Are Block weights correct?

[IllSpentYouth]

I was trying to add a shield unit on a construction platform. I had some pylons underneath the platform to support the weight. I also wanted to enclose it, just to be safe. I tried using full blocks of armored concrete, but the weight proved too much for the structure and it collapsed. After looking at the weight of armored concrete blocks and seeing they were 4 T apiece, I decided to try Wall L-Shape with armored concrete blocks for the corners because they were thin and I thought they would be easier to handle. Now, anyone looking at Wall L-Shape can see that a large portion of the block is not there. However, the weight using armored concrete blocks is 2.88 T. I'm not a master builder or mathematician, but it sure *looks* like it should weight less. Can anyone with sufficient knowledge confirm my thoughts? Thank you in advance.