Roadment is specified generically as alkali-activated slag in stabilisation tender documentation and is used as an alternative to other alkali-activated slag products such as slag/lime blends.

Prior to the use of Roadment or other cementitious binders.


Product standards
The alkali activator is subject to Boral Quality Assurance processes and must meet strict chemical parameters to ensure it is suitable for Roadment. Slag for use in Roadment conforms to AS 3582.2.


Working time for stabilisation projects
Recent years have seen a trend away from ordinary Portland cement (Type GP) towards blended cements (Type GB) and other cementitious binders such as Roadment and slag/lime. The use of these blended products in road stabilisation provides longer working times for the contractor to compact and trim the stabilised pavement than GP cement. Cementitious stabilising agents produce hydration reactions immediately upon contact with water, forming bonds with the host material.With GP cement, these reactions proceed very quickly, producing rapid bond formation. This provides only 2 to 3 hours working time to shape the pavement layer, achieve specified density requirements and trim to design levels. It should be noted that strength development will be hindered by a lack of density and that hot weather further reduces available working time to achieve compaction.


VicRoads evaluation
Boral commissioned GEOPAVE, formerly VicRoads Materials Technology Department, to undertake a laboratory study to evaluate the performance of Roadment as a road stabilisation agent1. This study compared the performance of different binders at 7, 28 and 90 days curing with varying delays between mixing and compaction. This delay represented working time. The results of the Unconfined Compressive Strength (UCS) testing for Class 3 subbase quality crushed rock, with 3% binder addition and zero
and 12 hours delay to compaction, is summarised in the table below.

1 Yeo, REY, Gazzard, G and Choummanivong, L Evaluation of New Products for Use in Rood Stabilisation, VicRoads Materials Technology Department, Burwood East,Victoria, March 1998. Note: Private report. Not for general distribution. Contact Boral regarding this report.


*Pozzoment is a Boral product also used in road stabilisation and classed as Type GB cement. It is a blend of Portland cement and fly ash (approximate ratio 70/30).

Analysis of results
The study found that with Roadment, delays to compaction, even up to 12 hours, had an insignificant effect on dry density and UCS. This indicates that Roadment is a slow-setting binder, similar to 85%/15% slag/lime and will provide working times of at least 8 hours (depending on ambient conditions), without affecting density and strength development. The UCS results for Pozzoment, a Type GB cement, with zero hours delay,were similar to Roadment, but on average around 35% lower with 12 hours delay, indicating the reduced working time available with binders containing high proportions of Portland cement (GP). In general, however, GB cements provide longer working times than GP.


Ride Quality
Another benefit of using Roadment is the enhanced ride quality that can result. This is because with Roadment more time is available to shape, grade and trim the stabilised pavement. This extended working time will assist contractors to achieve a smoother riding surface, once again without compromising on long-term strength.


Plastic Index (PI)
Further laboratory tests commissioned by Boral have shown that Roadment it is also effective in reducing the PI of the host material.


Mixing methods
Roadment can be blended with the existing road insitu using specialised equipment and contractors (road recycling) or in pugmill blending operations (new and recycled road material).


Mix design
Prior to the use of Roadment or other cementitious binders, laboratory testing should be carried out to determine the appropriate mix design to achieve the specified requirements of the stabilised road including particle size distribution, PI and UCS.


Handling
A Material Safety Data Sheet is available upon request by contacting Boral.


Supply and price
Roadment blended at our bulk storage and distribution facility at Somerton,Victoria and is delivered to site by bulk pneumatic tankers. Details on price are available from Boral upon request.