A cement-based decoration attached to the water slide of the Atlantis Water Adventure collapsed on Sunday, injuring four people, including a child at the Ancol Dreamland in North Jakarta.
Police said that the accident occurred at 1.30 p.m. when a cement-based decoration collapsed and fell onto the spiral slide below.
The victims sustained cuts and bruises and were taken to Satya Negara Hospital in Sunter, North Jakarta.
The injured were identified as Anggiat Silitonga, 31, Sulastri, 31, Rianto, 31, and Riki Alvian, 11.
“The decorative structure made of ferrocement collapsed due to corrosion,” said Pademangan Police chief Comr. Ahmad David.
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Steel bars inside a Quebec highway overpass that collapsed over the weekend were likely at the heart of the bridge’s failure, according to a structural engineer with expertise in bridges.
University of Toronto civil engineering professor Shamim Sheikh told The Canadian Press the bars probably lost their bond with the surrounding concrete.
As a result, the section of the roadway was unable to bear its own weight, said Sheikh, who watched the Laval drama unfold on television.
Sheikh noted that steel bars could be seen sticking out of the overpass, suggesting they were separated from the concrete.
“In a bridge like this, which is made of reinforced concrete, the corrosion of steel played a large part in some of these problems,” Sheikh told CTV’s Canada AM. Read more…
Corrosion monitoring in concrete has become increasingly important especially in reinforced concrete infrastructure. The steel reinforcement in concrete structures is susceptible to corrosion when chloride ions enter into the concrete from de-icing salts applied to the concrete surface, or from seawater in marine environments. If chlorides are present in sufficient quantity, they disrupt the passive film on the reinforcing steel, resulting in corrosion. Oxygen content, moisture availability and temperature also affect this corrosion rate. Read more…
Electrochemical corrosion may also occur as a consequence of concentration differences of ions or dissolved gases in the electrolyte solution, and between two regions of the same metal piece. For such a concentration cell, corrosion occurs in the locale that has the lower concentration. A good example of this type of corrosion occurs in crevices and recesses or under deposits of dirt or corrosion products where the solution becomes stagnant and there is localized depletion of dissolved oxygen. Read more…
Corrosion testing with polarization methods basically consists in forcing potential or current changes on a sample under study while monitoring the resulting response in current or potential. This may be achieved by using either a direct current (DC) or an alternating current (AC) source. The instrumentation for carrying polarization testing as illustrated in Figure below consists of: Read more…
The potential of a corroding metal, often termed Ecorr, is probably the single most useful variable measured in corrosion studies or for corrosion monitoring. It is readily measured by determining the voltage difference between a metal in its environment and an appropriate reference electrode.
Figure below illustrates an experimental technique for measuring the corrosion potential of a metal M using a laboratory Read more…
The displacement of each electrode potential from its equilibrium value is termed polarization, and the magnitude of this displacement is the overvoltage, normally represented by the symbol η. Overvoltage is expressed in terms of plus or minus volts (or millivolts) relative to the equilibrium potential. For example, suppose that the zinc electrode in Figure Read more…
One of the primary methods of corrosion control for buried or submerged metal structures is the application of cathodic protection. A direct current is applied through the soil or water from a source outside of the structure to the structure. One fundamental question arises as to how much direct current is required to control corrosion. Another related question involves measuring the effectiveness of a cathodic protection installation. The National Association of Corrosion Engineers (NACE) recognized the need to answer these questions and incorporated various criteria to evaluate cathodic protection installations in their Recommended Practice RP-01-69, “Control of External Corrosion on Underground or Submerged Metallic Piping Systems.” Read more…
The relatively high pH of concrete pore water (pH ≈ 13.0–13.8) helps form a protective oxide (passive) film about 10 nanometers thick. This film effectively insulates the metal and electrolytes so that the corrosion rate is negligible, allowing decades of relatively low maintenance.
Disrupting the passive film upon embedded reinforcement and onset of active corrosion can arise in conjunction with either of two causes: carbonation or chloride intrusion (or a combination of the two). In the case of carbonation, atmospheric carbon dioxide (CO2) reacts with pore water alkali according to the generalized reaction,
Ca(OH)2 + CO2 → CaCO3 + H2O …………………………………(1) Read more…
The first reported practical use of cathodic protection is generally credited to Sir Humphrey Davy in the 1820′s. Davy’s advice was sought by the Royal Navy in investigating the corrosion of copper sheeting used for cladding the hulls of naval vessels. Davy found that he could preserve copper in seawater by the attachment of small quantities of iron, zinc or tin. The copper became, as Davy put it, “cathodically protected”. Read more…
