How Much Weight is needed to break a concrete brick

[bandjoe]

We are doing the experiment where you mix different ratios of Portland cement, sand and water. I made a standard sized brick and we make a bracket to hang weights from the center of the brick to test how much weight is needed to break the brick. The one brick I got up to 225 lbs. hanging from it and it still did not break. I ran out of weights and a place to put the weights.

https://www.sciencebuddies.org/science- ... f-concrete

[Snehaarun]

Hi!

This is a very interesting project! Were you able to make several different bricks with different ratios of sand to cement? They are all listed in the Experimental Procedure section of the project instructions. What is the ratio you have right now?

(20% sand, 80% cement,
30% sand, 70% cement,
40% sand, 60% cement,
50% sand, 50% cement,
60% sand, 40% cement,
70% sand, 30% cement,
80% sand, 20% cement.)

Also, here's something you can try to make the brick break: try moving the tables further apart and then redo the experiment. If your tables are too close, it will be able to hold more weight than a brick placed on two tables that are spaced further. How close are your tables right now? And as you test each brick, is the distance between the two tables the same? (It's important to keep that distance a constant).

Let me know whether you have tried testing with different ratios of sand to cement and if you have tried moving the tables further apart.

[bandjoe]

I was more hoping for an answer.
We already have the tables as far apart as they’ll go.
We tried 100% Portland cement, 50/50 sand cement and 50/50 crushed gravel and cement so far. Also 50/50 Portland cement and dirt

[bandjoe]

Ok unfortunately I found out my answer for 50/50 it was 325 lbs. I think this is bordering if not outright too dangerous for a 12 yo. I have two more bricks to test although I believe they will break with much less weight. I'm at least hopeful...