kg of Sand / Cement In Mortar - Cannot Find Definite Answer?

[EViS]

I'm trying to establish the exact weight (in kg's) of cement and sand in a 1:5 mortar mix per brick or block.

Unfortunately different online calculators give different results and the listed density of cement and sand also varies between websites.

I have calculated the following using a cement density of 1.506 t/m3 and sand density of 1.602 t/m3 and assumed a 10 mm mortar joint.

Does this look right to anyone? Are the above densities correct? (I'm trying to create an Excel calculator ).

1 standard 'frog' brick requires:
0.0001189 m3 or 0.179 kg cement
0.0005945 m3 or 0.952 kg sand

1 standard 'flat' brick requires:
0.0000595 m3 or 0.090 kg cement
0.0.00029725 m3 or 0.476 kg sand

1 standard 140 mm block requires:
0.0001862 m3 or 0.280 kg cement
0.0009310 m3 or 1.491 kg sand

 

[DAZB]

Not sure why you are calculating this but it would also be affected by the water content of the sand and the fact that the mortar per brick is obviously shared by each adjoining brick.

 

[^woody^]

LOL at the workings to seven decimal places Its not particle physics ... its bricklaying

What about the 0.0000003m3 that slips off the trowel onto the floor or gets flicked somewhere or other?

And not all joints are 10mm, and is it frog up or down? It all adds up

Try 1kg sand per brick, 2 kg per block and a straight volume (not weight) relationship for sand and cement - ie 1 bag cement per 4 bags sand or 8 cement per a bulk bag

 

[EViS]

LOL at the workings to seven decimal places Its not particle physics ... its bricklaying

What about the 0.0000003m3 that slips off the trowel onto the floor or gets flicked somewhere or other?

And not all joints are 10mm, and is it frog up or down? It all adds up

Try 1kg sand per brick, 2 kg per block and a straight volume (not weight) relationship for sand and cement - ie 1 bag cement per 4 bags sand or 8 cement per a bulk bag

You hit the nail on the head there woody . This is for an interactive database we're creating where mortar relates to the quantity of bricks, hence the ridiculous decimal places, but on a 10,000 brick build, it all adds up .

You say 2kg per block, doesn't that sound a tad high seeing as a frogless brick requires 0.5kg sand (based on those calculations)?

 

[^woody^]

You say 2kg per block, doesn't that sound a tad high seeing as a frogless brick requires 0.5kg sand (based on those calculations)?

Those were sand quantities not mortar, and are based on how much to order as a rule of thumb. Obviously there are margins which get greater the more bricks/blocks. But if say I want to lay 10 blocks, then I need a 20kg bag of sand, but for 100 I may need 9 bags not 10

Some sand is lost, some sticks in the mixer, and then as mortar there are further slight losses. So you always get less kg of mortar per kg of sand. Also the bond and wall thickness will affect sand/mortar quantities per brick

Your 1/2 kg sand per brick is not correct as that implies that a 25kg bag of sand will lay 50 bricks, when its more like 30

 

[EViS]

Is the rule of thumb 1kg sand per brick applicable to a 'flat' brick or one with a 'frog' when all the frogs are facing upwards?

ps. I appreciate the 'loss' of mortar, and this is accounted for separately.