The application of reinforced concrete for permanent and temporary deep ocean structures has recently become more prevalent; however, the static and dynamic effects of high water pressure on concrete remain unexplored. This paper investigates the influence of high water pressure (60 MPa) on four series of concrete cylinders with and without an embedded steel bar under sustained and cyclic loading conditions. The residual compressive strength, bond strength, and associated evolution of surface and internal damage are evaluated after exposing concrete cylinders to a water pressure of 60 MPa. The first series is exposed to sustained water pressure for 7 and 60 days, while the other series is tested under repeated water pressure for 10, 20, 30, 60, and 150 cycles. The results reveal that residual compressive strength falls immediately by 16% within 7 days of sustained high water pressure, but the strength then remains stable up to 60 days. Under repeated high water pressure, residual compressive strength gradually reduces by up to 40% until 60 cycles, after which it remains reasonably stable until 150 cycles as crack propagation is arrested at a certain depth within the concrete cylinders. The bond strength between the steel bar and matrix is observed to decrease considerably under repeated cycles of 60 MPa water pressure up to 26%. The damage gradually propagates at the matrix/steel bar interface under the repeated water pressure, resulting in a reduction in residual pullout capacity.

Background: There is a concern to compare On- and Off-Pump coronary artery bypass grafting (CABG) regarding the benefits to the patient. The cardiopulmonary bypass (CPB) affects the left and the right ventricular functions. Is this the same with Off-Pump coronary artery bypass (OPCAB)? Methods: Between January 2012 and December 2014, we revised 400 patients; 200 received on-pump CABG and 200 off-pump CABG (OPCAB). We included patients with ejection fraction (EF) of 35% or lower. The patients were followed up by preoperative echocardiography, intra-operative trans-esophageal echocardiography (TEE) and post-operative echocardiography: one week, 1 month, 3 months, 6 months, 1 year and 2 years after the CABG. The obtained results were compared statistically. We referred to the on-pump as group A and the off-pump as group B. Results: The operative and postoperative data showed significant statistical differences between both groups; better in group B regarding the length of the operation, the intra-operative use of inotropic support, the use of intra-aortic balloon pump (IABP) intra- and post-operatively, the peri-operative myocardial infarction (MI), the post operative atrial fibrillation (AF), wound dehiscence, sternal wound infection, the incidence of strokes, renal impairment, chest infection and peripheral ischemia. The ICU stay and total hospital stay were longer in group A. The in-hospital mortality was more in group A. The LV function was more impaired in group A only in the first 3 months. Conclusions: The complications of the on-pump CABG were more than the OPCAB. Accordingly, we recommend the OPCAB technique especially in patients with ischemic cardiomyopathy (ICM)