Spanish “Pioneer of Thin Overlay” for Pavement Rehabilitation Excels in Tarragona
The Spanish contractor Sorigué is a trendsetter. Little wonder that the company was the first to use the SUPER 1800-3i SprayJet. In search of ways to gain an edge over rival regional road construction contractors, the company has made a name for itself as a pioneer for paving thin overlays and in the development of new mixes. Sorigué have already elicited a thoroughly positive response with the innovative and cost-efficient technique of paving thin overlays for the rehabilitation of surface courses.
Offering cost-efficiency and speed, Sorigué consequently won the contract for rehabilitating the surface course of the 3km-long dam promenade in the Catalonian port city of Tarragona. Sorigué’s idea was to overlay the existing surfacing with a thin layer applied to a spray seal of polymer-modified bitumen. The spray seal prevents water penetrating inside the structure – a major advantage for a dam promenade which is regularly flooded with sea water due to strong winds and heavy seas.
The points in favour of the process: it’s cost-effective, time-saving and durable. Cost-effective because the thinner layer significantly reduces milling and material costs. Besides which, there is no need for costly adjustments and the installation of new curbs. Time-saving because spraying the high-quality polymer-modified bitumen and paving the surface course can take place in a single pass. Last but not least, the pavements rehabilitated by paving thin overlays are exceedingly durable. The sprayed binder forms a continuous film on the lower layer, effectively sealing the road structure against water and significantly extending the service life of the new pavement.
Paving thin overlay on spray seal
In order to produce a particularly high-quality bond between layers when overlaying the surface course, Sorigué used an emulsion called ELASTAM which was developed by the company itself and contains 65% of polymer-modified bitumen and 35% of water. The polymer-modified emulsion guarantees very rapid “breaking” so that the film of emulsion can be overlaid with hot asphalt immediately after spraying. The SprayJet module ensures that the emulsion is always sprayed in exactly the right quantity. Unlike the case when using conventional methods, job site vehicles and paver do not drive over the film of emulsion so that it remains intact over the full width.
The set rate of spread was relatively high, at 1.1kg/m². Alfredo Bobis, product developer for Sorigué explains why this was so: “Using a high rate of spread produces a reliable tack coat on all bases and ensures a strong bond between the layers. In addition, it also allows more bitumen to be mixed into the asphalt retroactively. All in all, this extends the service life of the new surfacing in line with demands for sustainable road construction.”
The new SUPER 1800-3i SprayJet thrilled the Spanish paving pros
Sorigué have devoted more than three years to paving thin overlays on spray seal. Having focussed on VÖGELE SprayJet technology from the outset, the company is now fully familiar with this technique. The brand-new generation of VÖGELE spray pavers was used in Tarragona – the SUPER 1800-3i SprayJet. The paving team responsible for paving the 3km-long and 10m-wide surface course in less than two days was naturally very keyed up. José Antonio Rodríguez from Sorigué stressed:
“The new SprayJet module intrigued us. Particularly operation of the ‘Dash 3’ SprayJet module and the numerous automatic functions. Such as calculation of the optimum pave speed on the basis of the installed nozzle size and the selected rate of spread. This automatically guarantees perfect application of the emulsion.”
Three times greater ease of operation
Even for experienced paving pros, the SUPER 1800-3i SprayJet sets new standards in terms of handling. Operation of the SprayJet module has been consistently integrated into the ErgoPlus 3 operating concept. The central element is the colour touch screen. It’s positioning on the emulsion tank ensures that it can easily be seen and reached by the paver operator at all times. All preparatory, spraying and cleaning functions can be selected and started in a few swift moves via various menus. Settings for the work flows are mainly performed automatically. This assures the machine’s availability and long-term value and prevents potential operator errors.
“The nozzles can be calibrated and individually activated or deactivated just as easily. Another function that we liked was the all-automatic cleaning of emulsion lines and valves. Only a few settings are needed to start the cleaning programme. Up to three cleaning cycles can be set, depending on the degree of fouling. It is also possible to clean only a few selected circuits. A preservative can also be added to prevent emulsion sticking to the lines. It is a real innovation that saves a lot of time!” raves José Antonio Rodríguez. Manuel Álvarez Gálvez sums up: “A great machine and a unique concept! The new SUPER 1800-3i SprayJet is a big hit all round.”