My wall is bigger than Trump's wall...Finale

In the previous blog I wrote about the difficult task of digging a trench behind the seawall.  Once the trench was done, building the forms came next.  Rather than get into an in depth discussion about the forms I have decided to just show them to you.  They are kind of a work of art.

From the front side: (note: the pour was done in halves so you can see part of the first section of wall in the picture below)

 From the back side:

There were a few challenges with these forms.  One challenge was that on the canal side kickers could not be placed due to the water in the canal.  Another challenge was that the house side of the form was in 2.5 feet of water.  Another challenge was that there were multiple tie bars and weep holes pipes sticking through the forms causing difficulty in joining the forms together.  Finally the seawall was not level so that the height of the retaining wall changed from 1.5' to 1' relative to the seawall cap.  I kept the entire wall level using the canal water as my guide.

At first I did to know how to accomplish the form building task but after discussing it with dad who had some great ideas which saved me alot of headaches our ideas merged and I was able to pull it off.  Once they were built  it was time to place the rebar. 

Fiberglass rebar is the best rebar product that can be used where salt water intrusion might occur.  Since concrete is somewhat porous or because it may crack, water intrusion will cause steel rebar to rust and eventually fail.  There are a number of solutions to help prevent this from happening like galvanized rebar, epoxy coated rebar or they can even put an additive in the cement to inhibit corrosion.  All of this is extra money and there are issues with the solutions.

That's why fiberglass rebar is the best since it cannot rust and is stronger in tension then steel. The only thing better than fiberglass rebar is free fiberglass rebar which is what TUF-BAR in Canada gave me.  They said large orders are cost effective but because I had such a small order it was not so they gave me 25 pieces for free and just charged me shipping.  Shipping was surprisingly low for the weight involved and distance at about $100.  I always like to save some money on a project so I was very appreciative of the generous donation.  I later acquired 25 more pieces from TUF-BAR and was happy to pay the full price.

Below is a picture of the free rebar from TUF-BAR.

 

My rebar plan was to lay two lines of rebar down the wall one at 12" from the top and one at 24" from the top.  Once I had installed the rebar it was go time for the cement.

For the cement I chose 5000 psi double fiber cement.  As I have mentioned in previous blogs I like to use Advantage Concrete because they mix the cement on site and only charge for what I use.

It was about 4 o'clock when we started the pour on the first half.   The forms I had made to hold the cement were part wood and part seawall and were just under five feet in total wall depth.  The top part of the retaining wall was about 9" wide but below the seawall the width varied from 18" to 24".  This meant that the pour for the first 36' of the retaining wall would take 15 yards of cement which is 38000 pounds.  Yep once this cement was in there and set it was going anywhere.

As the pour started I was pretty nervous.  This was an experiment and I wasn't sure if the seawall would leak cement with all the seams it had and occasional hole.  After all I really could not see what was going on with the seawall under the water.  Way too murky.  Were there large gaps in the seams at the bottom?  If so a lot of concrete would flow through and end up in the canal.  My wood forms had some gaps in them as well.

As the pump guys began I instructed them to put cement in the wall in three passes.  I was hoping that the first pass would set up and alleviate some pressure as they pumped the additional layers in.

 As they started and made the first pass every thing looked good.  The seawall and forms were holding nicely.  It was fast pour though taking about only about 15 minutes which meant that there was not time for setting up.

I don't know what you think but I was thinking at the time that 38000 pounds was a lot and I was a little nervous about the forms being able to hold all that weight.  One thing I had in my favor was the water pressure from the canal would help equalize the force of the concrete on the other side of the seawall.  But concrete is heavier than water.

As the second pass of the poor was started, the pump guys got some concrete on the seawall cap which was right next to the dock I was standing on.  I got the trowel out and went to cleaning it up.  And then I saw something.  The seawall cap seemed to move right before my eyes a quarter of an inch away from the dock.  I looked again but the cap was stationary and I said to myself  "noway I must be imagining things."

I then decided to check the seawall by looking under the dock.  As I was laying down on the dock looking underneath it at the seawall I heard a quite crack.  I dismissed it as one of the pump guys hitting the hose against forms.  I then stood up on the dock and looked at the pump guys progress.  It was going good.

But then it happened.  A loud noise occurred that almost sounded like thunder from a short lightening burst and this time  even the pumps guys heard it over their noisy equipment and they immediately stopped there pump by flipping the kill switch.  I looked at the seawall cap and it had moved a whole 1.5" away from the dock.

After some excited chit chat with the pump guys, I was leaning toward calling the pour off. I told them to wait a half hour.  I then called my dad who was on stand by in Wyoming.  We talked about the consequences of stopping the pour and I was really not wanting a cold joint in my wall which would happen if the cement were allowed to set up and then the wall was finished off later.  The joint could possibly leak sand into the canal as it opened up in the future or the wall might buckle.  We both agreed that the original seawall was near complete failure and so I made the decision to call the pour off.

Because the wall was only half poured I had to adapt quickly before the cement set up.  I had not counted on a cold joint being in my wall.  I took my dads suggestion and cut several rebar in half and stuck them vertically into the pour.  This would help tie the two pours together.  Also my instinct told me to take a pointy 2x4 wood stake and make as many holes in the wet cement as possible.  This would help lock the two pours together.

Shown below is what I did:

 

Later on when the cement was done, I would read what is typically done when there is a cold joint in wall.  Usually, a sheer key is used which means that a channel is made in the wet cement of the first pour so that the second pour can fill into it and lock the lower and upper wall together when the cement is hardened.  My instinct had been right on the money and the stake idea as well as the vertical rebar had improved the walls chances of staying together in one piece.

At this point I was glad that I had chose a concrete company that mixes on site.  Because any excess concrete (which would have been about four yards) that I had ordered with the other companies would have been been thrown away and I would have been out $700.

The next day the cement for the first pour was hardened and therefore all the force on the seawall was diminished to zero.  The cement company came again and topped off the wall no problem.  Later on I did an underwater inspection with a go pro camera I borrowed from a friend at work and found that the seawall had indeed ruptured in one spot.  A sort of shelf was formed where a 1 to 2 foot lower portion of the seawall bent out and the concrete flowed out.  I don't have any good pictures as the water was so murky at the time.

The second half of the wall went without issue since I had I adopted the two pour method for it.   It required 11 yards of concrete and the forms held great.  I put even more vertical rebar in the second time and made many stake marks in the concrete for the sheer key.

After about 4 days I ripped off the forms.  Since there were so many places that the tie bars and weep hole pipes went through the forms and thus so many joints the forms were locked into place for good on the house side.  This was not an issue since it was a retaining wall I was building and the house side would be covered with dirt.  I cut the forms off about 1.5' below the top of the retaining wall.  The forms on the front side of the wall came off fine as I was very careful with the joints and the surface was very flat.

The end result for the wall is shown below.

 And here is another angle.

 

It was about the time that the forms came off that the water cleared up a lot in the canal.  In fact I could now see to the bottom of the canal.  I'm not sure what caused this.  Maybe it was the new rain or the death f the brown algae.  Its a mystery to me.  One things for sure.  There is still a lot of work to be done before the lagoon is healthy.

The wall is great in my opinion.  It could be made to look prettier by adding a stone veneer and stone cap or tile.  Maybe in the future I will do that or maybe not.

So the question is how much did I save by doing the project myself?

Dare we compare the retaining wall cost to the cost of a new seawall?  The retaining wall actually solves some problems that a new seawall would have.  One is the land height issue in that there was too much slope near the seawall.   Secondly, the sand leak issue which forms the trench behind the seawall is solved.  Thirdly it takes the land pressure off the old seawall.  On the other hand it does not provide the barrier to the water on the canal side.  The 70 year old seawall does that.

One bonus to the retaining wall method is that I have a convenient step formed by the original seawall cap which enables better access to the water than the towering vinyl seawall implementations in the neighborhood

As was mentioned before the cost of a new seawall would have been $16800.

 

For the retaining wall which took me 155 hours to build I paid $6675 which is broken down in the categories below:

ties bars                     275
form wood                 840
Nails / Misc               150
labor                          487
concrete                     4540
fiberglass rebar          383

 

That's means s whopping $10125 or 60% was saved.  Cue the cash register sound.

Happy Building!

The Dr