David Hernando

Bio: David Hernando is an academic researcher from University of Antwerp. The author has contributed to research in topics: Asphalt & Dynamic shear rheometer. The author has an hindex of 7, co-authored 29 publications receiving 199 citations. Previous affiliations of David Hernando include Technical University of Madrid & Florida Department of Transportation.

Estimating the rainfall erosivity factor from monthly precipitation data in the Madrid Region (Spain)

Abstract: The need for continuous recording rain gauges makes it difficult to determine the rainfall erosivity factor (Rfactor) of the Universal Soil Loss Equation in regions without good spatial and temporal data coverage. In particular, the R-factor is only known at 16 rain gauge stations in the Madrid Region (Spain). The objectives of this study were to identify a readily available estimate of the R-factor for the Madrid Region and to evaluate the effect of rainfall record length on estimate precision and accuracy. Five estimators based on monthly precipitation were considered: total annual rainfall (P), Fournier index (F), modified Fournier index (MFI), precipitation concentration index (PCI) and a regression equation provided by the Spanish Nature Conservation Institute (RICONA). Regression results from 8 calibration stations showed that MFI was the best estimator in terms of coefficient of determination and root mean squared error, closely followed by P. Analysis of the effect of record length indicated that little improvement was obtained for MFI and P over 5-year intervals. Finally, validation in 8 additional stations supported that the equation R = 1.05·MFI computed for a record length of 5 years provided a simple, precise and accurate estimate of the R-factor in the Madrid Region.

Cracking performance characterisation of asphalt mixtures containing reclaimed asphalt pavement with hybrid binder

Abstract: This study investigated the effect of reclaimed asphalt pavement (RAP) on the rheological properties of a hybrid binder and the fracture properties and cracking performance of resultant mixtures. F...

Performance evaluation of alternative polymer-modified asphalt binders

Abstract: Styrene–butadiene–styrene (SBS) polymer-modified asphalt (PMA) binder is widely known to provide superior performance, particularly in terms of cracking, as compared to unmodified asphalt binder. In recent years, alternative PMA binders have been developed to meet PG 76-22 specifications and requirements from the multiple stress creep recovery (MSCR) test. However, existing tests/requirements may not be sufficient to ensure the quality of alternative PMA binders. This study evaluated seven types of alternative PMA binders using different tests, including existing Superpave PG binder tests, the MSCR test, and a newly developed binder fracture energy (BFE) test. Results showed that four alternative PMA binders can potentially have equivalent performance to SBS binder. Three deficient binders were identified in both the MCSR and the BFE tests. Superpave PG binder tests, however, distinguished only one as deficient. Compared to the MSCR test, which provides a qualitative assessment (pass/fail criterion), the ...

Guidelines for the design of semi-rigid long-life pavements

Abstract: Pavement distress leads to frequent rehabilitation that increases the global cost of pavement sections. A clear understanding of distress mechanisms is the cornerstone for extending pavement service life. The overall objective of this study was to provide guidance for the design of semi-rigid long-life pavements. The potential distress mechanisms in semi-rigid pavements were revisited in order to synthesize the primary factors affecting performance. One key observation from the literature was that, while thickness primarily controls fatigue cracking, material requirements are the primary factor governing other distress mechanisms. Semi-rigid sections proposed for the heaviest traffic conditions in Spain were analytically evaluated from the long-life perspective. Results showed that only some sections met the structural requirements to be considered long-life pavements; however, two of them were clearly overdesigned. In addition, thick asphalt lifts are used to delay the onset of reflective cracking, which is not a cost-effective approach. Findings from linear elastic analysis of alternative sections and observations on potential distress mechanisms led to establishment of guidelines for a more efficient design of semi-rigid long-life pavements. The established design concept integrated both layer thickness and material requirements.

Influence of Six Rejuvenators on the Performance Properties of Reclaimed Asphalt Pavement (RAP) Binder and 100% Recycled Asphalt Mixtures

Abstract: 100% recycled hot mix asphalt lab samples were modified with five generic and one proprietary rejuvenators at 12% dose and tested for binder and mixture properties. Waste Vegetable Oil, Waste Vegetable Grease, Organic Oil, Distilled Tall Oil, and Aromatic Extract reduced the Superpave performance grade (PG) from 94–12 of extracted binder to PG 64-22 while waste engine oil required higher dose. All products ensured excellent rutting resistance while providing longer fatigue life when compared to virgin mixtures and most lowered critical cracking temperature. Rejuvenated samples required more compaction energy compared to virgin and some oils reduced moisture resistance slightly.