Biziwe

Blast Prone Ventilation Walls

The premier product supplier to ventilation wall applicators who deliver long-term ventilation solutions to the mining industry. The Robust Building System provides a unique blast prone ventilation wall up to 60 meters from the blast face. It has a superior strength of 40 Mpa compared to normal brick and mortar walls.

Method

Creates a backing to which the Robust core panels are fixed with pre-stressed wire of vertical props with horizontal timber at various intervals.

Tie or screw Robust core panels to the backing by overlapping each panel by 20mm. (Panel length size to the maximum height of opening).

For standard ventilation walls apply a 75mm thick 25Mpa shotcrete mix to only one face of core panels to complete the wall structure.

For blast prone walls, apply a 75mm thick 40Mpa shotcrete mix to both faces of Robust core panels with added 8mm horizontally spaced reinforcing bars.

Customer Benefits

Less time required to transport material and erection compared to other methods available
Cuts maintenance costs
Restricts access to illegal miners
Reduce cable theft
Saving on power costs associated with ventilation at the workface
Robust ventilation walls are blast prone – test has proven that walls remain intact 60m from a blasting face due to its monolithic structure
Good ventilation means excellent productivity.

Securing of walls to ground surface

Due to the fact that the ventilation walls do not carry substantial weight it is not necessary to make use of foundation.

Although it is preferable that all ventilation walls are built on solid ground, and not on soft soil, we suggest that the following standard and steps be taken when building on loose soil and/or solid rock:

Fitment of walls on loose soil base surfaces requires 2 x 1300mm x 10mm reinforcing bars and on solid base surfaces requires 2 x 650mm x 10mm reinforcing bars, placed 60mm parallel to each other, hammered in until it protrudes 500mm above ground surface, spaced at intervals of 400mm over the length of the wall. The Robust walling panels are then fitted and secured to these protruding vertical reinforcing bars using binding wire. If it is not possible to hammer any specific peace of steel up to the required depth due to specific rock structure, the 10mm rebar can be moved either way until it reaches a place where it can be hammered up to required depth on the condition that it is not further than 600mm away from the inserted rebar’s on either side thereof.
In order to strengthen the bottom section of the ventilation core walls that are on loose soil surfaces, we suggest that the first rebar steel rods that run horizontally and parallel to the ground level be done with 10mm rebar. These 10mm rebar rods must not be more than 200mm from the surface, and must be fully covered with shotcrete. Spaced horizontally at 500mm c/c on both sides of core wall panels, the rest of the horizontal reinforcement is done with 8mm reinforcing steel bars.
Fitment of walls on firm or solid ground surfaces requires 2 x 550mm x 8mm reinforcing bars, 60mm parallel to each other, hammered 150mm deep into 150 x 8mm pre-drilled holes, spaced at intervals of 500mm over the length and height of the wall. This will leave a protrusion of approximately 400mm reinforcing bars above ground surface and on the side and hanging walls to which the Robust walling panels can be fitted and secured.
The protruding 8mm rebar rods on either side of the two side walls must be connected to each other by way of splicing after the steel frames have been inserted into position. This will mean that the rebar rods will cover the total horizontal width of the opening at intervals of approximately 500mm. The steel frames must also then be fastened with wire to the 8mm rebar rods which runs parallel to each other on both sides of the steel frame.
When fitment is done on firm or solid ground surfaces, all horizontal reinforcing can be done with 8mm reinforcing bars.

Shotcrete applied to walling surfaces

After Robust core panel walls are checked and approved for being secured and stable, the walls are ready for shotcreting.

Each side of the Robust Core wall panel need to be shotcreted up to a thickness of at least 50mm from the deepest point of the Robust core. Because of the “zig-zag” pattern of the Robust core, the total thickness of the wall once shotcreted on both sides, will be approximately 50-55mm. This thickness will be satisfactory as long as all steel products are covered by the concrete, preventing oxidisation to occur on the steel.

Minimum curing time

We advise that the walls should have a minimum setting time of at least 24 hours, preferably 48 hours, before blasting commence within the section that the wall has been erected.

Wall area perimeter overspray specifications

Whole perimeter of wall area must be sprayed on both sides of wall, at a curve that is 75mm at its thickest point if measured to the middle of the steel frame of the wall at an angle of 45 degrees.