The below grade reinforced concrete sulfur pit at a major refining company in Texas began to experience degradation when water began to enter the pit through cracks in the concrete. Because water mixed with sulfur forms a destructive sulfurous acidic compound, the owner hired STRUCTURAL to perform a condition survey and evaluation (CS&E). The CS&E revealed severe deterioration affecting the structural integrity of the concrete walls. A comprehensive restoration would be needed or the sulfur pit could fail completely.
Work was scheduled for a planned outage with less than two weeks to complete the work. Extensive preplanning and logistical support was required. Ultimately, two STRUCTURAL crews worked around-the-clock on the repair.
For the repair, all loose concrete was removed from the existing pit walls – nearly 4 to 6 inches deep. Additionally, a layer of sulfur impurities had settled to the bottom of the pit and was excavated using pneumatic chipping hammers. All leaking cracks along wall surfaces were sawcut, packed with lead wool and covered with rapid setting hydraulic cement to prevent further water intrusion. To help prolong the life of the sulfur pit, STRUCTURAL recommended and installed high-performance concrete materials incorporating dense, shrinkage compensating, sulfate-resistant cements and non-reactive coarse aggregates. An engineered structural liner was designed and installed. The liner incorporated extremely durable materials and included reinforcing, anchorage and waterstops cast-in-place within the high-performance concrete matrix.
The roof panels of the sulfur pit also were deteriorated and needed to be replaced. STRUCTURAL designed, fabricated and installed the new components. The reinforced concrete modular roof panels were pre-cast off site using the same high-performance concrete used in the sulfur pit wall restoration. The panels were installed in a sequential manner to ensure a water-tight roof structure for the pit.
The Owner found the CS&E process to be a valuable tool and one of the main factors success of the project. By conducting the assessment at the onset of the project, STRUCTURAL was able to provide the Owner with an accurate cost for the repair and a realistic construction schedule.