Preliminary testing for determining the mix quality

Laboratory-scale foamed bitumen plant WLB 10 S

What is foamed bitumen?

For high-quality base layers from cold mixes

Foamed bitumen is produced from standard grade

bitumen used in asphalt road construction. When

heated and foamed, bitumen permits the economical

production of high-quality base layers from cold mixes.

Foamed bitumen is produced by injecting small quantities

of water and compressed air into hot bitumen. The water

evaporates, causing the bitumen to foam abruptly and

expand to around 15 to 20 times its original volume.

The quality of foamed bitumen is primarily described in

terms of the parameters “expansion ratio” and “half-life”.

For the larger its expansion and the higher its half-life, the

better suited to processing the foamed bitumen will be.

Hot bitumen

Water Air

Foamed bitumen

Expansion chamber with foam nozzle

2 //3

Innovative and economical

The foaming process takes place in expansion cham-

bers where water and air are injected into hot bitumen

(160°C to 180°C) at a pressure of approx. 5 bar.

The foamed bitumen sprayed from the nozzle at the

expansion chamber is suitable for direct mixing with the

mineral aggregate mixture.

Compared to other binding agents, foamed bitumen

offers the advantage of reduced transport and material

costs.

Bitumen used for the production of foamed bitumen is

readily available in all parts of the world.

Small quantities of water cause an abrupt increase in the volume of the hot bitumen

Development of half-life and expansion ratio for

determining the water content

Foamed bitumen nozzle: from the expansion chamber, foamed bitumen is injected into the mixer for the production of test specimens

Expansion ratio Half-life

Exp

ansi

on

rati

o

Hal

f-lif

e (s

)

Water content (% by weight)

40

35

30

25

20

15

10

5

0

42

37

32

27

22

17

12

7

20,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5

The WLB 10 S determines the optimum foamed bitumen quality

One-to-one simulation of the cold recycling process in the lab

Foamed bitumen is used to an ever-increasing

degree as a binding agent in economical cold

recycling. Preliminary testing with the mobile WLB 10 S

laboratory-scale plant enables the foamed bitumen qual-

ity to be precisely determined in the lab even prior to the

start of construction. Extremely simple handling permits

different parameters, such as water quantity, pressure and

temperature, to be varied quickly, and different types of

foamed bitumen to be produced within a short period of

time. Based on the results achieved, the WLM 30 labora-

tory-scale mixer can then be used to determine the mix

proportion and to define the optimum bitumen foam for

production of the test specimens.

4 //5

True ease of operation

The integrated air compressor (optional) enables the

plant to be operated even in those locations where

there is no external supply of compressed air.

The compact plant guarantees simple and ergonomical

handling and operation.

Comprehensive safety functions, such as compressed

air and temperature monitoring, permit the foamed

bitumen to be produced under ideal conditions.

The plant is also intended for testing the suitability of

mixes by adding cement or lime in combination with

foamed bitumen.

Controlled electrically: the plant offers maximum accuracy, for example, by

calibrating the bitumen flow

The clearly and logically arranged control panel permits easy setting and monitoring of key parameters

Precise process water settings enable the ideal foamed bitumen

quality to be determined

WLM 30 laboratory-scale mixer for the production of cold mixes

A perfect match for the WLB 10 S

Direct injection of the foamed bitumen into the mix-

ing chamber of the WLM 30 laboratory-scale mixer

enables mixes to be processed to specification and test

specimens to be produced. The twin-shaft compulsory

mixer is not only ideally tailored to the laboratory-scale

plant in terms of performance and design, however, but

is also connected to the plant’s power supply. The high

mixing intensity matches that of continuous mixers used

on the construction site. The WLM 30 has a capacity of

approx. 30 kg, and additionally offers variable settings

for speed and mixing time. The mixing chamber is simply

pivoted downwards about 180° and the cover opened to

allow discharge of the mix. And what’s more: when used

separately, the WLM 30 is suitable for most diverse mix

proportions.

Mixes every bit as homogeneous as on the job site

The powerful mixer (optional) with heavy-duty blades produces most diverse cold mixes

The two units are positioned relative to one another safely

by means of fixation points

Reliability even prior to the start of construction

6 //7

Maximum reliability for your cold

recycling project

Preliminary testing includes the procurement of

raw materials, determination of the mix formula,

and suitability testing on the test specimens.

Using the WLB 10 S and WLM 30 laboratory-scale

plants permits the final pavement design to be

determined in advance.

The two machines ensure an accurate analysis of

mixes produced from granulated asphalt material,

virgin materials or a mixture of both.

Our broad, innovative product portfolio enables us

to rehabilitate roads with maximum reliability and

economic efficiency.

Quality testing by means of the indirect tensile strength test

Ideal pavement properties are ensured by precisely determining

the mix proportion

Specimens produced from fresh mix for suitability testing

Wirtgen GmbHReinhard-Wirtgen-Str. 2 · 53578 Windhagen · Germany

Phone: +49 (0) 26 45 / 131-0 · Fax: +49 (0) 26 45 / 131-242Internet: www.wirtgen.com · E-Mail: info@wirtgen.com

Illustrations are non-binding and may include customized fittings. Subject to technical changes. Performance data depend on operational conditions. No. 54-12 EN-03/09 © by Wirtgen GmbH 2009. Printed in Germany