42” Pompeii in San Felipe, MX

[modified9v]

These cracks are popping up after two days. Using standard Homebrew with the ingredients shown in the pic... Thoughts??? Start over no big deal??? Now is the time to correct this.

Thanks, Mike

[Chach]

are you soaking your bricks so they are damp...looks like the mortar is drying out to quick or the mortar is too wet to begin with and shrinks when it drys out

[JRPizza]

I found just the opposite - I had some fairly dry mortar and even though I was dampening my bricks I had trouble when I first started out (see posts below). When I switched to a more sloppy mortar and just damp wiped my bricks so that the edges changed color, they seemed to draw the liquid slurry of the mortar into the imperfections/openings in the brick surface, and when that material set up provided the holding power needed. If the mortar isn't engaging into those imperfections, it won't hold. From what I found, the mortar can't be too dry or the brick surface too wet or that wicking action won't occur. When I got to the upper portions of my dome I was able to work without having to clamp my bricks in place - I kind of found the right combination to create "grabbiness"_.

https://community.fornobravo.com/for...558#post380558

[modified9v]

Thanks for taking the time to respond. JR, I went back and reviewed your build where you talked about mortar. That is exactly what I have going on. These bricks are super dry. They have been sitting in the desert sun for several months now. What I did was put about 5 half bricks in a bucket of water and then scrubbed each one with brush. When they were in the water they bubbled and hissed like crazy. I then set them in the sun for a few minutes... then mortared them in place.

I did notice that some of the comments on your thread were to NOT take it apart and re-do it. I think I’m going to leave it be and let gravity do the work.

One quick question, is it better to set the bricks with just the mortar on the bottom and then come back and fill in the wedges? Or, do you do the sides and bottom at the same time? I think they call that “pointing”?

Thanks again, Mike

[Gulf]

Though, I did point mine during my build, I think it is best to fill the entire head joint at once. What you may want to try on the next course is to leave the mortar mounded up over and bulging out of the joint for a few minutes (15 minutes max). Then, tool the joint. Tooling is not shaving the mortar off even with the brick with the edge of the trial. It is sort of pushing the slump into the joint and removing it at same time. Dragging the margin trowel over the joint should work ok for this. If not, find another flat metal tool tha is a little wider than the joint. The shade that you have over your build will help. But, given your dry climate, covering the dome underneath with plastic or a tarp should also help between sessions.

[JRPizza]

I agree with Gulf in that the more you can get in the joint initially the better. I would put a brick in my IT and place it in it's intended location, marking the location of both edges if it was a first brick in the row, or the free edge if there was a brick on one side. I'd then place a wedge of mortar under the brick foot print, thin at the inner edge and thicker at the rear. I would then "try" to pack some mortar in the angle wedges on the sides, then press the brick into place displacing as much mortar as needed. Quickly I'd try to pack in the sides to fill any voids, then after setting the next brick go back as Gulf says and scrape off the excess extruded material. I was never able to get the sides filled enough to not need to add more mortar as you have to drop the brick into place with the sides sliding relative to the adjacent brick. I never did any pointing on the interior with this method and only had to backfill the sides and some of the rear joints.
Lastly, don't have your bricks too wet. I learned on the forum (can't remember who or I'd give credit) that you need your bricks to draw the mortar into their surface. If they are saturated or the imperfections are filled with residue from cutting you won't get a good bond. I had even let bricks set after a good cleaning so that they weren't too wet.

[modified9v]

Thank you for the comments... I’m taking a piece of everything I read/see and this is where I am... yes, been ditching dealing with the arch... tomorrow! Thinking I like this Homebrew. Man, it is sticky.

[UtahBeehiver]

Finally making some headway after all the repours to correct the bad concrete. Courses looking good with good staggers. Probably will start to see some inverted "V" next course unless you start to bevel the sides. Remember, you only need to bevel the front or inner dome portion of the bricks where the joint surfaces conflict then fill the back side in with mortar like you are doing now. You might want to consider starting a taper inner arch now. It is easier to tie into an arch that is in place versa tying an arch into the dome.

[modified9v]

Thanks Utah, it feels good to get rolling. Your explaination for cutting the bevel at the contact point is crystal clear now. Those cuts will be really small... like slivers almost.

Now, about that tapered arch. Ugh, that is a difficult concept to wrap my head around but I will give it maximum effort. I think the next brick going up in the arch will be easy but after that I get lost. I think I’ve read every post here on tapered arches but for some reason it really screws with my head. I’ve seen how the IT is used to determine all the cuts and how it is suppose to look when its done... but I’m still lost. Maybe I need to just do it and quit thinking about it.

Thanks again, it’s starting to get fun... Mike V.

[UtahBeehiver]

PM me an email address. I have a pdf (which I cannot attach to this forum) to help explain the some of the aspects of a tapered arch. It is a difficult concept to visualize but not too hard to physically do. It is well worth the effort.

[UtahBeehiver]

On it's way, remember you need to start with "full" length bricks with the longest one being at the "top dead center" of the arch.

[modified9v]

Got it... gracias!!! In looking at the 1st picture in your last post... the face of the arch where the door will contact... those look to be tapered too (template)... is that necessary for the build to be strong or for aesthetic purpose. I understand that the inside is tapered to make the intersection cleaner and easier.

[UtahBeehiver]

I did taper the arch bricks so I would have uniform thickness mortar joints also my bricks were 5.5" wide vs 4.5" std bricks. That said, you do not need to taper the arch bricks but you will end up with a fairly wide mortar joint on the OD if you do not. There is a program link on the forum somewhere called the Angleizer that will calc the brick size, number based on arch size and joint width. You will have do a search to find it.

[modified9v]

I’d really like to taper them too... I have the angle figured out just struggling with the jig. 10” blade is an issue... pretty sure I’ve seen some killer jigs out there on the forum. Looks as though if I can get them cut I’ll have a solid arch that works out well mathematically. I think I also saw that some have used wedges of brick to fill the monster void as well. So little of that mortar wedge would be visible, but I’d much rather have brick than mortar in this critical location.

Thanks again for the help today... Mike V.

[UtahBeehiver]

I used a 10" HF saw and a simple jig. You need to cut from both sides and use a angle grinder with a diamond cup to smooth out or feather on the wet saw using the side of the blade.
bricks cut offs under the brick for the right angle and a flat piece of brick on the left to hold brick from moving laterally.