# Block Walls



## Tscarborough (Feb 25, 2006)

Horizontal reinforcing does create a slightly weaker mortar joint. However, it does not affect it enough to overcome the value it provides for lateral strength, which is what the horizontal wire is for. To say nothing of the fact that most mortar is specified wrong and is actually too strong in compressive and too weak in bond and flexural strength.


----------



## concretemasonry (Dec 1, 2006)

ch0mpoie is very accurate about the moisture content. If you have the right moisture content in good soil, you will have a very easy time getting the 95% of a standard proctor. If you have the wrong moisture or the wrong type of material it will be difficult and costly.

Joint reinforcement -

Dur O Wal (joint reinforcement) is generally for crack control and to hold walls together. It is not structural reinforcement, but it is normally specified in every other course of masonry for commercial work.

Some codes do allow an equivalent amount of steel to be placed in a bond beam in the middle of the wall as a substitute for joint reinforcement. Not normally done because of the cost.

The codes do not require a reduction of loads when joint reinforcement is used.

A bond beam is placed at the top of a wall for continuity and to provide a solid course of block to distribute any applied loads like beams, joists and concrete floor systems.

Fibermesh -

Fibermesh does not increase the compressive strength of concrete.

It can increase the tensile strength. That is why it may decrease the micro cracking and shrinkage cracks. That is also why is may be tougher to break out.

One of the problems with fibermesh is that it can be ineffective or detrimental if not used properly. Over-mixing can occur and the mesh will "ball up" and actually decrease the strength. Adding water on the job will require more mixing and can cause even more problems. All these are hidden problems that you cannot see or know whether it is doing what it costs. If you have a knowledgeable ready mix supplier (with mixer monitoring) and a knowledgeable contractor it will be an improvement.

Wire mesh is proven and you know if it is used properly. It cannot be stomped into the sand, but should be puled up enough to get surrounded by the concrete. In some advanced countries the wire is thicker and spaced further apart so you can get a foot between the wires. It does not have to be in the middle of the slab. You can see if it is effective!- In other words it is a no-brainer if you are a good contractor.

Where I lived in Michigan, the driveway aprons on public property could not contain wire mesh because of the problems encountered in removal for utility work. Fiber mesh was permitted because it was easier to remove than concrete with wire mesh.

I like concrete with both. If I had to take out one material, it would be the fiber mesh and not the wire.

Neither is a substitute for properly sawed deep control joints (1/3 thickness) when the concrete is relativelt fresh.

Tscarborough it right about mortar. Ususally it is too strong. The appendix to the mortar specification say you shouls use the weakest mortar possible to carry the loads required. - I have seen very many 20 story block loadbearing buildings (no steel or concrete columns) built out of 6" block using Type S mortar. The engineer could have specified stronger mortar (Type M) but did not.

You have to decide whether you want the mortar to hold the masonry units apart or hold them together.

Dick


----------



## POOLMANinCT (Oct 7, 2006)

ty tscar & concremasonry


----------



## Same Old (Mar 9, 2007)

I like the way you think Dick.

But I'm never touching mesh again. I don't really ever touch a trowel much anymore either so... 

Fibermesh should be added on-site IMO. Same with the Super-P.

Dick, do you know any good stone masons in Minneapolis. I bought one of those little tudor wannabe's in S. Minneapolis last year and I want to add some limestone around the door and some cheek walls for the new stoop. I'm looking for a guy with an eye for these era homes that can design and create something cool. Pm me if you know anyone.


----------



## Dik Redi (Apr 18, 2007)

Tscarborough said:


> Horizontal reinforcing does create a slightly weaker mortar joint. However, it does not affect it enough to overcome the value it provides for lateral strength, which is what the horizontal wire is for. To say nothing of the fact that most mortar is specified wrong and is actually too strong in compressive and too weak in bond and flexural strength.


TY Tscar,, and for the TYPE S ? that someone asked we only use type N for quick jobs other then that we use the type 2 portland (or type 1) with lime mix,, and about the bond-beam / bom-beam ,, i was taught by a old country italian with a and still has a accent and it sounds like bom-beam so i say that knowing it is actualy a bond-beam..and about that dura-wall u can run ya self out of breath trying to get me not too use and i will use it cuz in MANY if not all cases around here ITS CODE.


----------



## concretemasonry (Dec 1, 2006)

Same Old -

I would not rule out mesh. I think it helps, but not really replace wire installed properly. As I said, on my own driveway I used both, but if I could only use one it would be wire. - The lrft over wire also makes great 2' diameter by 6' high tomato cages.

I would never let an amateur add mesh on the site. It should be applied by someone with knowledge of the type of mesh and the controls that they have to stand behind.

I am just back to the Twin Cities after a few years of many different countries, so my knowledge of good stone masons currently active is poor. - There are some that have done the big buck fireplaced at million dollar summer homes, that might want to do some nice artsy local work. I guess you should contact one of the stone suppliers looking for a semi-retired man with pride.


----------



## RED HORSE 554 (Jun 26, 2008)

DaHammer said:


> I have a question regarding concrete block walls and lateral strength. I'm usually not involved until well after the foundation is in place, so I'm not familair with the exact order of things. Anyway, I'm about to build a house that will have a raised slab foundation (also called supported or floating slab). The slab will be raised approximately 2 to 3 feet above the surrounding grades, using concrete block walls that are sitting on footers. My question is concerning compacting the dirt fill that will be in the void, under the slab. How do you compact it without bowing or breaking the block walls? The reason I ask is that I stopped by a jobsite today to talk to a foundation contractor and he was filling and compacting the void on one that will be like mine. While compacting it using a jumping jack they bowed one of the walls on one end of the house and were bracing it back in place using 2 x 4s. At least he said that's what caused it, but I'm not sure he didn't get a little to close to the wall with his backhoe or dozer while placing the fill. Anyway, I noticed that none of the concrete block voids had been filled yet. They had vertical rebar in the wall about every 4 feet, but that wasn't helping since the voids weren't filled. He commented that it would be ok once the slab was poured and tied into it with the rebar, and he is probably right, but I think it would be better to prevent it to start with. So how exactly does everyone compact the fill without damaging the perimeter walls? My thoughts were that the walls should be filled with grout or concrete before putting the fill in place. Or at least the voids containing the vertical rebar. Prehaps even use a bond beam or some of the block remesh hortizontally on 1 or 2 of the courses. But if you fill all the block voids before doing the dirt fill, then the plumber would probably need to come out first and put whatever pipes he needed too in before hand. Thoughts?


http://www.lenntech.com/terrazyme.htm use this to stablize the soil it takes far less compaction to get the rait you need and this dosent settle once applied. The utility troff will need to be carved out before the dirt drys to allow for the plumming and eletrict.


----------



## concretemasonry (Dec 1, 2006)

What does "rait" mean? I assume dosent is just a typo. Troghs is a different matter.

Something like "terrazyme" works with organcic materials in the soil. This type of soil is generally called dirt and the amount of organics is severely limited because of the long term effects. The geo-tech engineer would have to approve the technique before it is used. Most codes follow what the real soils engineers will accept for foundation and road support/base materials.

It sounds good, but approvals are difficult because it requires organics the are not normally permitted and then they must be "eaten" by the enzymes. Where does the "eaten" organics go since they are far weaker than good soil, no matter what form they take?


----------



## RED HORSE 554 (Jun 26, 2008)

rate troff oops type o`s dick sorry. This turns the dirt to concrete dick the auzy`s use this to build roads across the outback to allow semi`s to travel east to west and k-mart and wal-mart uses this under every pad poured as well as thie parking lots. It workes devine for pumpy mud problems. This as well has no settling after installed so if the base is good thin the soil is stable NICE FISH DICK And i think as we do here he has a engineer to do up the prints we can`t start untill the county engineer has placed a seal on the prints. Dick many people know little about this new enzyme and still use lime in trying to do the same thing. Have you seen the tile hump up with white powder under this will stop the moisture that carries the dust to the surface causing this problem.and can be injected under but is costly.GOOD STUFF but i agree have a engineer look and see if it will work for his project. Basicly it is a soil solafaction enzyme


----------



## Tscarborough (Feb 25, 2006)

Are you on drugs?


----------

