Strength and Behavior of Materials for Low-Volume Roads as Affected by Moisture and Density

Author(s):  
P. Paige-Green

The relationships among strength, moisture, and density in pavement subgrades and layerworks are well known, but they have particular significance in low-volume roads. In these roads, the specified density is frequently not achieved (quality assurance testing tends to be reduced), and moisture fluctuations are more severe with greater consequences. Traditional studies of the material strength for these roads in southern Africa are based almost entirely on the California bearing ratio (CBR), a test with inherent problems. The test is routinely carried out to identify whether the materials under consideration have the required soaked strengths (typically CBRs of 80% or 45% for bases of different standards) at the design compaction density. Studies of the CBR at different moisture contents and densities should be carried out to identify the implications of variations in these properties on the behavior of pavement materials. A simple technique to be carried out during conventional laboratory testing was developed. Aspects pertaining to this type of study were evaluated, and the findings were related to low-volume road behavior.

2020 ◽  
Vol 12 (15) ◽  
pp. 6101
Author(s):  
Andrew Otto ◽  
John Rolt ◽  
Kenneth Mukura

Under the Research for Community Access Partnership (ReCAP) funded by the United Kingdom Aid (UKaid) program, a project entitled ‘Development of Specifications for Low Volume Sealed Roads through Back Analysis’ was carried out. Previous studies on the performance of low volume sealed roads have emphasized the importance of good drainage to ensure good performance. The emphasis has been on providing sealed shoulders, adequate crown height, and adequate camber. These studies have not related these cross-sectional features with materials characteristics. This paper investigates the influence of each of these features on the performance of low volume sealed roads and their relation to pavement materials. The features were considered each one at time, using a matrix of three levels of the value of each feature and three levels of performance categories. Thus, presenting a 3 × 3 performance matrix for each factor. Assessment of the matrices showed that provision of sealed shoulders permits the use of materials of higher plasticity (PI ≤ 16 and PM ≤ 560) without compromising performance compared to that permissible for sections with unsealed shoulders (PI ≤ 10 and PM ≤ 240). These results can be used to supplement existing selection criteria for road base material of low volume roads.


1998 ◽  
Vol 1624 (1) ◽  
pp. 148-159 ◽  
Author(s):  
B. M. Phares ◽  
T. J. Wipf ◽  
F. W. Klaiber

In Iowa there are over 20,000 bridges on the secondary road system. The majority of these bridges are under the jurisdiction of county engineers with limited budgets; therefore many county engineers design and construct their own short-span bridges with their own labor force. The objective of this research is to perform laboratory testing on a bridge alternative that counties can design and construct. This concept involves the fabrication of precast units composed of two steel beams connected by a thin concrete deck. The concrete deck thickness is limited so that the units can be fabricated at one location and then transported to the bridge site. The number of units required is obviously a function of the width of bridge desired. After the precast units have been connected, an additional concrete deck is placed. The concrete surface of the units is scarified so that the two layers of concrete are bonded together, thus providing the required deck thickness. Since this bridge replacement system is primarily intended for use on low-volume roads, the precast units could be constructed with new or used steel beams. The laboratory testing program consisted of a series of small-scale tests on different types of precast deck connections, “handling strength” tests of the precast units, a series of tests on the model bridge with only the precast portion of the deck in place, and a series of tests on the fully constructed model bridge. For the bridge model tested [ L = 9750 mm (32 ft), W = 6400 mm (21 ft)], five precast connectors gave the desired lateral load distribution; the addition of the cast-in-place deck significantly improved the load distribution characteristics of the bridge system. The units developed and tested result in a simple-span bridge for low-volume roads that is relatively easy to construct.


2016 ◽  
Vol 47 (2) ◽  
pp. 118
Author(s):  
Eutiquio Gallego ◽  
Manuel Moya ◽  
Esperanza Ayuga-Téllez ◽  
Ana I. García ◽  
Francisco Ayuga

This paper describes the entire process of the implementation of the Spanish low volume road network, including the design criteria, the construction techniques and the management policies during all the periods. The current situation of low volume roads in Spain was analyzed with respect to the legal framework and their actual condition. In addition, the budget required for the repair of 41 low volume roads throughout Spain was calculated in order to statistically analyze the influence of the pavement materials and the period of construction. The main conclusions were that low volume roads constructed during the 1970´s are currently those in the best state of repair and those requiring the lower repair costs, even lower than those constructed after 1980´s. In addition, low volume roads constructed with higher quality materials and using standardized techniques required five times lower repair costs than those made of lower quality materials.


2003 ◽  
Vol 1819 (1) ◽  
pp. 343-352 ◽  
Author(s):  
J. A. Grobler ◽  
A. Taute ◽  
I. Joubert

A pavement evaluation and rehabilitation design methodology is currently employed in southern Africa on relatively light pavement structures used for low-volume roads. The pavements normally consist of natural gravel materials in most layers and thin bituminous surfacings. When nearing the end of their design lives, they exhibit distresses ranging from minor deformation through aging of the surface to structural cracking and potholes. Rehabilitation options normally involve light stone seals or other inexpensive and cost-effective treatments. The phases of investigation for pavement evaluation and rehabilitation designs start with desk study to establish the history of the road and its past performance from pavement management system outputs. Detailed visual evaluations are then conducted of road features and extent of various forms of distress. These data are presented followed by a decision-making process to select areas for more detailed testing. All the information is used to determine the causes of distress and likely rehabilitation alternatives. Further destructive and nondestructive testing is carried out to predict performance of rehabilitation designs and equivalent annual cost comparisons. Rehabilitation design is also done with use of the dynamic cone penetrometer. Decision criteria are set for use of tests undertaken in the assessments, and test results are evaluated. This procedure normally results in a wide range of rehabilitation options, from application of a diluted emulsion as a surface rejuvenator to more extensive patching and resealing to major rehabilitation and overlays. This process effectively produces cost-effective solutions that maximize limited budgets. It is essential that the road authority be prepared to share the risks of the low-cost options with the designer. In this way benefits of low-cost solutions are realized, whereas, in a limited number of instances, premature distress may have to be repaired under routine maintenance.


Author(s):  
Suraj Pinate ◽  
Hitesh Sonawane ◽  
Jayesh Barhate ◽  
Mayur Chaudhari ◽  
Utkarsha Dhok ◽  
...  

Author(s):  
Affan Habib ◽  
Mustaque Hossain ◽  
Rajesh Kaldate ◽  
Glenn Fager

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.


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