We need to accept Physics…. Wise people do

There are many unique solutions floating around for rebuilding safe homes in Haiti. These ideas range from cutting edge to very ancient practices. None of these designs can escape the foundational laws of Physics: Mass and Weight

Mass and Weight are required to tie a building to the earth. Outside forces like wind and earthquakes require a certain level of mass and weight in order to avoid structural failure. This may be why the old parable about wise people building upon a rock is so accurate.

A unified mass like a big rock is a great foundation for a home as long as the rock holds together, is heavy enough and the house is securely anchored to boulder. It would be foolish to attempt to tie a structure to a sandy rock that may crumble at the first strong pull from the wind.

Because it is not always possible to find a big flat rock for a foundation, we use concrete to replace the mass and the weight of a rock. Concrete is the most cost-effective and practical solution to satisfy the physics of mass and weight.

In Haiti there is over 20 million cubic feet of rubble on the ground. These piles represent the failure of a poorly unified concrete to withstand movement. When the earth began shaking the bad concrete changed from a single mass and came crumbling down with deadly force.

Some may want to place the blame on the concrete, but the real villain is the poor use of concrete chemistry; a brew that requires just three items to create a strong unified mass:

1. Aggregates (sand and stone) to provide the weight and to create a mass.

2. Portland cement to provide the glue that binds the sand and the stone in unity.

3. Water that chemically reacts with the cement to coat the aggregates so that they harden into a single mass.

This mixture must use proper proportions in order to become hard like a rock and to provide enough mass and weight to resist the quake. If there is too much sand in the mix, you get a sandy mass. Too much water or too little cement powder dilutes the glue, and results in a mass that doesn’t hold together. It was the low cement volume and high water content that caused the bad chemistry found in the concrete of Haiti.

In Haiti the foundations, walls and columns produced from poorly prepared concrete cracked and buckled like a sandcastle. Physics applied more force than the poor quality mass could tolerate.

To rebuild a better Haiti it will require foundations on the right side of Physics and Chemistry. It will take millions of cubic feet of concrete to anchor the Haitian homes.

It seems foolish to spend money on any cutting edge or old-school designs without good concrete foundations. Wisdom suggests producing concrete in a strong unified mass.


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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