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Research Report 142 Materials & methods needed to prepare subgrades suitable for CAPTIF

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

The Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) is a state-of-the-art pavement testing facility located at Christchurch, New Zealand. This report presents the results of the third stage, carried out in 1998, of a three-stage project to determine the materials and methods necessary to prepare appropriate subgrades of a desired strength to be used at CAPTIF. A subgrade construction specification was developed using the recommendations of reports from previous stages of the project. This primariy involved controlling the water content of the subgrade to achieve different subgrade strengths. A trial pavement was constructed at CAPTIF and subjected to 147,000 load repetitions. The properties of each pavement layer were carefully monitored during construction, at intervals during the loading and at the completion of the loading sequence.

Research Report 291 Bitumen durability

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

This report describes research in 2004 and 2005 aimed at improving the means by which the durability of bitumens manufactured or imported to New Zealand for use in chipseals is assessed and monitored. Bitumen durability refers to the long-term resistance to oxidative hardening of the material in the field. Although, in-service, all bitumens harden with time through reaction with oxygen in the air, excessive rates of hardening (poor durability) can lead to premature binder embrittlement and surfacing failure resulting in cracking and chip loss. Some means of assessing durability by accelerating the process in the laboratory is necessary. However, no internationally accepted ‘standard’ exists for bitumen durability, as for some other bitumen tests (eg penetration). Keywords: bitumen, chipseal, durability, oxidation, pavements, roads, testing

Research Report 074 Non-traditional materials for trench & bridge abutment backfill

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

An overview of non-traditional backfill materials has been compiled from material identified in an international literature search carried out in 1992. Materials considered include controlled low strength materials (CLSM), foamed concrete, fly ash, wood waste, expanded polystyrene (EPS), and various miscellaneous materials. General information as well as composition, properties, advantages, limitations and typical applications are pr4esented for each material. The properties determine the backfilling application to which each material is best suited. Most of these materials have potential for use in New Zealand provided their advantages and limitations are recognised and understood by would-be users.

Research Report 202 Update and enhancement of traffic count guide

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

The measurement of traffic volumes on an extensive nationwide network is a very large task. It is not feasible to count all traffic on all roads all of the time. Considerable reduction or effort in the counting process can be achieved by identifying key factors that may allow for grouping of roads into similar groups. This project has derived nine major groups of roads based on the two-way hourly traffic pattern over the latest available two calendar years for continuous count/classification sites on state highways and local roads. This was achieved using hierarchical cluster analysis in the same manner as the similar, ground-breaking project undertook in the mid 1990's using older data, and prior to the introduction of the four term school year.

Research Report 250 Foamed bitumen stabilisation

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

Foamed bitumen stabilisation is gaining wide acceptance internationally for pavement stabilisation, but has not been practised in New Zealand. This report is of a preliminary experimental study, carried out in 2002, to investigate its feasibility and potential applications in this country.

Research Report 049 Assessment of torsional braid analysis technique for polymer-modified bitumens

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

Modified bituminous materials can be used to advantage on roads that are subject to high stress, such as on heavily trafficked sections, sharp bends, and bridge decks, or to wide variations of temperatures. Addition of polymer to bitumen improves the visco-elastic properties by increasing the resistance to permanent deformation at high stresses and temperatures. To encourage more accurate road surfacing design in New Zealand, accurate reproducible measurements of the mechanical properties of both unmodified and polymer-modified bitumens are needed.

Research Report 290 Road surface texture measurement using digital image processing and information theory

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

This report details the progress made in tests in Oklahoma, USA ,and Christchurch, New Zealand, during the period August 2004 to June 2005, exploring digital imaging technology to measure chipseal surface texture. It details the research methodology to develop a technology to replace the sand circle test as a means to measure chipseal surface texture more accurately and safely. The project used digital imagery and exploited ‘information theory’ to develop a quantitative relationship between texture measured by the sand circle test and the fast Fourier transform of a digital image of the surface taken at the same spot as the test. The preliminary correlation achieved and reported in the interim report has been confirmed by a larger group of data collected after the interim report was written. A reliable statistical correlation using linear regression analysis with a coefficient of determination of 80% between digital image processing output and sand circle...

Research Report 073 Assessing road surface friction with the British Pendulum Tester in NZ

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

The British Pendulum Tester (BPT) is used to assess the skid resistance of road surfaces. There are concerns that on chipseal surfaces the instrument may not deliver accurate or consistent results, recorded as British Pendulum Numbers (BPN). As a result, a study was carried out between 1992 and 1994, over a 30 month period, in four phases.

Research Report 001 Use of non-standard road aggregates from Whanganui and Taranaki regions

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

Road aggregates in the Wanganui and Taranaki regions are generally softer than those used elsewhere in New Zealand. However the costs of importing premium quality agreegate (e.g. that which complies with TNZ M/4 specification) is prohibitive. Instead, local practitioners have utilised local materials with success.

Research Report 199 Methods for determining structural number of New Zealand pavements

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

The structural number (SN) of a road pavement is a method for describing the strength of a road pavement, in pavement deterioration models that are currently being calibrated for New Zealand road conditions. To assist in the development of these models in New Zealand, and in implementing them in pavement design software, an investigation was carried out between 1999–2000, into the sensitivity and precision of the methods of obtaining the Structural Number.