One of the most common material used now a days in the Philippines from the traditional "bahay kubo" transitioned to concrete houses with CHB serving as walls and partitions.
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| image from commons.wikimedia.org |
Sizes
Common sizes from different CHB makers are 4", 5", 6" & 8" but mostly used are the 4" thk for interior walls and 6" thk for exterior walls, only 5" thk serves as an alternative if no available 6".
Some are also making 3" thk CHB but few are using this size on house constructions.
Width: 16"(40cm) Height: 8"(20cm) for all thickness, therefore you may say
- 4"thk x 8" x 16"
- 5"thk x 8" x 16"
- 6"thk x 8" x 16"
- 8"thk x 8" x 16"
Non-Load Bearing (commonly found in the market)
Take note that CHB today is no longer like before with a mixture of small pebbles/stones aggregates but commercially made out of "cement + sand" with very high sand to cement ratio which makes it too brittle that a simple drop from a foot height from the ground would break so easily.
In other words never consider any CHB today as a load bearing wall, rather just think of it as a wall covering to enclose areas for privacy and protection from the outdoors.
Load-bearing (must follow guidelines as per ASTM C90, PNS, NSCP)
Unless you can find a reputable CHB manufacturer near you that has the complete equipment and proper ratio of cement+aggregates with proper testing to get its compressive strength in accordance to ASTM C90 or to our own PNS(Philippines National Standard) as well.
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| image from ncma.org |
Base from our NSCP 2015 Table 710-2 on Compressive Strength for load-bearing masonry units:
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| from NSCP 2015 |
Taking 10.3 Mpa is around 1494psi for a single unit of masonry hollow block, but before deciding to use load-bearing blocks make sure to discuss with your Structural Engineer for recommendation to strengthen your walls from any lateral forces.
Mortar (mixture of cement and sand)
Since it is a hollow core type you'll need to mix cement and sand to fill in those voids including joints in between layers of CHB.
You can use mix ratio (Cement:Sand)
- 1:2 Class AA
- 1:3 Class A
If there are ready mix mortar available in the market like from the UK, that would be a time saver from mixing cement and sand manually.
Reinforcement
To secure and hold your CHB wall you will be adding up reinforcing bars of 10mm or 12mm diameter placed horizontally at every 3 layers of CHB and placed vertically at 16" or 24" distance apart which will depend on your Structural Engineer design layout of bars.
ESTIMATE (pcs needed in a wall?)
You can easily estimate the number of pieces needed for your house project and avoid getting taken advantage by your contractor.
Simply get the overall wall area needed and multiply with 13 and you get the number of pieces CHB needed, just add 10 to 15pcs as contingency for any broken units during installation, ask for replacement if damaged during delivery.
Why 13? because in a 1m x 1m wall area you can fit in 12.5pcs of CHB (rounded to 13) regardless of thickness (4",5",6",8").
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| 13pcs chb per sqm |
CHB Alternative?
a. Eco-Brick a Lego Bricks style
If you care for the environment and want to lessen waste and wants to support recycled products turned into bricks then you might want to check out eco-brick from greenantz.com or at avdph.com
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| image from avdph.com/eco-bricks |
Price may be higher than your ordinary CHB but somehow since it is more dense it will save you the cost of needed mortar in between hollows, plus skim coat ready is a plus without the need of plastering to be able to apply paint after.
b. Eco Cast (4", 6" load bearing and non load bearing products)
Another line of their product the "eco-cast" which has the same size as your ordinary 4" CHB with the same concept of recycled materials and available also in 6" thk (non-load bearing and load bearing of your choice).
Stackable and more compact, hence requires less concrete for mortar, makes this more superior than the ordinary CHB.
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| image from avdph.com/eco-bricks |
6" Thk Eco-Cast Load bearing, same size as your ordinary 6" thk CHB.
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| image from greenantz.com |
Before deciding materials to purchase
- always check for availability,
- gauge if you can save from labor cost and materials in the long run,
- easy to install and
- never forget it should be "matibay".
It's good thing to see these kinds of innovations to have alternative choices to what we already have accustomed to, the only downside is its availability in the market vs the regular CHB which we all know are not that hard to find.
Disclaimer: This is not a paid promotion of any brands mentioned in this post but for sample reference only to get some idea.
