 mm (1.5 in.)], little change in the middle 65 mm (2.5 in.), and a decrease in the bottom 65 mm (2.5 in.). The hypothesis suggested to explain these findings was that a loss of material in the upper lifts was occurring, most probably due to moisture damage as the upper, more permeable wear course, commonly used in Minnesota, allowed water trapping at the wear and binder course (i.e., less permeable) interface. A further investigation of in situ void changes on an interstate indicated that for a pavement constructed with the same fine gradation in all lifts, traffic compacted the mixtures in a manner similar to that in low-volume roads. When the initial in situ voids increased from around 7 percent to nearly 10 percent, the influence of traffic on the densification was substantially increased.

Modelling in situ shear strength testing of asphalt concrete pavements using the finite element method

2001 ◽  
Vol 28 (3) ◽  
pp. 541-544 ◽  
Author(s):  
Wael Bekheet ◽  
Yasser Hassan ◽  
AO Abd El Halim
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Traffic Safety ◽  
Asphalt Concrete ◽  
Material Properties ◽  
Fundamental Property ◽  
Analytical Models ◽  
Strength Testing ◽  
Concrete Pavements

Rutting is one of the well-recognized road surface distresses in asphalt concrete pavements that can affect the pavement service life and traffic safety. Previous studies have shown that the shear strength of asphalt concrete pavements is a fundamental property in resisting rutting. Laboratory investigation has shown that improving the shear strength of the asphalt concrete mix can reduce surface rutting by more than 30%, and the SUPERPAVE mix design method has acknowledged the importance of the shear resistance of asphalt mixes as a fundamental property in resisting deformation of the pavement. An in situ shear strength testing facility was developed at Carleton University, and a more advanced version of this facility is currently under development in cooperation with the Transportation Research Board and the Ontario Ministry of Transportation. In using this facility, a circular area of the pavement surface is forced to rotate about a normal axis by applying a torque on a circular plate bonded to the surface. The pavement shear strength is then related to the maximum torque. This problem has been solved mathematically in the literature for a linear, homogeneous, and isotropic material. However, the models for other material properties are mathematically complicated and are not applicable to all cases of material properties. Therefore, developing a model that can accurately analyze the behaviour of asphalt concrete pavements during the in situ shear test has proven pivotal. This paper presents the development of a three-dimensional finite element model that can simulate the forces applied while measuring the shear strength of the asphalt concrete pavement. A comparison between the model results and those obtained from available analytical models and field measurements proved the accuracy of the developed model.Key words: shear strength, in situ testing, finite element, asphalt, pavement, modelling.

Survey of State Practices to Control Skid Resistance on Hot-Mix Asphalt Concrete Pavements

1996 ◽  
Vol 1536 (1) ◽  
pp. 52-58 ◽  
Author(s):  
P. W. Jayawickrama ◽  
R. Prasanna ◽  
S. P. Senadheera
Keyword(s):  
Asphalt Concrete ◽  
Hot Mix Asphalt ◽  
Design Guidelines ◽  
State Agency ◽  
Laboratory Evaluation ◽  
Insoluble Residue ◽  
Petrographic Analysis ◽  
Skid Resistance ◽  
Concrete Pavements ◽  
Design Procedures

A nationwide survey on design methods for achieving adequate skid resistance on hot-mix asphalt concrete pavements was conducted. Information was collected on the design practices used by 48 state departments of transportation (DOTs) in the contiguous United States. Survey findings show that the emphasis placed on the skid resistance aspects in various state DOT design procedures vary considerably. Based on the data collected, 21 out of 48 state highway agencies either do not have any design guidelines specifically addressing pavement skid behavior or assume that adequate skid resistance may be ensured through proper mix design. The general approach used by these agencies involves frequent monitoring of pavements to identify pavements with skid-related problems so that appropriate action may be taken. Survey findings indicated that state DOTs that consider skid resistance in their design procedures emphasize controlling the quality of coarse aggregates used in pavement surface course construction. The procedures used for aggregate qualification, however, vary significantly from one state agency to another. Some state DOTs rely on simple aggregate classification methods based on aggregate type, whereas others perform detailed laboratory evaluation. The laboratory test procedures that are most commonly used in evaluating aggregate frictional properties are the polish value test, acid insoluble residue test, and petrographic analysis. In addition to laboratory testing, Florida, Kentucky, Pennsylvania, and Texas use alternative procedures to qualify aggregates based on their field skid performance.

Preliminary Study on X-Ray Computed Tomography to Evaluate Voids in Porous Asphalt Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 345-353 ◽  
Author(s):  
J. D. Lin ◽  
Ming Chin Yeh ◽  
Po Hsun Sung ◽  
R. H. Shiu
Keyword(s):  
Computed Tomography ◽  
Asphalt Concrete ◽  
Mix Design ◽  
Air Voids ◽  
Porous Asphalt ◽  
X Ray ◽  
X Ray Computed ◽  
Preliminary Study ◽  
Porous Asphalt Concrete ◽  
Pore Clogging

The study applies Computed Tomography technology to probe into the porous asphalt concrete and air voids content, and at the same time, try to qualify accessible voids and closed voids and to use the result to evaluate the performance of porous asphalt concrete. The nominal maximum aggregate of this study is 19.0mm. In order to adjust the image of the gray threshold, the void of PAC specimen was obtained by cut-and-try method with the mix design. After scanning through the PAC specimen, the self-innovated software is used to calculate the Va(%), accessible voids and closed voids. After careful calculation, it showed that the accessible voids are about 20.3%, and the closed voids are about 1.15%. Base on the study, it could analyze the effect of pore clogging in PAC with improved the durability and lifetime.

scholarly journals Chemical recycling of polyethylene terephthalate (waste water bottles) for improving the properties of asphalt mixture

2018 ◽  
Vol 162 ◽  
pp. 01042 ◽  
Author(s):  
Mohammed Alzuhairi ◽  
Ahmed Al-Ghaban ◽  
Shams Almutalabi
Keyword(s):  
Polyethylene Terephthalate ◽  
Asphalt Concrete ◽  
Asphalt Mixture ◽  
Mix Design ◽  
Engineering Properties ◽  
Chemical Recycling ◽  
Air Voids ◽  
Concrete Mixtures ◽  
Penetration Tests ◽  
Property Modification

One of the most prevalent of waste materials is Polyethylene Terephthalate (PET) which is used mainly to produce the drinking water bottles. In this research, the waste plastic bottles, which are normally made from PET was used to investigate the possibility of using this material as an additive in asphalt concrete mixtures. Six different proportions (w/w %) of Degradated Polyethylene Terephthalate (DPET) (2, 4, 6, 8, 10, and 12%) have been added to bitumen to prepare the specimens. The tests include Marshall Method of mix design and coating with asphalt. The results indicated that the mixture property modification increased as the content of (DPET) increases. This additive gives maximum flexibility and rigidity of the asphalt, according to ductility and penetration tests. Marshall Method gives better resistance against permanent deformations and better engineering properties in terms of stability, flow value, air voids and water absorption comparing with non-modified mixtures.

Comparison of Superpave and Marshall Mixtures for Low-Volume Roads and Shoulders

1998 ◽  
Vol 1609 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Affan Habib ◽  
Mustaque Hossain ◽  
Rajesh Kaldate ◽  
Glenn Fager
Keyword(s):  
Mix Design ◽  
River Sand ◽  
Low Volume Roads ◽  
Superpave Gyratory Compactor ◽  
Asphalt Content ◽  
Low Volume ◽  
Project Site ◽  
Axle Loads ◽  
Crushed Limestone ◽  
Asphalt Film

Superpave and Marshall mix designs using local aggregates were done to study the suitability of the Superpave mix design as compared with the Marshall mix design for low-volume roads, especially shoulders. The project site was Kansas Route 177 in northeast Kansas. Three locally available aggregates, crushed limestone and coarse and fine river sands, were used in this study. Five blends with varying proportions of coarse and fine river sands were selected. Mix samples were compacted in the Superpave gyratory compactor with the applicable number of gyrations and were compacted with the Marshall hammer by using 50 blows per face. Bulk densities of the compacted samples and maximum specific gravities of loose samples also were measured for each blend. The results show that the Superpave mix design for low-volume roads and shoulders results in lower estimated asphalt content than does the Marshall method. The required asphalt content increases as the proportion of coarse river sand increases in the mix. Superpave requirements for the voids filled with asphalt (VFA) for low-volume traffic, that is, less than 0.3 million equivalent single-axle loads, appeared to be too high. High asphalt film thicknesses were computed for the mixtures that did not meet the Superpave VFA requirements. Lowering the design number of gyrations (Ndes) for compaction of samples would result in increased asphalt requirement for the Superpave mixture with a given gradation.

Otta Seals and Gravseals as Low-Cost Surfacing Alternatives for Low-Volume Roads: Experiences in South Africa

2003 ◽  
Vol 1819 (1) ◽  
pp. 338-342 ◽  
Author(s):  
Simon Oloo ◽  
Rob Lindsay ◽  
Sam Mothilal
Keyword(s):  
South Africa ◽  
Low Cost ◽  
Cost Savings ◽  
Cost Effective ◽  
Field Trials ◽  
Low Volume Roads ◽  
Kwazulu Natal ◽  
Traffic Volumes ◽  
Low Volume ◽  
To Come

The geology of the northeastern part of the province of KwaZulu–Natal, South Africa, is predominantly alluvial with vast deposits of sands. Suitable gravel sources are hard to come by, which results in high graveling and regraveling costs brought about by long haul distances and accelerated gravel loss. Most gravel roads carry fewer than 500 vehicles per day of which less than 10% are heavy vehicles. The high cost of regraveling has led to consideration of upgrading such roads to surfaced standard, even though traffic volumes do not justify upgrading. Traditional chip seals are expensive and cannot be economically justified on roads that carry fewer than 500 vehicles per day. The KwaZulu–Natal Department of Transport is actively involved in efforts to identify cost-effective alternative surfacing products for low-volume roads. Field trials were conducted with Otta seals and Gravseals, which have been used successfully in other countries, as low-cost surfacing products for low-volume roads. The Otta seal is formed by placing graded aggregates on a relatively thick film of soft binder that, because of traffic and rolling, works its way through the aggregates. Gravseal consists of a special semipriming rubberized binder that is covered by a graded aggregate. Both Otta seals and Gravseals provide relatively flexible bituminous surfaces suitable for low-volume roads. Cost savings are derived mainly from the broad aggregate specifications, which allow for the use of marginal materials.

Sign in / Sign up

Export Citation Format

Share Document