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Research Report 501 Assessment of shear stress limits in New Zealand design standards for high-strength concrete bridge beams

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

The design of concrete beams for shear loading is governed in New Zealand by the provisions of NZS 3101. The shear design provisions of NZS 3101 impose two limits on the permissible design shear capacity, including a maximum shear capacity of 8MPa. This 8MPa limit influences the efficiency of concrete beam design, and in particular the design of concrete bridge beams that have concrete compressive strengths greater than 40MPa. The validity of this limit was assessed through an examination of a number of other international design standards, statistical analyses using databases composed of all previous experimental testing of reinforced concrete (RC) and prestressed concrete (PC) beams, and results from an experimental investigation aimed at addressing deficiencies in the compiled databases. The research found that the limits in NZS 3101 are excessively conservative compared with the limits imposed in most other design standards.

Research report 443 Potential of the Wehner-Schulze test to predict the on-road friction performance of aggregate

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

The specification for aggregates for use on New Zealand roads includes the British Polished Stone Value (PSV) test. This test and the acceptance criteria were adopted in New Zealand in the 1990s, based on British experience that they were the best available method of predicting the on-road friction performance of aggregate. However, research performed by a number of people in New Zealand has shown that the prediction of performance by the PSV test is extremely variable. The Wehner-Schulze (WS) test method, developed in Germany in the 1960s and commonly used there, can test samples taken from the road. This research, which was carried out between December 2009 and August 2010, aimed to assess the potential of the WS test for predicting chipseal surface friction. The chipseal samples taken from New Zealand roads could not be used for testing because their very high texture imposed too much stress on the equipment.

Research Report 560 - Reduced bitumen application rates using bitumen emulsions

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

This research project investigated the differences in cohesive energies of model chipseal samples prepared from bitumen emulsions, the base binders, and the kerosene cutback base binder.

Research report 447 The influence of binder rise in reducing tyre-road friction

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

Research undertaken between 2007 and 2009 examined the influence of binder rise in reducing tyre–road friction of chipseal surfaces. The emphasis was on the most extreme form of binder rise when the binder is level or above the sealing chip resulting in the formation of a black, slick surface. This condition is referred to as flushing.

Research Report 504 Seismic design of New Zealand highway bridges under spatially varying ground excitations

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

Bridge damage, especially due to pounding and unseating at expansion joints has been observed in almost all major earthquakes. It is the result of large relative displacements of girders, in excess of the designed gap width and seating length.

Research Report 564 Effects of water on chipseal and basecourse on high-volume roads

Published: | Category: Activity management , CAPTIF , Research programme , Research & reports | Audiences: Road traffic engineers & consultants, Roading contractors

The objectives of this study were to investigate the relationship between permeability of chipseals, waterfilm thickness, basecourse moisture sensitivity, heavy traffic volumes, and premature pavement failure following construction through the use of accelerated pavement testing at CAPTIF. The research has produced some surprising results in that the traditional M/4 basecourse was the worst performer in all cases. However, it must be borne in mind that this research can only be considered applicable to first coat seals, with high water film thicknesses at very high traffic volume.

Research Report 599 Review of the NZ Transport Agency treatment selection algorithm

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

The objective of this research, carried out between 2012 and 2015, was to improve the treatment selection algorithm (TSA). The TSA is used to forecast the timing and treatment type of works required to maintain roads in good condition for the least whole-of-life cost in the short to medium term. The output was a candidate list of sites intended for validation in the field combined with recommended drainage improvements and funding estimates.

Research Report 332 Total voids in unbound granular pavements

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

In New Zealand excessive deformation in the wheel paths due to post construction densification has occurred in a number of new pavements constructed in recent years. It is believed that much of the deformation could be avoided if the aggregate layers were to be compacted to a high level of density prior to the road being opened to traffic.

Research Report 448 Wider economic impacts of transport investments in New Zealand

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

This paper develops a methodology and evidence to enable the assessment of wider economic impacts of transport. Quantifying these wider economic impacts is important as they are likely to be non-trivial in magnitude and they are currently excluded from the current appraisal methods. The paper derives New Zealand-based values of key parameters on imperfect competition benefits, increased competition benefits, labour supply benefits and job relocation benefits. The methodology and the key parameters are then applied to a transport project to demonstrate how the wider economic impacts can be quantified.

Research Report 574 Geosynthetics in basecourse stablisation

Published: | Category: Activity management , Research programme , Research & reports | Audiences: Road controlling authorities, Road traffic engineers & consultants, Roading contractors

The application of geosynthetics (ie geogrids) for the stabilisation of basecourses prepared with a River Run rounded gravel aggregate was investigated.
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