GENERAL REQUIREMENT

          Storage

          BITUMAT  APP  Modified bitumen rolls shall be stored vertically on ends, on a flat           
          surface, one high without superpositioning, in a dry ventilated room.  Rolls shall not be laid
          flat until ready for installation.          

          Surface Cleaning

The Bridge deck concrete surface shall be clean and free from laitance, loose aggregates, dust and any other debris, oil, grease, curing compounds shall be washed out if necessary.

Priming

Immediately after cleaning and drying of the surface, a full coat of BITUMAT bituprime or Bitufast is to be applied over all the deck and any detail on which waterproofing membrane is to be applied.  The primer shall be well brushed in to avoid ponding in any depression of the deck.  Depending upon concrete surface condition, application rate varies from 0.2 to 0.4 LT/M2.  Primer coat shall be allowed to cure completely before membrane application (12-24 hours). 

LAYING OF THE HORIZONTAL MEMBRANE

Membrane rolls shall be laid parallel to the traffic direction.

Installation starting shall be done at the low edge (downhill) of the deck to ensure that water will drain away from the exposed edges.

In case of curved bridge, the rolls may be cut in shorter length, laid tangent to the curve in such a manner that overlaps are never less than the specified value.

The rolls end laps must be staggered so that at no point they should be more than 3 thicknesses of membrane.

Membrane shall be installed with 10cm side laps and 15cm steggered end laps.

The membrane should be free of wrinkle and footmarks.  Only light shoes with flat soles shall be worn by installation crew, and traffic on the membrane should be very limited while it is still hot. 

INSTALLATION PROCEDURE

Starting at the edge of the bridge deck the Polyglas membrane rolls shall be opened and properly aligned.  The membrane should be free of wrinkles and positioned to achieve the proper 10cm side lap and 15cm end lap.

The Polyglas will then be rolled back up to the middle of the roll and the butane torch flame shall be applied to the whole width of the roll until the surface reaches the proper application temperature (generally 200 Deg.C.) giving a slight sheen, burning of the polyethylene foil.  A small wave of melted bitumen is created at the base of the roll in contact with the primed deck.

The BITUMAT membrane roll is then gradually unrolled to create a heat weld between the membrane and the primed concrete deck over which it is being installed. 

When this section of the roll has been securely installed, re-roll the rest of the membrane upto the point of application and begin heat welding in the opposite direction.  If more than one roll is required to complete the starter course, lap ends 15cm.

Continue installing additional rolls in shingle fashion with 10cm side laps and 15cm end laps which must be staggered.

Seams at overlaps shall be checked for proper weld by running a heated trowel along the edge of the seam to re-seal all voids in the laps.  Seal all edges with the heated trowel by slightly melting the modified bitumen compound evenly creating a fully welded seam.

After covering the whole deck area, recheck to ensure that the membrane is fully heat welded at all laps and around the perimeter and all vertical protrusions.   

DETAILS

            FLASHINGS

            General Rules :

The top of the membrane base flashing must be higher than the finished road level by at least 100mm.

The upper horizontal joint of the base flashing strip must be protected by a counter flashing system (metal strip, neglect, groove or drip in concrete….).

The membrane base flashing shall in protected against accidental damages.

Mortar cant strips shall be provided at all wall and curb type protrusion flashings, except where there is no stress expected.

Protrusions shall be at least 50cm away from curbs walls and edges to provide adequate space for proper flashing. 

BITUMAT Membrane flashing shall be installed in strips not longer than 1 meter and cut to the width required for the flashing girth. 

           Installation : 

        ----- flashing ------------- in the proper width according to the height required with the top level of wall flashing.  Hold the flashing strip at cant strip level, turning down the top portion of the flashing strip.  Apply the butane flame carefully in the surface of the wall and the inner surface of flashing strip and press well to ensure complete bond along the wall for the whole 1 meter length of strip.

Turning the bottom portion of the flashing strip up. Apply the flame to the membrane over the cant strip, approximately 10 cm onto the flat area as well as the inner side of the flashing strip.  Press the strip carefully onto the cant strip and the membrane.Eleminate any voids between them and avoid any installation at the flashing point.

Reseal all seams and edges with the heated trowel running it along all joints. Overheating and overmelting of surface bitumen must be avoided.

Continue installing additional flashing strips with 10cm overlaps fully torched and seamed.  Flashing strips side laps and horizontal membrane side laps shall not be superimposed. 

           Corners

All external and internal corners shall be cut and shaped using a second reinforcing piece at the central joint, and shall be fully heat welded with resealed edges and seams and the rest of the flashing. 

           Edge Flashing

In case of flat edges, BITUMAT Membrane will be stopped at the extreme corner, and reinforcing strip will be installed, below or under the main membrane depending upon slope. 

            PENETRATIONS

Penetrations through the waterproofing shall be restricted to necessary equipments (security cables, lightnings ….)

The basic system shall consist of a metallic flange laid onto a Polyglass base membrane.  Covered with the polyglas  main membrane fully bonded.  Bolts shall be tightend with Neoprene rings. 

            DRAINS

Drains should installed in a recess so that the water is drained both at the membrane level and the road level.

The determination of the rainwater down pipes diameter and quantity is to be done by the mechanical contractor.

The rainwater outlet could be designed in two ways :

(a)Prefabricated lead (2.5mm thick), special rubber  or adequate metal to be installed fully bonded between layers of BITUMAT Polyglas.

(b)Cast iron, fixed onto the bridge deck, properly sealed with BITUMAT Polyglas welded onto primed metal with at least 10 cm overlaps between metal and polyglas.

Outlets and overflows made of normal PVC are to be avoided as durable torch welding of bitumen membrane onto PVC is impossible. 

            EXPANSION JOINTS

It is necessary to ensure continuity of the waterproofing over all movement joints.  The mechanical bridging should be capable of accommodating the following :

                  The imposed loading from traffic.

                  The accumulative range of movements imposed by :

·        Creep and shrinkage

·        Expansion and contraction caused by temperature cycles

·        Rotation caused by deflection under loading

·        Braking forces transmitted to deck structure

·        Elastic shortening due to prestress. 

                  Good skid resistant wearing surface at road level. 

Depending upon the expected movement, Bridge expansion jointing system shall be designed on a case-per-case basis.  Care will be taken to specify a joint system ensuring continuity with the Polyglas waterproofing membrane, such as Waboflex SR expansion joints manufactured by Bitumat Servicised Systems (see enclosed construction detail). 

The nominal thickness requested to ensure sufficient protection of the BITUMAT membrane is 5cm after compacting.

The laying of the asphalt wearing course shall be done on a dry and clean surfance.

Its temperature shall not exceed: 

160 Deg.C when laid onto the BITUMAT membrane 

140 Deg.C at starting of compacting 

The access to the non protected membrane shall be strictly restricted.  Only trucks and vehicles involved in the asphalt wearing course laying shall  be permitted.  They shall be equipped with rubber tyres and shall avoid brutal maneuver.

The laying of the ashphalt wearing course shall be done with care by a well informed asphalt contractor in order to avoid mechanical damages to the waterproofing membrane. 

            Some specific parts of the bridge deck (side walk, road dividers ….) may not receive asphalt             wearing course but concrete screed, precast pavers or other top covering. 

In such cases the top covering shall not be laid directly onto the membrane.  An adequate seperation ---------150 Microns polyethylene or 120-140gm non-woven polyester felt shall be laid on the membrane prior to any covering.