By: Greg Higgins, Architect and Managing Director, HabiTek, LLC
One of my goals in visiting Haiti in September, a trip hosted by HRDF, was to get a general idea about whether building back better was in fact happening. Of course, six days in Haiti was hardly enough to make anything but cursory observations, so I limited much of my time to looking for evidence of whether weak quarry sand and aggregate was still being used.
Back in February, 2010, a news article caught my eye that offered a ray of hope. A month after the earthquake the Government of Haiti banned the use of white quarry sand for structural purposes. Since weak concrete, and associated poor construction techniques, arguably led to a majority of the deaths in the quake, the Government’s action certainly made sense. But white quarry sand, called La Boule sand, was everywhere. The Government’s action was ignored, to say the least.
If the Government had been effective, the issue of where to source higher quality sand would raise an important issue: what would the vast quantities of the sand and aggregate required to rebuild do to Haiti’s rivers? Sand and aggregate from river beds is likely the only alternative. The issue of how to make stronger concrete and concrete blocks remains a huge conundrum – and a problem HRDF will be researching further, and report in future “Dispatches”.
Here is an excerpt from an engineering master’s thesis written by Havanna Radford that gets right to the point (thesis is no longer online):
When asked how the concrete quality is assured, the Construction Sector Advisor for Tearfund replied: ‘There is no quality assurance. The majority of the concrete I’ve seen uses pulverized chalk with sand as aggregate, without any gravel involved. The standard way of mixing concrete seems to be by weight of cement per cubic metre, typically 250kg/m3, and they don’t specify how much aggregate or sand should be in it. Even the qualified engineers do that, and it’s not good enough.
The EERI [Earthquake Engineering Research Institute] reported that fine aggregate is sourced from nearby limestone quarry sites. Use of light coloured, weak limestone from the largest quarry, La Boule, was banned for aggregate use due to its weakness, however its use persists (EERI, May, 2010). Local people are often seen manually screening the aggregates into piles ready for a concrete mix.
And does it persist! Piles of the white limestone were everywhere along the road from Port-au-Prince to Aquin, a small town I visited on the south coast, approximately 90 miles (145km) from Port-au-Prince. Here are just a few examples:
The challenges evidenced in these photos are extreme, both in terms of the materials involved and the techniques used in construction. There are some serious efforts underway in Haiti to address the quality control issues regarding confined masonry construction, and concrete in general. However important this work is, it may be a drop in the bucket, as what I witnessed suggests. There appears to be two rebuilding paths in Haiti: the efforts by various NGOs and faith-based organizations to build back better (but not in every case), and those not seemingly touched by these organizations; regular folks who have been building the same way for decades, and are continuing as if the earthquake never happened.
My observations also confirmed one of the key findings listed in that US State Department’s Workshop on “Rebuilding for Resilience” issued in March, 2010:
Owner-built construction represents 80-90% of the construction within Haiti, and thus building back better requires improvements to the owner-built construction process
The owner-builder is a key component of the Haitian culture, and they build with blocks and concrete. Do-it-yourself is how it’s done in Haiti. Until solutions are identified that intervene to substitute high quality sand and aggregate for quarry sourced materials, and building techniques are improved, building back better will ring hollow for the majority of Haitians.