Specification Development for Cold In-Situ Recycling of Asphalt

In-situ cold recycling provides a valuable means to reduce the environmental impact of road construction. The reduced energy requirements relative to traditional hot mix recycling can lead to significant reductions in cost and associated CO2 emissions. Worldwide, in-situ cold recycling has been found to be particularly useful in the rehabilitation of rural roads where site locations are far from asphalt plants. However, practical issues remain due to the evolving nature of cold bituminous materials. Unlike hot-mix asphalts which gain strength quickly as they cool, cold-mix bituminous materials gain strength slowly over time. This is particularly an issue in countries with cooler, wetter climates, such as Ireland. Consequently the specification of cold materials poses a number of challenges relating to curing and testing protocols. This paper reports on the development of a specification for cold recycled materials and the application to a case study in Ireland. This work was conducted as part of the CEDR funded project CoRePaSol which focused on the development of harmonised design procedures for cold recycled mixes. In collaboration with the Irish National Roads Authority a 2.5km site on a national road was identified for a recycling trial. The existing guidance for Low Energy Pavements was used to classify the road with respect to traffic levels and a testing programme was implemented which sought to reflect best practice across Europe. A series of recycling options were assessed and four different mix designs were proposed. These included variation in the binder type (foam mix or emulsion, with or without cement), binder content and recycling depth, reflecting the wide array of options available to engineers seeking to promote cold recycling. Due to the lack of harmonised guidelines across the Europe on design and evaluation of cold mixtures a specific focus is given in this paper to the mix evaluation procedure where alternative laboratory test specimen curing and testing procedures are investigated and recommendations are given. Key words: Cold asphalt mix recycling, Emulsion cold mix, Foam cold mix, in-situ recyclin

Supporting the delivery of Information Management and BIM in Ireland: Learnings from Selected International Regions

The Executive Summary introduction the report recommendations for Build Digital with respect to information management and the use of BIM as a critical vehicle of innovation to unlock improved project outcomes in construction

Experimental axial-compressive behaviour of bare cold-formed-steel studs with semirigid-track and ideal-hinged boundary-conditions

Studs are the primary load-bearing components in cold-formed steel (CFS) wall panels, connected to tracks at both ends with self-tapping screws, forming a semirigid boundary condition (BCT). Most existing tests on the axial compressive behaviour of bare CFS studs are based on either theoretically-hinged (BCH) or fully-fixed boundary conditions. Previous researchers have employed BCT only on sheathed stud-wall panels. However, practicing engineers and current design codes, e.g., Eurocode 3, follow an all-steel design. Therefore, this research experimentally investigated bare-CFS-studs' axial compressive behaviour with BCT, considering, for the first time, the combined effect of the tracks' warping rigidity, stud-to-track gap, non-linear connection stiffness, and bare studs' various cross-sectional slenderness. Forty-two industry-standard lipped channel sections (studs) of five thicknesses (1.2-3 mm), three depths (75–125 mm), and two heights (1.2 & 1.5 m) were tested under static-concentric axial compressive loading with BCT. Another fourteen studs were tested with BCH, a comparator to BCT. Results demonstrated that the studs' global failure mechanisms were flexural-torsional in BCT instead of flexural in BCH. Studs' axial stiffness was two-phased in BCT due to the stud-to-track gap, compared to single-phased stiffness in BCH. >1.8 mm stud-to-track gap caused stud-to-track connections' failure and studs' sudden capacity reduction during gap closure. Studs achieved 1.22 times higher axial-compressive strength, 2.3 times more axial-shortening, 0.7 times lower axial stiffness, and 58% lower axial-compressive strain at the web-midheight under BCT-PhaseII than BCH. Tested strengths were compared with EC3 design strength, and an effective-length-factor of 0.65 was suggested for efficient design of studs with BCT

Replicating natural topography on marine artificial structures:A novel approach to eco-engineering

Ocean sprawl is a growing threat to marine and coastal ecosystems globally, with wide-ranging consequences for natural habitats and species. Artificial structures built in the marine environment often support less diverse communities than natural rocky marine habitats because of low topographic complexity. Some structures can be eco-engineered to increase their complexity and promote biodiversity. Tried-and-tested eco-engineering approaches include building-in habitat designs to mimic features of natural reef topography that are important for biodiversity. Most designs mimic discrete microhabitat features like crevices or holes and are geometrically-simplified. Here we propose that directly replicating the full fingerprint of natural reef topography in habitat designs makes a novel addition to the growing toolkit of eco-engineering options. We developed a five-step process for designing natural topography-based eco-engineering interventions for marine artificial structures. Given that topography is highly spatially variable in rocky reef habitats, our targeted approach seeks to identify and replicate the ‘best’ types of reef topography to satisfy specific eco-engineering objectives. We demonstrate and evaluate the process by designing three natural topography-based habitat units for intertidal structures, each targeting one of three hypothetical eco-engineering objectives. The process described can be adapted and applied according to user-specific priorities. Expanding the toolkit for eco-engineering marine structures is crucial to enable ecologically-informed designs that maximise biodiversity benefits from burgeoning ocean sprawl

Effective use of corrosion inhibitors in highway structures

Paper presented at the IABSE Symposium 'Improving Infrastructure Worldwide- brining people closer', Weimar, Germany, September 19-21, 2007The corrosion of European concrete highway structures leads to traffic disruption, significant expenditure on remedial works and ultimately threatens to impact on European competitiveness. A potentially more efficient component in maintenance strategies is the use of surface applied corrosion inhibitors, which may delay the onset of corrosion or retard the corrosion rate of steel in concrete. This paper presents a proposed framework of guidelines for the effective use of corrosion inhibitors based on a study conducted as part of the EU Fifth Framework SAMARIS project. The proposed guidelines call for an initial desk study to assess the potential use of inhibitor and an assessment of risk control to the specifiers satisfaction. If necessary (for risk assessment and control) a preview trial is recommended, based on defined performance criteria from which a proposed rehabilitation strategy is finalised and again considered against the risk assessment. If resources permit, performance monitoring post repair is recommended as part of a pro-active maintenance strategy, since such an approach may represent one of the most effective uses of corrosion inhibitors in service life management.European Research CouncilSAMARIS projectConference website no longer available. Link to organisers at http://www.iabse.org/ and programme at http://www.iabse.ethz.ch/conferences/weimar2007/pdf/iabse_final_programme_print.pdf. Link to published proceedings - . DG 06/07/10 ke - TS 20.07.1

The performance of Irish aggregates in the 'ultra-accelerated test' for alkali-aggregate reactivity with particular reference to chert content

Presented at the 5th Canmet/ACI International Conference on Durability of Concrete, Barcelona, Spain, June, 2000Irish aggregates have a satisfactory history of service regarding alkali-aggregate reaction despite containing significant amounts of chert and use for a period in conjunction with cements of high alkali level. An investigation was conducted of the performance in the draft RILEM ‘ultra-accelerated mortar-bar test’ of 23 individual aggregates and 14 combinations found in Irish practice. An X-ray diffraction study was also carried out. Definitive expansion limits have yet to be finalised but a value of 0.15% after 14 days immersion has been suggested as the innocuous/deleterious threshold and 0.25% expansion is suggested as the lower limit for reactive aggregates. Despite their satisfactory history of use, almost half of the aggregates tested individually and one third of the combinations exceeded the innocuous/deleterious threshold value. However, the lower limit for reactive aggregates was reached by only four individual aggregates and by one of the combinations. The X-ray diffraction study revealed the presence of well-crystallised quartz, confirming the likelihood that the aggregates would not be reactive. The highest expansions were recorded in samples from argillaceous limestones and those containing small amounts of greywacke and chalcedonic chert. As expected, there was no correlation between chert content and degree of expansion. It is concluded that most Irish cherts are unreactive; that the draft mortar-bar test returns pessimistic results and is therefore a suitable screening test but could not be used universally for definitive assessment unless national expansion limits could be agreed in the place of use; and that X-ray diffractometry may be used in conjunction with the rapid screening test to assist early judgement on likely reactivity.Not applicableIrish-American Scholars ProgrammeIrish CementThe proceedings of this conference were published but "In addition to the papers that have been published in the refereed proceedings, more than 30 papers were presented at the conference". This paper was one of those that were unpublished. Link to proceedings - http://www.concrete.org/PUBS/JOURNALS/AbstractDetails.asp?srchtype=ALL&keywords=SP-192&ID=14232. DG 06/07/10. Check forms of authors names - ti sp ke 100729 RB

Examination of a novel wavelet based approach for bender element testing

Presented at the 4th Symposium on Bridge & Infrastructure Research in Ireland, 4-5 December 2008, Galway, IrelandAccurate determination of shear wave arrival time using bender elements may be severely affected by a combination of near field effects and reflected waves. In most cases, the nearfield effect masks the first arrival and it makes its detection difficult in the time domain. Nevertheless the arrival of a shear wave creates a detectable singular point. This paper tests a recent approach for the assessment of shear wave arrival time by analysing the output signal in the time-scale domain using a multi-scale wavelet transform. Indeed, one can follow the local maxima lines of the wavelet transform modulus across scales, to detect the location of all singularities leading to detection of the first arrival.Not applicableConference website n/a. Organisers website at http://www.bcri.ie/site/view/33/. DG 06/07/10. ti ab ke - 100721 RB

Performance of high alkali slag concretes in the context of alkali-silica reaction

Presented at the International Conference on the Performance of Construction Materials in the New Millennium (ICPCM), Cairo, Egypt, February 18-20, 2003The depletion of natural resources, the requirement for sustainable development and environmental restrictions, such as those associated with the Kyoto Agreement, makes the re-use of waste materials increasingly important as we enter the new millennium. The use of one such material in concrete, ground granulated blast furnace slag is well-accepted in many parts of the world. However much research and experience of use is based on slags with low alkali levels and low chloride contents. Environmental and economic constraints may force the increased use of slags with higher alkali levels and chloride contents in future works. The alkali level parameter raises concern in respect of alkali-silica reaction (ASR) where susceptible aggregates are used. The performance of high alkali slags in the context of ASR was assessed by a modified version of the concrete prism expansion test, X-Ray diffraction and scanning electron microscopy. Variables in the test programme were binder combination, slag alkali level, aggregate combination, and storage temperature. Previous research by the authors had identified Irish argillaceous limestone aggregate as potentially classifiable as ASR-vulnerable, despite a low silica content and a satisfactory service record. The performance, in the context of ASR, of argillaceous limestone slag concretes was specifically studied. The study found that inclusion of slag in concrete can be beneficial in inhibiting ASR irrespective of the alkali content of the slag. The particular case of argillaceous limestone slag concrete is commented on.Other funderIrish CementUnpublished - conference proceedings only available to the conference participants. Details of conference available at http://www.springerlink.com/content/2206g24892121860/. DG 06/07/10. Changed forms of authors names (please check) au ti ke 100729 RB

Fatigue resistance of bituminous layers incorporating reclaimed asphalt pavement

5th International Conference on Research & Practical Applications Using Wastes & Secondary Materials in Pavement Engineering, Liverpool, U. K., 22nd and 23rd February 2006This paper presents the results of an investigation into the fatigue performance of a 20mm Binder Course Asphalt Pavement Mix incorporating Recycled Asphalt Pavement (RAP). For the study, a series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material, was selected as the control mix for the investigation. A Circular Wheel Tracker (CWT) was developed in order to simulate the dynamic loading conditions of a rolling wheel and to study the initiation and growth of fatigue cracks in an asphalt pavement mix. The CWT was commissioned within a temperature-controlled room with a customised data acquisition system. The test specimens were subjected to dynamic loading in the CWT and the dynamic strain on the underside of the slab was monitored throughout the test. A digital image processing technique was also used to measure the crack area and crack length at the underside of the test specimen. Parallel to this a separate testing programme was undertaken, whereby the fatigue resistance of bituminous mixtures incorporating same RAP contents was assessed using the indirect tensile fatigue test as described in BS DD ABF:1997. The results from these parallel strands are compared, and the performance of the various mixes incorporating RAP is assessed.Other funderEnterprise Ireland (ATRP)Conference website n/a. Conference organised by http://www.ljmu.ac.uk/BLT/. Selected papers from this conference are published in International Journal of Pavement Engineering and Asphalt Technology but this paper wasn't included. DG 05/07/10 au, ke, ti - TS 20.07.1

The influence of recycled asphalt pavement on 20mm binder course mix performance

Paper presented at the 3rd National Symposium on Bridge and Infrastructure Research in Ireland, Dublin, 2006 and at ICAP (International Conference on Asphalt Pavements) conference Quebec, Canada, 2006This paper presents the results of ongoing research on the mechanical performance of a 20mm binder course asphalt pavement mix incorporating recycled asphalt pavement (RAP). A series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall Test, Indirect Tensile Stiffness Modulus Test, Indirect Tensile Fatigue Test and Water Sensitivity Test. A Circular Wheel Track (CWT) was developed in order to study the dynamic effects of a rolling wheel travelling over an asphalt pavement. The CWT was commissioned within a temperature controlled room along with a customised Data Acquisition (DAQ) system. The system involves the testing of rectangular slabs and allows for the investigation of the dynamic tensile strain. The dynamic tensile strain is digitally recorded and the loading effect assessed. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. This was also observed in the dynamic tensile strain test.Other funderEnterprise Ireland (ATRP)Conference website no longer available. Conference organiser's website - http://www.bcri.ie/site/view/33/. DG 06/07/10 ti ke SB. 23/7/1