Structural Support Membrane and Dam Sealant

USERS GUIDE

STRUCTURAL SUPPORT MEMBRANE AND DAM SEALANT

PACKAGING:

In 20 litres stepped buckets containing a total of 20 kg product per unit, consisting of 17 kg liquid and 3 kg cement, separately sealed in plastic liners, by means of cable ties.

STORAGE:

Always store under roof in an enclosed shed or store. Prolonged heating by exposure to sunlight will result in the rapid development of destructive enzymes in the liquid. Freezing will result in the immediate breakdown of the liquid.

STORAGE (underground):

This will usually be short duration storage immediately prior to usage. The main problem to be aware of is, when used immediately after being removed from a very hot, unventilated store, the reaction of the cement on the liquid is speeded up. Make sure then, beforehand, that there will be no delays in applying the mixed product.

APPLICATION EQUIPMENT:

Developed, supplied and repaired by Ictus Equipment, consisting of:

a Short stem, long clearance pump, complete with lever valve and connection for 12 mm compressed air hose.

b Mixer which fits into stepped bucket complete with lid to fit over bucket to keep the mixer stabilized. This mixer allows the product to be applied in limited height working spaces. A double drum, pneumatically driven mixer for continuous mixing and spraying is available for use in higher working spaces such as tunnels. This mixer allows for batches of up to 60 litres to be mixed at one time in the upper drum whilst pumping is taking place from the lower drum. Upper and lower drums are separated by means of a dumping slide valve. The motor shaft extends through to the lower drum, where it rotates an agitator/pump feed scraper blade.

c Mixer reduction gearbox fitting onto mixer spindle and over lid.

d Pneumatic mixer motor complete with lubricator, lever valve and connection for 12 mm compressed air hose.

e Adjustable spray nozzle complete with connectors for 25 mm material and 12 mm compressed air hoses, 12 mm lever valve for compressed air, bracket to accept extension rods and 2 x 1.5 m length clip-in extension rods.

f Compressed air manifold with connections for 25 mm compressed air hose supply from mine, and 3 x 12 mm take-off hoses supplying pump, mixer motor and nozzle.

g One 10 m x 25 mm material hose and three 10 m x 12 mm compressed air hoses, all complete with fittings and heavy duty clamps.

h Tool bag containing a long, heavy duty flat bladed screwdriver and rubber mallet, used to remove lids of stepped buckets, a side cutter to clip and remove cable ties, an adjustable spanner for tightening connections and a litre bottle of oil for lubricating pump and mixer motor. Sundry clamps, fittings and spares are also carried in the tool bag.

TWO-PART LIQUID SYSTEM – ADHESION PROMOTER

The restraining force exerted by applied Sealaport is equal to its bonding strength x applied film thickness. It is therefore vital to ensure a good bond between the Sealaport skin and the rock to which it is applied.

Once the rock surface to be sprayed have been cleared as thoroughly as is practical and possible, the penetrating adhesion promoter is first applied as an extremely thin coating, using 1 litre per 10 m², i.e. a 0,1 mm thick film. This liquid has been developed to be completely compatible with Sealaport and ensures a bond strength of 3 MPa.

The liquid will penetrate certain rock types, such as Kimberlite, then dry very rapidly to form particle bonding within a thin layer of surface rock.

The adhesion promotion dries within minutes so that, as soon as the surface to be coated have been mist sprayed, the Sealaport can be applied over it. It also assists in acting as a powerful water and water vapour sealant.

Pour the adhesion promoter into a 2 litre bucket and pump it to spray nozzle at a slow pumping rate and with the nozzle’s compressed air supply fully open. This should break the liquid into a semi-mist which must be used to just dampen the surface. Excess liquid must be poured back into its container, using the top of a 2 litre cool drink bottle as a funnel, if necessary. Flush equipment with water when finished.

APPLYING SEALAPORT 3 ST AS A SUPPORT MEMBRANE OR DAM SEALANT:

This can be done as soon as the adhesion promoter has become tacky. It does not have to be completely dry.

Either use the double drum mixing system, mixing 3 x 20 kg units at a time, in which case:

a Pour in Sealaport 3ST from 1 x 20 kg bucket at a time and gradually add its cement with mixer at full speed.

b When all 3 x 20 kg units liquid and cement components have been mixed, dump into bottom drum with pump operating, add next 3 x 20 kg unit mix in upper drum.

OR

If it is preferable to only mix 1 x 20 kg unit and apply it at a time, then:

a Have 4 empty stepped buckets available by removing the sealed plastic liners containing the liquid and cement inside them.

b Fill one bucket with water and keep it at hand in case a stoppage occurs.

c Empty a bag of liquid into the second bucket. “Milk” as much of the sticky liquid out of the bag as possible.

d Place mixer in liquid and turn slowly.

e Slowly empty a bag of cement into the liquid and speed the mixer up until the liquid just does not slop out. The mix should be fine after about 2 minutes of this mixing.

f Whilst the above is being done another bag of liquid is emptied into the third bucket so that when the first mix is ready to be pumped and spray applied, the mixer is moved to this bucket and the mix is made.

g As soon as the pump man’s bucket is empty, he exchanges it for the full one and the next mix is made in the now empty bucket. Any residue from the previous mix is thereby mixed into the new mix, eliminating excessive wastage.

NOTES CONCERNING MIXING OF SEALAPORT 3ST IN BUCKETS

a As can be seen from the above the same two buckets are used for mixing until spraying is complete. The spraying is therefore virtually continuous.

b The stem pump is used to stir the mixture when not pumping to keep the thick product moving downwards to the pump inlet.

c The mixer is not stopped until the pump man is ready to take the next bucket. If left still, the mix will start to thicken so agitation must be maintained until the product has been spray applied.

d The spray operator must aim at covering around 6 to 7 m² per 20 kg unit as evenly as possible. Coverage will also depend on how even the surface is.

e In the event of a stoppage the system must be flushed by pumping water through it.

f The fourth bucket is used to temporarily hold the mixer whilst buckets are being exchanged. This ensures that the mixer does not come into contact with dirt.

CLEANING EQUIPMENT:

This must be done at the end of a spraying cycle or if there is likely to be lengthy stoppage.

Cleaning all equipment is done by means of pumping water through the nozzle and opening up its compressed air fully to create a water blast by means of which every bit of apparatus is blow washed clean. Despite doing this, some material will adhere to the 25 mm material hose. If left indefinitely this will eventually result in a blockage. Cleaning the hose is done periodically on surface by means of passing a stiff circular brush through it, either using screw-in plumber rods or a steel cable attached to the brush.

VARDY MINING & SERVICES

SEALAPORT STRUCTURAL SUPPORT MEMBRANE

1 WHAT IS SEALAPORT STRUCTURAL SUPPORT

A flame retardant, water-based acrylic mixed on site with a high water absorbent cement to promote curing, and then spray applied to freshly exposed rock walls in mine excavations. The applied product cures to form a flexible and elongatable skin, 2.5 mm to 3 mm thick, having a bond strength of 3 Mpa and a tensile strength exceeding 6 – 8 Mpa. These properties act to inhibit the movement of key blocks that result in unravelling of the rock surfaces between temporary or permanent follow-up support mechanisms, such as rock bolts, packs, props, sprays or a combination thereof.

2 WHAT IS MEANT BY “FRESHLY EXPOSED ROCK WALLS”?

Rock walls exposed by the most recent blast. Film application should be the very first operation on re-entry after the blast and barring down of loose rock. This is the time during which the freshly exposed rock walls are at their most competent, and therefore able to provide the most suitable substrate to ensure that the best results possible from the use of Sealaport 3 ST structural support are achieved.

3 WHAT IS THE RELATIONSHIP BETWEEN BOND STRENGTH AND

THE PRODUCT’S SUPPORT CAPABILITY?

As can be seen from the technical presentation, bond strength is directly related to support capability. Mpa bond strength x mm film thickness yields the force in Newton’s acting on each mm of the fracture planes which surround and define a separate rock mass or key block. As an example, assuming the fracture plane periphery surrounding a key block is 800 mm and the area of the key block is 0.15 m², the bond strength of the film is 3 Mpa and average film thickness is 2.75 mm.

Support provided by the film is then:

3.0 x 2.75 x 800 = 6600 N, or 6.6 KN, as support provided is usually expressed in kN/m²; this would be 6.6 / 0.15 = 44 kN/m².

4 HOW DOES DUST AFFECT THE BOND STRENGTH?

Apart from the cement, which is mixed into the liquid on site, the liquid contains numerous other solids, as well as anti-slag thickener and as such it cannot penetrate dust adhering to rock. Until very recently this has been the cause of numerous failures but not recognised as such. A very thin dust penetrating adhesion promoter is now used as a primer for all applications. It has the same adhesive strength as the film liquid and is applied very thin at 100 microns.

5 HOW DOES TEMPERATURE VARIATION AFFECT PRODUCT

PERFORMANCE?

A flexible acrylic is a form of plastic which exhibits both plastic and elastic behaviour. The lower the temperature, the less flexible and more brittle the product becomes whilst a raised temperature has the opposite effect. Prolonged exposure to a high temperature will result in a greater brittleness, although the film will continue to perform well at the high temperature. For this reason additives are used to optimise product performance at various extremes in operating temperature, e.g. 10° C for a shallow colliery in winter and 65° C for freshly exposed rock in a deep mine.

6 CAN THIS FILM STRUCTURAL SUPPORT REPLACE SHOTCRETE?

Definitely not where deterioration of the rock walls has already started. However, if applied prior to any deterioration commencing, and thereafter overcoated in any areas exhibiting undue stress, Sealaport might well be able to replace lacing, meshing and shot creting.

This would be particularly advantageous for mines where multiple in-series shaft systems exists to serve the deeper workings and shaft time is at a premium. The material requirements to be transported using Sealaport 3 ST structural support applied on average 2.75 mm thick is approximately between 3% and 5% of that for shotcrete.

In addition, the application rate is between 150 and 200 m² per hour, which is more than the amount of shotcrete.

7 CAN SEALAPORT 3 ST BE USED TO SEAL DAMS IN MINES?

Numerous dams have already been sealed this way. As a greater elongation and less tensile strength is required of a dam sealant, the product is usually modified to provide these qualities.

8 WHEN IS THE USE OF SEALAPORT STRUCTURAL SUPPORT

INDICATED?

a In face areas where rock falls or rapid deterioration of the rock wall is occurring between and/or ahead of installed conventional support mechanisms.

However, note that the product cannot stabilize already deteriorated rock walls. It is a preventative measure and not a cure.

b On any pillar, and preferably whilst it is being cut, to inhibit scaling so that the full cut area of the pillar remains available as a support mechanism.

c The hanging wall of stope dip and strike gullies must include sufficient membrane on either side to incorporate the first line of support packs.

d Coating of any rock type, which degrades when exposed to the atmosphere or water.

d Coating of any rock type, which degrades when exposed to the atmosphere or water.