Making good below ground

[NorthWest1]

Hello,
Can anyone advise on making good brickwork, below soil level. I am doing a lead replacement and am about to go through the foundation wall with a 4'' duct. I was originally going to core through, however the bricks ( cherry red ) look different to the ones above ground, I'm told these may be engineering brick and the core won't touch them. The mortar is a black/blue colour. When I remove the bricks and make good around duct, do I need a specialist mortar or will some ready mix concrete do ?

 

[Wayners]

Old property with lime mortar?
Maybe read up on that.

I used to cover bricks with duck tape to keep bricks clean when repairing.
Pull tape following day or when mortar is set.

 

[NorthWest1]

Thanks for reply.
The property is about 80 years old. I'll look into the lime mortar thing. I don't suppose it's a huge deal as I'm only removing a couple of bricks, I just assumed that mortar that sits below ground, wet most of time, would just erode away.

 

[noseall]

Thanks for reply.
The property is about 80 years old. I'll look into the lime mortar thing. I don't suppose it's a huge deal as I'm only removing a couple of bricks, I just assumed that mortar that sits below ground, wet most of time, would just erode away.

It will be stronger than ever.