Active fillers’ effect on in situ performances of foam bitumen recycled mixtures

Cold recycling is one of the most employed rehabilitation techniques for asphalt pavements and it is becoming more and more important as reducing emissions becomes a priority in the reduction of the greenhouse effect. The main advantages of asphalt cold recycling techniques are the use of reclaimed materials and the fact that there is no need of aggregate heating to make the mixtures. This paper describes the evolution with time of in-situ performances of different foam bitumen-stabilised mixtures made with different active fillers (cement and lime), monitored during the first year from construction. Results are part of a more extensive research programme aimed to investigate the effects of using lime as an active filler in cold-recycled mixtures. Mixtures have been laid down on a specifically designed trial section in Italy, close to Florence. Short-term bearing capacity, immediately after construction, has been evaluated using a light weight deflectometer while to evaluate the mid-term performances falling weight deflectometer (FWD) tests have been performed after 24 hours, 14 days, 28 days and 9 months from construction. During these 9 months the test road was not opened to traffic, so the mixtures experienced almost no traffic (only construction traffic loads). This fact allowed to have the curing process without any influences other than the temperature: it means same curing conditions for all mixtures. Subsequent FWD tests are still ongoing to evaluate the evolution over time of pavement bearing capacity due to traffic. Results obtained positively support the use of lime as an active filler in the foam bitumen-stabilised material and allow to underline the effect of different active fillers in the material behaviour, even if all the mixtures underline excellent performances under traffic loading. FWD tests are scheduled to be repeated every 6 months in order to monitor the stiffness evolution of the mixtures and evaluate the nature of traffic damage

A laboratory study on cold-mix, cold-lay emulsion mixtures

This paper describes laboratory experiments and presents results for the performances of cold-mix, cold-lay emulsion mixtures. The main objective of the experiments was to evaluate and improve the properties of the cold mixtures. The mixture properties evaluated were: volumetric properties, indirect tensile stiffness modulus (ITSM), repeated load axial creep and fatigue. These properties were compared with conventional hot asphalt mixtures not containing any waste/recycled materials. To optimise the performances of the mixtures, a target of ITSM value of 2000 MPa was selected. At full curing conditions, the stiffness of the cold mixes was found to be very similar to that of hot mixtures of the same penetration grade base bitumen (100 pen). Test results also show that the addition of 1–2% cement significantly improved the mechanical performance of the mixes and significantly accelerated their strength gain. The fatigue behaviour of the cold mixes that incorporated cement was comparable with that of the hot mixtures

New developments with cold asphalt concrete binder course mixtures containing binary blended cementitious filler (BBCF)

A weakness in early strength and the need for longer curing times in the case of cold bituminous emulsion mixtures (CBEMs) compared to hot mix asphalt have been cited as barriers to the wider utilization of these mixtures. A binary blended filler material produced from high calcium fly ash (HCFA) and a fluid catalytic cracking catalyst (FC3R) was found to be very effective in providing microstructural integrity with a novel fast-curing cold asphalt concrete for the binder course (CACB) mixture. Balanced oxide compositions within the novel filler were identified as responsible for an enhanced hydration reaction, resulting in a very high early strength and a significant improvement in permanent deformation and fatigue resistance. Improved water sensitivity for progressive hydration with the new binary filler was also established while SEM analysis confirmed the formation of hydration products after various curing ages. © 2016 Elsevier Lt

Main flexible pavement and mix design methods in Europe and challenges for the development of an european method

Pavement and mix design represent one of the key components within the life cycle of a road infrastructure, with links to political, economic, technical, societal and environmental issues. Recent researches related to the characteristics of materials and associated behavior models both for materials and pavement, made it appropriate to consider updating current pavement design methods, and especially in the USA this has already been in process while in Europe uses of the methods developed in the early 1970s. Thus, this paper firstly presents a brief historical overview of pavement design methods, highlighting early limitations of old empirical methods. Afterwards, French, UK and Shell methods currently in use in Europe will be presented, underlining their main components in terms of methodology, traffic, climatic conditions and subgrade. The asphalt mix design and modeling in Europe are presented with their inclusion in the pavement design methods. Finally, the main challenges for the development of a European pavement design method are presented as well as the recent research developments that can be used for that methodThe second author would like to express the support of Portuguese National Funding Agency for Science, Research and Technology (FCT) through scholarship SFRH/BSAB/114415/ 2016. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.info:eu-repo/semantics/publishedVersio

SUPERPAVE Asphalt Mixture Design Illustrated Level 1 Lab Method S

DTFH61-92-C-00098This manual provides sequential, illustrated steps for performing the SUPERPAVE test procedures on asphalt mixtures, level 1 design. It also serves as a self-contained laboratory reference document on those procedures. These tests and procedures represent the results of the SHRP 5 -year research effort to investigate and improve asphalt mix design technology. This manual was developed under the FHWA's National Asphalt Training Center

Probability of fire spread between vehicles in car parking buildings

Over recent years, performance-based design approach has gained acceptance in the engineering community around the world. This has prompted an expanded demand in engineering approaches to the assessment of fire safety in structures. Two arising questions in designing car parking buildings are (1) if there had been another vehicle parked next to or a space away from the van would the fire have spread given no interruption by firefighters and/or fire suppression systems? (2) If so, what is the probability that the spread occurs? This work quantitatively assesses these questions using recent research into the risk-based design of car parking buildings. The probability of fire spread is formulated using the knowledge of the possible rate of heat release outputs from single passenger vehicles coupled with a prediction of time to ignition. There are two scenarios considered for the assessment, either where the vehicles are parked next to each other or where the vehicles are parked one space apart. The analysis shows that the probability of fire spreading to a vehicle in an adjacent space 0.63–0.90 while when there is a space in between, the highest probability of fire spread is 0.23 but spread may not occur at all

Highly Modified Asphalt Florida Case Study

693JJ319D000016 Task Order 693JJ321F000082Highly modified asphalt (HiMA) is an asphalt mixture containing asphalt binder that is typically modified with 7 to 8 percent polymer. Styrene-butadiene-styrene is most commonly used and is more than twice what is typically used in conventional polymer-modified binders. By increasing the polymer content, the structure changes to a swollen polymer with a dispersed asphalt phase, making the resulting binder behave more like rubber. HiMA is used for a range of applications, including full-depth to thin asphalt overlays under different traffic conditions. The Florida Department of Transportation (FDOT) has increasingly used HiMA to address severe rutting, fatigue, reflective cracking, and raveling. This report is a case study of FDOT\u2019s experience and includes background, specifications, implementation, design, planning, construction, and performance

New laboratory procedure using a modal approach to obtain vibration attenuation properties of unaged and aged asphalt mixtures

[EN] During asphalt mixture service life, its structural and physical capabilities deteriorate progressively. A modal analysis using impact hammer excitation technique is put forward to measure the damping factor instead of the commonly destructive test described in the standards. Concerning to this modal approach, an aging procedure is presented to obtain and compare the vibration attenuation capacity variation of the mixtures considering aging deterioration. In this research, this new procedure has been applied to asphalt concrete and stone mastic asphalt mixtures with different amounts of polyethylene terephthalete. It has been validated using results from four-point bending test. Finally, the results confirmed that asphalt mixtures with 0 2% of polyethylene terephthalete present better vibration attenuation capacity than mixtures without it, even when aging appeared.Real Herraiz, TP.; Montalbán Domingo, ML.; Masanet Sendra, C.; Real Herráiz, JI. (2016). New laboratory procedure using a modal approach to obtain vibration attenuation properties of unaged and aged asphalt mixtures. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications. 230(2):627-639. doi:10.1177/1464420715584095S627639230

In-Service Performance of Airport Flexible Pavements Constructed Following State Specifications for Highway Pavement Materials

692M15-19-T-00026The Federal Aviation Administration (FAA) Reauthorization Act of 2018, Section 136 requires the FAA to allow the use of state highway specifications for airfield pavement construction at non-primary airports serving aircraft with a gross weight less than 60,000 lb if requested by the state. To confirm that state highway specifications provide an acceptable level of performance when used on airport pavements, the FAA initiated this project to compare the performance of airports constructed using state highway specifications with those constructed using FAA specifications. Performance data and specifications from 40 airport projects in five states were analyzed, with 21 using FAA specifications and 19 using state highway specifications. Based on the summarized pavement condition index (PCI) ratings from those projects (which are based on visual condition surveys and do not consider structural or functional performance), it was determined that the performance of airport asphalt pavements constructed using state highway specifications is statistically equivalent to asphalt pavements constructed using FAA specifications. The evaluations encompassed performance periods ranging from 1 to 15 years. Performance trends for the statistical analysis conducted showed an approximate PCI rating of 60 at year 14 for pavements constructed with both types of specifications. It was also determined that climate-based distresses were the predominant mode of distress for both FAA and state highway specification projects, with longitudinal and transverse cracking and weathering as the most prevalent types of distresses. The number of distresses that were load related was relatively minor, as only 8 of the 40 projects evaluated had load-related distresses. Of those projects, five used state highway specifications, and three used FAA specifications

Validation of Loose Mix Aging Procedures for Cracking Resistance Evaluation in Balanced Mix Design

(c) 1036333This project aimed to validate loose mix aging procedures for cracking resistance evaluation of asphalt mixtures in balanced mix design (BMD) with a broad range of field projects covering various mixture components, pavement ages, and climatic conditions. To that end, a two-phase research approach was followed, with Phase I focusing on a literature review, research gap analysis, and development of Phase II work plan. The literature review topics included development and preliminary field validation of existing loose mix aging procedures; the impact of loose mix aging on asphalt binder and mixture properties; and effects of silo storage, mix hauling, mix reheating, specimen storage, and asphalt weathering on asphalt binder and mixture properties