Inspection chamber benching

[Pepsiandshirlee]

What is the mix for benching an inspection chamber ? As in sand cement etc ? Any other liquids ? Needs to stop tissues sticking on benching . Also is it trial and error ?

 

[polesapart]

3:1 sand : cement (some would even go 1:1) , you lean in and contour/shape/polish it as it goes off.

Waterproofing/accelerant additives as you like.

 

[Pepsiandshirlee]

Thanks. .What products are used ? If you could attach a photo of products for waterproofing and accerlant additives . Has it got to be straight or more rounded or trial and error . Not sure of process .

 

[Hugh Jaleak]

If you really want the proper stuff, then that's Granolithic Mortar or 'Grano' for short. 6 parts grano dust, 2 parts Portland Cement, and 1 part sand, with just enough water to make it into a workable mix. https://www.pavingexpert.com/grano_01

No mix will stop tissue sticking, the art is in getting the benching shaped to prevent material building up.

 

[Pepsiandshirlee]

If you really want the proper stuff, then that's Granolithic Mortar or 'Grano' for short. 6 parts grano dust, 2 parts Portland Cement, and 1 part sand, with just enough water to make it into a workable mix. https://www.pavingexpert.com/grano_01

No mix will stop tissue sticking, the art is in getting the benching shaped to prevent material building up.

Thanks . Any particular way to get benching shaped ? More cement in one area ? Straight slope or bend with cement ? Hard to get it more rounded Or is it trial and error ?

 

[Hugh Jaleak]

A stiff mix of Grano, build it up in thin layers. Keep channel wall vertical up to the crown of the pipe, then slope it back to the walls. Photo of said Manhole will help us advise better.

 

[Pepsiandshirlee]

A stiff mix of Grano, build it up in thin layers. Keep channel wall vertical up to the crown of the pipe, then slope it back to the walls. Photo of said Manhole will help us advise better.

 

[Hugh Jaleak]

Thanks. I'd build the benching up on the opposite side, in thin layers if need be, to make a vertical 'wall' opposite the slipper, to at least level with the crown of the outgoing pipe, ideally to level with the crown of the slipper. Solids should then hit the opposite wall and fall into the channel, with following discharges washing any residue away.

You're lucky its a shallow chamber, nice and easy to work in.

 

[Pepsiandshirlee]

thanks . How long if laying a layer with extra rapid cement should I leave it dry between each layer ?

 

[Hugh Jaleak]

As long as it needs to go off.