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himzol
22nd October 2004, 10:34 AM
Hello folks,

One of the projects I have on the go at the moment, started before I went to the Melbourne WWW show is a retaining wall. I'm using garden wall blocks - you know the type get the base right and the rest just stack on top with a lip at the back.

Anyway the situatiuon I have is that one end of the wall will be some what free standing (the low end in the pic), what I need to know is what sort of adhesive could I use on this end to make sure that the blocks dont go wondering off, mainly concerned with lateral movement.

The end will be about 3-4 blocks high.

For what it's worth the original retaining wall was made up from redgum sleepers held back with star droppers (very elegant ), Oh well at least I get some salvaged timber out of it.

Himzo.

namtrak
22nd October 2004, 11:07 AM
When you say free standing, do you mean there is nothing behind the bricks? If I have it right the bricks you are talking about are generally held in place by their own weight and the weight behind them. I suspect if you take the weight from behind them they will mot likely topple over, regardless of the glue/mortar. Have you got a photo of the bricks or wall?

For the record you could use either liquid nails (there is a mortat mix) or mix up a brickies mud (4 parts brickies sand to one part cement - more or less)

vsquizz
22nd October 2004, 11:25 AM
What Namtrak said but drive some Reo rod vertically down through the bricks, at least for the lower two courses, if you can.


Cheers

himzol
22nd October 2004, 11:28 AM
When you say free standing, do you mean there is nothing behind the bricks? If I have it right the bricks you are talking about are generally held in place by their own weight and the weight behind them. I suspect if you take the weight from behind them they will mot likely topple over, regardless of the glue/mortar. Have you got a photo of the bricks or wall?

No, there will be plenty behind the wall, what I reall need is something that will stop the last one or two blocks from moving sideways.

How waterproof is the liquid nails ? where I am and more importantly where the blocks will be gets a bit of rain and run off during the winter months.


Himzo.

himzol
22nd October 2004, 11:32 AM
Reo rod :confused: :confused:

Whats that,

H.

vsquizz
22nd October 2004, 11:34 AM
Reinforcing rod that is normally put into concrete construction. Better known as Reo. Cheap as chips from most steel suppliers and hardwares. Nothing to do with Rio.

Cheers

himzol
22nd October 2004, 11:59 AM
Thanks Squizz,

I don't think I'm going to need that, the bottom two or three or somewhere in between will butt up against a fairly substancial step (brick/morter etc..).

I mainly wanted to know what adhesive was available as the wall will "step up" away from this end towards the higher end of the wall. The last block on each step up is what I want to fasten so that there is little lateral movement.

Himzo.

PS. I thought it was a Hot Rod made from a REO Speed wagon :rolleyes:

namtrak
22nd October 2004, 11:59 AM
Okay, use the reo (should use it on the whole wall anyway) and fill the blocks with a nice slurry. Are you capping off the blocks or are they solid already?

himzol
22nd October 2004, 12:21 PM
Are you capping off the blocks or are they solid already?

Solid already,

I'm not sure that the rod will be necessary as there will not be a huge amount of prssure behind the wall, the embankment is fairly stable it's mainly for asthetics and to stop soil erosion. In any case what I've done is made the base layer halfway below the soil line after the compacted roadbase etc. so it shouldn't move forward (touch wood).

As I said the original wall (if you can call it that) was just redgum sleepers held back with star droppers, this didn't move after a year to 18 months which is how long we've been at this place. The reasons for change is that I don't believe that redgum should be put in the ground to rot, and this is where we have our BBQ's in summer and it looked really ugly.

Himzo.

jackiew
22nd October 2004, 12:40 PM
hi himzol

how deep were your original star pickets into the ground? If only a few inches you are probably right that your embankment is stable. If they went down more than a foot then I suspect you would probably be safer with reinforcing rods. Wet earth can exert quite a pressure.

The extra effort and cost would be minimal.

cheers

Jackie

namtrak
22nd October 2004, 01:06 PM
I agree - dont underestimate the weight behind the retaining wall. The load is known as the lateral earth pressure. Any manufacturer of retaining wall blocks should have handy the specs for load carrying.

Having said that though, I think what your looking for would just be a mortar mix of some sort, either brickies mud, or pre-mix mortar. I personally have only used liquid nails mix on caps and they seemed to hold okay.

Cheers

Slavo
22nd October 2004, 01:32 PM
Himzol, what kind of blocks are you using? The place we recently bought has the same Euc sleepers and star pickets and we are looking to replace them. Can't identify the timber 'cause it has been in the weather for many years. And we don't like subsidising housing for termites (already had to replace the pergola). Anyway, what made you decide on the type of blocks you are using?

Slavo

barnsey
22nd October 2004, 01:55 PM
As a matter of interest, most of the paving, block makers have technical support people who will be able to tell you what their product can and can't do and how to do it.

Just a thought coz around these parts with the heavy rain earlier in the week one guy came home and found the terraced site he'd recently completed was siting on the road in front of his house :D :D Another one got crossed of the Christmas card list of his neighbour over the back fence when his landscaping moved significantly and prevented his neighbour from getting in or out of his house :eek: :eek: :D

himzol
22nd October 2004, 04:37 PM
how deep were your original star pickets into the ground?

Jackie,

Not very far, just far enough to hold the wall upright. All but one came out pretty easily. Most of the material behind the original wall was a mixture of topsoil and mulch which had been washed down behind the wall. I think the original wall was only put up to stop this stuff washing down onto the lawn (flat area covered in weeds).

Slavo,


Anyway, what made you decide on the type of blocks you are using?

The choice was made for me, I was given about fifty blocks by a work colegue who was moving house and these were surplus to requirements, I do however need to purchase more as there was only enough to start the job.
They are the solid concrete blocks that have a lip at the back on the bottom and sort of a rought three face front. I think they call them garden block. At the moment they are about $5-$6 each in Adelaide.

Before you even start to replace the stuff you have, check with the council, you may have to get an engineer in if the wall is over a certain height.

Himzo.

TassieKiwi
23rd October 2004, 08:44 AM
The main cause of failure of any retaining wall is from water pressure. Think of all of the crooked walls that youve seen around the older suburbs - evidence of drainage through the base of the walls is not to be seen. You MUST have some form of drainage behind the wall to release any water, either out the ends or through the base.


Den

Marc
23rd October 2004, 03:13 PM
Himzo, why don't you build a small pillar with corner blocks? this way you can forget lateral movement for the end of your wall.
You could also make the end of your wall turn into the embankment. You may need to dig a small trench. This will give you a curved finish and it would be very strong.

adrian
23rd October 2004, 06:45 PM
I think the re-bar suggestion was pretty well spot on as the most effective alternative. After you lay the second course drill a hole in the end block to the size of the re-bar lift it off and continue the hole in the first, hammer in the re-bar then repeat the process for the next.
Effectively nailed together and no way are they going to move until the re-bar rusts away and I think the re-bar would still be there long after any cement or glue would have given way because of earth movement.

himzol
25th October 2004, 10:07 AM
You MUST have some form of drainage behind the wall to release any water, either out the ends or through the base.

Den,

Way ahead of you on this one, I've spent the last eighteen months fixing drainage around the house where there was none, thanks to the previous owners home improvement ideas. Also repairing the resulting damage. This wall will have an Ag pipe inside a sock laid behind it with an exit on the odwn hill side. The pipe will then be covered with aggregate before the final topsoil.



Himzo, why don't you build a small pillar with corner blocks? this way you can forget lateral movement for the end of your wall.

Marc,

It's not the lateral movement at the end of the wall that concerns me, though the pillar idea does interest me, It's the lateral movement of blocks further along that step the wall up to the high point.


You could also make the end of your wall turn into the embankment. You may need to dig a small trench. This will give you a curved finish and it would be very strong.

This was one of the first thoughts I had but strange as it may seem it would look out of place.



Himzo.

Trav
26th October 2004, 01:07 PM
I reckon we may be going over the top here. I've got a wall like this and, while it is only 4 blocks high, I don't need any reo rod or mud between them etc. I didn't even think of it to be honest.

All I hvae done is set the bottom course in mud and piled the blocks up. The design of the wall is to lean backwards anyway and unless you have a big slope, I don't think it is going to go anywhere. There are heaps of small gaps that let any excess water seep through to prevent any build up of pressure etc.

I put some ag pipe down at the base of the wall and covered it with gravel and then brought in the soil. But I don't have much of a slope so it isn't much of an issue for me.

The brochure I have suggested that you use liquid nails (exterior) on the top course if you have a risk of vandals. I guess it would work on the ends to stop the blocks shifting laterally.

For what it is worth.

Trav