Anisotropic Modular Ratios as Unbound Aggregate Performance Indicators

Seyhan, Umit; Tutumluer, Erol

doi:10.1061/(asce)0899-1561(2002)14:5(409)

Cited by 37 publications

(12 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous work at Texas A&M University and the University of Illinois (9)(10)(11)(12) has shown that realistic pavement responses could be achieved only when the aggregate base layer is considered to be a nonlinear anisotropic material. The anisotropic resilient responses of the aggregate systems were measured with the Texas Transportation Institute (TTI) Rapid Triaxial Tester (RATT) following the ICAR loading protocol (9).…”

Section: Anisotropic Resilient Propertiesmentioning

confidence: 99%

Evaluation of the Impact of Fines on the Performance of Lightly Cement-Stabilized Aggregate Systems

Ashtiani

Little

Masad

2007

Transportation Research Record: Journal of the Transportation R

View full text Add to dashboard Cite

The impact of increasing fines content on the performance of unbound (unstabilized) and lightly stabilized aggregate systems was evaluated. The aggregate systems analyzed varied in amount of mineral fines, the moisture state during curing and at the time of testing, and the amount of portland cement used to stabilize the blend. The evaluation was based on measurements of anisotropic resilient properties, permanent deformation, and unconfined compressive strengths of aggregate systems. In addition, the nonlinear anisotropic resilient properties of the aggregate blends were used in a finite element program to determine critical pavement responses. Aggregate systems with higher fines content were, as expected, more sensitive to moisture than control systems with standard fines content. The increase in the fines content in the unbound systems when molding moisture was wet of optimum dramatically diminished the quality of performance. However, the aggregate systems with higher fines benefited considerably from low percentages of cement stabilizer. It was found that with the proper design of fines content, cement content, and moisture, the performance of the stabilized systems with high fines content can perform equivalent to or even better than the systems with standard fines content. This was clearly evinced by enhancing the resilient properties (increase in stiffness and decrease in anisotropy), decreasing the rate and magnitude of permanent deformation, and increasing compressive strength. The beneficial use of mineral fines will result in benefit to the aggregate industry.Approximately 75 to 80 million tons of fines smaller than the number 200 sieve (75 µm) are produced annually in the United States. These materials are not successfully marketed and therefore add to stockpiles and storage ponds. These waste fines total approximately 400 million tons in the United States (1, 2). Well-characterized aggregate layers containing higher fines content than currently permitted are an attractive means by which to use more fines and reduce stockpiles of fines. Achieving this objective would have significant economical and environmental impacts.Several researchers have studied the resilient behavior of high fine unbound systems. These studies reported a decrease in the resilient modulus caused by an increase in fines content (3-5). Gray (3) reported that in unbound aggregate bases with 25.4 mm maximum particle size, the highest strength was achieved through using a maximum of

show abstract

Section: Anisotropic Resilient Propertiesmentioning

confidence: 99%

Evaluation of the Impact of Fines on the Performance of Lightly Cement-Stabilized Aggregate Systems

Ashtiani

Little

Masad

2007

Transportation Research Record: Journal of the Transportation R

View full text Add to dashboard Cite

show abstract

“…Saeed et al found in the NCHRP Project 4-23 study that shear strength of unbound aggregates under repeated loading had the most significant influence on pavement performance (11). Seyhan and Tutumluer suggested that a limiting value of the shear stress ratio (the level of applied shear stress as a fraction of the shear strength of the material) controlled the permanent deformation behavior of aggregates and that "good" quality aggregates typically had low shear stress ratios in the range of 0.2 to 0.5 (12). = − ( )…”

Section: Background Unbound Aggregate Materialsmentioning

confidence: 99%

Mechanistic–Empirical Evaluation of Aggregate Base and Granular Subbase Quality Affecting Flexible Pavement Performance in Minnesota

Xiao

Tutumluer

Siekmeier

2011

Transportation Research Record: Journal of the Transportation R

Self Cite

View full text Add to dashboard Cite

Since high-quality aggregate materials are becoming increasingly scarce and expensive, optimizing the use of locally available materials for aggregate bases and granular subbases on the basis of cost and mechanistic properties linked to pavement performance has become an economically viable alternative. This study investigated the effect of quality of unbound aggregate material on conventional flexible pavement performance in Minnesota through a mechanistic–empirical pavement design approach. A comprehensive matrix of conventional flexible pavement layer thicknesses and mechanistic design moduli was carefully designed to conduct mechanistic analyses for the Minnesota Department of Transportation flexible pavement design program (MnPAVE) with the MnPAVE program for pavement sections in two climatic regions in Minnesota. The type and the quality classes of unbound aggregate materials, identified as high, medium, and low, were characterized with stress-dependent resilient modulus (MR) models from a statewide laboratory-tested aggregate MR database. Despite conventional wisdom to the contrary, in some cases the granular subbase material had much higher moduli than the aggregate base. The typical high, medium, and low modulus values for the aggregate base and granular subbase layers, determined from the modulus distributions predicted by the nonlinear finite element program GT-PAVE, were subsequently input during MnPAVE analyses to calculate fatigue and rutting life expectancies for the comprehensive matrix of pavement structures studied. From the results, use of locally available and somewhat marginal materials may be quite cost-effective for low-volume roads, provided that the 20-year design traffic level does not exceed 1.5 million equivalent single-axle loads. A high-quality, stiff subbase was also found to exhibit a bridging effect that better protected the subgrade and offset the detrimental effects of low base stiffness on rutting performance.

show abstract

“…Furthermore, Tutumluer and Seyhan (1999) and Seyhan and Tutumluer (2002) used a triaxial device to test aggregate samples with 150 mm diameter and 150 mm height. The vertical modulus was found to be larger than the horizontal modulus for all tested aggregates except one gravel specimen which contained 16% fines (defined as passing the No.…”

Section: Introductionmentioning

confidence: 99%