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success, not only did the technical

equipment need to operate fault-

lessly, but the team had to work

hand-in-hand, communicating

swiftly and clearly.”

One train – two

machines

Once the logistics is well organized,

precise high-grade paving is assured

by the intelligent technology of the

Wirtgen machines. The sub-processes

are divided between two machines. The bottom-layer

paver - a Wirtgen SP1500 - is equipped with dowel bar

and tie bar inserters, while the top-layer paver uses a

finishing beam and super smoother to produce a level

surface.

Both slipform pavers feature an intelligent control

system ensuring a perfect paved result. The surface is

subsequently finished as desired by a texture curing

machine of type TCM 1800.

Intelligent dowel bar and tie bar

inserter

The integrated dowel bar and tie bar inserter is one of

the technical highlights of the SP 1500 from Wirtgen.

Dowel bars and tie bars are inserted in the pre-compact-

ed wet concrete at freely determined intervals by these

two fully automatic vibrating components.

The process for inserting the dowel bars is quite in-

genious: Because the dowel bar inserter can move in

the direction of paving, it can remain in position over

the transverse joint until the vibratory insertion process

is complete, while the slipform paver continues to ad-

vance uniformly.

The entire procedure is monitored electronically to

assure that the dowel bars are positioned correctly.

For the projects described here, the dowel bars were

typically positioned in the middle of the finished concrete

surfacing, i.e. at intervals of 14-15 cm and exactly as

specified by the regulation ZTV Beton (Additional tech-

nical contract conditions and guidelines for the construc-

tion of roadway surfacings made of concrete).

A closed, even and homogeneous surface was then

assured by a finishing beam and super smoother inte-

grated in the top-layer paver.

So that roadways can be paved with maximum sur-

face accuracy, three of the four contractors use specially

developed sensors to adjust the height of the front

metering screed.

These sensors continuously measure the filling level

of the concrete in the compaction zone and adjust the

height of the front metering screed accordingly.

This ensures that the amount of concrete delivered

to the compaction zone is exactly as required. Dirk

Böttcher, Project Manager for Eurovia Beton, explains

the advantage:

“This relieves the paver operator, particularly

when the top-layer concrete is to be paved as a

thin layer.”

The TCM 1800 texture curing machine applies a com-

bination of surface retarder and dispersion to the ex-

posed aggregate concrete freshly paved.

Curing is a further aspect of great importance when

paving exposed aggregate concrete. The TCM can be

fitted with brooms or combs to give the concrete a de-

fined texture. This is unnecessary when placing exposed

aggregate concrete.

The retarding agent delays the setting and initial

hardening of the concrete surface (approx. 1 mm) for a

limited time, while the dispersion prevents the concrete

surface from drying out and cracking. As soon as the

concrete has cured sufficiently to be driven over, the

surface is brushed to expose the coarse aggregate.

An additional dispersion is then applied to the

brushed surface. Exposing the coarse aggregate gives

the concrete pavement the required non-skid properties

which are subsequently of high importance for traffic

safety.

The non-woven material on the subbase prevents

reflective cracking being transferred from the subbase

to the concrete surfacing. In this way, Eurovia was able

to reliably pave concrete in two layers over a width of

15.25 m and a length of 5.3 km on the A1 near Lübeck

using the slipform pavers SP 1500 L / SP 1500 from

Wirtgen.

Max Bögl had some 70 people working simultane-

ously on the A9 project. In addition to the two machine

operators of the two Wirtgen SP 1500 slipform pavers,

the team on site included ground staff, as well as the

operators of the concrete mixing plant and the truck

drivers.

Wirtgen Pavers

The texture curing machine TCM 1800

from Wirtgen

Contractors World International Vol 7 No 5

18