It was Tuesday,16:53 local time in Haiti when the January day was rocked by a 7.0 magnitude quake. On that day, and in the days that followed, 52 aftershocks of 4.5 or more rattled down buildings and homes with crushing force.
The numbers continue to be unbelievable;
An estimated 230,000 people lost their lives, 300,000 were injured and 1,000,000 were made homeless.
If we are looking for a definition of sadness and despair, we can find it today in the images of tent cities that include 97,054 tents and 681,490 tarpaulins.
The shovel is a remarkably simple and useful tool, but in the hands of the poor it causes much of the crumbling devastation which we witness in every natural disaster. We say that earthquakes don’t kill people, but that the buildings do. Yet, we never blame the shovel, and we should. You see, shovels in cement are the overlooked enemy of safe structures in Haiti.
Cement is the most consumed product on earth, after water. In the right hands, and with the correct processes, it can build the strongest structures in the world. But when used incorrectly it offers a deadly false sense of security to those who trust it as shelter. To the poorest nations, cement is the most cost-effective material to produces concrete foundations, concrete blocks, masonry walls and roofing slabs. In many cases, concrete in one form or another is the only reasonable solution to lasting shelter.
Unfortunately in all too many cases the cement is mixed into concrete using a shovel.
Blaming the shovel alone is not completely fair, but the shovel represents a part of a chain of events which regularly ends in tragedy. The shovel partners with poverty to produce the problem.
Concrete is a mixture of Portland cement, water, sand and stone. It is not a complicated recipe to follow, yet when we add in poverty we begin to create some issues.
The first issue becomes the cost of Portland cement. The price of one bag of cement is equal to the daily wage of two Haitian workers, and a good concrete recipe will have six 94lb bags of cement for every cubic yard of concrete produced. In Haiti, a small house would use more that 3 cubic yards of concrete, for just the foundation and wall supports.
When poverty is a part of this mixture, there is extreme pressure to skimp on some of the expensive cement in the recipe, weakening the result. But the sad fact is that low cement volume is just the start of the problem.
The next issue involves the cheapest component used in the process; water. Water has an enormous effect on concrete quality. Water that is dirty or that might be salty weakens the mix and corrodes the steel reinforcements. But it is the amount of water in the mix that makes concrete the weakest. Good concrete uses a recipe of about 5-gallons of water per sack of Portland cement.
Much of the concrete produced for Haitian homes uses more water than is needed. They add water to make it easier to move the concrete from the mixing area to the building site using buckets. These “bucket-brigades” are used to scoop-up a couple of gallons of concrete mix in each pail for distribution down the line. The wetter the mix the easier it is to drag the bucket through the concrete for distribution. But, the wetter the mix, the weaker the resulting concrete
The next problem involves the sand and the stone. These two components are not as critical as too little cement or too much water. Still, taking steps to find good materials is important to concrete quality.
These components are not expensive, yet the quality can vary greatly. Sand from the beach has salts and corrodes steel. Sand with too much dirt is weak. Rock piles full of twigs or recycled rubble produces poor concrete. Because of the enormous volume of debris from the quake, there will be pressure to reuse the rubble to rebuild Haiti, but this will not be a good practice.
Now, let’s get back to the shovel, particularly when it is used as a concrete mixer…
Logic and evidence point to the folly of shovels in producing consistent batches of concrete. This is because consistent concrete requires two things to succeed:
1. Accurate measuring of all the components in the recipe.
2. Consistent and adequate blending of these mixtures.
Buckets and shovels mixing on the ground can get close to accomplishing these two objectives, but will never produce the type of concrete that can be trusted to withstand an earthquake. In the industrialized world we don’t use the shovel to produce concrete anymore, because it has been proven to fail, time and again.
If tomorrow we where to have an earthquake that devastated the poorest neighborhoods of LA, we wouldn’t pass out shovels as concrete mixers. Yet we still collect money from well-meaning donors to help people who continue to be killed from the action of their shovels. Why?
We can do better by teaching them how to make better concrete. When they can’t afford to purchase enough cement, we can make up the difference with our charity. When they don’t have access to a good concrete mixer, we can fund the purchase or provide the access. The technology is not hard to use, in fact if you can operate a shovel you can be trained to operate a mixer. Further, anyone who can learn a repetitive action, can follow a simple consistent recipe.
It is not that hard to raise the bar in concrete quality for places like Haiti. If we want to save them from a repeat story of earthquake destruction, it won’t take that much effort. The fact is that when they have better tools, they will gladly put down their shovels.