Use of Thin Asphalt Surfaces over Aggregate Base Course for Heavy-Axle Truck Loads

2008 ◽  
pp. 64-64-14
Author(s):  
EL Dukatz
Keyword(s):  
Base Course ◽  
Aggregate Base

scholarly journals Studies on the Volumetric Stability and Mechanical Properties of Cement-Fly-Ash-Stabilized Steel Slag

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 495
Author(s):  
Mingkai Zhou ◽  
Xu Cheng ◽  
Xiao Chen
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Steel Slag ◽  
Critical Issue ◽  
Expansion Behavior ◽  
Strength Tests ◽  
Road Materials ◽  
Base Course ◽  
The Stability ◽  
Aggregate Base

The stability of steel-slag road materials remains a critical issue in their utilization as an aggregate base course. In this pursuit, the present study was envisaged to investigate the effects of fly ash on the mechanical properties and expansion behavior of cement-fly-ash-stabilized steel slag. Strength tests and expansion tests of the cement-fly-ash-stabilized steel slag with varying additions of fly ash were carried out. The results indicate that the cement-fly-ash-stabilized steel slag exhibited good mechanical properties. The expansion rate and the number of bulges of the stabilized material reduced with an increase in the addition. When the addition of fly ash was 30–60%, the stabilized material was not damaged due to expansion. Furthermore, the results of X-CT, XRD and SEM-EDS show that fly ash reacted with the expansive component of the steel slag. In addition, the macro structure of the stabilized material was found to be changed by an increase in the concentration of the fly ash, in order to improve the volumetric stability. Our study shows that the cement-fly-ash-stabilized steel slag exhibits good mechanical properties and volumetric stability with reasonable additions of fly ash.

Full-Scale Evaluation of Relatively Thin Airfield Pavements

2020 ◽  
Vol 2674 (10) ◽  
pp. 658-669
Author(s):  
W. Jeremy Robinson ◽  
Jeb S. Tingle ◽  
Carlos R. Gonzalez
Keyword(s):  
Asphalt Concrete ◽  
Test Section ◽  
Concrete Surface ◽  
Full Scale ◽  
Test Items ◽  
Pavement Structures ◽  
Base Course ◽  
And Performance ◽  
Rutting Behavior ◽  
Aggregate Base

A full-scale airfield pavement test section was constructed and trafficked by the U.S. Army Engineer Research and Development Center (ERDC) to evaluate the performance of relatively thin airfield pavement structures. The test section consisted of four test items that included three asphalt pavement thicknesses and two different aggregate base courses. The test items were subjected to simulated aircraft traffic to evaluate their response and performance to realistic aircraft loads. Rutting behavior, instrumentation response, and falling weight deflectometer response were monitored at selected traffic intervals. It was found that the performance of the airfield pavement sections were most sensitive to aggregate base course properties, where a 50% reduction in base course strength resulted in a 99% reduction in allowable passes. The data suggested that when sufficient asphalt thickness is not provided, the failure mechanism shifted from subgrade failure to base course failure, particularly at higher subgrade CBR values. In addition, the number of aircraft passes sustained was less than that predicted by current Department of Defense (DOD) methods that include assumptions of a high-quality aggregate base and a minimum asphalt concrete thickness. The results of this study were used to extend existing DOD pavement design and evaluation techniques to include the evaluation of airfield pavement sections that do not meet the current criteria for aggregate base quality and minimum asphalt concrete surface thickness. These performance data were used to develop a new base failure design curve using existing stress-based design criteria.

The effect of laboratory compaction method on the resilient behaviour and fabric of aggregate base course materials

2019 ◽  
Vol 21 (7) ◽  
pp. 1955-1967
Author(s):  
Arash Bozorgi ◽  
Andrew Fried ◽  
Brina M. Montoya ◽  
Cassie Castorena
Keyword(s):  
Course Materials ◽  
Base Course ◽  
Aggregate Base ◽  
Compaction Method

Use of Shredded Rubber in Unbound Granular Flexible Pavement Layers

1996 ◽  
Vol 1547 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Richard H. Speir ◽  
Matthew W. Witczak
Keyword(s):  
Resilient Modulus ◽  
Constitutive Models ◽  
Friction Angle ◽  
Flexible Pavement ◽  
Partial Replacement ◽  
Universal Model ◽  
Rubber Blends ◽  
State Highway ◽  
Base Course ◽  
Aggregate Base

The major objective of the research was to conduct a study into the feasibility of using shredded rubber as a partial replacement for aggregate within conventional base and subbase materials in a flexible pavement system. A graded aggregate base and sand subbase meeting specifications for the Maryland State Highway Administration were used. The rubber used in the study consisted of a shredded product with 60 to 70 percent retained on a 9.5-mm (⅜-in.) sieve. This size was selected because of the relatively inexpensive cost to produce it and because of its adaptability to an aggregate blend. Modified and standard Proctor, California bearing ratio (CBR), and resilient modulus tests were conducted on the base/subbase-rubber blends with up to 15 percent rubber content by weight. The aggregate base blend resulted in significant decreases in both CBR and nonlinear resilient modulus at 15 percent rubber. These significant reductions led the authors to conclude that the use of shredded rubber in a dense-graded aggregate base course is not feasible. In contrast, the sand-subbase blends resulted in insignificant changes to the CBR, friction angle, permeability, and resilient modulus at higher rubber percentages. It was concluded that the sand-rubber sub-base exhibits little change compared with the virgin sand-subbase material. As a result the use of shredded rubber may be a technically feasible alternative in the construction process. Finally, two constitutive models were used in the resilient modulus analysis: the conventional K1, K2 model and a universal model incorporating an octahedral stress term (k1, k2, k3 model). Direct comparisons revealed greatly improved predictability and accuracy with the universal model for assessing the nonlinear behaviors of both aggregate types evaluated.

Application of steel slag in cement treated aggregate base course

2020 ◽  
Vol 269 ◽  
pp. 121733 ◽  
Author(s):  
Jinzhou Liu ◽  
Bin Yu ◽  
Qian Wang
Keyword(s):  
Steel Slag ◽  
Base Course ◽  
Aggregate Base

scholarly journals Investigation of the Effect of Recycled Asphalt Pavement Material on Permeability and Bearing Capacity in the Base Layer

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Ayşegül Güneş Seferoğlu ◽  
Mehmet Tevfik Seferoğlu ◽  
Muhammet Vefa Akpınar
Keyword(s):  
Bearing Capacity ◽  
Asphalt Pavement ◽  
Linear Increase ◽  
Base Layer ◽  
Sieve Analysis ◽  
Recycled Asphalt Pavement ◽  
Recycled Asphalt ◽  
Suitable Material ◽  
Base Course ◽  
Aggregate Base

The purpose of this research was to investigate the effects of recycled asphalt pavement (RAP) and cement content on the permeability and bearing capacity characteristics of aggregate base courses. Mixtures containing untreated RAP ranging between 0 and 100 percent and 1, 2, and 3% cement-treated RAP were subjected to laboratory tests (bitumen content, sieve analysis, modified proctor, soaked California bearing ratio (CBR), and constant-level permeability tests). The results showed that, as the RAP percentage in the mixture increased, CBR values decreased considerably. Moreover, there is a linear increase in the CBR values with cement treatment. Optimum moisture contents (OMC) and maximum dry densities (MDD) showed a decreasing trend. Increasing the cement percentages in 100% RAP blend increases the OMC and MDD values. The permeability of RAP showed a decrease as the percentage of RAP and cement increased in blends. The study showed that the CBR value of the 20% RAP blend is also obtained in the 100% RAP/3% cement-treated blend. Thus, it has been understood that cement is a suitable material in order to increase the use of RAP. In addition, the increase in the percentage of RAP and cement made the base course more impermeable.

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