## 5 Construction of NME Stabilised Granular Pavement Layers--Practical Aspects
### NME Stabilisation Using Recycling Equipment  
Centralised, computerised mixing equipment is generally not reliably available in most countries throughout the world. However, this does not exclude the use of anionic NME-stabilised naturally available materials from being used for the construction of  
Figure 9: One week after placement of base (1.2% NME—0.7% residual bitumen) and the exposed sub-base (0.7% NME—0.4% residual bitumen), 200 mm of rain fell with (**a**) the sub-base-layer and (**b**) base-layer representing rivers. (**c**) After drying, no water-related damage could be observed. highways or, for that matter, any other road. NME stabilisation lends itself towards road construction using basically any construction equipment. The finishing achieved using basic equipment is normally a function of the training and skills of the operators. The use of sophisticated equipment in road construction normally just simplifies operations and lends itself towards higher productivity and reduced construction periods. The use of modern recycling equipment can also be classified in the same category of equipment. Experience has shown that it is not unusual to stabilise a 1 km length, 10 m wide section of road with an anionic NME stabilising agent and to finish compaction within a single day. These production rates are achievable when all related logistical aspects are well planned and in place. The NME stabilising agent is easily added to a water-bowser using gravity as shown in Figure 5c. The water-bowser should already contain the required construction water for the section of the road, taking the volume of material into account as per previous discussion. The anionic NME stabilising agent will automatically disperse into the construction water to create a uniform mix for immediate use at ambient temperatures. No preheating of a quality anionic NME stabilising agent will be required for temperatures above freezing. The water quality could influence the stabilisation process and the normal water construction quality requirement specified for any other type of road construction is also applicable to NME stabilisation. In order to control application rates using recyclers for the mixing of the construction water premixed with the NME stabilising agent, the recycler should be equipped with a microprocessor which will regulate the application of the stabilising agent with the speed of travelling. These requirements are standard with most manufacturers of modern recyclers, which also allows for the depth of stabilisation to be controlled with a high degree of accuracies. However, few recycler manufacturers used to have these automatic controls and it is still recommended that these basic requirements for recyclers should be written into project-specific specifications in order to pre-empt and prevent any construction-related dispute as to minimise equipment requirements. Figure 10a shows the use of a recycler for the mixing of the stabilising agent and construction water with the granular material on the same highway shown in Figures 7 and 8. Note the uniformity of the mix at the back of the recycler, showing the good working order of the recycler with all nozzles fully in operation and no problems associated with the mixing drum or the supply of the NME stabilising agent pre-mixed with the construction water. Figure 10b shows the construction train used in the mixing and the compaction of a full width of a secondary road using an anionic NME stabilising agent. The use of recyclers for the in-situ recycling and stabilisation of distressed roads using material-compatible anionic NME stabilising agents are especially a cost-effective procedure for the quick reinstatement of roads, with a minimum disruption to traffic and inconvenience to property owners in urban areas. Figures 11 and 12 show the rehabilitation of a severely distressed urban road through the in-situ recycling of the G7-quality base material mixed with the remainder of the surfacing material.