I have a brick front to my house, and have two 7' wide foot garage doors which have a roughly 2 foot wide column of brick that separates the doors. There is a brick lintel above each door which appears to be about 3/8" thick, and is attached to the respective header above each door. Each lintel extends about 3" on each side into the neighboring bricks (leaving a roughly 20 inch gap between the two separate lintels). There are 4 courses of brick above the lintels, so not too much weight supported. My goal is to remove the roughly 2 foot wide column of brick in the middle of the doors, create one large 16' door, and ensure the bricks above the current "gap" between the existing doors is strong enough to support the bricks. I'm planning on leaving the existing (separate) door headers in place, and "sistering" one long laminated header on the inside of the garage to support the weight. My question is this: Can I use the existing lintels and connect them together somehow to support the bricks above the entire 16' span once I remove the center column of bricks? I was thinking I could either weld a piece of bar steel to connect the two lintels, OR I could get a larger lintel which I connect to the new 16' header which will below each separate lintel and support their weight. I'm assuming the option of getting a larger lintel, connecting it to the new laminated header, and using that to support the weight of the separate lintels which is currently supported by the brick column between the doors. Let me know if I'm on the right track, or may have other options. I know that removing the lowest course of bricks along the existing door headers, removing the existing lintels, and replacing them with one long 16+ foot lintel is an option, but it one I'd like to avoid if possible.

This is actually and indoor question, but I didn't see anywhere to post it. I am wanting to make concrete countertops for my bathroom remodels I am doing. I can't find any "countertop mix" here. The closest is over 3 hours away. What would you recommend that I use for a concrete mix for my countertops? Thanks!