20 lbs.
In America: 8x8x16 inches, This is the standard CMU: Concrete Masonry Unit There also the half blocks 8x8x8. Source: http://concreteblocksizes.blogspot.com/
A standard 8x8x16 2 core block contains about .25cf of open space
An 8x8x16 solid concrete block typically weighs around 135-150 pounds.
Strecher is the term for the common "field" block in a cmu wall.
The weight of an 8x8x16 masonry block typically ranges from 28 to 35 pounds (about 12.7 to 15.9 kg), depending on the density of the concrete mix used. Standard concrete blocks are often around 32 pounds (14.5 kg). It's important to note that variations in moisture content and manufacturing processes can slightly affect the weight.
Basic concrete block it 8x8x16 inches.
2700 8x8x16 block
1.125 sq ft in 1 block
The dry weight of a medium density concrete block (215 x 450 x 100mm thick) is approximately 7.5Kg --- There are many different sizes, shapes and mixes used to make concrete block. Additionally the weight varies if the unit is wet or not since they absorb water. I see varying weights of 35 to 55 pounds for 8x8x16 block.
2600 lbs
Light. Sorry, I don't mean to be flippant, but "lightweight" just isn't enough to answer this question. You're going to have to be more specific than "lightweight".