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Displaying Page 5 of 24

Research Report 578 Removing barriers to the use of crumb rubber in roads

Published: | Category: Activity management , Research programme , Research & reports | Audiences: General, Roading contractors

The purpose of this research was to identify the barriers to using tyre-derived crumb rubber in bitumen binder in New Zealand roading and the methods to remove these barriers to create market demand for New Zealand waste tyre-derived products.

Research Report 460 Multigrade bitumen for chipsealing applications

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

Research was undertaken in 2009–11 to evaluate the potential benefits of multigrade bitumens in chipsealing in New Zealand. A field trial demonstrated that multigrade bitumen seals could be constructed without significant modifications to existing practice except that higher spraying temperatures are required and adhesion agent choice is limited. Experimental measurements of bitumen-tyre adhesion temperatures were made using a rolling wheel apparatus. The cohesive energy of bitumen in artificial seals at 60°C under impact loading was studied using a pendulum device. In both tests, the results for multigrade bitumens were found to be similar to standard bitumens of similar 25°C penetration even though the 60°C viscosity of the multigrade materials was 2-3 times higher.

Research Report 358 Developing and trialling a climate based section guideline for chip seal binders

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

In recent years, the standard practice in New Zealand regarding binder selection for state highways has been to use harder penetration grade binders and reduced diluents, after some research indicated that the use of harder binders slowed the onset of flushing. However, the use of harder binders and less diluents increases the risk of early failure of chipseals, because the higher viscosity of the binders causes chipseal construction issues and increased brittleness at low temperatures, both of which can lead to chip loss. This report discusses the development and trial of a guideline based on the performance of a binder at the high and low temperatures likely to be encountered at the chipseal construction site. The research follows on from initial work in developing and trialling a ‘Surface Performance Grade (SPG) Specification’ by the Texas Transportation Institute (TTI) for the Texas Department of Transportation (TxDOT).

Research report 430 Identifying pavement deterioration by enhancing the definition of road roughness

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

Current road roughness deterioration modelling and analysis tends to focus on the prediction of roughness progression in terms of change in the IRI over time. Since the IRI is simply a summary index of the actual roughness, which simulates the response of a specific type of vehicle (quarter-car), it is difficult to identify the factors that contribute to the deterioration of road roughness. Understanding the factors that lead to the deterioration of roads and identifying the actual mode of road roughness deterioration will help road controlling authorities refine their specifications on road roughness requirements for road design, construction and maintenance to reduce their adverse influence on roughness. This research project looked at an alternative method to analyse and define the roughness deterioration modes of different pavement sections of the New Zealand road network by analysing the characteristics of the longitudinal profile of the road surface using wavelet analysis.

Research report 466 High-stress corners

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

A programme of research was undertaken to better understand chip loss on curves with the aim to improve chipseal design and selection practices. The research involved on-road measurements and computer simulation of tyre forces during cornering manoeuvres; correlation analysis using road surface, road geometry and traffic variables contained in the NZ Transport Agency's RAMM database; and finite element analysis of pavement surface stresses induced by a cornering truck.

Research Report 587 Bitumen performance tests

Published: | Audience: General

Aspects of bitumen performance in chipseals related to the development of a New Zealand performance-based specification for chipseal binders were investigated.

Research Report 304 Predicting in-service performance of alternative pavement materials

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

This research proposes a new practical method for predicting the performance of unbound granular materials, including alternative, industrial by-products and recycled materials in New Zealand. This investigation, carried out in 2005, utilised available field performance data in New Zealand to calibrate/validate available material assessment methods based on laboratory repeated load triaxial testing. The recommendation is that the simple ARRB performance assessment method, which is based on a reduced set of permanent strain results obtained from the existing Austroads repeated load triaxial test method, be used in material specification. Further research should be undertaken to improve and simplify general deformation prediction models, which are based on a full set of permanent strain results at various tress levels, to make them suitable for practical use in pavement design. Keywords: aggregates, deformation, performance specifications, recycled materials, repeated load triaxial, rutting

Research Report 361 Review of Australian standard AS 5100 bridge design with a view to adoption

Published: | Category: Activity management , Research programme , Research & reports | Audience: General

The objective of this project was to investigate the practicality of adopting the AS 5100 bridge design standard for New Zealand. The significant differences and gaps between current design requirements as presented by AS 5100 and the Transit NZ Bridge manual and its supporting standards were identified. The project gave consideration to the New Zealand regulatory environment and identified measures that would need to be taken to enable AS 5100 to be used in New Zealand. Although many advantages and disadvantages were identified for adopting AS 5100 for bridge design in New Zealand, it was considered that the best option was to retain the Bridge manual and to revise it to incorporate more of the AS 5100 material relevant to bridge design than presently adopted. The overriding consideration in reaching this conclusion was the difficulty of preparing supplementary material for AS 5100.5 and AS 5100.6 to incorporate seismic design requirements...

Research Report 576 Flushing in chipseals

Published: | Category: Activity management , Research programme , Research & reports | Audience: Road traffic engineers & consultants

This report details research carried out from 2012 to 2015 into chipseal flushing. The physical mechanisms causing flushing were investigated and a model was developed to predict the growth of flushing over the New Zealand state highway network.

Research Report 543 Pavement design for specialist surfacings

Published: | Category: Activity management , Research programme , Research & reports | Audience: Road traffic engineers & consultants

Leutner shear tests to measure bond strength and flexural beam tests to measure flexibility were conducted on specialist surfacing resins used in New Zealand for coloured and high-friction surfacings.
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