Analysis and Evaluation of the Performance of Porous Asphalt: The Spanish Experience

Abstract

The excellent qualities of pervious wearing courses which enhance road safety and comfort are well known. However, there are very few test and control methods which allow these courses to be planned and used adequately. The design of the porous asphalts used in the construction of these pervious wearing courses depends on a number of rules of thumb derived from their use, but there is no test method or procedure which might allow their properties to be characterized and optimized. In this paper, we describe the procedure and planning criteria which are used in Spain in the design of porous mixes and which were established both from the behavior of these mixes in use and from the results of tests performed in the laboratory. The procedure used is based on optimizing two fundamental characteristics of these mixes: permeability and resistance to disintegration. We have developed two testing methods which allow both properties to be assessed. Permeability is assessed in situ by means of the Laboratorió de Caminos de Santander (LCS) permeameter and resistance to disintegration is evaluated by means of the Cantabrian abrasion loss test. These two tests optimize the design of these mixes and allow the effect on their behavior of using modified binders to be evaluated. We also describe the effects that these mixes have on adhesion, texture, and noise of the wearing course surface compared with other materials used in road surfacing.

Performance of Block Correlated Coupled Cluster Method with the CASSCF Reference Function for the Prediction of Activation Barriers, Spectroscopic Constants in Diatomic Molecules, and Singlet−Triplet Gaps in Diradicals

“…The dissociation potential energy surfaces (PESs) in diatomic molecules have been extensively studied with various theoretical methods. ,,– Here we will focus on the following multibond diatomic molecules: C 2 , O 2 , CO, and N 2 . For these four molecules, the CASSCF wave function with the active space (4,6), (6,6), (6,6), and (8,6), respectively, can be used to provide qualitative descriptions.…”

Spectroscopic Constants of Single-Bond Diatomic Molecules and Singlet−Triplet Gaps of Diradicals by the Block-Correlated Coupled Cluster Theory

“…The dissociation PESs in diatomic molecules have been extensively studied with various theoretical methods. ,,,,,,– Here, we will focus on the following single-bond diatomics, including LiH, HF, HCl, Li 2 , F 2 , ClF, and Cl 2 . For these molecules, the CASSCF(2,2) reference function is sufficient for a qualitatively correct description for the whole dissociation curve.…”

“… a Refs and a. b Refs and b,c. Values are from the experimental atomization energies at 0 K, corrected by the zero-point energy calculated from the experimental spectroscopic constants. …”

Unrestricted Prescriptions for Open-Shell Singlet Diradicals: Using Economical Ab Initio and Density Functional Theory to Calculate Singlet–Triplet Gaps and Bond Dissociation Curves

“…One solution to improve the accuracy of calculating ST gaps with the PBEPBE and LSDA functionals is to use the fractional spin method. , This method uses an ensemble of closed-shell densities to give the correct open-shell singlet density. For the PBEPBE and LSDA functionals ST gaps were modeled with errors of less than 3 kcal/mol .…”