Concrete repair

I need to make a cosmetic repair to a four foot high square concrete column in the basement of my parent's sixty year old house. I plant to clean all loose material and build a form and pour loose mortar mix in helping it along with a steel rod with a little flex to it. Then I got to thinking that Portland may be better than mortar mix. Any masonry experts out there?

If its only cosmetic box it in with PT wood or pvc
trim and go fishing its Friday!

I'd go with a Portland mix. Mortar mixes are softer. Not an expert, just my $.02.

Larry in Michigan

Portland is Portland Cement, the cementitious material that bonds the aggregate together in concrete, mortar etc. There are 2 types; Type I & Type II Portland cement and I don't know the differences between them, believe it or not and I should, seeing it was part of my construction career.

You should clean the substrate, (column) back to good material, hopefully the spalling is not occurring through the middle of the column, meaning the column is failing or will fail, you should determine this, or your work is a waste of time, meaning time to replace it. Also have to wonder what caused the problem, poor materials, moisture, things like that, so you can prevent it from happening again.

Once you have determined that the majority of the column is still good, clean the substrate and wash it down, get rid of loose fines etc. There are a myriad of materials you could encase or parge the column with. I would suggest panzer mesh, or similar woven reinforcing, then use a portland based non sag material to parge it with, and follow the MFR's instructions closely, surface prep and application. You can attach the mesh to the substrate, leaving some space between it and the substrate, just don't bubble it out beyond the thickness of your parge coat. Dryvit makes a great system that you can apply to something like this, it's meant for exterior use, but the base (Primus-what they call it) does trowel/plaster on nicely, and can look good if you are good with those tools. The mesh will really reinforce it and tie back to the substrate, powder actuated fasteners, masonry fasteners, are fine, use something that won't rust. You may also find materials that require something to bond the parge coat, like an epoxy, like when doing this to a cold joint on concrete, always pay attention to the MFR's instructions.

If using a portland based mortar, which is superior to say anything acrylic, gypsum based etc. make sure when you apply it that the substrate is not bone dry, when you apply a material like that, the substrate will quickly and too rapidly absorb the water out of your portland/water based material, causing it to fail, I always soak the substrate or existing material so that this does not occur, it can prevent it from bonding and cause it to fracture.

If you form out and pour, you will need a little more thickness for rebar and the material, and I think a concrete would be better than a mortar. You still have to prep and reinforce the column, have enough thickness to cover the aggregate, use a woven wire mesh at this point you would be better going out 4"-6" and just pouring a box around it, using vertical and horizontal rebar. I don't see forming out a thin coat/wall around something like this working out well as you describe, better off using a parge/stucco system like Dryvit with a mesh, pouring a wall, or using C.M.U. ( concrete masonry units- block) to encase the existing column, you could also fill the cells in the block, would be load bearing too. All I can think of right now.

I think if you were to use straight portland cement, it might be too brittle when hydrated/cured, it will bond, but I believe it really needs to be part of a material mix design, like a mortar, concrete, grout etc. You need the aggregate and other composite materials of different sieve sizes to achieve thickness, I don't recall ever seeing straight up portland used for parging. It's a fine particulate material, like dust, would make a slurry with too much water, will sag off, and may not work well if mixed up stiff too, (less water) Mortar if applied too thick can also sag and will come off, need to have that mesh and or a material suited for this to achieve good results, as I see it, could be wrong too though !

Post a picture. What you are describing sounds very difficult and come out with a cosmetic appearance. Why 4' high? Does something sit on top of it?

I'd box it in with wood. A treated 2x2 on each corner, form 2x2 frame at the bottom and top or lay 2x4s flat. Frame with your favorite wood or hardiepanel.

Or you might be better off with stucco. A little wire screen and stucco troweled on will give it a nice effect.

If this is a load bearing pillar and its falling apart on its own, not by outside source like hitting it with the car or something. Then you need to completely remove it and replace it with a new pillar. It sounds like it was poured to wet and if so it will just continue to collapse.
Personally if I didn't know a whole lot about cement work I would get a contractor to do the job as the whole house could come down around you.
Better to be safe than dead.
Walt

I agree Walt. It has me stumped on why there would be a 4' tall concrete pillar all by its lonesome in a basement. A basement isn't a basement unless it is 7' or 8' tall. If it was a crawlspace and not a basement, then there would be no need to make it cosmetically better. That's why I wanted a picture and asked a couple questions.

Covering up a little spalling is one thing, but a crumbling support beam is a whole new ball game. Then I'd probably suggest digging a new footing, pour a new footing, and go back with a steel support all sized and spaced accordingly for the load being born.

Guess we'll wait till he posts back with more information.

If it is purely cosmetic it won't matter what material you use. Gypsum plaster skim over a base coat is as good as anything, or maybe a 'polyfiller' material. It depends on the size of the repair. You might just consider a gypsum plaster board onto wood battens.

If you are talking anything structural - that is a completely different ball game. A bit of formwork filled with grout will not be appropriate in that context.

Regards, RAB