Ignacio Pérez

Measures of Effectiveness for Level-of-Service Assessment of Two-Lane Roads: An Alternative Proposal Using a Threshold Speed

This paper presents an alternative way of using average travel speed and percentage of traffic in platoons [the two measures of effectiveness currently in Highway Capacity Manual (HCM) methodology] to evaluate level of service. The definition of a threshold speed that is acceptable to users is implied. Travelers expect different things of different roads, and in the case of two-lane highways the desire to pass and the stress or mild frustration of being delayed are not a function only of headway or of the difference between actual and desired travel speed. Therefore, simplistic approaches do not accurately reflect the point of view of the roadway user. The procedure can be adapted to various two-lane highway types. It could be used for Types I and II already in HCM procedure and for other types that may be considered in the future.

The Effect of Hydrated Lime on the Bond Between Asphalt and Recycled Concrete Aggregates

In this investigation, rolling bottle tests and boiling water tests were performed to evaluate the effect of hydrated lime on the adhesion between recycled concrete aggregates (RCA) and the asphalt binder. RCA from construction and demolition waste (C&DW) were used in this investigation. To generalize the findings, three asphalt penetration grades were analyzed: B40/50, B60/70, and B150/200. The results indicate that the use of hydrated lime does not improve the RCA-aggregate bond. Additionally, the results indicate that a higher asphalt-aggregate adhesion correlates to a lower asphalt penetration grade.

Adhesion of Recycled Concrete Aggregates, Demolition Debris, and Asphalt

In this investigation, rolling bottle tests and boiling water tests were conducted to evaluate the effect of different fillers and treatments on the adhesion between recycled concrete aggregates (RCA) and asphalt. The test results when 100% RCA loose mixtures were evaluated indicated that the filler that achieves the best asphalt aggregate bond was grey Portland cement. Curing the mixture in an oven for 4 h at mix temperature before compacting and coating RCA with bitumen emulsion are treatments that achieved satisfactory adhesion results as well.

Recycled aggregates (RAs) for asphalt materials

In this chapter, we gather the results of the most innovative studies about recycled aggregates (RA) from construction and demolition waste (CDW), in an attempt to better understand the physical and mechanical performance of these materials, which are more economical, sustainable and environmentally friendlier, as an integral part of bituminous mixtures.

An algorithm for the estimation of road traffic space mean speeds from double loop detector data

Most algorithms trying to analyze or forecast road traffic rely on many inputs, but in practice, calculations are usually limited by the available data and measurement equipment. Generally, some of these inputs are substituted by raw or even inappropriate estimations, which in some cases come into conflict with the fundamentals of traffic flow theory. This paper refers to one common example of these bad practices. Many traffic management centres depend on the data provided by double loop detectors, which supply, among others, vehicle speeds. The common data treatment is to compute the arithmetic mean of these speeds over different aggregation periods (i.e. the time mean speeds). Time mean speed is not consistent with Edie’s generalized definitions of traffic variables, and therefore it is not the average speed which relates flow to density. This means that current practice begins with an error that can have negative effects in later studies and applications. The algorithm introduced in this paper enables easily the estimation of space mean speeds from the data provided by the loops. It is based on two key hypotheses: stationarity of traffic and log-normal distribution of the individual speeds in each time interval of aggregation. It could also be used in case of transient traffic as a part of any data fusion methodology. DOI: http://dx.doi.org/10.4995/CIT2016.2016.3208

Characterization of Hot-Mix Asphalt Made with Recycled Concrete Aggregates that Have Been Cured for 4 Hours in the Oven

In this research a laboratory characterization of hot-mix asphalt (HMA) made with recycled concrete aggregates (RCA) from construction and demolition waste (CDW) as base layer in road construction has been conducted. HMA containing 5%, 10%, 20% and 30% of RCA in place of virgin aggregate were evaluated. To improve water resistance of the mixtures, they were left in an oven for 4 hours at mixing temperature before compaction to allow the bitumen absorption and, in addition, obstructing the mortar pores, strengthening the attached mortar onto the RCA surface and thus, preventing water pathways. The tested mixtures complied with Spanish water resistance requirement and also showed a water resistance performance much higher than that of the mixtures that were not cured in the oven. Stiffness and resistance to permanent deformation were also studied showing satisfactory results.

Construction and Demolition Debris in Hot Mix Asphalt

This work evaluates the resistance to fatigue cracking of hot asphalt mixtures made with aggregates from construction and demolition debris. The mixtures were fabricated with 50% recycled aggregates to be used as road bases and binder courses in roads with low traffic volumes. For each mixture studied the fatigue law constants in deformation were obtained as well as the dynamic modulus. These results were compared to those obtained in hot asphalt mixtures elaborated with only virgin aggregates from quarries.