Masonry block construction in Haiti

Abstract

Most of the building failures in Haiti during the January 12th, 2010 earthquake were CMU block buildings. It is the locally preferred building material. Since it is difficult to import materials into Haiti, CMU block is made with local sand (sometimes beach sand which includes a significant amount of salt) and aggregate and only requires Portland cement to be imported. The blocks are made in a press-type machine without steam and at comparatively little pressure. The blocks contain as little as 1/30th Portland cement by volume and are left in a yard to dry cure, rather than moist curing. The blocks are sometimes so weak that they must be handled by workers with two hands or they break under their own weight. Tests at the University of Oklahoma reveal the blocks have an extremely low compressive strength (as low as 300 psi). Given the typical construction techniques used in Haiti, which include heavy concrete slab roof, focusing on hurricane resistance rather than earthquakes, the current CMU block fabrication method was a recipe for disaster that was realized.OU researchers worked with local Haitian organizations, primarily at Christianville Mission, to improve the quality of CMU blocks in Haiti. They provided guidelines for the CMU block mix, and curing instructions. Tests show the compressive strength of the CMU block has increased by more than three times with relatively little additional cost. This paper discusses the problems with current fabrication techniques for CMU block in Haiti, changes which can be made with relatively little cost or effort, and the resulting improvements in block strength realized.

Performance Evaluation of the Quality of Cina Cement and Basf Admixture Commonly Used in Concrete Production in the Republic of Haiti

“…Previous in-situ compression tests conducted on Haitian cement samples have showed average maximum compressive strengths of approximately 11.0 MPa (1,600 psi) with a standard deviation of 2.5 MPa (360 psi) (Lang and Marshall, 2011). For the 28-day compressive strength tests of fresh mix with proper curing, Haitian concrete samples ranged from peaks of 8.7 MPa (1,260 psi) to lows of just 2.8 MPa (410 psi) (Gordon, et al, 2016;Holliday et. al., 2011).…”

Haiti Building Failures and a Replicable Building Design for Improved Earthquake Safety

“…The CMU block samples were chalky to the touch and fell apart easily. Test results showed a compressive strength of about 500 psi (Holliday 2011). Workers interviewed said the concrete mix used to make the blocks used one thirtieth portland cement by volume compared to sand and aggregate.…”

“…This option was chosen, but the quality of the block would have to be improved to ensure this construction method is structurally sound. The block from previous construction projects on the campus was tested (Holliday 2011) and had compressive strengths of 545 psi to 1,135 psi (Table 2) as compared to typical U.S. CMU block with a tested ultimate compressive strength of about 2,500 psi. CMU blocks from various vendors in Haiti were purchased and sent to OU for testing and had similarly poor ultimate compressive strengths (Table 2).…”