CHB Strength and cement ratio

[OnMyWay]

I'm looking for good CHB and I asked neighbors.  One guy recommended a place that will make the strength you want.  He said he had his made 20:1 and typical cheap CHB is 40:1.  Does that sound right?  E.g., his is 20 blocks for 1 bag of cement.

[Clermont]

Google it, the ratio doesn’t change because of county 

[Mike J]

I ask Google "what is the best ratio to make strong hollow blocks"

Below was the response.  I still do not know is how many blocks this will make.   So I then ask Google "how many hollow blocks can you produce with one bag of cement with a 1 cement to 7 sand ratio".  The answer 25-40 did not make sense to me unless they are referring to different size blocks? 

So - I would tell the guy building the blocks to use the 1/7 ratio.  One bucket cement and seven buckets of clean coarse sand.  You should get good strong blocks if they follow the ratio. 

[OnMyWay]

3 hours ago, Mike J said:

The answer 25-40 did not make sense to me unless they are referring to different size blocks? 

Yes, seems that way.  He is older and this was a year or more ago, so maybe he forgot.

[Possum]

I helped set up a large concrete block machine once. We would make about 25 8 inch hollow blocks per bag. The mixture for concrete blocks is different though. I've not seen a concrete block here in the Philippines.

[OnMyWay]

3 hours ago, Mike J said:

I ask Google "what is the best ratio to make strong hollow blocks"

Below was the response.  I still do not know is how many blocks this will make.   So I then ask Google "how many hollow blocks can you produce with one bag of cement with a 1 cement to 7 sand ratio".  The answer 25-40 did not make sense to me unless they are referring to different size blocks? 

So - I would tell the guy building the blocks to use the 1/7 ratio.  One bucket cement and seven buckets of clean coarse sand.  You should get good strong blocks if they follow the ratio. 

So if 1:7 makes a good block, then those crumbly blocks must be 1:10 or more??

[Mike J]

56 minutes ago, OnMyWay said:

So if 1:7 makes a good block, then those crumbly blocks must be 1:10 or more??

Or maybe even worse.  I have watched workers unloading blocks from a delivery truck and stacking them.   They handled them so gently, as if each was a new born baby.  One time I saw a mason working.  Not sure why but he seemed to be turning blocks back into sand.  He would lift a block, give a just a little tap with a hammer, and the block would completely disintegrate. 😳

[OnMyWay]

32 minutes ago, Mike J said:

Or maybe even worse.  I have watched workers unloading blocks from a delivery truck and stacking them.   They handled them so gently, as if each was a new born baby.  One time I saw a mason working.  Not sure why but he seemed to be turning blocks back into sand.  He would lift a block, give a just a little tap with a hammer, and the block would completely disintegrate. 😳

The guy I originally spoke of said they dropped one and it was still perfect.  The numbers he gave were not right but he did say they made them twice as good as the normal ratio.  However, if 1:7 is "normal", 1:3.5 doesn't sound right.

[Mike J]

6 minutes ago, OnMyWay said:

The guy I originally spoke of said they dropped one and it was still perfect.  The numbers he gave were not right but he did say they made them twice as good as the normal ratio.  However, if 1:7 is "normal", 1:3.5 doesn't sound right.

I think 1:7 is the ratio for a strong block.  The ratio on weak blocks found here are probably 1:12 or worse, just enough cement to keep the shape.  In other countries hollow blocks are structural in nature and load bearing to a degree.  Here they are used more like a form to hold the concrete and rebar which provides the strength in a wall.   So strength of the block is not as important.  But like you, I want strong blocks. 

[Snowy79]

On 11/9/2024 at 11:48 AM, Mike J said:

Or maybe even worse.  I have watched workers unloading blocks from a delivery truck and stacking them.   They handled them so gently, as if each was a new born baby.  One time I saw a mason working.  Not sure why but he seemed to be turning blocks back into sand.  He would lift a block, give a just a little tap with a hammer, and the block would completely disintegrate. 😳

I watched one labourer shaping the blocks to fit with his bare hands. Literally karate chopping them to the size to fit a hole. I was cringing as it was a tall property and no lintels above the windows, just a thin wooden plank holding the blocks in place until they set. I think the window was going to be the lintel.