Bad Concrete Blocks Crumble and Crush in Earthquakes – See why!

Block making requires 3 steps for success

Concrete block is a popular component in construction for developing countries. Cement-based products are relatively inexpensive, they are created from local materials and they are easy to build with.

In Haiti we learned how deadly concrete blocks can be when not produced correctly. Like the story of Noe (pronounced NO-wee) and the earthquake of 2010. Noe was at the university when the earthquake occurred. He managed to escape, but a concrete block fell on his best friend who was running next to him, killing the friend. Noe escaped with just a serious gash on his arm from the concrete. This story is very common and thousands died from the same problem; bad concrete blocks.

Bad concrete block becomes rubbleThe problem with block making in these countries rests with a broken concrete supply chain. These bad blocks become a crushing instrument of destruction and death. The evidence of this fact can be found in the rubble piles following any natural disaster in a poor country. To make a good block requires a good recipe, a consistent compaction and proper curing.

Now observe the next 3 images…

Crumbling concrete block in Haiti

Look at the poor compaction and the crumbling corners

Mixing block recipe on the ground

No recipe measuring and no consistency in the mixing

Concrete block cured in the sun in Haiti

Sun cured without cover or moisture

These three images are from the video that you can view at the end of this posting. In the video you will witness one portion of the concrete supply chain that is working and three parts that are not.

The Haitian crew has the use of a mechanized block forming machine that can produce good block. Unfortunately the broken supply chain in Haiti is delivering bad sand to the site. Then the workers are using this bad sand in a ground-mixing process that fails to use a consistent recipe, and finally the inconsistent blocks are placed out in the direct sun to cure.

Good blocks use well graded sand, a correct proportion of cement, consistent mixing practices and then curing in a high moisture environment to avoid cracking. The chemistry of cement requires these things to be a part of the process in order to create a product that will not fail.

These are the missing links that you will see in this video. Until we begin improving every link in the supply chain, we will continue to hear the stories of Noe from every developing country.

Watch in Memory of Noe’s Friends in Haiti

Thanks to HalfanIsland for the video

Bruce Christensen is the author at CementTrust

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About cementtrust

I am a director with Cement Trust and passionate about improving cement-based production in the poorest nations of the world.
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