15-06-2012, 12:31 PM
BITUMEN SCRAP RUBBER SEALS
[attachment=24543]
INTRODUCTION
This Engineering Road Note is intended to provide guidance on the use of rubberised
bitumen in the application of sprayed treatments. The guide only deals with the use of
granulated scrap rubber and not with polymer modified binders.
The note describes the circumstances in which the use of rubberised binders should be
considered, and gives details of material requirements, binder composition and application
rates, equipment and field procedures.
USES
Granulated scrap rubber is added to bitumen to provide an elastic binder whose properties
can be an advantage in a number of circumstances, i.e.:
Prevention of Reflection Cracking
Cracks in a pavement will normally reflect through any thin bituminous surfacing
unless it is specifically designed to prevent this occurrence. The use of rubberised
binders provides one means of preventing or minimising reflection cracking. When
used as a surface treatment the application of a rubberised seal is termed a strain
alleviating membrane (SAM). When used as a layer prior to the application of an
asphalt overlay the system is known as a strain alleviating membrane interlayer
(SAMI).
A complete understanding of the applicability of rubberised bitumen as a SAM or
SAMI is not presently available, however, the treatments are considered most
effective when the existing pavement or surface cracks have relatively stable fatigue
cracks. The treatment of shrinkage cracks which open and close markedly with
changing environment is not as effective, although some reduction in the extent and
width of reflection cracking can be expected.
SAMs or SAMIs are only intended for application to pavements, which are basically
sound structurally, apart from the occurrence of cracks. The treatments should be
carried out before the pavement has been weakened by the ingress of water through
the cracks.
Waterproof Bridge Deck Membrane
Experience has shown that rubberised bitumen can provide an effective waterproof
membrane for bridge decks because of its ability to be applied at high application
rates and to resist the reflection of cracks in the deck.
MATERIALS
Bitumen
Class 170 bitumen conforming to the requirements of, AS 2008 "Residual Bitumen for
Pavements" should be used unless otherwise directed.
Engineering Road Note No. 7
October 2003
Rubber Granules
The rubber granules should be natural or synthetic rubber, which may be processed
from scrap tyres or other, approved rubber products. The granules should not contain
more than 0.1 percent (by mass) of foreign material such as iron, steel or sand. The
quantity of ferrous material can be determined in accordance with MRWA Test
Method WA 237.1.
[attachment=24543]
INTRODUCTION
This Engineering Road Note is intended to provide guidance on the use of rubberised
bitumen in the application of sprayed treatments. The guide only deals with the use of
granulated scrap rubber and not with polymer modified binders.
The note describes the circumstances in which the use of rubberised binders should be
considered, and gives details of material requirements, binder composition and application
rates, equipment and field procedures.
USES
Granulated scrap rubber is added to bitumen to provide an elastic binder whose properties
can be an advantage in a number of circumstances, i.e.:
Prevention of Reflection Cracking
Cracks in a pavement will normally reflect through any thin bituminous surfacing
unless it is specifically designed to prevent this occurrence. The use of rubberised
binders provides one means of preventing or minimising reflection cracking. When
used as a surface treatment the application of a rubberised seal is termed a strain
alleviating membrane (SAM). When used as a layer prior to the application of an
asphalt overlay the system is known as a strain alleviating membrane interlayer
(SAMI).
A complete understanding of the applicability of rubberised bitumen as a SAM or
SAMI is not presently available, however, the treatments are considered most
effective when the existing pavement or surface cracks have relatively stable fatigue
cracks. The treatment of shrinkage cracks which open and close markedly with
changing environment is not as effective, although some reduction in the extent and
width of reflection cracking can be expected.
SAMs or SAMIs are only intended for application to pavements, which are basically
sound structurally, apart from the occurrence of cracks. The treatments should be
carried out before the pavement has been weakened by the ingress of water through
the cracks.
Waterproof Bridge Deck Membrane
Experience has shown that rubberised bitumen can provide an effective waterproof
membrane for bridge decks because of its ability to be applied at high application
rates and to resist the reflection of cracks in the deck.
MATERIALS
Bitumen
Class 170 bitumen conforming to the requirements of, AS 2008 "Residual Bitumen for
Pavements" should be used unless otherwise directed.
Engineering Road Note No. 7
October 2003
Rubber Granules
The rubber granules should be natural or synthetic rubber, which may be processed
from scrap tyres or other, approved rubber products. The granules should not contain
more than 0.1 percent (by mass) of foreign material such as iron, steel or sand. The
quantity of ferrous material can be determined in accordance with MRWA Test
Method WA 237.1.