Tested blocks come in at a fifth of the minimum acceptable strength

An analysis published in 2011 tested samples taken from masonry blocks in Port-au-Prince buildings of various ages that had been damaged in the earthquake. The concrete measured between 545 and 1,135 pounds per square inch. The minimum acceptable standard set by the American Concrete Institute is 2,500 pounds per square inch, so the weakest samples came in at about a fifth of what the material was supposed to deliver and the strongest at under half. The assessment also worked out the remedy. Raising the proportion of cement in a block from one part in thirty to one part in six, and using better aggregate, doubled the compressive strength. The ratio was known and the ingredients existed. What was missing was money to buy cement at the price Haitians were charged for it, and any institution able to insist that they did.