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-   -   How to repair crumbling cement and mortar? (http://www.diychatroom.com/f2/how-repair-crumbling-cement-mortar-67723/)

jerseyguy1996 03-27-2010 02:21 PM

How to repair crumbling cement and mortar?
 
I purchased a home last August in NJ. We had a few good strong snow storms this winter and now the concrete on the front porch is crumbling in a few places. In addition, the mortar in between the bricks is turning to powder. From what I understand this porch is not that old. When I pick up pieces of the cracked cement it seems that it is mostly sand with just a tiny amount of cement. The mortar is the same way. I am just wondering if this was just a really cheap job done by the contractor or if it was caused by all of the snow storms. I have included pictures. My question is: What is the best way of fixing it? I am guessing I will need to remove all of the layers of brick and put in new mortar but what to do with the cracked concrete? In most of the pictures below, my hand is placed there for scale.

This photo shows a cracked top plate (Not sure if I am using the right term)

http://farm3.static.flickr.com/2757/...48af2bf5_o.jpg

This is the mortar between the top plate and the bricks.

http://farm3.static.flickr.com/2791/...719d47bd_o.jpg

Close up of the crumbling mortar.

http://farm5.static.flickr.com/4013/...beef04df_o.jpg

The top plate isn't adhering to the bricks underneath at all and I can lift it with my hand.

http://farm3.static.flickr.com/2760/...fa5eb5fb_o.jpg

This is a piece of the concrete that chipped out. This image shows the thickness of the piece that came out. As you can see it is only about an inch thick. Underneath it is a crumbling and I can't tell if it is just loose sand underneath or more crumbling concrete. I will be extremely upset if the thickness of the concrete turns out to be only 1" unless someone on here tells me that this is normal.

http://farm5.static.flickr.com/4072/...09023e30_o.jpg

More crumbling mortar.

http://farm5.static.flickr.com/4062/...dacf30da_o.jpg

More crumbling concrete.

http://farm5.static.flickr.com/4025/...7b29e163_o.jpg

tpolk 03-27-2010 05:26 PM

how old is the work i'm looking at, appears some freeze thaw issues but not so good mortar mix. is there a skim coat on some of that material

Ron6519 03-27-2010 09:33 PM

Looks like you'll be removing everything pictured. Powdered and crumbing would be words describing a very bad mix of mortar. The cracking I see would be helped by the weather and maybe a poorly graded landing. water gets in and freezes, spliting whatever is close.
Ron

Snav 03-27-2010 09:53 PM

If I were tackling your issue I'd:

Scrape out the bad junk with a chisel.
Get some good quality mortar that will handle weather well (not all are created equal).
Craft a form for the verticle-edge out of wood (nothing fancy) so the new mortar can be set in place, of course, coat it with mortar-release so it doesn't become permanent.
Get a grout bag - fill it with mortar - and inject, fill all areas, smooth it with a scraper, press wood form against vertical area and hold in place with bricks or weights.
Let dry . . tada . . . magic.

ccarlisle 03-28-2010 07:48 AM

It's not just a question of a good or bad quality mortar...and I'm pretty sure that wasn't the gist of what one poster mentioned. It's the type of mortar that is important.

Type N, Type O, Type S etc are all types of mortar and every manufacturer makes each one. There is one specific mortar for in between exterior bricks and stonework like you have. Most problems like that occur because of the wrong product used...

Giles 03-28-2010 02:23 PM

I am no expert but I have dealt with this type problem many times. I worked at a large industrial plant where there were many "brickmasons" available for me to ask questions.
By what I have been told---morter of any brand should not be used if it has "lumps". It has partually hydrated and will be weak. This could have been the issue in your case.
If I was dealing with this issue, I would tear out all the defective work and start from scratch using what I could.
Also thin concrete will be weak and subject to heaving in cold weather.

ccarlisle 03-28-2010 02:46 PM

A lot more than lumps...Up north here you have to consider the fact that some mortars expand when frozen more than others...beyond a certain point they become stronger than the brick they are meant to hold together. So they shatter the brick. Common around chimneys and ledges.

jerseyguy1996 03-28-2010 05:04 PM

This is all great information guys. Regarding the type of mortar to use for the bricks. Does anyone know what type to use? Someone mentioned type N, type O, type S, etc. In addition, is there a specific type of concrete (I was going to use a quikcrete product) that I should be using for the concrete surface?

ccarlisle 03-29-2010 07:19 AM

Type N.

Tscarborough 03-29-2010 07:20 PM

You always use the weakest mortar that will work. Type N is probably the best choice, especially if it has a lime component. That is all tearout and redo work, no other way.

jerseyguy1996 03-31-2010 11:19 AM

Quote:

Originally Posted by Tscarborough (Post 421436)
You always use the weakest mortar that will work. Type N is probably the best choice, especially if it has a lime component. That is all tearout and redo work, no other way.

Looks like I will be tearing it out, assuming this rain ever stops. Hopefully the concrete will get thicker the further back I go. I pulled out a few pieces and it is indeed only about 1" thick. Underneath is loose sand. No rebar or reinforcement anything as far as I can tell. Can anyone tell me how thick the concrete should have been? Also should it have some sort of rebar?

ccarlisle 03-31-2010 12:18 PM

Over time, any mortar that gets repeatedly wet, then dries - with or without freezing thrown in - will eventually weaken as the salts within the concrete leach out, a process called efflorescence. But that only applies to the actual mortar that gets wet, so any mortar that remains dry will not be thus affected. So I wouldn't expect crumbling mortar the further down you go...

Now if you still find disintegrating mortar further down, then that points more towards a bad batch like too much water or something.

But in all this, you are going to have to think about some way of reducing the amount of water that collects there, if possible. I mean you can't very well put an umbrella out there every time it rains but you can do something about water collecting after a storm with better grading of slopes etc. But using the correct mortar in the first place - with proper build-up of joints - will go along way in wiping out the problem in the short and medium term.

AlDaja 04-01-2010 02:23 AM

Man...that sucks. I had to deal with something very similar, or lose my porch. I wound up resurfacing my porch and masonry work and as already mentioned, completely rebuilding areas that had crumbled like yours has. I personally went with Type S. It's a bit more expensive but can handle the compression from the bricks, rocks, etc. plus heavy foot traffic and severe weather swings. I live in Colorado and have had great success with Type S masonry.

Type S mortar

This uses a 2 / 1 / 9 mix and results in a mortar with a 1,800 psi compressive strength. Type S is used for below grade work and in such areas as masonry foundation walls, brick manholes, retaining walls, sewers, brick walkways, brick pavement and brick patios.

If using concrete ready mixes, the crack resistant pre-mixed bags stand up great against extreme temperature swings and is very good at repealing freezing damage.

As a note, when you finish rebuilding/repairing your masonry, coat everything with Thomson Water sealant. I do this every couple of years. It helps resist water damage and put a nice shine on the rock/brick work.

Missfix 07-31-2010 06:28 PM

Mortar Repair
 
Found some really good info, glad I joined!

Hemingway 08-01-2010 10:49 AM

You could look up my posts on the same subject. Bottom line, my repairs failed because there are no expansion joints in the original work. I'm going to have to rent a cut off saw and create some separation between slabs.

I've also had a problem with some of the concrete here and I wonder if they used beach sand. Sand from Raritan Bay is cheap but salty.

I'm from Jersey, you from Jersey?


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