grout

I have never heard that one that the P.S.I. of grout should not exceed the strength of block . I believe most block has a P.S.I. of around 2500-3000 P.S.I. I have seen grout design mixes range from 2500--5000 P.S.I. I believe the slump of grout should range from 9"--11". So unlike concrete grout is poured at a much higher slump however,the design mix takes that into consideration and the finished strength is not compromised. Even with that high slump the water to cement ratio still yields the proper strength.

 

I have a bigger problem with your footer size than your grout ratio.

I don't think that grout strength is a huge deal as you basically end up with a concrete wall with block forms that are left in place.

 

Grout

I have a bigger problem with your footer size than your grout ratio.

That was a good catch by dakzaag! Footings typically are twice the wall width,if not wider,with that said it should be atleast 16"

 

I pour 12" monos all the time - just depends on height, type, wall design, soil, etc...

Need more info to call it insufficient.

 

If you bother to look at the ASTM grout standards, you will find that:

1. The slump should be 8" to 11". The goal is to makes sure ALL voids in the cores required to be filled are filled completely.

2. The maximum size of the aggregate is determined by the dimension size of the void and the spacing of the reinforcement.

3. There are 2 types of grout (fine and coarse) although I do not have the specs in front of me but the fine is basically a coarse sand mix with a top size (3/8"?) specified and the coarse mix has a larger maximum size.

The purpose of the grout is to transfer loads from the steel to lapped steel and to the the block in the wall.

Codes separate the placement into low-lift and high lift (up to 12') procedures and there are more specifics for critical walls. Generally good practice to only fill the cores containing reinforcement, but in some areas using old fashioned "standard" block there is usually some slop and waste bleeding out. Many plant make special block with all webs aligning to seal off the filled cores from the empty ones. It is not good to just dump a core completely and move on the next one because it is better to consolidate, repour and then top off after final consolidation later.

The strength of grout should always be less than the strength of the block. Actual required minimum block strengths are 1900 psi on the net area (now being increased to 2000 psi) up to over 7500 psi on specified jobs. Many engineers place a maximum allowable strength for the grout. - Arbitrarily filling all cores does little to increase the strength of the beyond what the codes assume and can be detrimental on major jobs. In the end, the actual strength of the wall is determined by the block strengths and very few block are even close to the minimums, because manufacturing methods automatically make block 30% to 50% over the minimums and over 3 times the minimums are possible if someone can find and excuse to specify that level.

Just a side note, the compressive strength of the mortar really immaterial to the strength of the wall as long as it is either Type S or Type M and usually Type N is adequate. - That is pointed out in the ASTM mortar specifications that say the weakest type of mortar should be used because of the beneficial effects of to other properties like workability, bond and possibly water resistance.

In South America, they build developments of 10 to 20 story load bearing (no steel or concrete) apartment buildings out of partially reinforced/grouted 6" thick walls using the same standards as the the U.S. codes. - The difference is that the engineer is employed by the developer/contractor that allows the "red tape" to be cut minimizing the site inspections and using products certified at the plant before construction and color-coding the block (paint sprayed inside the cores) to agree with color codes on the drawings.

 

Very interesting post, Dick.

Could you explain this a little more?

Arbitrarily filling all cores does little to increase the strength of the beyond what the codes assume and can be detrimental on major jobs.

Detrimental because of increased cost, when there is no need for it, or is it something else?

Thanks.

 

If the walls arbitrarily dumped full when not needed, the properties of the wall and changed and the distribution of the loads is different than planned (some types of loads end up getting shifted/redistributed to other walls since all loads are not simply vertical. Especially important on taller, multi-story buildings. This was discovered after seismic activity where, at one time, it was common for contractors to dump all of the cores because they did not use the right shape block or just had excess grout available and wanted to get rid of it cheaply. Since this was found out about 30 years ago many new shapes were developed to make the cores align properly and make grouting cheaper.

Even for lower building dumping grout into all the cores eliminates the possibility using empty cores for other uses (electrical, drainage).

Even for basements many contractors have special block made to include the open cores into a water control system. Usually they are the most profitable contractors because of marketing and appreciation of real costs.

 

Even for lower building dumping grout into all the cores eliminates the possibility using empty cores for other uses (electrical, drainage).

And empty beer cans

 

Exellent information , finally an answer i can go by . I did some research and could'nt find anything that made sense . Thanks Dick !!!

 

When I was in the block business, we had a contractor that wanted special block for the first 2 courses to keep out the beer cans and the rock and dirt that the kids would trow into the wall at night. He used the cores to drain the leakage from failure of the exterior waterproofing and drain it into the interior drain with pre-cut clear vinyl pipe into the gravel fill around the drain tile. - A standard on every home with no add-ons since it was cheap to do while building and he had a reputation that he was also selling. - He was a builder with his own concrete and masonry crews.

 

When I was in the block business, we had a contractor that wanted special block for the first 2 courses to keep out the beer cans and the rock and dirt that the kids would trow into the wall at night. He used the cores to drain the leakage from failure of the exterior waterproofing and drain it into the interior drain with pre-cut clear vinyl pipe into the gravel fill around the drain tile. - A standard on every home with no add-ons since it was cheap to do while building and he had a reputation that he was also selling. - He was a builder with his own concrete and masonry crews.

Dick

We rarely do any block basements here anymore, but we've always utilized the interior cavity of the wall as a second line of defense against water intrusion. Now-a-days, we smack a hammer-hole in every cross-bleeder as it intersects the block wall and fill the bottom course 1/2 full to minimize mortar damning. Many years ago, the same thing could be accomplished by installing red rosin paper on top of the first course. Actually, until maybe 10 years ago, most block suppliers still stocked 7", 9", and 11" wide rolls of rosin paper...............

 

Would bottles fit?

 

Grout

Arbitraily dumping grout? There seems to be some dissension amongst the professionals.






http://www.eng-tips.com/viewthread.cfm?qid=311187

 

Arbitraily dumping grout? There seems to be some dissension amongst the professionals.






http://www.eng-tips.com/viewthread.cfm?qid=311187

Can't say for sure, but it seems like the "hokie" individual merely had a bone to pick with Dick or something, and I'd be willing to bet Dick's forgotten more about masonry const. than that guy will likely learn in his life................

 

I am one of the "professionals" with engineering registration and 40 years experience and I just offer examples of observations and serving on both code writing and establishment/maintenance of material standards and design standards.

Arbitrary is a very common term for people just to do it because they know no better or want to get rid of it and they usually have little experience, no patience and no knowledge of the reasons for the importance for controlling the grout.

I had a friend that was an international expert on masonry design and construction, but he always had to bite his tongue when it came to grouting because he was supported/influenced by a regional association that was controlled by some well experienced people, but they just developed bad habits. He was appalled when we inspected the results of the Northridge, CA quake were you could see the problems and reasons for much of the damage that was not a design problem, but a construction problem.

The arbitrary guys would be run off a major masonry job in Brazil before the end of a day since the Brazilians are more experienced in the design of masonry buildings, quality control since they really use masonry with controlled grouting. If you have ever had to do grouting on a 20 story 6" loadbearing block building, you would understand the problems, cost and detrimental effects of clean-outs for inspection. On a project of 15 or 20 buildings, they eliminated all clean-outs and inspected by the random and periodic use a video camera dropped in the cores of the walls (both planned to be grouted) to determine if the construction was adequate and frequently went back after grouting to the ungrouted cores to see how well the grouting was done. - The engineer and inspection was paid for by the contractor/developer and were involved in both the design and construction. and the engineers in Brazil were strongly influenced by my friend beginning in the early 1970's.

Some professionals are members of the "more is better or adequate" belt and suspenders crowd, while others like to see it done better and cheaper in the end.

 

In my experience, most (i.e. 99.9%) engineers are trained in concrete engineering methodologies and have very little comprehension of the differences between masonry and concrete. That is the only reason for dissension or any degree of arbitrariness of the correct method of grouting CMU walls.

 

Just to point out. The OP's wall is only 3 courses high. You could fill the thing solid, fill it with liquid diamonds or with a type O slurry. It won't make much difference. It's a nothing wall (no offence to the OP but unless I'm seriously mistaken the wall isn't load bearing, maybe just a small retaining wall?) The strength of the grout and whether it gets filled is almost immaterial.

As for the argument between Hokie and conctretemasonry. I can certainly see both sides of the equation. And I agree, there seems to be some history between the 2, but to say that Hokie is wrong and concrete is right is silly. They are both professionals (Again I'm assuming) who I'm sure could argue their sides all day and night, just as I'm sure many masons here with equal experience could and have argued 2 sides of a coin for days on end.

 

I don't see anyone named Hokie in this thread?

 

Threads





It is here.


http://www.eng-tips.com/viewthread.cfm?qid=311187

 

Hokie is a very good engineer, but not the esteemed friend I referred to.

Hokie is on the engineering forum and has some very good points based on his exposure to different standards and methods, since it is a big world.

 

As noted its a small retaining wall , non load bearing. My question was just not specific to this job , but all block walls that are grouted wheather specified or not. Just wanted to be educated , thanks for your generous replies . :thumbsup:

 

In my (limited) experience with block construction, justa bout anything is a decent grout so long as there are no voids and the grout is reasonably strong, say over 1000PSI.

When I was a labourer the guys I worked for did quite a bit of block and we rarely grouted with anything but a soupy type S mix. Most of the walls I've torn into have had the same material (at least there was no aggregate besides sand) These buildings were engineered and inspected. Unless the building is fully engineered, and the grout is speced I would use whatever i had on hand (not quite but close)

 

You really shouldn't use any lime in the grout, and you're typically not allowed to in any commercial work here, as it's corrosive to the rebar.............

 

There's no lime in any type N or S masonry cement here. It's all portland and plasticizers. The only cements I'd typically have on a block job would be either type S or maybe type N and portland. Maybe some non shrink grout but I don't think there's any lime in there.

 

We did an elevator shaft once.. It was core filled with a ratio of portland type II~(32-36) sand