All prefilled bagwork should remain palletised and wrapped until ready to use. Palletised bagwork should be stored in the dry, or suitably covered and protected if stored outside.

Care should be taken in removing protective wrapping, so as not to cut or damage the bagwork. Likewise, the bags should be inspected before placement for obvious signs of damage.

When ready to use, bagwork should be removed individually from the pallet wrapping, and individual bags gently shaken, rolled or squeezed to loosen any compacted dry mix concrete contained within each bag. Should there be any small amounts of cement powder on the outside of the bag, resulting from the filling process, this can be gently brushed off with a soft brush, prior to approaching the watercourse.

Where bags are more heavily dusty, it is likely that the liner has ruptured during transit and the bags should not be used. Only intact, undamaged bags should be carried into or used in the watercourse.

Where damage has occurred during transit, these damaged bags should not generally be used, although often the dry mix can be reused to refill empty bagwork or reutilised for other purposes.  We would also recommend periodic inspections are carried out to check for any damage from other factors such as adverse weather conditions, vandalism, contamination, etc.

Prefilled Underwater Bagwork relies upon the surrounding water to hydrate the concrete. For this to occur, steelwork is needed; the steelwork piercing each and every bag creating a pathway for the surrounding water to enter the bag and disperse around the concrete. When submerged underwater, and with a single standard pin through each bag, hydration and hardening typically takes around 6-12 hours, such that bagwork will have fully hardened by the next working day. Full strength is achieved within 28 days.

The procedure for placement below water level is:

• Unopened, loosened pre-filled underwater bagwork should be carefully carried, individually and by hand, through the watercourse to the location where they are needed. Each bag should be carefully placed horizontally, taking care not to drop, snag or tear the bags on sharp objects. Bagwork is to be placed flat and built up in rows, typically alternating or cross bonding bagwork to improve the strength of the finished blockwork. Bagwork can be patted flat or shaped once placed, to improve the appearance of the bagwork and reduce the amount of voids within the finished blockwork. Patting or shaping must be completed before the bagwork is pierced with steelwork.
• Underwater bagwork placed by divers can also be lowered into the river in 1T bulk bags. The divers can then remove individual prefilled bags from the bulk bag, by hand, to be carried and placed by the divers.
• After the second or third row of bags, steel rebar pins should be used to provide a pathway for water to enter the bag and hydrate the concrete, and to tie all the finished blockwork together.  Pins can be inserted by hand, or if a hammer is used, this should be a rubber mallet.  Steelwork pins should be pushed down vertically through the bags, with steelwork passing through each and every bag.  Once placed and stacked, the tight seal between the steelwork and the liners, the tight packing between the individual bags and the fact that the steelwork is inserted vertically through the bags, ensures there is no loss of cement fines from the bags during placement or from piercing the bags.
• Further rows of bagwork and steelwork can be added, to take the wall or bagwork up to the required height. Typically standard 300mm long steelwork pins are inserted every two rows of bagwork, piercing 3 rows of bagwork with a single 300mm long pin. Ensure all the bagwork is pierced with at least one rebar pin, creating up to four entry points for each bag.
• Once pierced, air bubbles will typically escape from each bag, as water enters the bagwork and displaces any trapped air.

In situations where water levels can be manipulated or is expected to rise and submerge the bagwork for a 12hr period following placement of the bagwork, it can also be possible to utilise Underwater Bagwork for higher level works. In all instances however, dry bagwork should not be left on site without either being wetted or anticipated to be fully hydrated within the following 24hr period.

Prefilled bagwork placed away from any watercourse needs to be hydrated prior to or during placement. This can either be achieved by pre-soaking the lined bagwork in a bath of water for approximately 15 minutes prior to placement, or by thoroughly wetting the bagwork during placement (typically for a minimum of 3 minutes). The water soluble liner will begin to dissolve in 5 seconds and is typically fully dissolved within approximately 15 seconds, sufficient enough to allow water to readily soak into the dry mix to harden the concrete. Typically a 20kg bag will absorb around 4L of water during this process so it is important to have a ready supply of water available and to top up at regular intervals.

When ready to use, each of the bags should be removed from the pallet and if pre-soaked, fully submerged in a suitable bath of water. Once hydrated (approximately 15 minutes), the bagwork can be carefully lifted from the bath and excess water allowed to drain. The pre-soaked bagwork should be carried, individually by hand or using a wheel barrow, to the site of placement.

Each bag should be carefully placed horizontally, taking care not to drop, snag or tear the bags on sharp objects. Bagwork is to be placed flat and built up in rows, typically alternating or cross bonding bagwork. Cross bonding improves the strength and effectiveness of the finished concrete blockwork. Bagwork can be patted flat or shaped once placed, to improve the appearance of the bagwork and reduce the amount of voids within the finished blockwork.

After the second or third row of bags, steel rebar pins can be pushed down vertically through the bagwork to tie all the blockwork together, with additional steel used to tie subsequent rows. Pins can be inserted by hand, or if a hammer is used, this should be a rubber mallet.  Steelwork is not always needed for above water bagwork although we do recommend that it is used wherever the bags are needed for medium to long term works, or where additional wall strength is needed. Typically standard 300mm long steelwork pins are inserted every two rows of bagwork, piercing 3 rows of bagwork with a single 300mm long pin.

Should the bagwork be placed dry with the intention of hosing the bagwork in situ, we recommend that each row is placed and wetted in situ individually, wetted for at least 3 minutes to ensure adequate take up of water to achieve full hydration and strength.
Upon completion of the works, if used, the temporary bath of water should be emptied and disposed of in a safe and environmentally acceptable manner. Bear in mind that the water will be of high pH, may be sediment laden and will contain dissolved liner material. This water should therefore not be discharged into any watercourse.

We would also recommend periodic inspections are carried out to check for any damage from other factors such as adverse weather conditions, vandalism, contamination, etc.

The main difference between bagwork placed above a watercourse and bagwork placed away from a watercourse is that typically bagwork cannot be hosed down during placement and will need to be pre-soaked. This is to avoid the potential for water flushing off the bagwork and directly entering the watercourse. Where the watercourse has been dewatered for the construction works, hosing concrete bagwork can sometimes be undertaken although this is usually subject to regulatory consent and a suitable and approved method statement. In those instances, care and consideration should be made to the potential risk and consequences of any flushings then entering the watercourse.

For above water placement, similarly prefilled bagwork supplied as a dry mix needs to be hydrated prior to placement. This should typically be achieved by pre-soaking the lined bagwork in a bath of water for approximately 15 minutes prior to placement. The water soluble liner will begin to dissolve in 5 seconds and is typically fully dissolved within approximately 15 seconds, sufficient enough to allow water to readily soak into the dry mix to harden the concrete. Typically a 20kg bag will absorb around 4L of water during this process so it is important to have a ready supply of water available and to top up at regular intervals.

When ready to use, each of the bags should be removed from the pallet and fully submerged in a suitable bath of water. Once hydrated, the bagwork can be carefully lifted from the bath and excess water allowed to drain. The pre-soaked bagwork should be carried, individually by hand or using a wheel barrow, to the site of placement. The worksite should be approached from the dry side, such that pre-soaked bagwork is not carried over or through the watercourse unnecessarily, where slips, trips or falls could result in the bagwork being dropped into the water. The Contractor’s method statement should include measures to ensure that pre-soaked bagwork is not carried through a watercourse, unavoidably.

Each bag should be carefully placed horizontally, taking care not to drop, snag or tear the bags on sharp objects. Bagwork is to be placed flat and built up in rows, typically alternating or cross bonding bagwork. Cross bonding improves the strength and effectiveness of the finished concrete blockwork. Bagwork can be patted flat or shaped once placed, to improve the appearance of the bagwork and reduce the amount of voids within the finished blockwork.

After the second or third row of bags, steel rebar pins can be pushed down vertically through the bagwork to tie all the blockwork together, with additional steel used to tie subsequent rows. Pins can be inserted by hand, or if a hammer is used, this should be a rubber mallet.  Steelwork is not always needed for above water bagwork although we do recommend that it is used wherever the bags are needed for medium to long term works, or where they fulfil a role of providing protection against scour. It also protects against vandalism, or blocks becoming dislodged during flood conditions. Typically standard 300mm long steelwork pins are inserted every two rows of bagwork, piercing 3 rows of bagwork with a single 300mm long pin.

Due to the risk of uncontrolled flushings entering the watercourse, we do not generally recommend wetting insitu for over water works, however in controlled situations this may still be possible. The use of non pre-soaked water soluble bagwork in above water applications should only be considered following an assessment of environmental risk and regulatory approval. Should the bagwork be placed dry with the intention of hosing the bagwork in situ, we recommend that each row is placed and wetted in situ individually, wetted for at least 3 minutes to ensure adequate take up of water to achieve full hydration and strength.

Upon completion of the works, the temporary bath of water should be emptied and disposed of in a safe and environmentally acceptable manner. Bear in mind that the water will be of high pH, may be sediment laden and will contain dissolved liner material. This water should therefore not be discharged into any watercourse.  We would also recommend periodic inspections are carried out to check for any damage from other factors such as adverse weather conditions, vandalism, contamination, etc.