Estimating Concrete Hollow Blocks in a Masonry Wall

Concrete hollow block is classified into two:
     1. Load Bearing Concrete Hollow Block
     2. Non-load Bearing Concrete Hollow Block

Load bearing concrete hollow block are block that can or intended to carry load aside from its own weight.

Non-load bearing concrete hollow block are used for fences, wall partition or divider. and this is not intended to carry load.

The two methods in estimating the number of hollow blocks in the masonry wall:
     1. Fundamental Method
     2. Area  Method
Fundamental method, in this method the number of concrete hollow blocks can be determined by dividing         directly the total area over the total area of one concrete hollow block.

Area method, to obtain the number of concrete hollow blocks that cover the whole area.in this method we must determined first the number of hollow blocks that can cover a square meter area and then the value obtained will serve as multiplier in obtaining the total number of blocks that can cover the required area.

46 Comment:

kinglove said...

hi engr edwin i am in new business start this monht lost for fully hollow block and solid block. so i am very cofused for masonry units and water ratio. please tell me sir. please i am truly asking please

engr. edwin said...

For every 4 lbs of cement, 1 lb of water is needed to fully complete the reaction. This results in a water-cement ratio of 1:4 or 25%. In reality, a mix formed with 25% water is too dry and does not flow well enough to be placed, and some of the water is taken up by the sand and stone and is not available to participate in the hydration reaction. So more water is used than is technically necessary to react with the cement. More typical Water-Cement ratios of 35% to 40% are used, along with a plasticizer

florence angela rocero said...

hi engr edwin this is flor. may i ask you what is the right proportion of cement, gravel and sand in making a concrete hollow blocks??

fae said...

what is jack built 700psi all about?

engr. edwin said...

I think 700 psi is the strength of the hollow blocks.

alyanna03 said...

Hi Engineer! Im having a 2 storey house constructed by the developer. As the construction progresses, i found out that the columns are only until the flooring of 2nd floor and did not get through until the roofing. Is it ok that the jack built chb will take the load of the trusses and concrete roofing. Thanks!

engr. edwin said...

just ask first the contractor if the CHB they used are load bearing. . if not. .just tell the contractor to put additional column to support the truss and concrete roofing, .. Concrete roofing is too heavy, for CHB

alyanna03 said...

The CHB's that they are going to used according to them are load bearing.

engr. edwin said...

If that the case, you don't have to worry about. the CHB(load bearing) can carry the load of the truss and the load of the concrete roofing.

alyanna03 said...

Thanks you so much Engr. Edwin!

Vicky said...

Hi engg i want to know the no of hollow concrete blocks used for 1 mt cube of size 400 x 150 x 200..please reply.

engr. edwin said...

no problem alyanna

engr. edwin said...

you mean, no. of hollow blocks that can be created out from 1 cubic meter concrete mixture?

120- 130 pcs of 400X150X200 concrete hollow blocks approximately.

engr. edwin said...

Hi, angela florence rocero, you can used concrete mixture of 1-4(example: 1 bag of cement, 4 bag of sand) to 1-6 mixture but depending on the strength of hollow blocks, but if the case that is for load bearing CHB, pls refer to structural engineers for that. .

For commercial hollow blocks (non-load bearing CHB) they used 1-15 mixtures to 1-20, accordding to CHB manufacturer but they have additional concrete admixtures for additional concrete bonding. I forgot the term

Steve said...

hi, i wanna know the unit weight of a load bearing CHB

engr. edwin said...

I am not sure with the load bearing CHB but you can refer to ASTM C 318

"The unit weight, or density, of concrete varies withthe amount and density of the aggregate, the amount ofentrapped or entrained air, and the water and cementcontents. Conventional concrete used in structures, suchas buildings and pavements, has a unit weight in therange of 140 to 150 pounds per cubic foot (pcf). Forother types of concrete, the unit weight ranges from 15pcf for lightweight insulating concrete to 400 pcf forheavyweight concrete."

Anonymous said...

hello po..
i just wanna ask if there's a standard ratio of cement-sand for testing CHBs po..if there's any, anu po un??
student po kasi ako and were having feasibility about CHB's right now..

Anonymous said...

It depends on what is your desired strength for the CHB.

Anonymous said...

engr, how many hollow blocks should i use in a 150 square meter lot area of lot for fencing only?? height of fence 2 meters.. thank you

engr edwin said...

Hi, thanks for the question, just get the perimeter and multiply it with the height which is 2 meters to get the total area. After that multiply it with 12.5 to get the total number of hollow blocks,

12.5 is a standard multiplier to get the number of hollow blocks, per sq.m

Anonymous said...

Hi engr edwin,

just would like to know whether required or not. i've some idea plan for CHB business, my question is should be neccesary required to send for testing before sale it to customer? i mean need to be certified? thank you in advance.

Unknown said...

hello engr. i'm jacque. i would just like to ask the intensity of earthquake that the nonload bearing hollow blocks can withstand?

Engr Edwin said...

Non load bearing hollow block is not design to carry earthquake load or any lateral force.

Unknown said...

thank you for the answer sir i am a student who is conducting a feasibility study. can i ask again if that's the case it means that non load bearing hollow blocks cannot be used even in bungalow type of houses or the low cost housing projects?

Engr. Edwin said...

exactly, non load bearing hollow blocks is not designed to carry any loads, for the Bungalow type of houses and low cost housing projects, You need to provide a structural elements to carry the deadload, self-weight,live load and the lateral forces like beams and columns and etc.

Anonymous said...

good day po engr.
just wanna know how to estimate the structural excavation and embankment of a building. . .tnx

Anonymous said...

i JUST WANT TO KNOW THE RIGHT PROPORTION OF CEMENT, SAND AND GRAVEL IN MAKING NON-LOAD BEARING CHB. I'M MAKING A FEASIBILITY STUDY ON THIS SUBJECT BUT I AM HAVING TROUBLE FIGURING OUT THE RIGHT PROPORTION. THANK YOU VERY MUCH

Unknown said...

good day sir...i would like to ask for the common water - cement ratio that you are using for non-load bearing hollow blocks...

Unknown said...

ps. specifically for the 1:12 and 1:24 ratios of non-load bearing hollow blocks.

Anonymous said...

Hi po Engr.
I loaned a house and it's being constructed now,It's a two-storey house, just small, about 80 sq/m but it doesn't have columns, what I noticed are just 16mm bar on each corner. The architect said that it's fine since they are using load bearing CHB. Please help.

engr edwin said...

Along the chb wall, Any other 16mm rebars? Aside from 16mm rebars at the corner.

As long as the the strength of chb can carry the load of the 2nd floor. Its fine. Just ask the architect about the strength of the chb? If you can send me the detail drawing so that I can review the chb strength capacity maybe, I can provide u the accurate answer about your question.

Thanks,
Engr edwin

Anonymous said...

Hi po engr. Good day po ok lng po b s 2 storey house n wl columns kc po kumuha kmi house nung mkita nmin maconstruct wl columns sabi ng engr. Ky ganun po kc gamit nila chb is load bearing. Tested po b s earthquake ang load bearing? Thanks

Anonymous said...

Hi Engr. may I ask if how can an ordinary person like me be able to know or to distinguish load bearing or non-load bearing hollow blocks if I will buy them from ordinary hardware. please reply. thanks.

engr. edwin said...

Do not use visual inspection to distinguish between the non-load bearing and load bearing CHB, Material Testing should be done just to ensure the quality and strength of the materials, this is for your safety and the safety of your property. don't trust the supplier of di mo sila kakilala. .

Thanks

engr. edwin said...

"Hi Engr. may I ask if how can an ordinary person like me be able to know or to distinguish load bearing or non-load bearing hollow blocks if I will buy them from ordinary hardware. please reply. thanks."

You can ask the copy of the analysis sa structure from the engineer who constructed your building, tingnan mo if they analyze the structure to resist earth quake load..

Thanks

Unknown said...

hello po, angel po here.
Ano po ang recommended ratio ng concrete mix para sa column, beam at slab ng ipapagawang up&down house with slab roof.... thanks po

engr marinduque said...

Sa practice po. 1:2:3, 1 bag of cement, 2 bag of sand and 3 bag of gravel pero kun titingnan mo sa mga estimating book, ang suggested ratio ng sand dapat half sa volume ng gravel.. based lang sa nabasahan ko. Pero if available ang ready mix concrete sa location sa project. Mag ready mix concrete ka nalang para makuha mo ang desired strength as specified sa design.

Unknown said...

what should be the design strength of CHB in psi (either load or non bearing) to withstand the penetration of a fire? or is it feasible for CHB, instead of a solid concrete firewall? thanks..

Anonymous said...

hello engr..ilan po b ang kelangang tubig sa paggawa ng hollow block sa mixing ratio na 1:2:3..thanks.

Unknown said...

what if I am going to use light weight materials to make hollow blocks what will be the standard ratio of cement,sand and gravel if I am going to utilize coarse aggregate??

Unknown said...

helo engr, what is the ratio of cement and sand and water, of load bearing hollowblocks, with average strength of 1000psi. and how long is the curing period b4 testing?

Unknown said...

Bait mo naman Engr.

Anonymous said...

hi engr.. may thesis po kame about sa load bearing hollow blocks.. kaso po di namen alm yung exact ratio na gagamitin naten sa load bearing hollow blocks at kung panu po gumawa nito??? plano po kc namen lagyan ng egg shell pero di namen alam yung ratio..

salamat po talaga sa tulong :)

Unknown said...

700 o 1900 psi po yung strength na gagawin namen kaso po di po namen alam yung ratio na dapat gawin sa load bearing hollow blocks o jackbuilt

Anonymous said...

Hello Engr. Pwede po malaman ilan interval vertical and horizontal bars sa construction of CHB FENCE?Salamat.

Anonymous said...

Follow up question. Engr. pwede po malaman ilan bag of cement kailangan para s construction of fence? I mean ratio ng cement at CHB for the construction of fence. Also ratio ng bars at CHB for the construction of fence. Ang bars ay horizontal at vertical. Salamat.

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