around twenty kgs
18 pounds No one else agrees. 30 to 35 pounds for typical hollow block, and about 70 pounds for solid is the figure cited by most block manufacturers.
It weighs 59 lbs. There is a difference between a "real" cinder block and a concrete block. A cinder block uses cinders--ash from the burning of coal--as its aggregate. Concrete blocks are made from concrete. Concrete block is far stronger than is cinder block, and some jurisdictions prohibit the use of cinder block. The only justification for cinder block is that it weighs less than concrete block, which is important if the ground you're building on isn't strong enough to support a heavy structure. This justification has gone away, because now you can buy concrete block made from expanded-shale aggregate that's as light as cinder block and as strong as standard-weight concrete masonry.
The standard concrete building block for load-bearing walls is 8 x 8 x 16
37.8 LBS
A standard concrete block in the US is 16 inches long, 8 inches tall, and 4 inches wide.
Concrete weighs about 150#'s per cubic foot. Given that your measurements are 2'x2'x4', the block contains about 16 cubic feet. 16 cubic feet of concrete at 150#'s is about 2400#'s per block.
An M150 concrete block typically weighs around 35-40 pounds (16-18 kg). The weight can vary slightly depending on the specific mix design and dimensions of the block.
I was always tought "One pallet of block equals one yard". There are 90, 8•8•16 block on a pallet.
A 16 foot by 16 foot block has an area of 256 square feet. It would require 4.836 16 foot by 16 foot blocks to cover an area of 1238 square feet.
8 x 8 x 16 = 1,024 cubic inches.
Footing for chimneys should usually be double the width of the concrete block. For example, an 8-foot concrete block should have a 16-foot wide footing.